[bugfix/chore] Refactor timeline code (#1656)

* start poking timelines

* OK yes we're refactoring, but it's nothing like the last time so don't worry

* more fiddling

* update tests, simplify Get

* thanks linter, you're the best, mwah mwah kisses

* do a bit more tidying up

* start buggering about with the prepare function

* fix little oopsie

* start merging lists into 1

* ik heb een heel zwaar leven
nee nee echt waar

* hey it works we did it reddit

* regenerate swagger docs

* tidy up a wee bit

* adjust paging

* fix little error, remove unused functions

docs/api/swagger.yaml

@@ -5582,11 +5582,11 @@ paths:
                   in: query
                   name: max_id
                   type: string
-                - description: Return only statuses *NEWER* than the given since status ID. The status with the specified ID will not be included in the response.
+                - description: Return only statuses *newer* than the given since status ID. The status with the specified ID will not be included in the response.
                   in: query
                   name: since_id
                   type: string
-                - description: Return only statuses *NEWER* than the given since status ID. The status with the specified ID will not be included in the response.
+                - description: Return only statuses *immediately newer* than the given since status ID. The status with the specified ID will not be included in the response.
                   in: query
                   name: min_id
                   type: string

internal/api/client/timelines/home.go

@@ -62,14 +62,14 @@ import (
 //		name: since_id
 //		type: string
 //		description: >-
-//			Return only statuses *NEWER* than the given since status ID.
+//			Return only statuses *newer* than the given since status ID.
 //			The status with the specified ID will not be included in the response.
 //		in: query
 //	-
 //		name: min_id
 //		type: string
 //		description: >-
-//			Return only statuses *NEWER* than the given since status ID.
+//			Return only statuses *immediately newer* than the given since status ID.
 //			The status with the specified ID will not be included in the response.
 //		in: query
 //		required: false

internal/db/bundb/timeline.go

@@ -42,7 +42,10 @@ func (t *timelineDB) GetHomeTimeline(ctx context.Context, accountID string, maxI
 	}
 
 	// Make educated guess for slice size
-	statusIDs := make([]string, 0, limit)
+	var (
+		statusIDs   = make([]string, 0, limit)
+		frontToBack = true
+	)
 
 	q := t.conn.
 		NewSelect().
@@ -56,11 +59,9 @@ func (t *timelineDB) GetHomeTimeline(ctx context.Context, accountID string, maxI
 			bun.Ident("follow.target_account_id"),
 			bun.Ident("status.account_id"),
 			bun.Ident("follow.account_id"),
-			accountID).
+			accountID)
-		// Sort by highest ID (newest) to lowest ID (oldest)
-		Order("status.id DESC")
 
-	if maxID == "" {
+	if maxID == "" || maxID == id.Highest {
 		const future = 24 * time.Hour
 
 		var err error
@@ -83,6 +84,9 @@ func (t *timelineDB) GetHomeTimeline(ctx context.Context, accountID string, maxI
 	if minID != "" {
 		// return only statuses HIGHER (ie., newer) than minID
 		q = q.Where("? > ?", bun.Ident("status.id"), minID)
+
+		// page up
+		frontToBack = false
 	}
 
 	if local {
@@ -95,6 +99,14 @@ func (t *timelineDB) GetHomeTimeline(ctx context.Context, accountID string, maxI
 		q = q.Limit(limit)
 	}
 
+	if frontToBack {
+		// Page down.
+		q = q.Order("status.id DESC")
+	} else {
+		// Page up.
+		q = q.Order("status.id ASC")
+	}
+
 	// Use a WhereGroup here to specify that we want EITHER statuses posted by accounts that accountID follows,
 	// OR statuses posted by accountID itself (since a user should be able to see their own statuses).
 	//
@@ -110,8 +122,20 @@ func (t *timelineDB) GetHomeTimeline(ctx context.Context, accountID string, maxI
 		return nil, t.conn.ProcessError(err)
 	}
 
-	statuses := make([]*gtsmodel.Status, 0, len(statusIDs))
+	if len(statusIDs) == 0 {
+		return nil, nil
+	}
 
+	// If we're paging up, we still want statuses
+	// to be sorted by ID desc, so reverse ids slice.
+	// https://zchee.github.io/golang-wiki/SliceTricks/#reversing
+	if !frontToBack {
+		for l, r := 0, len(statusIDs)-1; l < r; l, r = l+1, r-1 {
+			statusIDs[l], statusIDs[r] = statusIDs[r], statusIDs[l]
+		}
+	}
+
+	statuses := make([]*gtsmodel.Status, 0, len(statusIDs))
 	for _, id := range statusIDs {
 		// Fetch status from db for ID
 		status, err := t.state.DB.GetStatusByID(ctx, id)

internal/db/bundb/timeline_test.go

@@ -100,6 +100,32 @@ func (suite *TimelineTestSuite) TestGetHomeTimelineWithFutureStatus() {
 	suite.Len(s, 16)
 }
 
+func (suite *TimelineTestSuite) TestGetHomeTimelineBackToFront() {
+	ctx := context.Background()
+
+	viewingAccount := suite.testAccounts["local_account_1"]
+
+	s, err := suite.db.GetHomeTimeline(ctx, viewingAccount.ID, "", "", id.Lowest, 5, false)
+	suite.NoError(err)
+
+	suite.Len(s, 5)
+	suite.Equal("01F8MHAYFKS4KMXF8K5Y1C0KRN", s[0].ID)
+	suite.Equal("01F8MH75CBF9JFX4ZAD54N0W0R", s[len(s)-1].ID)
+}
+
+func (suite *TimelineTestSuite) TestGetHomeTimelineFromHighest() {
+	ctx := context.Background()
+
+	viewingAccount := suite.testAccounts["local_account_1"]
+
+	s, err := suite.db.GetHomeTimeline(ctx, viewingAccount.ID, id.Highest, "", "", 5, false)
+	suite.NoError(err)
+
+	suite.Len(s, 5)
+	suite.Equal("01G36SF3V6Y6V5BF9P4R7PQG7G", s[0].ID)
+	suite.Equal("01FCTA44PW9H1TB328S9AQXKDS", s[len(s)-1].ID)
+}
+
 func getFutureStatus() *gtsmodel.Status {
 	theDistantFuture := time.Now().Add(876600 * time.Hour)
 	id, err := id.NewULIDFromTime(theDistantFuture)

internal/processing/fromcommon.go

@@ -455,8 +455,8 @@ func (p *Processor) timelineStatusForAccount(ctx context.Context, account *gtsmo
 		return nil
 	}
 
-	// stick the status in the timeline for the account and then immediately prepare it so they can see it right away
+	// stick the status in the timeline for the account
-	if inserted, err := p.statusTimelines.IngestAndPrepare(ctx, status, account.ID); err != nil {
+	if inserted, err := p.statusTimelines.IngestOne(ctx, account.ID, status); err != nil {
 		return fmt.Errorf("timelineStatusForAccount: error ingesting status %s: %w", status.ID, err)
 	} else if !inserted {
 		return nil

internal/processing/statustimeline.go

@@ -41,10 +41,10 @@ func StatusGrabFunction(database db.DB) timeline.GrabFunction {
 	return func(ctx context.Context, timelineAccountID string, maxID string, sinceID string, minID string, limit int) ([]timeline.Timelineable, bool, error) {
 		statuses, err := database.GetHomeTimeline(ctx, timelineAccountID, maxID, sinceID, minID, limit, false)
 		if err != nil {
-			if err == db.ErrNoEntries {
+			if errors.Is(err, db.ErrNoEntries) {
 				return nil, true, nil // we just don't have enough statuses left in the db so return stop = true
 			}
-			return nil, false, fmt.Errorf("statusGrabFunction: error getting statuses from db: %s", err)
+			return nil, false, fmt.Errorf("statusGrabFunction: error getting statuses from db: %w", err)
 		}
 
 		items := make([]timeline.Timelineable, len(statuses))
@@ -61,20 +61,20 @@ func StatusFilterFunction(database db.DB, filter *visibility.Filter) timeline.Fi
 	return func(ctx context.Context, timelineAccountID string, item timeline.Timelineable) (shouldIndex bool, err error) {
 		status, ok := item.(*gtsmodel.Status)
 		if !ok {
-			return false, errors.New("statusFilterFunction: could not convert item to *gtsmodel.Status")
+			return false, errors.New("StatusFilterFunction: could not convert item to *gtsmodel.Status")
 		}
 
 		requestingAccount, err := database.GetAccountByID(ctx, timelineAccountID)
 		if err != nil {
-			return false, fmt.Errorf("statusFilterFunction: error getting account with id %s", timelineAccountID)
+			return false, fmt.Errorf("StatusFilterFunction: error getting account with id %s: %w", timelineAccountID, err)
 		}
 
 		timelineable, err := filter.StatusHomeTimelineable(ctx, requestingAccount, status)
 		if err != nil {
-			log.Warnf(ctx, "error checking hometimelineability of status %s for account %s: %s", status.ID, timelineAccountID, err)
+			return false, fmt.Errorf("StatusFilterFunction: error checking hometimelineability of status %s for account %s: %w", status.ID, timelineAccountID, err)
 		}
 
-		return timelineable, nil // we don't return the error here because we want to just skip this item if something goes wrong
+		return timelineable, nil
 	}
 }
 
@@ -83,12 +83,12 @@ func StatusPrepareFunction(database db.DB, tc typeutils.TypeConverter) timeline.
 	return func(ctx context.Context, timelineAccountID string, itemID string) (timeline.Preparable, error) {
 		status, err := database.GetStatusByID(ctx, itemID)
 		if err != nil {
-			return nil, fmt.Errorf("statusPrepareFunction: error getting status with id %s", itemID)
+			return nil, fmt.Errorf("StatusPrepareFunction: error getting status with id %s: %w", itemID, err)
 		}
 
 		requestingAccount, err := database.GetAccountByID(ctx, timelineAccountID)
 		if err != nil {
-			return nil, fmt.Errorf("statusPrepareFunction: error getting account with id %s", timelineAccountID)
+			return nil, fmt.Errorf("StatusPrepareFunction: error getting account with id %s: %w", timelineAccountID, err)
 		}
 
 		return tc.StatusToAPIStatus(ctx, status, requestingAccount)
@@ -137,21 +137,24 @@ func StatusSkipInsertFunction() timeline.SkipInsertFunction {
 }
 
 func (p *Processor) HomeTimelineGet(ctx context.Context, authed *oauth.Auth, maxID string, sinceID string, minID string, limit int, local bool) (*apimodel.PageableResponse, gtserror.WithCode) {
-	preparedItems, err := p.statusTimelines.GetTimeline(ctx, authed.Account.ID, maxID, sinceID, minID, limit, local)
+	statuses, err := p.statusTimelines.GetTimeline(ctx, authed.Account.ID, maxID, sinceID, minID, limit, local)
 	if err != nil {
+		err = fmt.Errorf("HomeTimelineGet: error getting statuses: %w", err)
 		return nil, gtserror.NewErrorInternalError(err)
 	}
 
-	count := len(preparedItems)
+	count := len(statuses)
-
 	if count == 0 {
 		return util.EmptyPageableResponse(), nil
 	}
 
-	items := []interface{}{}
+	var (
-	nextMaxIDValue := ""
+		items          = make([]interface{}, count)
-	prevMinIDValue := ""
+		nextMaxIDValue string
-	for i, item := range preparedItems {
+		prevMinIDValue string
+	)
+
+	for i, item := range statuses {
 		if i == count-1 {
 			nextMaxIDValue = item.GetID()
 		}
@@ -159,7 +162,8 @@ func (p *Processor) HomeTimelineGet(ctx context.Context, authed *oauth.Auth, max
 		if i == 0 {
 			prevMinIDValue = item.GetID()
 		}
-		items = append(items, item)
+
+		items[i] = item
 	}
 
 	return util.PackagePageableResponse(util.PageableResponseParams{
@@ -174,37 +178,54 @@ func (p *Processor) HomeTimelineGet(ctx context.Context, authed *oauth.Auth, max
 func (p *Processor) PublicTimelineGet(ctx context.Context, authed *oauth.Auth, maxID string, sinceID string, minID string, limit int, local bool) (*apimodel.PageableResponse, gtserror.WithCode) {
 	statuses, err := p.state.DB.GetPublicTimeline(ctx, maxID, sinceID, minID, limit, local)
 	if err != nil {
-		if err == db.ErrNoEntries {
+		if errors.Is(err, db.ErrNoEntries) {
-			// there are just no entries left
+			// No statuses (left) in public timeline.
 			return util.EmptyPageableResponse(), nil
 		}
-		// there's an actual error
+		// An actual error has occurred.
+		err = fmt.Errorf("PublicTimelineGet: db error getting statuses: %w", err)
 		return nil, gtserror.NewErrorInternalError(err)
 	}
 
-	filtered, err := p.filterPublicStatuses(ctx, authed, statuses)
+	count := len(statuses)
-	if err != nil {
-		return nil, gtserror.NewErrorInternalError(err)
-	}
-
-	count := len(filtered)
-
 	if count == 0 {
 		return util.EmptyPageableResponse(), nil
 	}
 
-	items := []interface{}{}
+	var (
-	nextMaxIDValue := ""
+		items          = make([]interface{}, 0, count)
-	prevMinIDValue := ""
+		nextMaxIDValue string
-	for i, item := range filtered {
+		prevMinIDValue string
+	)
+
+	for i, s := range statuses {
+		// Set next + prev values before filtering and API
+		// converting, so caller can still page properly.
 		if i == count-1 {
-			nextMaxIDValue = item.GetID()
+			nextMaxIDValue = s.ID
 		}
 
 		if i == 0 {
-			prevMinIDValue = item.GetID()
+			prevMinIDValue = s.ID
 		}
-		items = append(items, item)
+
+		timelineable, err := p.filter.StatusPublicTimelineable(ctx, authed.Account, s)
+		if err != nil {
+			log.Debugf(ctx, "skipping status %s because of an error checking StatusPublicTimelineable: %s", s.ID, err)
+			continue
+		}
+
+		if !timelineable {
+			continue
+		}
+
+		apiStatus, err := p.tc.StatusToAPIStatus(ctx, s, authed.Account)
+		if err != nil {
+			log.Debugf(ctx, "skipping status %s because it couldn't be converted to its api representation: %s", s.ID, err)
+			continue
+		}
+
+		items = append(items, apiStatus)
 	}
 
 	return util.PackagePageableResponse(util.PageableResponseParams{
@@ -219,26 +240,29 @@ func (p *Processor) PublicTimelineGet(ctx context.Context, authed *oauth.Auth, m
 func (p *Processor) FavedTimelineGet(ctx context.Context, authed *oauth.Auth, maxID string, minID string, limit int) (*apimodel.PageableResponse, gtserror.WithCode) {
 	statuses, nextMaxID, prevMinID, err := p.state.DB.GetFavedTimeline(ctx, authed.Account.ID, maxID, minID, limit)
 	if err != nil {
-		if err == db.ErrNoEntries {
+		if errors.Is(err, db.ErrNoEntries) {
-			// there are just no entries left
+			// There are just no entries (left).
 			return util.EmptyPageableResponse(), nil
 		}
-		// there's an actual error
+		// An actual error has occurred.
+		err = fmt.Errorf("FavedTimelineGet: db error getting statuses: %w", err)
 		return nil, gtserror.NewErrorInternalError(err)
 	}
 
+	count := len(statuses)
+	if count == 0 {
+		return util.EmptyPageableResponse(), nil
+	}
+
 	filtered, err := p.filterFavedStatuses(ctx, authed, statuses)
 	if err != nil {
+		err = fmt.Errorf("FavedTimelineGet: error filtering statuses: %w", err)
 		return nil, gtserror.NewErrorInternalError(err)
 	}
 
-	if len(filtered) == 0 {
+	items := make([]interface{}, len(filtered))
-		return util.EmptyPageableResponse(), nil
+	for i, item := range filtered {
-	}
+		items[i] = item
-
-	items := []interface{}{}
-	for _, item := range filtered {
-		items = append(items, item)
 	}
 
 	return util.PackagePageableResponse(util.PageableResponseParams{
@@ -250,47 +274,17 @@ func (p *Processor) FavedTimelineGet(ctx context.Context, authed *oauth.Auth, ma
 	})
 }
 
