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gitea/modules/queue/unique_queue_channel.go

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Go

// Copyright 2020 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package queue
import (
"context"
"fmt"
"runtime/pprof"
"sync"
"sync/atomic"
"time"
"code.gitea.io/gitea/modules/json"
"code.gitea.io/gitea/modules/log"
)
// ChannelUniqueQueueType is the type for channel queue
const ChannelUniqueQueueType Type = "unique-channel"
// ChannelUniqueQueueConfiguration is the configuration for a ChannelUniqueQueue
type ChannelUniqueQueueConfiguration ChannelQueueConfiguration
// ChannelUniqueQueue implements UniqueQueue
//
// It is basically a thin wrapper around a WorkerPool but keeps a store of
// what has been pushed within a table.
//
// Please note that this Queue does not guarantee that a particular
// task cannot be processed twice or more at the same time. Uniqueness is
// only guaranteed whilst the task is waiting in the queue.
type ChannelUniqueQueue struct {
*WorkerPool
lock sync.Mutex
table map[string]bool
shutdownCtx context.Context
shutdownCtxCancel context.CancelFunc
terminateCtx context.Context
terminateCtxCancel context.CancelFunc
exemplar interface{}
workers int
name string
}
// NewChannelUniqueQueue create a memory channel queue
func NewChannelUniqueQueue(handle HandlerFunc, cfg, exemplar interface{}) (Queue, error) {
configInterface, err := toConfig(ChannelUniqueQueueConfiguration{}, cfg)
if err != nil {
return nil, err
}
config := configInterface.(ChannelUniqueQueueConfiguration)
if config.BatchLength == 0 {
config.BatchLength = 1
}
terminateCtx, terminateCtxCancel := context.WithCancel(context.Background())
shutdownCtx, shutdownCtxCancel := context.WithCancel(terminateCtx)
queue := &ChannelUniqueQueue{
table: map[string]bool{},
shutdownCtx: shutdownCtx,
shutdownCtxCancel: shutdownCtxCancel,
terminateCtx: terminateCtx,
terminateCtxCancel: terminateCtxCancel,
exemplar: exemplar,
workers: config.Workers,
name: config.Name,
}
queue.WorkerPool = NewWorkerPool(func(data ...Data) (unhandled []Data) {
for _, datum := range data {
// No error is possible here because PushFunc ensures that this can be marshalled
bs, _ := json.Marshal(datum)
queue.lock.Lock()
delete(queue.table, string(bs))
queue.lock.Unlock()
if u := handle(datum); u != nil {
if queue.IsPaused() {
// We can only pushback to the channel if we're paused.
go func() {
if err := queue.Push(u[0]); err != nil {
log.Error("Unable to push back to queue %d. Error: %v", queue.qid, err)
}
}()
} else {
unhandled = append(unhandled, u...)
}
}
}
return unhandled
}, config.WorkerPoolConfiguration)
queue.qid = GetManager().Add(queue, ChannelUniqueQueueType, config, exemplar)
return queue, nil
}
// Run starts to run the queue
func (q *ChannelUniqueQueue) Run(atShutdown, atTerminate func(func())) {
pprof.SetGoroutineLabels(q.baseCtx)
atShutdown(q.Shutdown)
atTerminate(q.Terminate)
log.Debug("ChannelUniqueQueue: %s Starting", q.name)
_ = q.AddWorkers(q.workers, 0)
}
// Push will push data into the queue if the data is not already in the queue
func (q *ChannelUniqueQueue) Push(data Data) error {
return q.PushFunc(data, nil)
}
// PushFunc will push data into the queue
func (q *ChannelUniqueQueue) PushFunc(data Data, fn func() error) error {
if !assignableTo(data, q.exemplar) {
return fmt.Errorf("unable to assign data: %v to same type as exemplar: %v in queue: %s", data, q.exemplar, q.name)
}
bs, err := json.Marshal(data)
if err != nil {
return err
}
q.lock.Lock()
locked := true
defer func() {
if locked {
q.lock.Unlock()
}
}()
if _, ok := q.table[string(bs)]; ok {
return ErrAlreadyInQueue
}
// FIXME: We probably need to implement some sort of limit here
// If the downstream queue blocks this table will grow without limit
q.table[string(bs)] = true
if fn != nil {
err := fn()
if err != nil {
delete(q.table, string(bs))
return err
}
}
locked = false
q.lock.Unlock()
q.WorkerPool.Push(data)
return nil
}
// Has checks if the data is in the queue
func (q *ChannelUniqueQueue) Has(data Data) (bool, error) {
bs, err := json.Marshal(data)
if err != nil {
return false, err
}
q.lock.Lock()
defer q.lock.Unlock()
_, has := q.table[string(bs)]
return has, nil
}
// Flush flushes the channel with a timeout - the Flush worker will be registered as a flush worker with the manager
func (q *ChannelUniqueQueue) Flush(timeout time.Duration) error {
if q.IsPaused() {
return nil
}
ctx, cancel := q.commonRegisterWorkers(1, timeout, true)
defer cancel()
return q.FlushWithContext(ctx)
}
// FlushWithContext is very similar to CleanUp but it will return as soon as the dataChan is empty
func (q *ChannelUniqueQueue) FlushWithContext(ctx context.Context) error {
log.Trace("ChannelUniqueQueue: %d Flush", q.qid)
paused, _ := q.IsPausedIsResumed()
for {
select {
case <-paused:
return nil
default:
}
select {
case data, ok := <-q.dataChan:
if !ok {
return nil
}
if unhandled := q.handle(data); unhandled != nil {
log.Error("Unhandled Data whilst flushing queue %d", q.qid)
}
atomic.AddInt64(&q.numInQueue, -1)
case <-q.baseCtx.Done():
return q.baseCtx.Err()
case <-ctx.Done():
return ctx.Err()
default:
return nil
}
}
}
// Shutdown processing from this queue
func (q *ChannelUniqueQueue) Shutdown() {
log.Trace("ChannelUniqueQueue: %s Shutting down", q.name)
select {
case <-q.shutdownCtx.Done():
return
default:
}
go func() {
log.Trace("ChannelUniqueQueue: %s Flushing", q.name)
if err := q.FlushWithContext(q.terminateCtx); err != nil {
log.Warn("ChannelUniqueQueue: %s Terminated before completed flushing", q.name)
return
}
log.Debug("ChannelUniqueQueue: %s Flushed", q.name)
}()
q.shutdownCtxCancel()
log.Debug("ChannelUniqueQueue: %s Shutdown", q.name)
}
// Terminate this queue and close the queue
func (q *ChannelUniqueQueue) Terminate() {
log.Trace("ChannelUniqueQueue: %s Terminating", q.name)
q.Shutdown()
select {
case <-q.terminateCtx.Done():
return
default:
}
q.terminateCtxCancel()
q.baseCtxFinished()
log.Debug("ChannelUniqueQueue: %s Terminated", q.name)
}
// Name returns the name of this queue
func (q *ChannelUniqueQueue) Name() string {
return q.name
}
func init() {
queuesMap[ChannelUniqueQueueType] = NewChannelUniqueQueue
}