mirror of
https://github.com/ceph/ceph-csi.git
synced 2024-12-29 08:20:20 +00:00
121 lines
4.2 KiB
Go
121 lines
4.2 KiB
Go
/*
|
|
Copyright 2022 The Kubernetes Authors.
|
|
|
|
Licensed under the Apache License, Version 2.0 (the "License");
|
|
you may not use this file except in compliance with the License.
|
|
You may obtain a copy of the License at
|
|
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
Unless required by applicable law or agreed to in writing, software
|
|
distributed under the License is distributed on an "AS IS" BASIS,
|
|
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
See the License for the specific language governing permissions and
|
|
limitations under the License.
|
|
*/
|
|
|
|
// Package synctrack contains utilities for helping controllers track whether
|
|
// they are "synced" or not, that is, whether they have processed all items
|
|
// from the informer's initial list.
|
|
package synctrack
|
|
|
|
import (
|
|
"sync"
|
|
"sync/atomic"
|
|
|
|
"k8s.io/apimachinery/pkg/util/sets"
|
|
)
|
|
|
|
// AsyncTracker helps propagate HasSynced in the face of multiple worker threads.
|
|
type AsyncTracker[T comparable] struct {
|
|
UpstreamHasSynced func() bool
|
|
|
|
lock sync.Mutex
|
|
waiting sets.Set[T]
|
|
}
|
|
|
|
// Start should be called prior to processing each key which is part of the
|
|
// initial list.
|
|
func (t *AsyncTracker[T]) Start(key T) {
|
|
t.lock.Lock()
|
|
defer t.lock.Unlock()
|
|
if t.waiting == nil {
|
|
t.waiting = sets.New[T](key)
|
|
} else {
|
|
t.waiting.Insert(key)
|
|
}
|
|
}
|
|
|
|
// Finished should be called when finished processing a key which was part of
|
|
// the initial list. Since keys are tracked individually, nothing bad happens
|
|
// if you call Finished without a corresponding call to Start. This makes it
|
|
// easier to use this in combination with e.g. queues which don't make it easy
|
|
// to plumb through the isInInitialList boolean.
|
|
func (t *AsyncTracker[T]) Finished(key T) {
|
|
t.lock.Lock()
|
|
defer t.lock.Unlock()
|
|
if t.waiting != nil {
|
|
t.waiting.Delete(key)
|
|
}
|
|
}
|
|
|
|
// HasSynced returns true if the source is synced and every key present in the
|
|
// initial list has been processed. This relies on the source not considering
|
|
// itself synced until *after* it has delivered the notification for the last
|
|
// key, and that notification handler must have called Start.
|
|
func (t *AsyncTracker[T]) HasSynced() bool {
|
|
// Call UpstreamHasSynced first: it might take a lock, which might take
|
|
// a significant amount of time, and we can't hold our lock while
|
|
// waiting on that or a user is likely to get a deadlock.
|
|
if !t.UpstreamHasSynced() {
|
|
return false
|
|
}
|
|
t.lock.Lock()
|
|
defer t.lock.Unlock()
|
|
return t.waiting.Len() == 0
|
|
}
|
|
|
|
// SingleFileTracker helps propagate HasSynced when events are processed in
|
|
// order (i.e. via a queue).
|
|
type SingleFileTracker struct {
|
|
// Important: count is used with atomic operations so it must be 64-bit
|
|
// aligned, otherwise atomic operations will panic. Having it at the top of
|
|
// the struct will guarantee that, even on 32-bit arches.
|
|
// See https://pkg.go.dev/sync/atomic#pkg-note-BUG for more information.
|
|
count int64
|
|
|
|
UpstreamHasSynced func() bool
|
|
}
|
|
|
|
// Start should be called prior to processing each key which is part of the
|
|
// initial list.
|
|
func (t *SingleFileTracker) Start() {
|
|
atomic.AddInt64(&t.count, 1)
|
|
}
|
|
|
|
// Finished should be called when finished processing a key which was part of
|
|
// the initial list. You must never call Finished() before (or without) its
|
|
// corresponding Start(), that is a logic error that could cause HasSynced to
|
|
// return a wrong value. To help you notice this should it happen, Finished()
|
|
// will panic if the internal counter goes negative.
|
|
func (t *SingleFileTracker) Finished() {
|
|
result := atomic.AddInt64(&t.count, -1)
|
|
if result < 0 {
|
|
panic("synctrack: negative counter; this logic error means HasSynced may return incorrect value")
|
|
}
|
|
}
|
|
|
|
// HasSynced returns true if the source is synced and every key present in the
|
|
// initial list has been processed. This relies on the source not considering
|
|
// itself synced until *after* it has delivered the notification for the last
|
|
// key, and that notification handler must have called Start.
|
|
func (t *SingleFileTracker) HasSynced() bool {
|
|
// Call UpstreamHasSynced first: it might take a lock, which might take
|
|
// a significant amount of time, and we don't want to then act on a
|
|
// stale count value.
|
|
if !t.UpstreamHasSynced() {
|
|
return false
|
|
}
|
|
return atomic.LoadInt64(&t.count) <= 0
|
|
}
|