-func (p *Processor) filterPublicStatuses(ctx context.Context, authed *oauth.Auth, statuses []*gtsmodel.Status) ([]*apimodel.Status, error) {
-	apiStatuses := []*apimodel.Status{}
-	for _, s := range statuses {
-		if _, err := p.state.DB.GetAccountByID(ctx, s.AccountID); err != nil {
-			if err == db.ErrNoEntries {
-				log.Debugf(ctx, "skipping status %s because account %s can't be found in the db", s.ID, s.AccountID)
-				continue
-			}
-			return nil, gtserror.NewErrorInternalError(fmt.Errorf("filterPublicStatuses: error getting status author: %s", err))
-		}
-
-		timelineable, err := p.filter.StatusPublicTimelineable(ctx, authed.Account, s)
-		if err != nil {
-			log.Debugf(ctx, "skipping status %s because of an error checking status visibility: %s", s.ID, err)
-			continue
-		}
-		if !timelineable {
-			continue
-		}
-
-		apiStatus, err := p.tc.StatusToAPIStatus(ctx, s, authed.Account)
-		if err != nil {
-			log.Debugf(ctx, "skipping status %s because it couldn't be converted to its api representation: %s", s.ID, err)
-			continue
-		}
-
-		apiStatuses = append(apiStatuses, apiStatus)
-	}
-
-	return apiStatuses, nil
-}
-
 func (p *Processor) filterFavedStatuses(ctx context.Context, authed *oauth.Auth, statuses []*gtsmodel.Status) ([]*apimodel.Status, error) {
-	apiStatuses := []*apimodel.Status{}
+	apiStatuses := make([]*apimodel.Status, 0, len(statuses))
+
 	for _, s := range statuses {
 		if _, err := p.state.DB.GetAccountByID(ctx, s.AccountID); err != nil {
-			if err == db.ErrNoEntries {
+			if errors.Is(err, db.ErrNoEntries) {
 				log.Debugf(ctx, "skipping status %s because account %s can't be found in the db", s.ID, s.AccountID)
 				continue
 			}
-			return nil, gtserror.NewErrorInternalError(fmt.Errorf("filterPublicStatuses: error getting status author: %s", err))
+			err = fmt.Errorf("filterFavedStatuses: db error getting status author: %w", err)
+			return nil, gtserror.NewErrorInternalError(err)
 		}
 
 		timelineable, err := p.filter.StatusVisible(ctx, authed.Account, s)

internal/timeline/get.go

@@ -25,11 +25,11 @@ import (
 	"time"
 
 	"codeberg.org/gruf/go-kv"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/id"
 	"github.com/superseriousbusiness/gotosocial/internal/log"
 )
 
-const retries = 5
-
 func (t *timeline) LastGot() time.Time {
 	t.Lock()
 	defer t.Unlock()
@@ -47,339 +47,368 @@ func (t *timeline) Get(ctx context.Context, amount int, maxID string, sinceID st
 		}...)
 	l.Trace("entering get and updating t.lastGot")
 
-	// regardless of what happens below, update the
+	// Regardless of what happens below, update the
-	// last time Get was called for this timeline
+	// last time Get was called for this timeline.
 	t.Lock()
 	t.lastGot = time.Now()
 	t.Unlock()
 
-	var items []Preparable
+	var (
-	var err error
+		items []Preparable
+		err   error
+	)
 
-	// no params are defined to just fetch from the top
+	switch {
-	// this is equivalent to a user asking for the top x items from their timeline
+	case maxID == "" && sinceID == "" && minID == "":
-	if maxID == "" && sinceID == "" && minID == "" {
+		// No params are defined so just fetch from the top.
-		items, err = t.getXFromTop(ctx, amount)
+		// This is equivalent to a user starting to view
-		// aysnchronously prepare the next predicted query so it's ready when the user asks for it
+		// their timeline from newest -> older posts.
-		if len(items) != 0 {
+		items, err = t.getXBetweenIDs(ctx, amount, id.Highest, id.Lowest, true)
+
+		// Cache expected next query to speed up scrolling.
+		// Assume the user will be scrolling downwards from
+		// the final ID in items.
+		if prepareNext && err == nil && len(items) != 0 {
 			nextMaxID := items[len(items)-1].GetID()
-			if prepareNext {
+			t.prepareNextQuery(amount, nextMaxID, "", "")
-				// already cache the next query to speed up scrolling
-				go func() {
-					// use context.Background() because we don't want the query to abort when the request finishes
-					if err := t.prepareNextQuery(context.Background(), amount, nextMaxID, "", ""); err != nil {
-						l.Errorf("error preparing next query: %s", err)
-					}
-				}()
-			}
-		}
 		}
 
-	// maxID is defined but sinceID isn't so take from behind
+	case maxID != "" && sinceID == "" && minID == "":
-	// this is equivalent to a user asking for the next x items from their timeline, starting from maxID
+		// Only maxID is defined, so fetch from maxID onwards.
-	if maxID != "" && sinceID == "" {
+		// This is equivalent to a user paging further down
-		attempts := 0
+		// their timeline from newer -> older posts.
-		items, err = t.getXBehindID(ctx, amount, maxID, &attempts)
+		items, err = t.getXBetweenIDs(ctx, amount, maxID, id.Lowest, true)
-		// aysnchronously prepare the next predicted query so it's ready when the user asks for it
+
-		if len(items) != 0 {
+		// Cache expected next query to speed up scrolling.
+		// Assume the user will be scrolling downwards from
+		// the final ID in items.
+		if prepareNext && err == nil && len(items) != 0 {
 			nextMaxID := items[len(items)-1].GetID()
-			if prepareNext {
+			t.prepareNextQuery(amount, nextMaxID, "", "")
-				// already cache the next query to speed up scrolling
-				go func() {
-					// use context.Background() because we don't want the query to abort when the request finishes
-					if err := t.prepareNextQuery(context.Background(), amount, nextMaxID, "", ""); err != nil {
-						l.Errorf("error preparing next query: %s", err)
-					}
-				}()
-			}
-		}
 		}
 
-	// maxID is defined and sinceID || minID are as well, so take a slice between them
+	// In the next cases, maxID is defined, and so are
-	// this is equivalent to a user asking for items older than x but newer than y
+	// either sinceID or minID. This is equivalent to
-	if maxID != "" && sinceID != "" {
+	// a user opening an in-progress timeline and asking
-		items, err = t.getXBetweenID(ctx, amount, maxID, minID)
+	// for a slice of posts somewhere in the middle, or
-	}
+	// trying to "fill in the blanks" between two points,
-	if maxID != "" && minID != "" {
+	// paging either up or down.
-		items, err = t.getXBetweenID(ctx, amount, maxID, minID)
+	case maxID != "" && sinceID != "":
+		items, err = t.getXBetweenIDs(ctx, amount, maxID, sinceID, true)
+
+		// Cache expected next query to speed up scrolling.
+		// We can assume the caller is scrolling downwards.
+		// Guess id.Lowest as sinceID, since we don't actually
+		// know what the next sinceID would be.
+		if prepareNext && err == nil && len(items) != 0 {
+			nextMaxID := items[len(items)-1].GetID()
+			t.prepareNextQuery(amount, nextMaxID, id.Lowest, "")
 		}
 
-	// maxID isn't defined, but sinceID || minID are, so take x before
+	case maxID != "" && minID != "":
-	// this is equivalent to a user asking for items newer than x (eg., refreshing the top of their timeline)
+		items, err = t.getXBetweenIDs(ctx, amount, maxID, minID, false)
-	if maxID == "" && sinceID != "" {
+
-		items, err = t.getXBeforeID(ctx, amount, sinceID, true)
+		// Cache expected next query to speed up scrolling.
+		// We can assume the caller is scrolling upwards.
+		// Guess id.Highest as maxID, since we don't actually
+		// know what the next maxID would be.
+		if prepareNext && err == nil && len(items) != 0 {
+			prevMinID := items[0].GetID()
+			t.prepareNextQuery(amount, id.Highest, "", prevMinID)
 		}
-	if maxID == "" && minID != "" {
+
-		items, err = t.getXBeforeID(ctx, amount, minID, true)
+	// In the final cases, maxID is not defined, but
+	// either sinceID or minID are. This is equivalent to
+	// a user either "pulling up" at the top of their timeline
+	// to refresh it and check if newer posts have come in, or
+	// trying to scroll upwards from an old post to see what
+	// they missed since then.
+	//
+	// In these calls, we use the highest possible ulid as
+	// behindID because we don't have a cap for newest that
+	// we're interested in.
+	case maxID == "" && sinceID != "":
+		items, err = t.getXBetweenIDs(ctx, amount, id.Highest, sinceID, true)
+
+		// We can't cache an expected next query for this one,
+		// since presumably the caller is at the top of their
+		// timeline already.
+
+	case maxID == "" && minID != "":
+		items, err = t.getXBetweenIDs(ctx, amount, id.Highest, minID, false)
+
+		// Cache expected next query to speed up scrolling.
+		// We can assume the caller is scrolling upwards.
+		// Guess id.Highest as maxID, since we don't actually
+		// know what the next maxID would be.
+		if prepareNext && err == nil && len(items) != 0 {
+			prevMinID := items[0].GetID()
+			t.prepareNextQuery(amount, id.Highest, "", prevMinID)
+		}
+
+	default:
+		err = errors.New("Get: switch statement exhausted with no results")
 	}
 
 	return items, err
 }
 
-// getXFromTop returns x amount of items from the top of the timeline, from newest to oldest.
+// getXBetweenIDs returns x amount of items somewhere between (not including) the given IDs.
-func (t *timeline) getXFromTop(ctx context.Context, amount int) ([]Preparable, error) {
+//
-	// make a slice of preparedItems with the length we need to return
+// If frontToBack is true, items will be served paging down from behindID.
-	preparedItems := make([]Preparable, 0, amount)
+// This corresponds to an api call to /timelines/home?max_id=WHATEVER&since_id=WHATEVER
+//
+// If frontToBack is false, items will be served paging up from beforeID.
+// This corresponds to an api call to /timelines/home?max_id=WHATEVER&min_id=WHATEVER
+func (t *timeline) getXBetweenIDs(ctx context.Context, amount int, behindID string, beforeID string, frontToBack bool) ([]Preparable, error) {
+	l := log.
+		WithContext(ctx).
+		WithFields(kv.Fields{
+			{"amount", amount},
+			{"behindID", behindID},
+			{"beforeID", beforeID},
+			{"frontToBack", frontToBack},
+		}...)
+	l.Trace("entering getXBetweenID")
 
-	if t.preparedItems.data == nil {
+	// Assume length we need to return.
-		t.preparedItems.data = &list.List{}
+	items := make([]Preparable, 0, amount)
+
+	if beforeID >= behindID {
+		// This is an impossible situation, we
+		// can't serve anything between these.
+		return items, nil
 	}
 
-	// make sure we have enough items prepared to return
+	// Try to ensure we have enough items prepared.
-	if t.preparedItems.data.Len() < amount {
+	if err := t.prepareXBetweenIDs(ctx, amount, behindID, beforeID, frontToBack); err != nil {
-		if err := t.PrepareFromTop(ctx, amount); err != nil {
+		// An error here doesn't necessarily mean we
+		// can't serve anything, so log + keep going.
+		l.Debugf("error calling prepareXBetweenIDs: %s", err)
+	}
+
+	var (
+		beforeIDMark *list.Element
+		served       int
+		// Our behavior while ranging through the
+		// list changes depending on if we're
+		// going front-to-back or back-to-front.
+		//
+		// To avoid checking which one we're doing
+		// in each loop iteration, define our range
+		// function here outside the loop.
+		//
+		// The bool indicates to the caller whether
+		// iteration should continue (true) or stop
+		// (false).
+		rangeF func(e *list.Element) (bool, error)
+		// If we get certain errors on entries as we're
+		// looking through, we might want to cheekily
+		// remove their elements from the timeline.
+		// Everything added to this slice will be removed.
+		removeElements = []*list.Element{}
+	)
+
+	defer func() {
+		for _, e := range removeElements {
+			t.items.data.Remove(e)
+		}
+	}()
+
+	if frontToBack {
+		// We're going front-to-back, which means we
+		// don't need to look for a mark per se, we
+		// just keep serving items until we've reached
+		// a point where the items are out of the range
+		// we're interested in.
+		rangeF = func(e *list.Element) (bool, error) {
+			entry := e.Value.(*indexedItemsEntry) //nolint:forcetypeassert
+
+			if entry.itemID >= behindID {
+				// ID of this item is too high,
+				// just keep iterating.
+				l.Trace("item is too new, continuing")
+				return true, nil
+			}
+
+			if entry.itemID <= beforeID {
+				// We've gone as far as we can through
+				// the list and reached entries that are
+				// now too old for us, stop here.
+				l.Trace("reached older items, breaking")
+				return false, nil
+			}
+
+			l.Trace("entry is just right")
+
+			if entry.prepared == nil {
+				// Whoops, this entry isn't prepared yet; some
+				// race condition? That's OK, we can do it now.
+				prepared, err := t.prepareFunction(ctx, t.accountID, entry.itemID)
+				if err != nil {
+					if errors.Is(err, db.ErrNoEntries) {
+						// ErrNoEntries means something has been deleted,
+						// so we'll likely not be able to ever prepare this.
+						// This means we can remove it and skip past it.
+						l.Debugf("db.ErrNoEntries while trying to prepare %s; will remove from timeline", entry.itemID)
+						removeElements = append(removeElements, e)
+						return true, nil
+					}
+					// We've got a proper db error.
+					return false, fmt.Errorf("getXBetweenIDs: db error while trying to prepare %s: %w", entry.itemID, err)
+				}
+				entry.prepared = prepared
+			}
+
+			items = append(items, entry.prepared)
+
+			served++
+			return served < amount, nil
+		}
+	} else {
+		// Iterate through the list from the top, until
+		// we reach an item with id smaller than beforeID;
+		// ie., an item OLDER than beforeID. At that point,
+		// we can stop looking because we're not interested
+		// in older entries.
+		rangeF = func(e *list.Element) (bool, error) {
+			// Move the mark back one place each loop.
+			beforeIDMark = e
+
+			//nolint:forcetypeassert
+			if entry := e.Value.(*indexedItemsEntry); entry.itemID <= beforeID {
+				// We've gone as far as we can through
+				// the list and reached entries that are
+				// now too old for us, stop here.
+				l.Trace("reached older items, breaking")
+				return false, nil
+			}
+
+			return true, nil
+		}
+	}
+
+	// Iterate through the list until the function
+	// we defined above instructs us to stop.
+	for e := t.items.data.Front(); e != nil; e = e.Next() {
+		keepGoing, err := rangeF(e)
+		if err != nil {
 			return nil, err
 		}
+
+		if !keepGoing {
+			break
+		}
 	}
 
-	// work through the prepared items from the top and return
+	if frontToBack || beforeIDMark == nil {
-	var served int
+		// If we're serving front to back, then
-	for e := t.preparedItems.data.Front(); e != nil; e = e.Next() {
+		// items should be populated by now. If
-		entry, ok := e.Value.(*preparedItemsEntry)
+		// we're serving back to front but didn't
-		if !ok {
+		// find any items newer than beforeID,
-			return nil, errors.New("getXFromTop: could not parse e as a preparedItemsEntry")
+		// we can just return empty items.
+		return items, nil
 	}
-		preparedItems = append(preparedItems, entry.prepared)
+
+	// We're serving back to front, so iterate upwards
+	// towards the front of the list from the mark we found,
+	// until we either get to the front, serve enough
+	// items, or reach behindID.
+	//
+	// To preserve ordering, we need to reverse the slice
+	// when we're finished.
+	for e := beforeIDMark; e != nil; e = e.Prev() {
+		entry := e.Value.(*indexedItemsEntry) //nolint:forcetypeassert
+
+		if entry.itemID == beforeID {
+			// Don't include the beforeID
+			// entry itself, just continue.
+			l.Trace("entry item ID is equal to beforeID, skipping")
+			continue
+		}
+
+		if entry.itemID >= behindID {
+			// We've reached items that are
+			// newer than what we're looking
+			// for, just stop here.
+			l.Trace("reached newer items, breaking")
+			break
+		}
+
+		if entry.prepared == nil {
+			// Whoops, this entry isn't prepared yet; some
+			// race condition? That's OK, we can do it now.
+			prepared, err := t.prepareFunction(ctx, t.accountID, entry.itemID)
+			if err != nil {
+				if errors.Is(err, db.ErrNoEntries) {
+					// ErrNoEntries means something has been deleted,
+					// so we'll likely not be able to ever prepare this.
+					// This means we can remove it and skip past it.
+					l.Debugf("db.ErrNoEntries while trying to prepare %s; will remove from timeline", entry.itemID)
+					removeElements = append(removeElements, e)
+					continue
+				}
+				// We've got a proper db error.
+				return nil, fmt.Errorf("getXBetweenIDs: db error while trying to prepare %s: %w", entry.itemID, err)
+			}
+			entry.prepared = prepared
+		}
+
+		items = append(items, entry.prepared)
+
 		served++
 		if served >= amount {
 			break
 		}
 	}
 
