A fork of Gitea (see branch `mj`) adding Majority Judgment Polls 𐄷 over Issues and Merge Requests. https://git.mieuxvoter.fr
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// Copyright 2019 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"
"sync"
"sync/atomic"
"time"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/util"
)
// WorkerPool represent a dynamically growable worker pool for a
// provided handler function. They have an internal channel which
// they use to detect if there is a block and will grow and shrink in
// response to demand as per configuration.
type WorkerPool struct {
lock sync.Mutex
baseCtx context.Context
cancel context.CancelFunc
cond *sync.Cond
qid int64
maxNumberOfWorkers int
numberOfWorkers int
batchLength int
handle HandlerFunc
dataChan chan Data
blockTimeout time.Duration
boostTimeout time.Duration
boostWorkers int
numInQueue int64
}
// WorkerPoolConfiguration is the basic configuration for a WorkerPool
type WorkerPoolConfiguration struct {
QueueLength int
BatchLength int
BlockTimeout time.Duration
BoostTimeout time.Duration
BoostWorkers int
MaxWorkers int
}
// NewWorkerPool creates a new worker pool
func NewWorkerPool(handle HandlerFunc, config WorkerPoolConfiguration) *WorkerPool {
ctx, cancel := context.WithCancel(context.Background())
dataChan := make(chan Data, config.QueueLength)
pool := &WorkerPool{
baseCtx: ctx,
cancel: cancel,
batchLength: config.BatchLength,
dataChan: dataChan,
handle: handle,
blockTimeout: config.BlockTimeout,
boostTimeout: config.BoostTimeout,
boostWorkers: config.BoostWorkers,
maxNumberOfWorkers: config.MaxWorkers,
}
return pool
}
// Push pushes the data to the internal channel
func (p *WorkerPool) Push(data Data) {
atomic.AddInt64(&p.numInQueue, 1)
p.lock.Lock()
if p.blockTimeout > 0 && p.boostTimeout > 0 && (p.numberOfWorkers <= p.maxNumberOfWorkers || p.maxNumberOfWorkers < 0) {
p.lock.Unlock()
p.pushBoost(data)
} else {
p.lock.Unlock()
p.dataChan <- data
}
}
func (p *WorkerPool) pushBoost(data Data) {
select {
case p.dataChan <- data:
default:
p.lock.Lock()
if p.blockTimeout <= 0 {
p.lock.Unlock()
p.dataChan <- data
return
}
ourTimeout := p.blockTimeout
timer := time.NewTimer(p.blockTimeout)
p.lock.Unlock()
select {
case p.dataChan <- data:
util.StopTimer(timer)
case <-timer.C:
p.lock.Lock()
if p.blockTimeout > ourTimeout || (p.numberOfWorkers > p.maxNumberOfWorkers && p.maxNumberOfWorkers >= 0) {
p.lock.Unlock()
p.dataChan <- data
return
}
p.blockTimeout *= 2
ctx, cancel := context.WithCancel(p.baseCtx)
mq := GetManager().GetManagedQueue(p.qid)
boost := p.boostWorkers
if (boost+p.numberOfWorkers) > p.maxNumberOfWorkers && p.maxNumberOfWorkers >= 0 {
boost = p.maxNumberOfWorkers - p.numberOfWorkers
}
if mq != nil {
log.Warn("WorkerPool: %d (for %s) Channel blocked for %v - adding %d temporary workers for %s, block timeout now %v", p.qid, mq.Name, ourTimeout, boost, p.boostTimeout, p.blockTimeout)
start := time.Now()
pid := mq.RegisterWorkers(boost, start, false, start, cancel, false)
go func() {
<-ctx.Done()
mq.RemoveWorkers(pid)
cancel()
}()
} else {
log.Warn("WorkerPool: %d Channel blocked for %v - adding %d temporary workers for %s, block timeout now %v", p.qid, ourTimeout, p.boostWorkers, p.boostTimeout, p.blockTimeout)
