135 lines
3.6 KiB
Go
135 lines
3.6 KiB
Go
package sqlite3
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// Backup is an handle to an ongoing online backup operation.
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//
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// https://sqlite.org/c3ref/backup.html
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type Backup struct {
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c *Conn
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handle uint32
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otherc uint32
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}
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// Backup backs up srcDB on the src connection to the "main" database in dstURI.
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//
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// Backup opens the SQLite database file dstURI,
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// and blocks until the entire backup is complete.
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// Use [Conn.BackupInit] for incremental backup.
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//
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// https://sqlite.org/backup.html
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func (src *Conn) Backup(srcDB, dstURI string) error {
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b, err := src.BackupInit(srcDB, dstURI)
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if err != nil {
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return err
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}
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defer b.Close()
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_, err = b.Step(-1)
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return err
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}
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// Restore restores dstDB on the dst connection from the "main" database in srcURI.
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//
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// Restore opens the SQLite database file srcURI,
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// and blocks until the entire restore is complete.
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//
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// https://sqlite.org/backup.html
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func (dst *Conn) Restore(dstDB, srcURI string) error {
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src, err := dst.openDB(srcURI, OPEN_READONLY|OPEN_URI)
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if err != nil {
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return err
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}
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b, err := dst.backupInit(dst.handle, dstDB, src, "main")
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if err != nil {
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return err
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}
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defer b.Close()
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_, err = b.Step(-1)
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return err
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}
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// BackupInit initializes a backup operation to copy the content of one database into another.
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//
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// BackupInit opens the SQLite database file dstURI,
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// then initializes a backup that copies the contents of srcDB on the src connection
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// to the "main" database in dstURI.
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//
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// https://sqlite.org/c3ref/backup_finish.html#sqlite3backupinit
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func (src *Conn) BackupInit(srcDB, dstURI string) (*Backup, error) {
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dst, err := src.openDB(dstURI, OPEN_READWRITE|OPEN_CREATE|OPEN_URI)
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if err != nil {
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return nil, err
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}
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return src.backupInit(dst, "main", src.handle, srcDB)
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}
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func (c *Conn) backupInit(dst uint32, dstName string, src uint32, srcName string) (*Backup, error) {
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defer c.arena.mark()()
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dstPtr := c.arena.string(dstName)
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srcPtr := c.arena.string(srcName)
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other := dst
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if c.handle == dst {
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other = src
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}
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r := c.call("sqlite3_backup_init",
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uint64(dst), uint64(dstPtr),
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uint64(src), uint64(srcPtr))
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if r == 0 {
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defer c.closeDB(other)
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r = c.call("sqlite3_errcode", uint64(dst))
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return nil, c.sqlite.error(r, dst)
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}
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return &Backup{
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c: c,
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otherc: other,
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handle: uint32(r),
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}, nil
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}
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// Close finishes a backup operation.
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//
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// It is safe to close a nil, zero or closed Backup.
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//
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// https://sqlite.org/c3ref/backup_finish.html#sqlite3backupfinish
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func (b *Backup) Close() error {
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if b == nil || b.handle == 0 {
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return nil
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}
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r := b.c.call("sqlite3_backup_finish", uint64(b.handle))
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b.c.closeDB(b.otherc)
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b.handle = 0
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return b.c.error(r)
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}
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// Step copies up to nPage pages between the source and destination databases.
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// If nPage is negative, all remaining source pages are copied.
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//
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// https://sqlite.org/c3ref/backup_finish.html#sqlite3backupstep
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func (b *Backup) Step(nPage int) (done bool, err error) {
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r := b.c.call("sqlite3_backup_step", uint64(b.handle), uint64(nPage))
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if r == _DONE {
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return true, nil
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}
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return false, b.c.error(r)
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}
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// Remaining returns the number of pages still to be backed up
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// at the conclusion of the most recent [Backup.Step].
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//
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// https://sqlite.org/c3ref/backup_finish.html#sqlite3backupremaining
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func (b *Backup) Remaining() int {
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r := b.c.call("sqlite3_backup_remaining", uint64(b.handle))
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return int(int32(r))
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}
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// PageCount returns the total number of pages in the source database
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// at the conclusion of the most recent [Backup.Step].
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//
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// https://sqlite.org/c3ref/backup_finish.html#sqlite3backuppagecount
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func (b *Backup) PageCount() int {
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r := b.c.call("sqlite3_backup_pagecount", uint64(b.handle))
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return int(int32(r))
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}
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