-	return preparedItems, nil
+	// Reverse order of items.
+	// https://zchee.github.io/golang-wiki/SliceTricks/#reversing
+	for l, r := 0, len(items)-1; l < r; l, r = l+1, r-1 {
+		items[l], items[r] = items[r], items[l]
+	}
+
+	return items, nil
 }
 
-// getXBehindID returns x amount of items from the given id onwards, from newest to oldest.
+func (t *timeline) prepareNextQuery(amount int, maxID string, sinceID string, minID string) {
-// This will NOT include the item with the given ID.
+	var (
-//
+		// We explicitly use context.Background() rather than
-// This corresponds to an api call to /timelines/home?max_id=WHATEVER
+		// accepting a context param because we don't want this
-func (t *timeline) getXBehindID(ctx context.Context, amount int, behindID string, attempts *int) ([]Preparable, error) {
+		// to stop/break when the calling context finishes.
-	l := log.WithContext(ctx).
+		ctx = context.Background()
+		err error
+	)
+
+	// Always perform this async so caller doesn't have to wait.
+	go func() {
+		switch {
+		case maxID == "" && sinceID == "" && minID == "":
+			err = t.prepareXBetweenIDs(ctx, amount, id.Highest, id.Lowest, true)
+		case maxID != "" && sinceID == "" && minID == "":
+			err = t.prepareXBetweenIDs(ctx, amount, maxID, id.Lowest, true)
+		case maxID != "" && sinceID != "":
+			err = t.prepareXBetweenIDs(ctx, amount, maxID, sinceID, true)
+		case maxID != "" && minID != "":
+			err = t.prepareXBetweenIDs(ctx, amount, maxID, minID, false)
+		case maxID == "" && sinceID != "":
+			err = t.prepareXBetweenIDs(ctx, amount, id.Highest, sinceID, true)
+		case maxID == "" && minID != "":
+			err = t.prepareXBetweenIDs(ctx, amount, id.Highest, minID, false)
+		default:
+			err = errors.New("Get: switch statement exhausted with no results")
+		}
+
+		if err != nil {
+			log.
+				WithContext(ctx).
 				WithFields(kv.Fields{
 					{"amount", amount},
-			{"behindID", behindID},
+					{"maxID", maxID},
-			{"attempts", attempts},
+					{"sinceID", sinceID},
-		}...)
+					{"minID", minID},
-
+				}...).
-	newAttempts := *attempts
+				Warnf("error preparing next query: %s", err)
-	newAttempts++
-	attempts = &newAttempts
-
-	// make a slice of items with the length we need to return
-	items := make([]Preparable, 0, amount)
-
-	if t.preparedItems.data == nil {
-		t.preparedItems.data = &list.List{}
 		}
-
+	}()
-	// iterate through the modified list until we hit the mark we're looking for
-	var position int
-	var behindIDMark *list.Element
-
-findMarkLoop:
-	for e := t.preparedItems.data.Front(); e != nil; e = e.Next() {
-		position++
-		entry, ok := e.Value.(*preparedItemsEntry)
-		if !ok {
-			return nil, errors.New("getXBehindID: could not parse e as a preparedPostsEntry")
-		}
-
-		if entry.itemID <= behindID {
-			l.Trace("found behindID mark")
-			behindIDMark = e
-			break findMarkLoop
-		}
-	}
-
-	// we didn't find it, so we need to make sure it's indexed and prepared and then try again
-	// this can happen when a user asks for really old items
-	if behindIDMark == nil {
-		if err := t.prepareBehind(ctx, behindID, amount); err != nil {
-			return nil, fmt.Errorf("getXBehindID: error preparing behind and including ID %s", behindID)
-		}
-		oldestID, err := t.oldestPreparedItemID(ctx)
-		if err != nil {
-			return nil, err
-		}
-		if oldestID == "" {
-			l.Tracef("oldestID is empty so we can't return behindID %s", behindID)
-			return items, nil
-		}
-		if oldestID == behindID {
-			l.Tracef("given behindID %s is the same as oldestID %s so there's nothing to return behind it", behindID, oldestID)
-			return items, nil
-		}
-		if *attempts > retries {
-			l.Tracef("exceeded retries looking for behindID %s", behindID)
-			return items, nil
-		}
-		l.Trace("trying getXBehindID again")
-		return t.getXBehindID(ctx, amount, behindID, attempts)
-	}
-
-	// make sure we have enough items prepared behind it to return what we're being asked for
-	if t.preparedItems.data.Len() < amount+position {
-		if err := t.prepareBehind(ctx, behindID, amount); err != nil {
-			return nil, err
-		}
-	}
-
-	// start serving from the entry right after the mark
-	var served int
-serveloop:
-	for e := behindIDMark.Next(); e != nil; e = e.Next() {
-		entry, ok := e.Value.(*preparedItemsEntry)
-		if !ok {
-			return nil, errors.New("getXBehindID: could not parse e as a preparedPostsEntry")
-		}
-
-		// serve up to the amount requested
-		items = append(items, entry.prepared)
-		served++
-		if served >= amount {
-			break serveloop
-		}
-	}
-
-	return items, nil
-}
-
-// getXBeforeID returns x amount of items up to the given id, from newest to oldest.
-// This will NOT include the item with the given ID.
-//
-// This corresponds to an api call to /timelines/home?since_id=WHATEVER
-func (t *timeline) getXBeforeID(ctx context.Context, amount int, beforeID string, startFromTop bool) ([]Preparable, error) {
-	// make a slice of items with the length we need to return
-	items := make([]Preparable, 0, amount)
-
-	if t.preparedItems.data == nil {
-		t.preparedItems.data = &list.List{}
-	}
-
-	// iterate through the modified list until we hit the mark we're looking for, or as close as possible to it
-	var beforeIDMark *list.Element
-findMarkLoop:
-	for e := t.preparedItems.data.Front(); e != nil; e = e.Next() {
-		entry, ok := e.Value.(*preparedItemsEntry)
-		if !ok {
-			return nil, errors.New("getXBeforeID: could not parse e as a preparedPostsEntry")
-		}
-
-		if entry.itemID >= beforeID {
-			beforeIDMark = e
-		} else {
-			break findMarkLoop
-		}
-	}
-
-	if beforeIDMark == nil {
-		return items, nil
-	}
-
-	var served int
-
-	if startFromTop {
-		// start serving from the front/top and keep going until we hit mark or get x amount items
-	serveloopFromTop:
-		for e := t.preparedItems.data.Front(); e != nil; e = e.Next() {
-			entry, ok := e.Value.(*preparedItemsEntry)
-			if !ok {
-				return nil, errors.New("getXBeforeID: could not parse e as a preparedPostsEntry")
-			}
-
-			if entry.itemID == beforeID {
-				break serveloopFromTop
-			}
-
-			// serve up to the amount requested
-			items = append(items, entry.prepared)
-			served++
-			if served >= amount {
-				break serveloopFromTop
-			}
-		}
-	} else if !startFromTop {
-		// start serving from the entry right before the mark
-	serveloopFromBottom:
-		for e := beforeIDMark.Prev(); e != nil; e = e.Prev() {
-			entry, ok := e.Value.(*preparedItemsEntry)
-			if !ok {
-				return nil, errors.New("getXBeforeID: could not parse e as a preparedPostsEntry")
-			}
-
-			// serve up to the amount requested
-			items = append(items, entry.prepared)
-			served++
-			if served >= amount {
-				break serveloopFromBottom
-			}
-		}
-	}
-
-	return items, nil
-}
-
-// getXBetweenID returns x amount of items from the given maxID, up to the given id, from newest to oldest.
-// This will NOT include the item with the given IDs.
-//
-// This corresponds to an api call to /timelines/home?since_id=WHATEVER&max_id=WHATEVER_ELSE
-func (t *timeline) getXBetweenID(ctx context.Context, amount int, behindID string, beforeID string) ([]Preparable, error) {
-	// make a slice of items with the length we need to return
-	items := make([]Preparable, 0, amount)
-
-	if t.preparedItems.data == nil {
-		t.preparedItems.data = &list.List{}
-	}
-
-	// iterate through the modified list until we hit the mark we're looking for
-	var position int
-	var behindIDMark *list.Element
-findMarkLoop:
-	for e := t.preparedItems.data.Front(); e != nil; e = e.Next() {
-		position++
-		entry, ok := e.Value.(*preparedItemsEntry)
-		if !ok {
-			return nil, errors.New("getXBetweenID: could not parse e as a preparedPostsEntry")
-		}
-
-		if entry.itemID == behindID {
-			behindIDMark = e
-			break findMarkLoop
-		}
-	}
-
-	// we didn't find it
-	if behindIDMark == nil {
-		return nil, fmt.Errorf("getXBetweenID: couldn't find item with ID %s", behindID)
-	}
-
-	// make sure we have enough items prepared behind it to return what we're being asked for
-	if t.preparedItems.data.Len() < amount+position {
-		if err := t.prepareBehind(ctx, behindID, amount); err != nil {
-			return nil, err
-		}
-	}
-
-	// start serving from the entry right after the mark
-	var served int
-serveloop:
-	for e := behindIDMark.Next(); e != nil; e = e.Next() {
-		entry, ok := e.Value.(*preparedItemsEntry)
-		if !ok {
-			return nil, errors.New("getXBetweenID: could not parse e as a preparedPostsEntry")
-		}
-
-		if entry.itemID == beforeID {
-			break serveloop
-		}
-
-		// serve up to the amount requested
-		items = append(items, entry.prepared)
-		served++
-		if served >= amount {
-			break serveloop
-		}
-	}
-
-	return items, nil
 }

internal/timeline/get_test.go

@@ -25,6 +25,7 @@ import (
 
 	"github.com/stretchr/testify/suite"
 	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/id"
 	"github.com/superseriousbusiness/gotosocial/internal/processing"
 	"github.com/superseriousbusiness/gotosocial/internal/timeline"
 	"github.com/superseriousbusiness/gotosocial/internal/visibility"
@@ -43,8 +44,8 @@ func (suite *GetTestSuite) SetupSuite() {
 func (suite *GetTestSuite) SetupTest() {
 	suite.state.Caches.Init()
 
-	testrig.InitTestLog()
 	testrig.InitTestConfig()
+	testrig.InitTestLog()
 
 	suite.db = testrig.NewTestDB(&suite.state)
 	suite.tc = testrig.NewTestTypeConverter(suite.db)
@@ -52,8 +53,9 @@ func (suite *GetTestSuite) SetupTest() {
 
 	testrig.StandardDBSetup(suite.db, nil)
 
-	// let's take local_account_1 as the timeline owner
+	// Take local_account_1 as the timeline owner, it
-	tl, err := timeline.NewTimeline(
+	// doesn't really matter too much for these tests.
+	tl := timeline.NewTimeline(
 		context.Background(),
 		suite.testAccounts["local_account_1"].ID,
 		processing.StatusGrabFunction(suite.db),
@@ -61,20 +63,27 @@ func (suite *GetTestSuite) SetupTest() {
 		processing.StatusPrepareFunction(suite.db, suite.tc),
 		processing.StatusSkipInsertFunction(),
 	)
-	if err != nil {
-		suite.FailNow(err.Error())
-	}
 
-	// put the status IDs in a determinate order since we can't trust a map to keep its order
+	// Put testrig statuses in a determinate order
+	// since we can't trust a map to keep order.
 	statuses := []*gtsmodel.Status{}
 	for _, s := range suite.testStatuses {
 		statuses = append(statuses, s)
 	}
+
 	sort.Slice(statuses, func(i, j int) bool {
 		return statuses[i].ID > statuses[j].ID
 	})
 
-	// prepare the timeline by just shoving all test statuses in it -- let's not be fussy about who sees what
+	// Statuses are now highest -> lowest.
+	suite.highestStatusID = statuses[0].ID
+	suite.lowestStatusID = statuses[len(statuses)-1].ID
+	if suite.highestStatusID < suite.lowestStatusID {
+		suite.FailNow("", "statuses weren't ordered properly by sort")
+	}
+
+	// Put all test statuses into the timeline; we don't
+	// need to be fussy about who sees what for these tests.
 	for _, s := range statuses {
 		_, err := tl.IndexAndPrepareOne(context.Background(), s.GetID(), s.BoostOfID, s.AccountID, s.BoostOfAccountID)
 		if err != nil {
@@ -89,219 +98,292 @@ func (suite *GetTestSuite) TearDownTest() {
 	testrig.StandardDBTeardown(suite.db)
 }
 
-func (suite *GetTestSuite) TestGetDefault() {
+func (suite *GetTestSuite) checkStatuses(statuses []timeline.Preparable, maxID string, minID string, expectedLength int) {
-	// lastGot should be zero
+	if l := len(statuses); l != expectedLength {
-	suite.Zero(suite.timeline.LastGot())
+		suite.FailNow("", "expected %d statuses in slice, got %d", expectedLength, l)
-
+	} else if l == 0 {
-	// get 10 20 the top and don't prepare the next query
+		// Can't test empty slice.
-	statuses, err := suite.timeline.Get(context.Background(), 20, "", "", "", false)
+		return
-	if err != nil {
-		suite.FailNow(err.Error())
 	}
 
-	// we only have 16 statuses in the test suite
+	// Check ordering + bounds of statuses.
-	suite.Len(statuses, 17)
+	highest := statuses[0].GetID()
+	for _, status := range statuses {
+		id := status.GetID()
 
-	// statuses should be sorted highest to lowest ID
+		if id >= maxID {
-	var highest string
+			suite.FailNow("", "%s greater than maxID %s", id, maxID)
-	for i, s := range statuses {
-		if i == 0 {
-			highest = s.GetID()
-		} else {
-			suite.Less(s.GetID(), highest)
-			highest = s.GetID()
-		}
 		}
 
-	// lastGot should be up to date
+		if id <= minID {
-	suite.WithinDuration(time.Now(), suite.timeline.LastGot(), 1*time.Second)
+			suite.FailNow("", "%s smaller than minID %s", id, minID)
+		}
+
+		if id > highest {
+			suite.FailNow("", "statuses in slice were not ordered highest -> lowest ID")
+		}
+
+		highest = id
+	}
 }
 