}
go func() {
<-time.After(p.boostTimeout)
cancel()
p.lock.Lock()
p.blockTimeout /= 2
p.lock.Unlock()
}()
p.lock.Unlock()
p.addWorkers(ctx, boost)
p.dataChan <- data
}
}
}
// NumberOfWorkers returns the number of current workers in the pool
func (p *WorkerPool) NumberOfWorkers() int {
p.lock.Lock()
defer p.lock.Unlock()
return p.numberOfWorkers
}
// MaxNumberOfWorkers returns the maximum number of workers automatically added to the pool
func (p *WorkerPool) MaxNumberOfWorkers() int {
p.lock.Lock()
defer p.lock.Unlock()
return p.maxNumberOfWorkers
}
// BoostWorkers returns the number of workers for a boost
func (p *WorkerPool) BoostWorkers() int {
p.lock.Lock()
defer p.lock.Unlock()
return p.boostWorkers
}
// BoostTimeout returns the timeout of the next boost
func (p *WorkerPool) BoostTimeout() time.Duration {
p.lock.Lock()
defer p.lock.Unlock()
return p.boostTimeout
}
// BlockTimeout returns the timeout til the next boost
func (p *WorkerPool) BlockTimeout() time.Duration {
p.lock.Lock()
defer p.lock.Unlock()
return p.blockTimeout
}
// SetPoolSettings sets the setable boost values
func (p *WorkerPool) SetPoolSettings(maxNumberOfWorkers, boostWorkers int, timeout time.Duration) {
p.lock.Lock()
defer p.lock.Unlock()
p.maxNumberOfWorkers = maxNumberOfWorkers
p.boostWorkers = boostWorkers
p.boostTimeout = timeout
}
// SetMaxNumberOfWorkers sets the maximum number of workers automatically added to the pool
// Changing this number will not change the number of current workers but will change the limit
// for future additions
func (p *WorkerPool) SetMaxNumberOfWorkers(newMax int) {
p.lock.Lock()
defer p.lock.Unlock()
p.maxNumberOfWorkers = newMax
}
func (p *WorkerPool) commonRegisterWorkers(number int, timeout time.Duration, isFlusher bool) (context.Context, context.CancelFunc) {
var ctx context.Context
var cancel context.CancelFunc
start := time.Now()
end := start
hasTimeout := false
if timeout > 0 {
ctx, cancel = context.WithTimeout(p.baseCtx, timeout)
end = start.Add(timeout)
hasTimeout = true
} else {
ctx, cancel = context.WithCancel(p.baseCtx)
}
mq := GetManager().GetManagedQueue(p.qid)
if mq != nil {
pid := mq.RegisterWorkers(number, start, hasTimeout, end, cancel, isFlusher)
go func() {
<-ctx.Done()
mq.RemoveWorkers(pid)
cancel()
}()
log.Trace("WorkerPool: %d (for %s) adding %d workers with group id: %d", p.qid, mq.Name, number, pid)
} else {
log.Trace("WorkerPool: %d adding %d workers (no group id)", p.qid, number)
}
return ctx, cancel
}
// AddWorkers adds workers to the pool - this allows the number of workers to go above the limit
func (p *WorkerPool) AddWorkers(number int, timeout time.Duration) context.CancelFunc {
ctx, cancel := p.commonRegisterWorkers(number, timeout, false)
p.addWorkers(ctx, number)
return cancel
}
// addWorkers adds workers to the pool
func (p *WorkerPool) addWorkers(ctx context.Context, number int) {
for i := 0; i < number; i++ {
p.lock.Lock()
if p.cond == nil {
p.cond = sync.NewCond(&p.lock)
}
p.numberOfWorkers++
p.lock.Unlock()
go func() {
p.doWork(ctx)
p.lock.Lock()
p.numberOfWorkers--
if p.numberOfWorkers == 0 {
p.cond.Broadcast()
} else if p.numberOfWorkers < 0 {
// numberOfWorkers can't go negative but...
