152 lines
4.4 KiB
Go
152 lines
4.4 KiB
Go
/*
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*
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* Copyright 2024 gRPC authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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package channelz
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import (
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"fmt"
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"sync/atomic"
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)
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// SubChannel is the channelz representation of a subchannel.
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type SubChannel struct {
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Entity
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// ID is the channelz id of this subchannel.
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ID int64
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// RefName is the human readable reference string of this subchannel.
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RefName string
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closeCalled bool
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sockets map[int64]string
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parent *Channel
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trace *ChannelTrace
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traceRefCount int32
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ChannelMetrics ChannelMetrics
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}
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func (sc *SubChannel) String() string {
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return fmt.Sprintf("%s SubChannel #%d", sc.parent, sc.ID)
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}
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func (sc *SubChannel) id() int64 {
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return sc.ID
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}
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func (sc *SubChannel) Sockets() map[int64]string {
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db.mu.RLock()
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defer db.mu.RUnlock()
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return copyMap(sc.sockets)
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}
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func (sc *SubChannel) Trace() *ChannelTrace {
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db.mu.RLock()
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defer db.mu.RUnlock()
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return sc.trace.copy()
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}
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func (sc *SubChannel) addChild(id int64, e entry) {
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if v, ok := e.(*Socket); ok && v.SocketType == SocketTypeNormal {
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sc.sockets[id] = v.RefName
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} else {
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logger.Errorf("cannot add a child (id = %d) of type %T to a subChannel", id, e)
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}
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}
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func (sc *SubChannel) deleteChild(id int64) {
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delete(sc.sockets, id)
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sc.deleteSelfIfReady()
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}
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func (sc *SubChannel) triggerDelete() {
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sc.closeCalled = true
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sc.deleteSelfIfReady()
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}
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func (sc *SubChannel) getParentID() int64 {
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return sc.parent.ID
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}
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// deleteSelfFromTree tries to delete the subchannel from the channelz entry relation tree, which
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// means deleting the subchannel reference from its parent's child list.
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//
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// In order for a subchannel to be deleted from the tree, it must meet the criteria that, removal of
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// the corresponding grpc object has been invoked, and the subchannel does not have any children left.
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//
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// The returned boolean value indicates whether the channel has been successfully deleted from tree.
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func (sc *SubChannel) deleteSelfFromTree() (deleted bool) {
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if !sc.closeCalled || len(sc.sockets) != 0 {
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return false
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}
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sc.parent.deleteChild(sc.ID)
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return true
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}
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// deleteSelfFromMap checks whether it is valid to delete the subchannel from the map, which means
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// deleting the subchannel from channelz's tracking entirely. Users can no longer use id to query
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// the subchannel, and its memory will be garbage collected.
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//
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// The trace reference count of the subchannel must be 0 in order to be deleted from the map. This is
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// specified in the channel tracing gRFC that as long as some other trace has reference to an entity,
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// the trace of the referenced entity must not be deleted. In order to release the resource allocated
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// by grpc, the reference to the grpc object is reset to a dummy object.
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//
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// deleteSelfFromMap must be called after deleteSelfFromTree returns true.
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//
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// It returns a bool to indicate whether the channel can be safely deleted from map.
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func (sc *SubChannel) deleteSelfFromMap() (delete bool) {
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return sc.getTraceRefCount() == 0
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}
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// deleteSelfIfReady tries to delete the subchannel itself from the channelz database.
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// The delete process includes two steps:
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// 1. delete the subchannel from the entry relation tree, i.e. delete the subchannel reference from
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// its parent's child list.
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// 2. delete the subchannel from the map, i.e. delete the subchannel entirely from channelz. Lookup
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// by id will return entry not found error.
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func (sc *SubChannel) deleteSelfIfReady() {
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if !sc.deleteSelfFromTree() {
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return
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}
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if !sc.deleteSelfFromMap() {
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return
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}
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db.deleteEntry(sc.ID)
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sc.trace.clear()
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}
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func (sc *SubChannel) getChannelTrace() *ChannelTrace {
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return sc.trace
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}
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func (sc *SubChannel) incrTraceRefCount() {
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atomic.AddInt32(&sc.traceRefCount, 1)
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}
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func (sc *SubChannel) decrTraceRefCount() {
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atomic.AddInt32(&sc.traceRefCount, -1)
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}
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func (sc *SubChannel) getTraceRefCount() int {
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i := atomic.LoadInt32(&sc.traceRefCount)
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return int(i)
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}
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func (sc *SubChannel) getRefName() string {
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return sc.RefName
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}
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