-func (suite *GetTestSuite) TestGetDefaultPrepareNext() {
+func (suite *GetTestSuite) TestGetNewTimelinePageDown() {
-	// get 10 from the top and prepare the next query
+	// Take a fresh timeline for this test.
-	statuses, err := suite.timeline.Get(context.Background(), 10, "", "", "", true)
+	// This tests whether indexing works
+	// properly against uninitialized timelines.
+	tl := timeline.NewTimeline(
+		context.Background(),
+		suite.testAccounts["local_account_1"].ID,
+		processing.StatusGrabFunction(suite.db),
+		processing.StatusFilterFunction(suite.db, suite.filter),
+		processing.StatusPrepareFunction(suite.db, suite.tc),
+		processing.StatusSkipInsertFunction(),
+	)
+
+	// Get 5 from the top.
+	statuses, err := tl.Get(context.Background(), 5, "", "", "", true)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+	suite.checkStatuses(statuses, id.Highest, id.Lowest, 5)
+
+	// Get 5 from next maxID.
+	nextMaxID := statuses[len(statuses)-1].GetID()
+	statuses, err = tl.Get(context.Background(), 5, nextMaxID, "", "", false)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+	suite.checkStatuses(statuses, nextMaxID, id.Lowest, 5)
+}
+
+func (suite *GetTestSuite) TestGetNewTimelinePageUp() {
+	// Take a fresh timeline for this test.
+	// This tests whether indexing works
+	// properly against uninitialized timelines.
+	tl := timeline.NewTimeline(
+		context.Background(),
+		suite.testAccounts["local_account_1"].ID,
+		processing.StatusGrabFunction(suite.db),
+		processing.StatusFilterFunction(suite.db, suite.filter),
+		processing.StatusPrepareFunction(suite.db, suite.tc),
+		processing.StatusSkipInsertFunction(),
+	)
+
+	// Get 5 from the back.
+	statuses, err := tl.Get(context.Background(), 5, "", "", id.Lowest, false)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+	suite.checkStatuses(statuses, id.Highest, id.Lowest, 5)
+
+	// Page upwards.
+	nextMinID := statuses[len(statuses)-1].GetID()
+	statuses, err = tl.Get(context.Background(), 5, "", "", nextMinID, false)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+	suite.checkStatuses(statuses, id.Highest, nextMinID, 5)
+}
+
+func (suite *GetTestSuite) TestGetNewTimelineMoreThanPossible() {
+	// Take a fresh timeline for this test.
+	// This tests whether indexing works
+	// properly against uninitialized timelines.
+	tl := timeline.NewTimeline(
+		context.Background(),
+		suite.testAccounts["local_account_1"].ID,
+		processing.StatusGrabFunction(suite.db),
+		processing.StatusFilterFunction(suite.db, suite.filter),
+		processing.StatusPrepareFunction(suite.db, suite.tc),
+		processing.StatusSkipInsertFunction(),
+	)
+
+	// Get 100 from the top.
+	statuses, err := tl.Get(context.Background(), 100, id.Highest, "", "", false)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+	suite.checkStatuses(statuses, id.Highest, id.Lowest, 16)
+}
+
+func (suite *GetTestSuite) TestGetNewTimelineMoreThanPossiblePageUp() {
+	// Take a fresh timeline for this test.
+	// This tests whether indexing works
+	// properly against uninitialized timelines.
+	tl := timeline.NewTimeline(
+		context.Background(),
+		suite.testAccounts["local_account_1"].ID,
+		processing.StatusGrabFunction(suite.db),
+		processing.StatusFilterFunction(suite.db, suite.filter),
+		processing.StatusPrepareFunction(suite.db, suite.tc),
+		processing.StatusSkipInsertFunction(),
+	)
+
+	// Get 100 from the back.
+	statuses, err := tl.Get(context.Background(), 100, "", "", id.Lowest, false)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+	suite.checkStatuses(statuses, id.Highest, id.Lowest, 16)
+}
+
+func (suite *GetTestSuite) TestGetNoParams() {
+	// Get 10 statuses from the top (no params).
+	statuses, err := suite.timeline.Get(context.Background(), 10, "", "", "", false)
 	if err != nil {
 		suite.FailNow(err.Error())
 	}
 
-	suite.Len(statuses, 10)
+	suite.checkStatuses(statuses, id.Highest, id.Lowest, 10)
 
-	// statuses should be sorted highest to lowest ID
+	// First status should have the highest ID in the testrig.
-	var highest string
+	suite.Equal(suite.highestStatusID, statuses[0].GetID())
-	for i, s := range statuses {
-		if i == 0 {
-			highest = s.GetID()
-		} else {
-			suite.Less(s.GetID(), highest)
-			highest = s.GetID()
-		}
-	}
-
-	// sleep a second so the next query can run
-	time.Sleep(1 * time.Second)
 }
 
 func (suite *GetTestSuite) TestGetMaxID() {
-	// ask for 10 with a max ID somewhere in the middle of the stack
+	// Ask for 10 with a max ID somewhere in the middle of the stack.
-	statuses, err := suite.timeline.Get(context.Background(), 10, "01F8MHBQCBTDKN6X5VHGMMN4MA", "", "", false)
+	maxID := "01F8MHBQCBTDKN6X5VHGMMN4MA"
+
+	statuses, err := suite.timeline.Get(context.Background(), 10, maxID, "", "", false)
 	if err != nil {
 		suite.FailNow(err.Error())
 	}
 
-	// we should only get 6 statuses back, since we asked for a max ID that excludes some of our entries
+	// We'll only get 6 statuses back.
-	suite.Len(statuses, 6)
+	suite.checkStatuses(statuses, maxID, id.Lowest, 6)
-
-	// statuses should be sorted highest to lowest ID
-	var highest string
-	for i, s := range statuses {
-		if i == 0 {
-			highest = s.GetID()
-		} else {
-			suite.Less(s.GetID(), highest)
-			highest = s.GetID()
-		}
-	}
-}
-
-func (suite *GetTestSuite) TestGetMaxIDPrepareNext() {
-	// ask for 10 with a max ID somewhere in the middle of the stack
-	statuses, err := suite.timeline.Get(context.Background(), 10, "01F8MHBQCBTDKN6X5VHGMMN4MA", "", "", true)
-	if err != nil {
-		suite.FailNow(err.Error())
-	}
-
-	// we should only get 6 statuses back, since we asked for a max ID that excludes some of our entries
-	suite.Len(statuses, 6)
-
-	// statuses should be sorted highest to lowest ID
-	var highest string
-	for i, s := range statuses {
-		if i == 0 {
-			highest = s.GetID()
-		} else {
-			suite.Less(s.GetID(), highest)
-			highest = s.GetID()
-		}
-	}
-
-	// sleep a second so the next query can run
-	time.Sleep(1 * time.Second)
-}
-
-func (suite *GetTestSuite) TestGetMinID() {
-	// ask for 15 with a min ID somewhere in the middle of the stack
-	statuses, err := suite.timeline.Get(context.Background(), 10, "", "01F8MHBQCBTDKN6X5VHGMMN4MA", "", false)
-	if err != nil {
-		suite.FailNow(err.Error())
-	}
-
-	// we should only get 10 statuses back, since we asked for a min ID that excludes some of our entries
-	suite.Len(statuses, 10)
-
-	// statuses should be sorted highest to lowest ID
-	var highest string
-	for i, s := range statuses {
-		if i == 0 {
-			highest = s.GetID()
-		} else {
-			suite.Less(s.GetID(), highest)
-			highest = s.GetID()
-		}
-	}
 }
 
 func (suite *GetTestSuite) TestGetSinceID() {
-	// ask for 15 with a since ID somewhere in the middle of the stack
+	// Ask for 10 with a since ID somewhere in the middle of the stack.
-	statuses, err := suite.timeline.Get(context.Background(), 15, "", "", "01F8MHBQCBTDKN6X5VHGMMN4MA", false)
+	sinceID := "01F8MHBQCBTDKN6X5VHGMMN4MA"
+	statuses, err := suite.timeline.Get(context.Background(), 10, "", sinceID, "", false)
 	if err != nil {
 		suite.FailNow(err.Error())
 	}
 
-	// we should only get 10 statuses back, since we asked for a since ID that excludes some of our entries
+	suite.checkStatuses(statuses, id.Highest, sinceID, 10)
-	suite.Len(statuses, 10)
 
-	// statuses should be sorted highest to lowest ID
+	// The first status in the stack should have the highest ID of all
-	var highest string
+	// in the testrig, because we're paging down.
-	for i, s := range statuses {
+	suite.Equal(suite.highestStatusID, statuses[0].GetID())
-		if i == 0 {
-			highest = s.GetID()
-		} else {
-			suite.Less(s.GetID(), highest)
-			highest = s.GetID()
-		}
-	}
 }
 
-func (suite *GetTestSuite) TestGetSinceIDPrepareNext() {
+func (suite *GetTestSuite) TestGetSinceIDOneOnly() {
-	// ask for 15 with a since ID somewhere in the middle of the stack
+	// Ask for 1 with a since ID somewhere in the middle of the stack.
-	statuses, err := suite.timeline.Get(context.Background(), 15, "", "", "01F8MHBQCBTDKN6X5VHGMMN4MA", true)
+	sinceID := "01F8MHBQCBTDKN6X5VHGMMN4MA"
+	statuses, err := suite.timeline.Get(context.Background(), 1, "", sinceID, "", false)
 	if err != nil {
 		suite.FailNow(err.Error())
 	}
 
-	// we should only get 10 statuses back, since we asked for a since ID that excludes some of our entries
+	suite.checkStatuses(statuses, id.Highest, sinceID, 1)
-	suite.Len(statuses, 10)
 
-	// statuses should be sorted highest to lowest ID
+	// The one status we got back should have the highest ID of all in
-	var highest string
+	// the testrig, because using sinceID means we're paging down.
-	for i, s := range statuses {
+	suite.Equal(suite.highestStatusID, statuses[0].GetID())
-		if i == 0 {
+}
-			highest = s.GetID()
+
-		} else {
+func (suite *GetTestSuite) TestGetMinID() {
-			suite.Less(s.GetID(), highest)
+	// Ask for 5 with a min ID somewhere in the middle of the stack.
-			highest = s.GetID()
+	minID := "01F8MHBQCBTDKN6X5VHGMMN4MA"
-		}
+	statuses, err := suite.timeline.Get(context.Background(), 5, "", "", minID, false)
+	if err != nil {
+		suite.FailNow(err.Error())
 	}
 
-	// sleep a second so the next query can run
+	suite.checkStatuses(statuses, id.Highest, minID, 5)
-	time.Sleep(1 * time.Second)
+
+	// We're paging up so even the highest status ID in the pile
+	// shouldn't be the highest ID we have.
+	suite.NotEqual(suite.highestStatusID, statuses[0])
+}
+
+func (suite *GetTestSuite) TestGetMinIDOneOnly() {
+	// Ask for 1 with a min ID somewhere in the middle of the stack.
+	minID := "01F8MHBQCBTDKN6X5VHGMMN4MA"
+	statuses, err := suite.timeline.Get(context.Background(), 1, "", "", minID, false)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	suite.checkStatuses(statuses, id.Highest, minID, 1)
+
+	// The one status we got back should have the an ID equal to the
+	// one ID immediately newer than it.
+	suite.Equal("01F8MHC0H0A7XHTVH5F596ZKBM", statuses[0].GetID())
+}
+
+func (suite *GetTestSuite) TestGetMinIDFromLowestInTestrig() {
+	// Ask for 1 with minID equal to the lowest status in the testrig.
+	minID := suite.lowestStatusID
+	statuses, err := suite.timeline.Get(context.Background(), 1, "", "", minID, false)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	suite.checkStatuses(statuses, id.Highest, minID, 1)
+
+	// The one status we got back should have an id higher than
+	// the lowest status in the testrig, since minID is not inclusive.
+	suite.Greater(statuses[0].GetID(), suite.lowestStatusID)
+}
+
+func (suite *GetTestSuite) TestGetMinIDFromLowestPossible() {
+	// Ask for 1 with the lowest possible min ID.
+	minID := id.Lowest
+	statuses, err := suite.timeline.Get(context.Background(), 1, "", "", minID, false)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	suite.checkStatuses(statuses, id.Highest, minID, 1)
+
+	// The one status we got back should have the an ID equal to the
+	// lowest ID status in the test rig.
+	suite.Equal(suite.lowestStatusID, statuses[0].GetID())
 }
 
 func (suite *GetTestSuite) TestGetBetweenID() {
-	// ask for 10 between these two IDs
+	// Ask for 10 between these two IDs
-	statuses, err := suite.timeline.Get(context.Background(), 10, "01F8MHCP5P2NWYQ416SBA0XSEV", "", "01F8MHBQCBTDKN6X5VHGMMN4MA", false)
+	maxID := "01F8MHCP5P2NWYQ416SBA0XSEV"
+	minID := "01F8MHBQCBTDKN6X5VHGMMN4MA"
+
+	statuses, err := suite.timeline.Get(context.Background(), 10, maxID, "", minID, false)
 	if err != nil {
 		suite.FailNow(err.Error())
 	}
 
-	// we should only get 2 statuses back, since there are only two statuses between the given IDs
+	// There's only two statuses between these two IDs.
-	suite.Len(statuses, 2)
+	suite.checkStatuses(statuses, maxID, minID, 2)
-
-	// statuses should be sorted highest to lowest ID
-	var highest string
-	for i, s := range statuses {
-		if i == 0 {
-			highest = s.GetID()
-		} else {
-			suite.Less(s.GetID(), highest)
-			highest = s.GetID()
-		}
-	}
 }
 
-func (suite *GetTestSuite) TestGetBetweenIDPrepareNext() {
+func (suite *GetTestSuite) TestGetBetweenIDImpossible() {
-	// ask for 10 between these two IDs
+	// Ask for 10 between these two IDs which present
-	statuses, err := suite.timeline.Get(context.Background(), 10, "01F8MHCP5P2NWYQ416SBA0XSEV", "", "01F8MHBQCBTDKN6X5VHGMMN4MA", true)
+	// an impossible query.
+	maxID := id.Lowest
+	minID := id.Highest
+
+	statuses, err := suite.timeline.Get(context.Background(), 10, maxID, "", minID, false)
 	if err != nil {
 		suite.FailNow(err.Error())
 	}
 
-	// we should only get 2 statuses back, since there are only two statuses between the given IDs
+	// We should have nothing back.
-	suite.Len(statuses, 2)
+	suite.checkStatuses(statuses, maxID, minID, 0)
+}
 
-	// statuses should be sorted highest to lowest ID
+func (suite *GetTestSuite) TestLastGot() {
-	var highest string
+	// LastGot should be zero
-	for i, s := range statuses {
+	suite.Zero(suite.timeline.LastGot())
-		if i == 0 {
+
-			highest = s.GetID()
+	// Get some from the top
-		} else {
+	_, err := suite.timeline.Get(context.Background(), 10, "", "", "", false)
-			suite.Less(s.GetID(), highest)
+	if err != nil {
-			highest = s.GetID()
+		suite.FailNow(err.Error())
-		}
 	}
 
-	// sleep a second so the next query can run
+	// LastGot should be updated
-	time.Sleep(1 * time.Second)
+	suite.WithinDuration(time.Now(), suite.timeline.LastGot(), 1*time.Second)
 }
 
 func TestGetTestSuite(t *testing.T) {

internal/timeline/index.go

@@ -24,103 +24,205 @@ import (
 	"fmt"
 
 	"codeberg.org/gruf/go-kv"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
 	"github.com/superseriousbusiness/gotosocial/internal/log"
 )
 
-func (t *timeline) ItemIndexLength(ctx context.Context) int {
+func (t *timeline) indexXBetweenIDs(ctx context.Context, amount int, behindID string, beforeID string, frontToBack bool) error {
-	if t.indexedItems == nil || t.indexedItems.data == nil {
+	l := log.
-		return 0
+		WithContext(ctx).
-	}
+		WithFields(kv.Fields{
-	return t.indexedItems.data.Len()
+			{"amount", amount},
-}
+			{"behindID", behindID},
+			{"beforeID", beforeID},
+			{"frontToBack", frontToBack},
+		}...)
+	l.Trace("entering indexXBetweenIDs")
 
-func (t *timeline) indexBehind(ctx context.Context, itemID string, amount int) error {
+	if beforeID >= behindID {
-	l := log.WithContext(ctx).
+		// This is an impossible situation, we
-		WithFields(kv.Fields{{"amount", amount}}...)
+		// can't index anything between these.
-
-	// lazily initialize index if it hasn't been done already
-	if t.indexedItems.data == nil {
-		t.indexedItems.data = &list.List{}
-		t.indexedItems.data.Init()
-	}
-
-	// If we're already indexedBehind given itemID by the required amount, we can return nil.
-	// First find position of itemID (or as near as possible).
-	var position int
-positionLoop:
-	for e := t.indexedItems.data.Front(); e != nil; e = e.Next() {
-		entry, ok := e.Value.(*indexedItemsEntry)
-		if !ok {
-			return errors.New("indexBehind: could not parse e as an itemIndexEntry")
-		}
-
-		if entry.itemID <= itemID {
-			// we've found it
-			break positionLoop
-		}
-		position++
-	}
-
-	// now check if the length of indexed items exceeds the amount of items required (position of itemID, plus amount of posts requested after that)
-	if t.indexedItems.data.Len() > position+amount {
-		// we have enough indexed behind already to satisfy amount, so don't need to make db calls
-		l.Trace("returning nil since we already have enough items indexed")
 		return nil
 	}
 
-	toIndex := []Timelineable{}
-	offsetID := itemID
-
-	l.Trace("entering grabloop")
-grabloop:
-	for i := 0; len(toIndex) < amount && i < 5; i++ { // try the grabloop 5 times only
-		// first grab items using the caller-provided grab function
-		l.Trace("grabbing...")
-		items, stop, err := t.grabFunction(ctx, t.accountID, offsetID, "", "", amount)
-		if err != nil {
-			return err
-		}
-		if stop {
-			break grabloop
-		}
-
-		l.Trace("filtering...")
-		// now filter each item using the caller-provided filter function
-		for _, item := range items {
-			shouldIndex, err := t.filterFunction(ctx, t.accountID, item)
-			if err != nil {
-				return err
-			}
-			if shouldIndex {
-				toIndex = append(toIndex, item)
-			}
-			offsetID = item.GetID()
-		}
-	}
-	l.Trace("left grabloop")
-
-	// index the items we got
-	for _, s := range toIndex {
-		if _, err := t.IndexOne(ctx, s.GetID(), s.GetBoostOfID(), s.GetAccountID(), s.GetBoostOfAccountID()); err != nil {
-			return fmt.Errorf("indexBehind: error indexing item with id %s: %s", s.GetID(), err)
-		}
-	}
-
-	return nil
-}
-
-func (t *timeline) IndexOne(ctx context.Context, itemID string, boostOfID string, accountID string, boostOfAccountID string) (bool, error) {
 	t.Lock()
 	defer t.Unlock()
 