log.Warn("Number of Workers < 0 for QID %d - this shouldn't happen", p.qid)
p.numberOfWorkers = 0
p.cond.Broadcast()
}
p.lock.Unlock()
}()
}
}
// Wait for WorkerPool to finish
func (p *WorkerPool) Wait() {
p.lock.Lock()
defer p.lock.Unlock()
if p.cond == nil {
p.cond = sync.NewCond(&p.lock)
}
if p.numberOfWorkers <= 0 {
return
}
p.cond.Wait()
}
// CleanUp will drain the remaining contents of the channel
// This should be called after AddWorkers context is closed
func (p *WorkerPool) CleanUp(ctx context.Context) {
log.Trace("WorkerPool: %d CleanUp", p.qid)
close(p.dataChan)
for data := range p.dataChan {
p.handle(data)
atomic.AddInt64(&p.numInQueue, -1)
select {
case <-ctx.Done():
log.Warn("WorkerPool: %d Cleanup context closed before finishing clean-up", p.qid)
return
default:
}
}
log.Trace("WorkerPool: %d CleanUp Done", p.qid)
}
// Flush flushes the channel with a timeout - the Flush worker will be registered as a flush worker with the manager
func (p *WorkerPool) Flush(timeout time.Duration) error {
ctx, cancel := p.commonRegisterWorkers(1, timeout, true)
defer cancel()
return p.FlushWithContext(ctx)
}
// IsEmpty returns if true if the worker queue is empty
func (p *WorkerPool) IsEmpty() bool {
return atomic.LoadInt64(&p.numInQueue) == 0
}
// FlushWithContext is very similar to CleanUp but it will return as soon as the dataChan is empty
// NB: The worker will not be registered with the manager.
func (p *WorkerPool) FlushWithContext(ctx context.Context) error {
log.Trace("WorkerPool: %d Flush", p.qid)
for {
select {
case data := <-p.dataChan:
p.handle(data)
atomic.AddInt64(&p.numInQueue, -1)
case <-p.baseCtx.Done():
return p.baseCtx.Err()
case <-ctx.Done():
return ctx.Err()
default:
return nil
}
}
}
func (p *WorkerPool) doWork(ctx context.Context) {
delay := time.Millisecond * 300
var data = make([]Data, 0, p.batchLength)
for {
select {
case <-ctx.Done():
if len(data) > 0 {
log.Trace("Handling: %d data, %v", len(data), data)
p.handle(data...)
atomic.AddInt64(&p.numInQueue, -1*int64(len(data)))
}
log.Trace("Worker shutting down")
return
case datum, ok := <-p.dataChan:
if !ok {
// the dataChan has been closed - we should finish up:
if len(data) > 0 {
log.Trace("Handling: %d data, %v", len(data), data)
p.handle(data...)
atomic.AddInt64(&p.numInQueue, -1*int64(len(data)))
}
log.Trace("Worker shutting down")
return
}
data = append(data, datum)
if len(data) >= p.batchLength {
log.Trace("Handling: %d data, %v", len(data), data)
p.handle(data...)
atomic.AddInt64(&p.numInQueue, -1*int64(len(data)))
data = make([]Data, 0, p.batchLength)
}
default:
timer := time.NewTimer(delay)
select {
case <-ctx.Done():
util.StopTimer(timer)
if len(data) > 0 {
log.Trace("Handling: %d data, %v", len(data), data)
p.handle(data...)
atomic.AddInt64(&p.numInQueue, -1*int64(len(data)))
}
log.Trace("Worker shutting down")
return
case datum, ok := <-p.dataChan:
util.StopTimer(timer)
if !ok {
// the dataChan has been closed - we should finish up:
if len(data) > 0 {
log.Trace("Handling: %d data, %v", len(data), data)
p.handle(data...)
atomic.AddInt64(&p.numInQueue, -1*int64(len(data)))
}
log.Trace("Worker shutting down")
return
}
data = append(data, datum)
if len(data) >= p.batchLength {
log.Trace("Handling: %d data, %v", len(data), data)
p.handle(data...)
atomic.AddInt64(&p.numInQueue, -1*int64(len(data)))
data = make([]Data, 0, p.batchLength)
}
case <-timer.C:
delay = time.Millisecond * 100
if len(data) > 0 {
log.Trace("Handling: %d data, %v", len(data), data)
p.handle(data...)
atomic.AddInt64(&p.numInQueue, -1*int64(len(data)))
data = make([]Data, 0, p.batchLength)
}
}
}
}
}