-	postIndexEntry := &indexedItemsEntry{
+	// Lazily init indexed items.
-		itemID:           itemID,
+	if t.items.data == nil {
-		boostOfID:        boostOfID,
+		t.items.data = &list.List{}
-		accountID:        accountID,
+		t.items.data.Init()
-		boostOfAccountID: boostOfAccountID,
 	}
 
-	return t.indexedItems.insertIndexed(ctx, postIndexEntry)
+	// Start by mapping out the list so we know what
+	// we have to do. Depending on the current state
+	// of the list we might not have to do *anything*.
+	var (
+		position         int
+		listLen          = t.items.data.Len()
+		behindIDPosition int
+		beforeIDPosition int
+	)
+
+	for e := t.items.data.Front(); e != nil; e = e.Next() {
+		entry := e.Value.(*indexedItemsEntry) //nolint:forcetypeassert
+
+		position++
+
+		if entry.itemID > behindID {
+			l.Trace("item is too new, continuing")
+			continue
+		}
+
+		if behindIDPosition == 0 {
+			// Gone far enough through the list
+			// and found our behindID mark.
+			// We only need to set this once.
+			l.Tracef("found behindID mark %s at position %d", entry.itemID, position)
+			behindIDPosition = position
+		}
+
+		if entry.itemID >= beforeID {
+			// Push the beforeID mark back
+			// one place every iteration.
+			l.Tracef("setting beforeID mark %s at position %d", entry.itemID, position)
+			beforeIDPosition = position
+		}
+
+		if entry.itemID <= beforeID {
+			// We've gone beyond the bounds of
+			// items we're interested in; stop.
+			l.Trace("reached older items, breaking")
+			break
+		}
+	}
+
+	// We can now figure out if we need to make db calls.
+	var grabMore bool
+	switch {
+	case listLen < amount:
+		// The whole list is shorter than the
+		// amount we're being asked to return,
+		// make up the difference.
+		grabMore = true
+		amount -= listLen
+	case beforeIDPosition-behindIDPosition < amount:
+		// Not enough items between behindID and
+		// beforeID to return amount required,
+		// try to get more.
+		grabMore = true
+	}
+
+	if !grabMore {
+		// We're good!
+		return nil
+	}
+
+	// Fetch additional items.
+	items, err := t.grab(ctx, amount, behindID, beforeID, frontToBack)
+	if err != nil {
+		return err
+	}
+
+	// Index all the items we got. We already have
+	// a lock on the timeline, so don't call IndexOne
+	// here, since that will also try to get a lock!
+	for _, item := range items {
+		entry := &indexedItemsEntry{
+			itemID:           item.GetID(),
+			boostOfID:        item.GetBoostOfID(),
+			accountID:        item.GetAccountID(),
+			boostOfAccountID: item.GetBoostOfAccountID(),
+		}
+
+		if _, err := t.items.insertIndexed(ctx, entry); err != nil {
+			return fmt.Errorf("error inserting entry with itemID %s into index: %w", entry.itemID, err)
+		}
+	}
+
+	return nil
+}
+
+// grab wraps the timeline's grabFunction in paging + filtering logic.
+func (t *timeline) grab(ctx context.Context, amount int, behindID string, beforeID string, frontToBack bool) ([]Timelineable, error) {
+	var (
+		sinceID  string
+		minID    string
+		grabbed  int
+		maxID    = behindID
+		filtered = make([]Timelineable, 0, amount)
+	)
+
+	if frontToBack {
+		sinceID = beforeID
+	} else {
+		minID = beforeID
+	}
+
+	for attempts := 0; attempts < 5; attempts++ {
+		if grabbed >= amount {
+			// We got everything we needed.
+			break
+		}
+
+		items, stop, err := t.grabFunction(
+			ctx,
+			t.accountID,
+			maxID,
+			sinceID,
+			minID,
+			// Don't grab more than we need to.
+			amount-grabbed,
+		)
+
+		if err != nil {
+			// Grab function already checks for
+			// db.ErrNoEntries, so if an error
+			// is returned then it's a real one.
+			return nil, err
+		}
+
+		if stop || len(items) == 0 {
+			// No items left.
+			break
+		}
+
+		// Set next query parameters.
+		if frontToBack {
+			// Page down.
+			maxID = items[len(items)-1].GetID()
+			if maxID <= beforeID {
+				// Can't go any further.
+				break
+			}
+		} else {
+			// Page up.
+			minID = items[0].GetID()
+			if minID >= behindID {
+				// Can't go any further.
+				break
+			}
+		}
+
+		for _, item := range items {
+			ok, err := t.filterFunction(ctx, t.accountID, item)
+			if err != nil {
+				if !errors.Is(err, db.ErrNoEntries) {
+					// Real error here.
+					return nil, err
+				}
+				log.Warnf(ctx, "errNoEntries while filtering item %s: %s", item.GetID(), err)
+				continue
+			}
+
+			if ok {
+				filtered = append(filtered, item)
+				grabbed++ // count this as grabbed
+			}
+		}
+	}
+
+	return filtered, nil
 }
 
 func (t *timeline) IndexAndPrepareOne(ctx context.Context, statusID string, boostOfID string, accountID string, boostOfAccountID string) (bool, error) {
@@ -134,46 +236,49 @@ func (t *timeline) IndexAndPrepareOne(ctx context.Context, statusID string, boos
 		boostOfAccountID: boostOfAccountID,
 	}
 
-	inserted, err := t.indexedItems.insertIndexed(ctx, postIndexEntry)
+	if inserted, err := t.items.insertIndexed(ctx, postIndexEntry); err != nil {
+		return false, fmt.Errorf("IndexAndPrepareOne: error inserting indexed: %w", err)
+	} else if !inserted {
+		// Entry wasn't inserted, so
+		// don't bother preparing it.
+		return false, nil
+	}
+
+	preparable, err := t.prepareFunction(ctx, t.accountID, statusID)
 	if err != nil {
-		return inserted, fmt.Errorf("IndexAndPrepareOne: error inserting indexed: %s", err)
+		return true, fmt.Errorf("IndexAndPrepareOne: error preparing: %w", err)
 	}
+	postIndexEntry.prepared = preparable
 
-	if inserted {
+	return true, nil
-		if err := t.prepare(ctx, statusID); err != nil {
-			return inserted, fmt.Errorf("IndexAndPrepareOne: error preparing: %s", err)
-		}
-	}
-
-	return inserted, nil
 }
 
-func (t *timeline) OldestIndexedItemID(ctx context.Context) (string, error) {
+func (t *timeline) Len() int {
-	var id string
+	t.Lock()
-	if t.indexedItems == nil || t.indexedItems.data == nil || t.indexedItems.data.Back() == nil {
+	defer t.Unlock()
-		// return an empty string if postindex hasn't been initialized yet
+
-		return id, nil
+	if t.items == nil || t.items.data == nil {
+		// indexedItems hasnt been initialized yet.
+		return 0
 	}
 
-	e := t.indexedItems.data.Back()
+	return t.items.data.Len()
-	entry, ok := e.Value.(*indexedItemsEntry)
-	if !ok {
-		return id, errors.New("OldestIndexedItemID: could not parse e as itemIndexEntry")
-	}
-	return entry.itemID, nil
 }
 
-func (t *timeline) NewestIndexedItemID(ctx context.Context) (string, error) {
+func (t *timeline) OldestIndexedItemID() string {
-	var id string
+	t.Lock()
-	if t.indexedItems == nil || t.indexedItems.data == nil || t.indexedItems.data.Front() == nil {
+	defer t.Unlock()
-		// return an empty string if postindex hasn't been initialized yet
+
-		return id, nil
+	if t.items == nil || t.items.data == nil {
+		// indexedItems hasnt been initialized yet.
+		return ""
 	}
 
-	e := t.indexedItems.data.Front()
+	e := t.items.data.Back()
-	entry, ok := e.Value.(*indexedItemsEntry)
+	if e == nil {
-	if !ok {
+		// List was empty.
-		return id, errors.New("NewestIndexedItemID: could not parse e as itemIndexEntry")
+		return ""
 	}
-	return entry.itemID, nil
+
+	return e.Value.(*indexedItemsEntry).itemID //nolint:forcetypeassert
 }

internal/timeline/index_test.go

@@ -52,7 +52,7 @@ func (suite *IndexTestSuite) SetupTest() {
 	testrig.StandardDBSetup(suite.db, nil)
 
 	// let's take local_account_1 as the timeline owner, and start with an empty timeline
-	tl, err := timeline.NewTimeline(
+	suite.timeline = timeline.NewTimeline(
 		context.Background(),
 		suite.testAccounts["local_account_1"].ID,
 		processing.StatusGrabFunction(suite.db),
@@ -60,10 +60,6 @@ func (suite *IndexTestSuite) SetupTest() {
 		processing.StatusPrepareFunction(suite.db, suite.tc),
 		processing.StatusSkipInsertFunction(),
 	)
-	if err != nil {
-		suite.FailNow(err.Error())
-	}
-	suite.timeline = tl
 }
 
 func (suite *IndexTestSuite) TearDownTest() {
@@ -72,12 +68,11 @@ func (suite *IndexTestSuite) TearDownTest() {
 
 func (suite *IndexTestSuite) TestOldestIndexedItemIDEmpty() {
 	// the oldest indexed post should be an empty string since there's nothing indexed yet
-	postID, err := suite.timeline.OldestIndexedItemID(context.Background())
+	postID := suite.timeline.OldestIndexedItemID()
-	suite.NoError(err)
 	suite.Empty(postID)
 
 	// indexLength should be 0
-	indexLength := suite.timeline.ItemIndexLength(context.Background())
+	indexLength := suite.timeline.Len()
 	suite.Equal(0, indexLength)
 }
 
@@ -85,12 +80,12 @@ func (suite *IndexTestSuite) TestIndexAlreadyIndexed() {
 	testStatus := suite.testStatuses["local_account_1_status_1"]
 
 	// index one post -- it should be indexed
-	indexed, err := suite.timeline.IndexOne(context.Background(), testStatus.ID, testStatus.BoostOfID, testStatus.AccountID, testStatus.BoostOfAccountID)
+	indexed, err := suite.timeline.IndexAndPrepareOne(context.Background(), testStatus.ID, testStatus.BoostOfID, testStatus.AccountID, testStatus.BoostOfAccountID)
 	suite.NoError(err)
 	suite.True(indexed)
 
 	// try to index the same post again -- it should not be indexed
-	indexed, err = suite.timeline.IndexOne(context.Background(), testStatus.ID, testStatus.BoostOfID, testStatus.AccountID, testStatus.BoostOfAccountID)
+	indexed, err = suite.timeline.IndexAndPrepareOne(context.Background(), testStatus.ID, testStatus.BoostOfID, testStatus.AccountID, testStatus.BoostOfAccountID)
 	suite.NoError(err)
 	suite.False(indexed)
 }
@@ -120,12 +115,12 @@ func (suite *IndexTestSuite) TestIndexBoostOfAlreadyIndexed() {
 	}
 
 	// index one post -- it should be indexed
-	indexed, err := suite.timeline.IndexOne(context.Background(), testStatus.ID, testStatus.BoostOfID, testStatus.AccountID, testStatus.BoostOfAccountID)
+	indexed, err := suite.timeline.IndexAndPrepareOne(context.Background(), testStatus.ID, testStatus.BoostOfID, testStatus.AccountID, testStatus.BoostOfAccountID)
 	suite.NoError(err)
 	suite.True(indexed)
 
 	// try to index the a boost of that post -- it should not be indexed
-	indexed, err = suite.timeline.IndexOne(context.Background(), boostOfTestStatus.ID, boostOfTestStatus.BoostOfID, boostOfTestStatus.AccountID, boostOfTestStatus.BoostOfAccountID)
+	indexed, err = suite.timeline.IndexAndPrepareOne(context.Background(), boostOfTestStatus.ID, boostOfTestStatus.BoostOfID, boostOfTestStatus.AccountID, boostOfTestStatus.BoostOfAccountID)
 	suite.NoError(err)
 	suite.False(indexed)
 }

internal/timeline/indexeditems.go

@@ -20,7 +20,7 @@ package timeline
 import (
 	"container/list"
 	"context"
-	"errors"
+	"fmt"
 )
 
 type indexedItems struct {
@@ -33,53 +33,87 @@ type indexedItemsEntry struct {
 	boostOfID        string
 	accountID        string
 	boostOfAccountID string
+	prepared         Preparable
 }
 
+// WARNING: ONLY CALL THIS FUNCTION IF YOU ALREADY HAVE
+// A LOCK ON THE TIMELINE CONTAINING THIS INDEXEDITEMS!
 func (i *indexedItems) insertIndexed(ctx context.Context, newEntry *indexedItemsEntry) (bool, error) {
+	// Lazily init indexed items.
 	if i.data == nil {
 		i.data = &list.List{}
+		i.data.Init()
 	}
 
-	// if we have no entries yet, this is both the newest and oldest entry, so just put it in the front
 	if i.data.Len() == 0 {
+		// We have no entries yet, meaning this is both the
+		// newest + oldest entry, so just put it in the front.
 		i.data.PushFront(newEntry)
 		return true, nil
 	}
 
-	var insertMark *list.Element
+	var (
-	var position int
+		insertMark      *list.Element
-	// We need to iterate through the index to make sure we put this item in the appropriate place according to when it was created.
+		currentPosition int
-	// We also need to make sure we're not inserting a duplicate item -- this can happen sometimes and it's not nice UX (*shudder*).
+	)
+
+	// We need to iterate through the index to make sure we put
+	// this item in the appropriate place according to its id.
+	// We also need to make sure we're not inserting a duplicate
+	// item -- this can happen sometimes and it's sucky UX.
 	for e := i.data.Front(); e != nil; e = e.Next() {
-		position++
+		currentPosition++
 
-		entry, ok := e.Value.(*indexedItemsEntry)
+		currentEntry := e.Value.(*indexedItemsEntry) //nolint:forcetypeassert
-		if !ok {
-			return false, errors.New("insertIndexed: could not parse e as an indexedItemsEntry")
-		}
 
-		skip, err := i.skipInsert(ctx, newEntry.itemID, newEntry.accountID, newEntry.boostOfID, newEntry.boostOfAccountID, entry.itemID, entry.accountID, entry.boostOfID, entry.boostOfAccountID, position)
+		// Check if we need to skip inserting this item based on
-		if err != nil {
+		// the current item.
-			return false, err
+		//
-		}
+		// For example, if the new item is a boost, and the current
-		if skip {
+		// item is the original, we may not want to insert the boost
+		// if it would appear very shortly after the original.
+		if skip, err := i.skipInsert(
+			ctx,
+			newEntry.itemID,
+			newEntry.accountID,
+			newEntry.boostOfID,
+			newEntry.boostOfAccountID,
+			currentEntry.itemID,
+			currentEntry.accountID,
+			currentEntry.boostOfID,
+			currentEntry.boostOfAccountID,
+			currentPosition,
+		); err != nil {
+			return false, fmt.Errorf("insertIndexed: error calling skipInsert: %w", err)
+		} else if skip {
+			// We don't need to insert this at all,
+			// so we can safely bail.
 			return false, nil
 		}
 
-		// if the item to index is newer than e, insert it before e in the list
+		if insertMark != nil {
-		if insertMark == nil {
+			// We already found our mark.
-			if newEntry.itemID > entry.itemID {
+			continue
+		}
+
+		if currentEntry.itemID > newEntry.itemID {
+			// We're still in items newer than
+			// the one we're trying to insert.
+			continue
+		}
+
+		// We found our spot!
 		insertMark = e
 	}
-		}
-	}
 
-	if insertMark != nil {
+	if insertMark == nil {
-		i.data.InsertBefore(newEntry, insertMark)
+		// We looked through the whole timeline and didn't find
-		return true, nil
+		// a mark, so the new item is the oldest item we've seen;
-	}
+		// insert it at the back.
-
-	// if we reach this point it's the oldest item we've seen so put it at the back
 		i.data.PushBack(newEntry)
 		return true, nil
+	}
+
+	i.data.InsertBefore(newEntry, insertMark)
+	return true, nil
 }

internal/timeline/manager.go

@@ -20,14 +20,18 @@ package timeline
 import (
 	"context"
 	"fmt"
-	"strings"
 	"sync"
 	"time"
 
-	"codeberg.org/gruf/go-kv"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
 	"github.com/superseriousbusiness/gotosocial/internal/log"
 )
 
+const (
+	pruneLengthIndexed  = 400
+	pruneLengthPrepared = 50
+)
+
 // Manager abstracts functions for creating timelines for multiple accounts, and adding, removing, and fetching entries from those timelines.
 //
 // By the time a timelineable hits the manager interface, it should already have been filtered and it should be established that the item indeed
@@ -41,38 +45,37 @@ import (
 // Prepared items consist of the item's database ID, the time it was created, AND the apimodel representation of that item, for quick serialization.
 // Prepared items of course take up more memory than indexed items, so they should be regularly pruned if they're not being actively served.
 type Manager interface {
-	// Ingest takes one item and indexes it into the timeline for the given account ID.
+	// IngestOne takes one timelineable and indexes it into the timeline for the given account ID, and then immediately prepares it for serving.
-	//
-	// It should already be established before calling this function that the item actually belongs in the timeline!
-	//
-	// The returned bool indicates whether the item was actually put in the timeline. This could be false in cases where
-	// the item is a boosted status, but a boost of the original status or the status itself already exists recently in the timeline.
-	Ingest(ctx context.Context, item Timelineable, timelineAccountID string) (bool, error)
-	// IngestAndPrepare takes one timelineable and indexes it into the timeline for the given account ID, and then immediately prepares it for serving.
 	// This is useful in cases where we know the item will need to be shown at the top of a user's timeline immediately (eg., a new status is created).
 	//
 	// It should already be established before calling this function that the item actually belongs in the timeline!
 	//
 	// The returned bool indicates whether the item was actually put in the timeline. This could be false in cases where
 	// a status is a boost, but a boost of the original status or the status itself already exists recently in the timeline.
-	IngestAndPrepare(ctx context.Context, item Timelineable, timelineAccountID string) (bool, error)
+	IngestOne(ctx context.Context, accountID string, item Timelineable) (bool, error)
+
 	// GetTimeline returns limit n amount of prepared entries from the timeline of the given account ID, in descending chronological order.
-	// If maxID is provided, it will return prepared entries from that maxID onwards, inclusive.
 	GetTimeline(ctx context.Context, accountID string, maxID string, sinceID string, minID string, limit int, local bool) ([]Preparable, error)
-	// GetIndexedLength returns the amount of items that have been *indexed* for the given account ID.
+
-	GetIndexedLength(ctx context.Context, timelineAccountID string) int
+	// GetIndexedLength returns the amount of items that have been indexed for the given account ID.
+	GetIndexedLength(ctx context.Context, accountID string) int
+
 	// GetOldestIndexedID returns the id ID for the oldest item that we have indexed for the given account.
-	GetOldestIndexedID(ctx context.Context, timelineAccountID string) (string, error)
+	// Will be an empty string if nothing is (yet) indexed.
-	// PrepareXFromTop prepares limit n amount of items, based on their indexed representations, from the top of the index.
+	GetOldestIndexedID(ctx context.Context, accountID string) string
-	PrepareXFromTop(ctx context.Context, timelineAccountID string, limit int) error
+
 	// Remove removes one item from the timeline of the given timelineAccountID
-	Remove(ctx context.Context, timelineAccountID string, itemID string) (int, error)
+	Remove(ctx context.Context, accountID string, itemID string) (int, error)
+
 	// WipeItemFromAllTimelines removes one item from the index and prepared items of all timelines
 	WipeItemFromAllTimelines(ctx context.Context, itemID string) error
+
 	// WipeStatusesFromAccountID removes all items by the given accountID from the timelineAccountID's timelines.
 	WipeItemsFromAccountID(ctx context.Context, timelineAccountID string, accountID string) error
+
 	// Start starts hourly cleanup jobs for this timeline manager.
 	Start() error
+
 	// Stop stops the timeline manager (currently a stub, doesn't do anything).
 	Stop() error
 }
@@ -97,31 +100,41 @@ type manager struct {
 }
 
 func (m *manager) Start() error {
-	// range through all timelines in the sync map once per hour + prune as necessary
+	// Start a background goroutine which iterates
+	// through all stored timelines once per hour,
+	// and cleans up old entries if that timeline
+	// hasn't been accessed in the last hour.
 	go func() {
 		for now := range time.NewTicker(1 * time.Hour).C {
-			m.accountTimelines.Range(func(key any, value any) bool {
+			// Define the range function inside here,
-				timelineAccountID, ok := key.(string)
+			// so that we can use the 'now' returned
+			// by the ticker, instead of having to call
+			// time.Now() multiple times.
+			//
+			// Unless it panics, this function always
+			// returns 'true', to continue the Range
+			// call through the sync.Map.
+			f := func(_ any, v any) bool {
+				timeline, ok := v.(Timeline)
 				if !ok {
-					panic("couldn't parse timeline manager sync map key as string, this should never happen so panic")
+					log.Panic(nil, "couldn't parse timeline manager sync map value as Timeline, this should never happen so panic")
 				}
 
-				t, ok := value.(Timeline)
+				if now.Sub(timeline.LastGot()) < 1*time.Hour {
-				if !ok {
+					// Timeline has been fetched in the
-					panic("couldn't parse timeline manager sync map value as Timeline, this should never happen so panic")
+					// last hour, move on to the next one.
+					return true
 				}
 
-				anHourAgo := now.Add(-1 * time.Hour)
+				if amountPruned := timeline.Prune(pruneLengthPrepared, pruneLengthIndexed); amountPruned > 0 {
-				if lastGot := t.LastGot(); lastGot.Before(anHourAgo) {
+					log.WithField("accountID", timeline.AccountID()).Infof("pruned %d indexed and prepared items from timeline", amountPruned)
-					amountPruned := t.Prune(defaultDesiredPreparedItemsLength, defaultDesiredIndexedItemsLength)
-					log.WithFields(kv.Fields{
-						{"timelineAccountID", timelineAccountID},
-						{"amountPruned", amountPruned},
-					}...).Info("pruned indexed and prepared items from timeline")
 				}
 
 				return true
-			})
+			}
+
+			// Execute the function for each timeline.
+			m.accountTimelines.Range(f)
 		}
 	}()
 
@@ -132,146 +145,69 @@ func (m *manager) Stop() error {
 	return nil
 }
 
-func (m *manager) Ingest(ctx context.Context, item Timelineable, timelineAccountID string) (bool, error) {
+func (m *manager) IngestOne(ctx context.Context, accountID string, item Timelineable) (bool, error) {
-	l := log.WithContext(ctx).
+	return m.getOrCreateTimeline(ctx, accountID).IndexAndPrepareOne(
-		WithFields(kv.Fields{
+		ctx,
-			{"timelineAccountID", timelineAccountID},
+		item.GetID(),
-			{"itemID", item.GetID()},
+		item.GetBoostOfID(),
-		}...)
+		item.GetAccountID(),
-
+		item.GetBoostOfAccountID(),
-	t, err := m.getOrCreateTimeline(ctx, timelineAccountID)
+	)
-	if err != nil {
-		return false, err
-	}
-
-	l.Trace("ingesting item")
-	return t.IndexOne(ctx, item.GetID(), item.GetBoostOfID(), item.GetAccountID(), item.GetBoostOfAccountID())
 }
 
-func (m *manager) IngestAndPrepare(ctx context.Context, item Timelineable, timelineAccountID string) (bool, error) {
+func (m *manager) Remove(ctx context.Context, accountID string, itemID string) (int, error) {
-	l := log.WithContext(ctx).
+	return m.getOrCreateTimeline(ctx, accountID).Remove(ctx, itemID)
-		WithFields(kv.Fields{
-			{"timelineAccountID", timelineAccountID},
-			{"itemID", item.GetID()},
-		}...)
-
-	t, err := m.getOrCreateTimeline(ctx, timelineAccountID)
-	if err != nil {
-		return false, err
-	}
-
-	l.Trace("ingesting item")
-	return t.IndexAndPrepareOne(ctx, item.GetID(), item.GetBoostOfID(), item.GetAccountID(), item.GetBoostOfAccountID())
 }
 
-func (m *manager) Remove(ctx context.Context, timelineAccountID string, itemID string) (int, error) {
+func (m *manager) GetTimeline(ctx context.Context, accountID string, maxID string, sinceID string, minID string, limit int, local bool) ([]Preparable, error) {
-	l := log.WithContext(ctx).
+	return m.getOrCreateTimeline(ctx, accountID).Get(ctx, limit, maxID, sinceID, minID, true)
-		WithFields(kv.Fields{
-			{"timelineAccountID", timelineAccountID},
-			{"itemID", itemID},
-		}...)
-
-	t, err := m.getOrCreateTimeline(ctx, timelineAccountID)
-	if err != nil {
-		return 0, err
-	}
-
-	l.Trace("removing item")
-	return t.Remove(ctx, itemID)
 }
 
-func (m *manager) GetTimeline(ctx context.Context, timelineAccountID string, maxID string, sinceID string, minID string, limit int, local bool) ([]Preparable, error) {
+func (m *manager) GetIndexedLength(ctx context.Context, accountID string) int {
-	l := log.WithContext(ctx).
+	return m.getOrCreateTimeline(ctx, accountID).Len()
-		WithFields(kv.Fields{{"timelineAccountID", timelineAccountID}}...)
-
-	t, err := m.getOrCreateTimeline(ctx, timelineAccountID)
-	if err != nil {
-		return nil, err
-	}
-
-	items, err := t.Get(ctx, limit, maxID, sinceID, minID, true)
-	if err != nil {
-		l.Errorf("error getting statuses: %s", err)
-	}
-	return items, nil
 }
 
-func (m *manager) GetIndexedLength(ctx context.Context, timelineAccountID string) int {
+func (m *manager) GetOldestIndexedID(ctx context.Context, accountID string) string {
-	t, err := m.getOrCreateTimeline(ctx, timelineAccountID)
+	return m.getOrCreateTimeline(ctx, accountID).OldestIndexedItemID()
-	if err != nil {
-		return 0
-	}
-
-	return t.ItemIndexLength(ctx)
-}
-
-func (m *manager) GetOldestIndexedID(ctx context.Context, timelineAccountID string) (string, error) {
-	t, err := m.getOrCreateTimeline(ctx, timelineAccountID)
-	if err != nil {
-		return "", err
-	}
-
-	return t.OldestIndexedItemID(ctx)
-}
-
-func (m *manager) PrepareXFromTop(ctx context.Context, timelineAccountID string, limit int) error {
-	t, err := m.getOrCreateTimeline(ctx, timelineAccountID)
-	if err != nil {
-		return err
-	}
-
-	return t.PrepareFromTop(ctx, limit)
 }
 
 func (m *manager) WipeItemFromAllTimelines(ctx context.Context, statusID string) error {
-	errors := []string{}
+	errors := gtserror.MultiError{}
-	m.accountTimelines.Range(func(k interface{}, i interface{}) bool {
+
-		t, ok := i.(Timeline)
+	m.accountTimelines.Range(func(_ any, v any) bool {
-		if !ok {
+		if _, err := v.(Timeline).Remove(ctx, statusID); err != nil {
-			panic("couldn't parse entry as Timeline, this should never happen so panic")
+			errors.Append(err)
 		}
 
-		if _, err := t.Remove(ctx, statusID); err != nil {
+		return true // always continue range
-			errors = append(errors, err.Error())
-		}
-
-		return true
 	})
 
-	var err error
 	if len(errors) > 0 {
-		err = fmt.Errorf("one or more errors removing status %s from all timelines: %s", statusID, strings.Join(errors, ";"))
+		return fmt.Errorf("WipeItemFromAllTimelines: one or more errors wiping status %s: %w", statusID, errors.Combine())
 	}
 
-	return err
+	return nil
 }
 
 func (m *manager) WipeItemsFromAccountID(ctx context.Context, timelineAccountID string, accountID string) error {
-	t, err := m.getOrCreateTimeline(ctx, timelineAccountID)
+	_, err := m.getOrCreateTimeline(ctx, timelineAccountID).RemoveAllByOrBoosting(ctx, accountID)
-	if err != nil {
-		return err
-	}
-
-	_, err = t.RemoveAllBy(ctx, accountID)
 	return err
 }
 
-func (m *manager) getOrCreateTimeline(ctx context.Context, timelineAccountID string) (Timeline, error) {
+// getOrCreateTimeline returns a timeline for the given
-	var t Timeline
+// accountID. If a timeline does not yet exist in the
-	i, ok := m.accountTimelines.Load(timelineAccountID)
+// manager's sync.Map, it will be created and stored.
-	if !ok {
+func (m *manager) getOrCreateTimeline(ctx context.Context, accountID string) Timeline {
-		var err error
+	i, ok := m.accountTimelines.Load(accountID)
-		t, err = NewTimeline(ctx, timelineAccountID, m.grabFunction, m.filterFunction, m.prepareFunction, m.skipInsertFunction)
+	if ok {
-		if err != nil {
+		// Timeline already existed in sync.Map.
-			return nil, err
+		return i.(Timeline) //nolint:forcetypeassert
-		}
-		m.accountTimelines.Store(timelineAccountID, t)
-	} else {
-		t, ok = i.(Timeline)
-		if !ok {
-			panic("couldn't parse entry as Timeline, this should never happen so panic")
-		}
 	}
 
-	return t, nil
+	// Timeline did not yet exist in sync.Map.
+	// Create + store it.
+	timeline := NewTimeline(ctx, accountID, m.grabFunction, m.filterFunction, m.prepareFunction, m.skipInsertFunction)
+	m.accountTimelines.Store(accountID, timeline)
+
+	return timeline
 }

internal/timeline/manager_test.go

@@ -72,23 +72,9 @@ func (suite *ManagerTestSuite) TestManagerIntegration() {
 	suite.Equal(0, indexedLen)
 
 	// oldestIndexed should be empty string since there's nothing indexed
-	oldestIndexed, err := suite.manager.GetOldestIndexedID(ctx, testAccount.ID)
+	oldestIndexed := suite.manager.GetOldestIndexedID(ctx, testAccount.ID)
-	suite.NoError(err)
 	suite.Empty(oldestIndexed)
 
-	// trigger status preparation
-	err = suite.manager.PrepareXFromTop(ctx, testAccount.ID, 20)
-	suite.NoError(err)
-
-	// local_account_1 can see 16 statuses out of the testrig statuses in its home timeline
-	indexedLen = suite.manager.GetIndexedLength(ctx, testAccount.ID)
-	suite.Equal(16, indexedLen)
-
-	// oldest should now be set
-	oldestIndexed, err = suite.manager.GetOldestIndexedID(ctx, testAccount.ID)
-	suite.NoError(err)
-	suite.Equal("01F8MH75CBF9JFX4ZAD54N0W0R", oldestIndexed)
-
 	// get hometimeline
 	statuses, err := suite.manager.GetTimeline(ctx, testAccount.ID, "", "", "", 20, false)
 	suite.NoError(err)
@@ -103,22 +89,20 @@ func (suite *ManagerTestSuite) TestManagerIntegration() {
 	suite.Equal(15, indexedLen)
 
 	// oldest should now be different
-	oldestIndexed, err = suite.manager.GetOldestIndexedID(ctx, testAccount.ID)
+	oldestIndexed = suite.manager.GetOldestIndexedID(ctx, testAccount.ID)
-	suite.NoError(err)
 	suite.Equal("01F8MH82FYRXD2RC6108DAJ5HB", oldestIndexed)
 
 	// delete the new oldest status specifically from this timeline, as though local_account_1 had muted or blocked it
 	removed, err := suite.manager.Remove(ctx, testAccount.ID, "01F8MH82FYRXD2RC6108DAJ5HB")
 	suite.NoError(err)
-	suite.Equal(2, removed) // 1 status should be removed, but from both indexed and prepared, so 2 removals total
+	suite.Equal(1, removed) // 1 status should be removed
 
 	// timeline should be shorter
 	indexedLen = suite.manager.GetIndexedLength(ctx, testAccount.ID)
 	suite.Equal(14, indexedLen)
 
 	// oldest should now be different
-	oldestIndexed, err = suite.manager.GetOldestIndexedID(ctx, testAccount.ID)
+	oldestIndexed = suite.manager.GetOldestIndexedID(ctx, testAccount.ID)
-	suite.NoError(err)
 	suite.Equal("01F8MHAAY43M6RJ473VQFCVH37", oldestIndexed)
 
 	// now remove all entries by local_account_2 from the timeline
@@ -129,24 +113,18 @@ func (suite *ManagerTestSuite) TestManagerIntegration() {
 	indexedLen = suite.manager.GetIndexedLength(ctx, testAccount.ID)
 	suite.Equal(7, indexedLen)
 
-	// ingest 1 into the timeline
-	status1 := suite.testStatuses["admin_account_status_1"]
-	ingested, err := suite.manager.Ingest(ctx, status1, testAccount.ID)
-	suite.NoError(err)
-	suite.True(ingested)
-
 	// ingest and prepare another one into the timeline
-	status2 := suite.testStatuses["local_account_2_status_1"]
+	status := suite.testStatuses["local_account_2_status_1"]
-	ingested, err = suite.manager.IngestAndPrepare(ctx, status2, testAccount.ID)
+	ingested, err := suite.manager.IngestOne(ctx, testAccount.ID, status)
 	suite.NoError(err)
 	suite.True(ingested)
 
 	// timeline should be longer now
 	indexedLen = suite.manager.GetIndexedLength(ctx, testAccount.ID)
-	suite.Equal(9, indexedLen)
+	suite.Equal(8, indexedLen)
 
-	// try to ingest status 2 again
+	// try to ingest same status again
-	ingested, err = suite.manager.IngestAndPrepare(ctx, status2, testAccount.ID)
+	ingested, err = suite.manager.IngestOne(ctx, testAccount.ID, status)
 	suite.NoError(err)
 	suite.False(ingested) // should be false since it's a duplicate
 }

internal/timeline/preparable.go

@@ -1,25 +0,0 @@
-// GoToSocial
-// Copyright (C) GoToSocial Authors admin@gotosocial.org
-// SPDX-License-Identifier: AGPL-3.0-or-later
-//
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU Affero General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU Affero General Public License for more details.
-//
-// You should have received a copy of the GNU Affero General Public License
-// along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-package timeline
-
-type Preparable interface {
-	GetID() string
-	GetAccountID() string
-	GetBoostOfID() string
-	GetBoostOfAccountID() string
-}

internal/timeline/prepare.go

@@ -25,240 +25,114 @@ import (
 
 	"codeberg.org/gruf/go-kv"
 	"github.com/superseriousbusiness/gotosocial/internal/db"
-	"github.com/superseriousbusiness/gotosocial/internal/id"
 	"github.com/superseriousbusiness/gotosocial/internal/log"
 )
 
-func (t *timeline) PrepareFromTop(ctx context.Context, amount int) error {
+func (t *timeline) prepareXBetweenIDs(ctx context.Context, amount int, behindID string, beforeID string, frontToBack bool) error {
-	l := log.WithContext(ctx).
+	l := log.
-		WithFields(kv.Fields{{"amount", amount}}...)
+		WithContext(ctx).
-
-	// lazily initialize prepared posts if it hasn't been done already
-	if t.preparedItems.data == nil {
-		t.preparedItems.data = &list.List{}
-		t.preparedItems.data.Init()
-	}
-
-	// if the postindex is nil, nothing has been indexed yet so index from the highest ID possible
-	if t.indexedItems.data == nil {
-		l.Debug("postindex.data was nil, indexing behind highest possible ID")
-		if err := t.indexBehind(ctx, id.Highest, amount); err != nil {
-			return fmt.Errorf("PrepareFromTop: error indexing behind id %s: %s", id.Highest, err)
-		}
-	}
-
-	l.Trace("entering prepareloop")
-	t.Lock()
-	defer t.Unlock()
-	var prepared int
-prepareloop:
-	for e := t.indexedItems.data.Front(); e != nil; e = e.Next() {
-		if e == nil {
-			continue
-		}
-
-		entry, ok := e.Value.(*indexedItemsEntry)
-		if !ok {
-			return errors.New("PrepareFromTop: could not parse e as a postIndexEntry")
-		}
-
-		if err := t.prepare(ctx, entry.itemID); err != nil {
-			// there's been an error
-			if err != db.ErrNoEntries {
-				// it's a real error
-				return fmt.Errorf("PrepareFromTop: error preparing status with id %s: %s", entry.itemID, err)
-			}
-			// the status just doesn't exist (anymore) so continue to the next one
-			continue
-		}
-
-		prepared++
-		if prepared == amount {
-			// we're done
-			l.Trace("leaving prepareloop")
-			break prepareloop
-		}
-	}
-
-	l.Trace("leaving function")
-	return nil
-}
-
-func (t *timeline) prepareNextQuery(ctx context.Context, amount int, maxID string, sinceID string, minID string) error {
-	l := log.WithContext(ctx).
 		WithFields(kv.Fields{
 			{"amount", amount},
-			{"maxID", maxID},
+			{"behindID", behindID},
-			{"sinceID", sinceID},
+			{"beforeID", beforeID},
-			{"minID", minID},
+			{"frontToBack", frontToBack},
 		}...)
+	l.Trace("entering prepareXBetweenIDs")
 
-	var err error
+	if beforeID >= behindID {
-	switch {
+		// This is an impossible situation, we
-	case maxID != "" && sinceID == "":
+		// can't prepare anything between these.
-		l.Debug("preparing behind maxID")
-		err = t.prepareBehind(ctx, maxID, amount)
-	case maxID == "" && sinceID != "":
-		l.Debug("preparing before sinceID")
-		err = t.prepareBefore(ctx, sinceID, false, amount)
-	case maxID == "" && minID != "":
-		l.Debug("preparing before minID")
-		err = t.prepareBefore(ctx, minID, false, amount)
-	}
-
-	return err
-}
-
-// prepareBehind instructs the timeline to prepare the next amount of entries for serialization, from position onwards.
-// If include is true, then the given item ID will also be prepared, otherwise only entries behind it will be prepared.
-func (t *timeline) prepareBehind(ctx context.Context, itemID string, amount int) error {
-	// lazily initialize prepared items if it hasn't been done already
-	if t.preparedItems.data == nil {
-		t.preparedItems.data = &list.List{}
-		t.preparedItems.data.Init()
-	}
-
-	if err := t.indexBehind(ctx, itemID, amount); err != nil {
-		return fmt.Errorf("prepareBehind: error indexing behind id %s: %s", itemID, err)
-	}
-
-	// if the itemindex is nil, nothing has been indexed yet so there's nothing to prepare
-	if t.indexedItems.data == nil {
 		return nil
 	}
 
-	var prepared int
+	if err := t.indexXBetweenIDs(ctx, amount, behindID, beforeID, frontToBack); err != nil {
-	var preparing bool
+		// An error here doesn't necessarily mean we
-	t.Lock()
+		// can't prepare anything, so log + keep going.
-	defer t.Unlock()
+		l.Debugf("error calling prepareXBetweenIDs: %s", err)
-prepareloop:
-	for e := t.indexedItems.data.Front(); e != nil; e = e.Next() {
-		entry, ok := e.Value.(*indexedItemsEntry)
-		if !ok {
-			return errors.New("prepareBehind: could not parse e as itemIndexEntry")
 	}
 
-		if !preparing {
-			// we haven't hit the position we need to prepare from yet
-			if entry.itemID == itemID {
-				preparing = true
-			}
-		}
-
-		if preparing {
-			if err := t.prepare(ctx, entry.itemID); err != nil {
-				// there's been an error
-				if err != db.ErrNoEntries {
-					// it's a real error
-					return fmt.Errorf("prepareBehind: error preparing item with id %s: %s", entry.itemID, err)
-				}
-				// the status just doesn't exist (anymore) so continue to the next one
-				continue
-			}
-			if prepared == amount {
-				// we're done
-				break prepareloop
-			}
-			prepared++
-		}
-	}
-
-	return nil
-}
-
-func (t *timeline) prepareBefore(ctx context.Context, statusID string, include bool, amount int) error {
 	t.Lock()
 	defer t.Unlock()
 
-	// lazily initialize prepared posts if it hasn't been done already
+	// Try to prepare everything between (and including) the two points.
-	if t.preparedItems.data == nil {
+	var (
-		t.preparedItems.data = &list.List{}
+		toPrepare      = make(map[*list.Element]*indexedItemsEntry)
-		t.preparedItems.data.Init()
+		foundToPrepare int
-	}
+	)
 
-	// if the postindex is nil, nothing has been indexed yet so there's nothing to prepare
+	if frontToBack {
-	if t.indexedItems.data == nil {
+		// Paging forwards / down.
-		return nil
+		for e := t.items.data.Front(); e != nil; e = e.Next() {
-	}
+			entry := e.Value.(*indexedItemsEntry) //nolint:forcetypeassert
 
-	var prepared int
+			if entry.itemID > behindID {
-	var preparing bool
+				l.Trace("item is too new, continuing")
-prepareloop:
-	for e := t.indexedItems.data.Back(); e != nil; e = e.Prev() {
-		entry, ok := e.Value.(*indexedItemsEntry)
-		if !ok {
-			return errors.New("prepareBefore: could not parse e as a postIndexEntry")
-		}
-
-		if !preparing {
-			// we haven't hit the position we need to prepare from yet
-			if entry.itemID == statusID {
-				preparing = true
-				if !include {
 				continue
 			}
-			}
+
+			if entry.itemID < beforeID {
+				// We've gone beyond the bounds of
+				// items we're interested in; stop.
+				l.Trace("reached older items, breaking")
+				break
 			}
 
-		if preparing {
+			// Only prepare entry if it's not
-			if err := t.prepare(ctx, entry.itemID); err != nil {
+			// already prepared, save db calls.
-				// there's been an error
+			if entry.prepared == nil {
-				if err != db.ErrNoEntries {
+				toPrepare[e] = entry
-					// it's a real error
-					return fmt.Errorf("prepareBefore: error preparing status with id %s: %s", entry.itemID, err)
 			}
-				// the status just doesn't exist (anymore) so continue to the next one
+
+			foundToPrepare++
+			if foundToPrepare >= amount {
+				break
+			}
+		}
+	} else {
+		// Paging backwards / up.
+		for e := t.items.data.Back(); e != nil; e = e.Prev() {
+			entry := e.Value.(*indexedItemsEntry) //nolint:forcetypeassert
+
+			if entry.itemID < beforeID {
+				l.Trace("item is too old, continuing")
 				continue
 			}
-			if prepared == amount {
+
-				// we're done
+			if entry.itemID > behindID {
-				break prepareloop
+				// We've gone beyond the bounds of
+				// items we're interested in; stop.
+				l.Trace("reached newer items, breaking")
+				break
+			}
+
+			if entry.prepared == nil {
+				toPrepare[e] = entry
+			}
+
+			// Only prepare entry if it's not
+			// already prepared, save db calls.
+			foundToPrepare++
+			if foundToPrepare >= amount {
+				break
 			}
-			prepared++
 		}
 	}
 
-	return nil
+	for e, entry := range toPrepare {
-}
+		prepared, err := t.prepareFunction(ctx, t.accountID, entry.itemID)
-
-func (t *timeline) prepare(ctx context.Context, itemID string) error {
-	// trigger the caller-provided prepare function
-	prepared, err := t.prepareFunction(ctx, t.accountID, itemID)
 		if err != nil {
-		return err
+			if errors.Is(err, db.ErrNoEntries) {
+				// ErrNoEntries means something has been deleted,
+				// so we'll likely not be able to ever prepare this.
+				// This means we can remove it and skip past it.
+				l.Debugf("db.ErrNoEntries while trying to prepare %s; will remove from timeline", entry.itemID)
+				t.items.data.Remove(e)
+			}
+			// We've got a proper db error.
+			return fmt.Errorf("prepareXBetweenIDs: db error while trying to prepare %s: %w", entry.itemID, err)
+		}
+		entry.prepared = prepared
 	}
 
-	// shove it in prepared items as a prepared items entry
+	return nil
-	preparedItemsEntry := &preparedItemsEntry{
-		itemID:           prepared.GetID(),
-		boostOfID:        prepared.GetBoostOfID(),
-		accountID:        prepared.GetAccountID(),
-		boostOfAccountID: prepared.GetBoostOfAccountID(),
-		prepared:         prepared,
-	}
-
-	return t.preparedItems.insertPrepared(ctx, preparedItemsEntry)
-}
-
-// oldestPreparedItemID returns the id of the rearmost (ie., the oldest) prepared item, or an error if something goes wrong.
-// If nothing goes wrong but there's no oldest item, an empty string will be returned so make sure to check for this.
-func (t *timeline) oldestPreparedItemID(ctx context.Context) (string, error) {
-	var id string
-	if t.preparedItems == nil || t.preparedItems.data == nil {
-		// return an empty string if prepared items hasn't been initialized yet
-		return id, nil
-	}
-
-	e := t.preparedItems.data.Back()
-	if e == nil {
-		// return an empty string if there's no back entry (ie., the index list hasn't been initialized yet)
-		return id, nil
-	}
-
-	entry, ok := e.Value.(*preparedItemsEntry)
-	if !ok {
-		return id, errors.New("oldestPreparedItemID: could not parse e as a preparedItemsEntry")
-	}
-
-	return entry.itemID, nil
 }

internal/timeline/prepareditems.go

@@ -1,91 +0,0 @@
-// GoToSocial
-// Copyright (C) GoToSocial Authors admin@gotosocial.org
-// SPDX-License-Identifier: AGPL-3.0-or-later
-//
-// This program is free software: you can redistribute it and/or modify
-// it under the terms of the GNU Affero General Public License as published by
-// the Free Software Foundation, either version 3 of the License, or
-// (at your option) any later version.
-//
-// This program is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU Affero General Public License for more details.
-//
-// You should have received a copy of the GNU Affero General Public License
-// along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-package timeline
-
-import (
-	"container/list"
-	"context"
-	"errors"
-)
-
-type preparedItems struct {
-	data       *list.List
-	skipInsert SkipInsertFunction
-}
-
-type preparedItemsEntry struct {
-	itemID           string
-	boostOfID        string
-	accountID        string
-	boostOfAccountID string
-	prepared         Preparable
-}
-
-func (p *preparedItems) insertPrepared(ctx context.Context, newEntry *preparedItemsEntry) error {
-	if p.data == nil {
-		p.data = &list.List{}
-	}
-
-	// if we have no entries yet, this is both the newest and oldest entry, so just put it in the front
-	if p.data.Len() == 0 {
-		p.data.PushFront(newEntry)
-		return nil
-	}
-
-	var insertMark *list.Element
-	var position int
-	// We need to iterate through the index to make sure we put this entry in the appropriate place according to when it was created.
-	// We also need to make sure we're not inserting a duplicate entry -- this can happen sometimes and it's not nice UX (*shudder*).
-	for e := p.data.Front(); e != nil; e = e.Next() {
-		position++
-
-		entry, ok := e.Value.(*preparedItemsEntry)
-		if !ok {
-			return errors.New("insertPrepared: could not parse e as a preparedItemsEntry")
-		}
-
-		skip, err := p.skipInsert(ctx, newEntry.itemID, newEntry.accountID, newEntry.boostOfID, newEntry.boostOfAccountID, entry.itemID, entry.accountID, entry.boostOfID, entry.boostOfAccountID, position)
-		if err != nil {
-			return err
-		}
-		if skip {
-			return nil
-		}
-
-		// if the entry to index is newer than e, insert it before e in the list
-		if insertMark == nil {
-			if newEntry.itemID > entry.itemID {
-				insertMark = e
-			}
-		}
-
-		// make sure we don't insert a duplicate
-		if entry.itemID == newEntry.itemID {
-			return nil
-		}
-	}
-
-	if insertMark != nil {
-		p.data.InsertBefore(newEntry, insertMark)
-		return nil
-	}
-
-	// if we reach this point it's the oldest entry we've seen so put it at the back
-	p.data.PushBack(newEntry)
-	return nil
-}

internal/timeline/prune.go

@@ -21,47 +21,63 @@ import (
 	"container/list"
 )
 
-const (
-	defaultDesiredIndexedItemsLength  = 400
-	defaultDesiredPreparedItemsLength = 50
-)
-
 func (t *timeline) Prune(desiredPreparedItemsLength int, desiredIndexedItemsLength int) int {
 	t.Lock()
 	defer t.Unlock()
 
-	pruneList := func(pruneTo int, listToPrune *list.List) int {
+	l := t.items.data
-		if listToPrune == nil {
+	if l == nil {
-			// no need to prune
+		// Nothing to prune.
 		return 0
 	}
 
-		unprunedLength := listToPrune.Len()
+	var (
-		if unprunedLength <= pruneTo {
+		position    int
-			// no need to prune
+		totalPruned int
-			return 0
+		toRemove    *[]*list.Element
+	)
+
+	// Only initialize toRemove if we know we're
+	// going to need it, otherwise skiperino.
+	if toRemoveLen := t.items.data.Len() - desiredIndexedItemsLength; toRemoveLen > 0 {
+		toRemove = func() *[]*list.Element { tr := make([]*list.Element, 0, toRemoveLen); return &tr }()
 	}
 
-		// work from the back + assemble a slice of entries that we will prune
+	// Work from the front of the list until we get
-		amountStillToPrune := unprunedLength - pruneTo
+	// to the point where we need to start pruning.
-		itemsToPrune := make([]*list.Element, 0, amountStillToPrune)
+	for e := l.Front(); e != nil; e = e.Next() {
-		for e := listToPrune.Back(); amountStillToPrune > 0; e = e.Prev() {
+		position++
-			itemsToPrune = append(itemsToPrune, e)
+
-			amountStillToPrune--
+		if position <= desiredPreparedItemsLength {
+			// We're still within our allotted
+			// prepped length, nothing to do yet.
+			continue
 		}
 
-		// remove the entries we found
+		// We need to *at least* unprepare this entry.
-		var totalPruned int
+		// If we're beyond our indexed length already,
-		for _, e := range itemsToPrune {
+		// we can just remove the item completely.
-			listToPrune.Remove(e)
+		if position > desiredIndexedItemsLength {
+			*toRemove = append(*toRemove, e)
+			totalPruned++
+			continue
+		}
+
+		entry := e.Value.(*indexedItemsEntry) //nolint:forcetypeassert
+		if entry.prepared == nil {
+			// It's already unprepared (mood).
+			continue
+		}
+
+		entry.prepared = nil // <- eat this up please garbage collector nom nom nom
 		totalPruned++
 	}
 
-		return totalPruned
+	if toRemove != nil {
+		for _, e := range *toRemove {
+			l.Remove(e)
+		}
 	}
 
-	prunedPrepared := pruneList(desiredPreparedItemsLength, t.preparedItems.data)
+	return totalPruned
-	prunedIndexed := pruneList(desiredIndexedItemsLength, t.indexedItems.data)
-
-	return prunedPrepared + prunedIndexed
 }

internal/timeline/prune_test.go

@@ -52,7 +52,7 @@ func (suite *PruneTestSuite) SetupTest() {
 	testrig.StandardDBSetup(suite.db, nil)
 
 	// let's take local_account_1 as the timeline owner
-	tl, err := timeline.NewTimeline(
+	tl := timeline.NewTimeline(
 		context.Background(),
 		suite.testAccounts["local_account_1"].ID,
 		processing.StatusGrabFunction(suite.db),
@@ -60,9 +60,6 @@ func (suite *PruneTestSuite) SetupTest() {
 		processing.StatusPrepareFunction(suite.db, suite.tc),
 		processing.StatusSkipInsertFunction(),
 	)
-	if err != nil {
-		suite.FailNow(err.Error())
-	}
 
 	// put the status IDs in a determinate order since we can't trust a map to keep its order
 	statuses := []*gtsmodel.Status{}
@@ -90,20 +87,30 @@ func (suite *PruneTestSuite) TearDownTest() {
 
 func (suite *PruneTestSuite) TestPrune() {
 	// prune down to 5 prepared + 5 indexed
-	suite.Equal(24, suite.timeline.Prune(5, 5))
+	suite.Equal(12, suite.timeline.Prune(5, 5))
-	suite.Equal(5, suite.timeline.ItemIndexLength(context.Background()))
+	suite.Equal(5, suite.timeline.Len())
+}
+
+func (suite *PruneTestSuite) TestPruneTwice() {
+	// prune down to 5 prepared + 10 indexed
+	suite.Equal(12, suite.timeline.Prune(5, 10))
+	suite.Equal(10, suite.timeline.Len())
+
+	// Prune same again, nothing should be pruned this time.
+	suite.Zero(suite.timeline.Prune(5, 10))
+	suite.Equal(10, suite.timeline.Len())
 }
 
 func (suite *PruneTestSuite) TestPruneTo0() {
 	// prune down to 0 prepared + 0 indexed
-	suite.Equal(34, suite.timeline.Prune(0, 0))
+	suite.Equal(17, suite.timeline.Prune(0, 0))
-	suite.Equal(0, suite.timeline.ItemIndexLength(context.Background()))
+	suite.Equal(0, suite.timeline.Len())
 }
 
 func (suite *PruneTestSuite) TestPruneToInfinityAndBeyond() {
 	// prune to 99999, this should result in no entries being pruned
 	suite.Equal(0, suite.timeline.Prune(99999, 99999))
-	suite.Equal(17, suite.timeline.ItemIndexLength(context.Background()))
+	suite.Equal(17, suite.timeline.Len())
 }
 
 func TestPruneTestSuite(t *testing.T) {

internal/timeline/remove.go

@@ -20,7 +20,6 @@ package timeline
 import (
 	"container/list"
 	"context"
-	"errors"
 
 	"codeberg.org/gruf/go-kv"
 	"github.com/superseriousbusiness/gotosocial/internal/log"
@@ -35,52 +34,35 @@ func (t *timeline) Remove(ctx context.Context, statusID string) (int, error) {
 
 	t.Lock()
 	defer t.Unlock()
-	var removed int
 
-	// remove entr(ies) from the post index
+	if t.items == nil || t.items.data == nil {
-	removeIndexes := []*list.Element{}
+		// Nothing to do.
-	if t.indexedItems != nil && t.indexedItems.data != nil {
+		return 0, nil
-		for e := t.indexedItems.data.Front(); e != nil; e = e.Next() {
-			entry, ok := e.Value.(*indexedItemsEntry)
-			if !ok {
-				return removed, errors.New("Remove: could not parse e as a postIndexEntry")
-			}
-			if entry.itemID == statusID {
-				l.Debug("found status in postIndex")
-				removeIndexes = append(removeIndexes, e)
-			}
-		}
-	}
-	for _, e := range removeIndexes {
-		t.indexedItems.data.Remove(e)
-		removed++
 	}
 
-	// remove entr(ies) from prepared posts
+	var toRemove []*list.Element
-	removePrepared := []*list.Element{}
+	for e := t.items.data.Front(); e != nil; e = e.Next() {
-	if t.preparedItems != nil && t.preparedItems.data != nil {
+		entry := e.Value.(*indexedItemsEntry) // nolint:forcetypeassert
-		for e := t.preparedItems.data.Front(); e != nil; e = e.Next() {
+
-			entry, ok := e.Value.(*preparedItemsEntry)
+		if entry.itemID != statusID {
-			if !ok {
+			// Not relevant.
-				return removed, errors.New("Remove: could not parse e as a preparedPostsEntry")
+			continue
-			}
-			if entry.itemID == statusID {
-				l.Debug("found status in preparedPosts")
-				removePrepared = append(removePrepared, e)
-			}
-		}
-	}
-	for _, e := range removePrepared {
-		t.preparedItems.data.Remove(e)
-		removed++
 		}
 
-	l.Debugf("removed %d entries", removed)
+		l.Debug("removing item")
-	return removed, nil
+		toRemove = append(toRemove, e)
+	}
+
+	for _, e := range toRemove {
+		t.items.data.Remove(e)
+	}
+
+	return len(toRemove), nil
 }
 
-func (t *timeline) RemoveAllBy(ctx context.Context, accountID string) (int, error) {
+func (t *timeline) RemoveAllByOrBoosting(ctx context.Context, accountID string) (int, error) {
-	l := log.WithContext(ctx).
+	l := log.
+		WithContext(ctx).
 		WithFields(kv.Fields{
 			{"accountTimeline", t.accountID},
 			{"accountID", accountID},
@@ -88,46 +70,28 @@ func (t *timeline) RemoveAllBy(ctx context.Context, accountID string) (int, erro
 
 	t.Lock()
 	defer t.Unlock()
-	var removed int
 
-	// remove entr(ies) from the post index
+	if t.items == nil || t.items.data == nil {
-	removeIndexes := []*list.Element{}
+		// Nothing to do.
-	if t.indexedItems != nil && t.indexedItems.data != nil {
+		return 0, nil
-		for e := t.indexedItems.data.Front(); e != nil; e = e.Next() {
-			entry, ok := e.Value.(*indexedItemsEntry)
-			if !ok {
-				return removed, errors.New("Remove: could not parse e as a postIndexEntry")
-			}
-			if entry.accountID == accountID || entry.boostOfAccountID == accountID {
-				l.Debug("found status in postIndex")
-				removeIndexes = append(removeIndexes, e)
-			}
-		}
-	}
-	for _, e := range removeIndexes {
-		t.indexedItems.data.Remove(e)
-		removed++
 	}
 
-	// remove entr(ies) from prepared posts
+	var toRemove []*list.Element
-	removePrepared := []*list.Element{}
+	for e := t.items.data.Front(); e != nil; e = e.Next() {
-	if t.preparedItems != nil && t.preparedItems.data != nil {
+		entry := e.Value.(*indexedItemsEntry) // nolint:forcetypeassert
-		for e := t.preparedItems.data.Front(); e != nil; e = e.Next() {
+
-			entry, ok := e.Value.(*preparedItemsEntry)
+		if entry.accountID != accountID && entry.boostOfAccountID != accountID {
-			if !ok {
+			// Not relevant.
-				return removed, errors.New("Remove: could not parse e as a preparedPostsEntry")
+			continue
-			}
-			if entry.accountID == accountID || entry.boostOfAccountID == accountID {
-				l.Debug("found status in preparedPosts")
-				removePrepared = append(removePrepared, e)
-			}
-		}
-	}
-	for _, e := range removePrepared {
-		t.preparedItems.data.Remove(e)
-		removed++
 		}
 
-	l.Debugf("removed %d entries", removed)
+		l.Debug("removing item")
-	return removed, nil
+		toRemove = append(toRemove, e)
+	}
+
+	for _, e := range toRemove {
+		t.items.data.Remove(e)
+	}
+
+	return len(toRemove), nil
 }

internal/timeline/timeline.go

@@ -78,32 +78,25 @@ type Timeline interface {
 		INDEXING + PREPARATION FUNCTIONS
 	*/
 
-	// IndexOne puts a item into the timeline at the appropriate place according to its 'createdAt' property.
+	// IndexAndPrepareOne puts a item into the timeline at the appropriate place according to its id, and then immediately prepares it.
-	//
-	// The returned bool indicates whether or not the item was actually inserted into the timeline. This will be false
-	// if the item is a boost and the original item or another boost of it already exists < boostReinsertionDepth back in the timeline.
-	IndexOne(ctx context.Context, itemID string, boostOfID string, accountID string, boostOfAccountID string) (bool, error)
-	// IndexAndPrepareOne puts a item into the timeline at the appropriate place according to its 'createdAt' property,
-	// and then immediately prepares it.
 	//
 	// The returned bool indicates whether or not the item was actually inserted into the timeline. This will be false
 	// if the item is a boost and the original item or another boost of it already exists < boostReinsertionDepth back in the timeline.
 	IndexAndPrepareOne(ctx context.Context, itemID string, boostOfID string, accountID string, boostOfAccountID string) (bool, error)
-	// PrepareXFromTop instructs the timeline to prepare x amount of items from the top of the timeline, useful during init.
-	PrepareFromTop(ctx context.Context, amount int) error
 
 	/*
 		INFO FUNCTIONS
 	*/
 
-	// ActualPostIndexLength returns the actual length of the item index at this point in time.
+	// AccountID returns the id of the account this timeline belongs to.
-	ItemIndexLength(ctx context.Context) int
+	AccountID() string
-	// OldestIndexedItemID returns the id of the rearmost (ie., the oldest) indexed item, or an error if something goes wrong.
+
-	// If nothing goes wrong but there's no oldest item, an empty string will be returned so make sure to check for this.
+	// Len returns the length of the item index at this point in time.
-	OldestIndexedItemID(ctx context.Context) (string, error)
+	Len() int
-	// NewestIndexedItemID returns the id of the frontmost (ie., the newest) indexed item, or an error if something goes wrong.
+
-	// If nothing goes wrong but there's no newest item, an empty string will be returned so make sure to check for this.
+	// OldestIndexedItemID returns the id of the rearmost (ie., the oldest) indexed item.
-	NewestIndexedItemID(ctx context.Context) (string, error)
+	// If there's no oldest item, an empty string will be returned so make sure to check for this.
+	OldestIndexedItemID() string
 
 	/*
 		UTILITY FUNCTIONS
@@ -111,27 +104,29 @@ type Timeline interface {
 
 	// LastGot returns the time that Get was last called.
 	LastGot() time.Time
-	// Prune prunes preparedItems and indexedItems in this timeline to the desired lengths.
+
+	// Prune prunes prepared and indexed items in this timeline to the desired lengths.
 	// This will be a no-op if the lengths are already < the desired values.
-	// Prune acquires a lock on the timeline before pruning.
+	//
-	// The return value is the combined total of items pruned from preparedItems and indexedItems.
+	// The returned int indicates the amount of entries that were removed or unprepared.
 	Prune(desiredPreparedItemsLength int, desiredIndexedItemsLength int) int
-	// Remove removes a item from both the index and prepared items.
+
+	// Remove removes an item with the given ID.
 	//
 	// If a item has multiple entries in a timeline, they will all be removed.
 	//
 	// The returned int indicates the amount of entries that were removed.
 	Remove(ctx context.Context, itemID string) (int, error)
-	// RemoveAllBy removes all items by the given accountID, from both the index and prepared items.
+
+	// RemoveAllByOrBoosting removes all items created by or boosting the given accountID.
 	//
 	// The returned int indicates the amount of entries that were removed.
-	RemoveAllBy(ctx context.Context, accountID string) (int, error)
+	RemoveAllByOrBoosting(ctx context.Context, accountID string) (int, error)
 }
 
 // timeline fulfils the Timeline interface
 type timeline struct {
-	indexedItems    *indexedItems
+	items           *indexedItems
-	preparedItems   *preparedItems
 	grabFunction    GrabFunction
 	filterFunction  FilterFunction
 	prepareFunction PrepareFunction
@@ -140,6 +135,10 @@ type timeline struct {
 	sync.Mutex
 }
 
+func (t *timeline) AccountID() string {
+	return t.accountID
+}
+
 // NewTimeline returns a new Timeline for the given account ID
 func NewTimeline(
 	ctx context.Context,
@@ -148,12 +147,9 @@ func NewTimeline(
 	filterFunction FilterFunction,
 	prepareFunction PrepareFunction,
 	skipInsertFunction SkipInsertFunction,
-) (Timeline, error) {
+) Timeline {
 	return &timeline{
-		indexedItems: &indexedItems{
+		items: &indexedItems{
-			skipInsert: skipInsertFunction,
-		},
-		preparedItems: &preparedItems{
 			skipInsert: skipInsertFunction,
 		},
 		grabFunction:    grabFunction,
@@ -161,5 +157,5 @@ func NewTimeline(
 		prepareFunction: prepareFunction,
 		accountID:       timelineAccountID,
 		lastGot:         time.Time{},
-	}, nil
+	}
 }

internal/timeline/timeline_test.go

@@ -36,6 +36,8 @@ type TimelineStandardTestSuite struct {
 
 	testAccounts    map[string]*gtsmodel.Account
 	testStatuses    map[string]*gtsmodel.Status
+	highestStatusID string
+	lowestStatusID  string
 
 	timeline timeline.Timeline
 	manager  timeline.Manager

internal/timeline/types.go

@@ -17,10 +17,18 @@
 
 package timeline
 
-// Timelineable represents any item that can be put in a timeline.
+// Timelineable represents any item that can be indexed in a timeline.
 type Timelineable interface {
 	GetID() string
 	GetAccountID() string
 	GetBoostOfID() string
 	GetBoostOfAccountID() string
 }
+
+// Preparable represents any item that can be prepared in a timeline.
+type Preparable interface {
+	GetID() string
+	GetAccountID() string
+	GetBoostOfID() string
+	GetBoostOfAccountID() string
+}