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workshop.go
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workshop.go
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package pool
import (
"fmt"
"math"
"sync"
"sync/atomic"
"time"
"github.com/andeya/goutil/coarsetime"
)
/**
* Non-blocking asynchronous multiplex resource pool.
*
* Conditions of Use:
* - Limited resources
* - Resources can be multiplexed non-blockingly and asynchronously
* - Typical application scenarios, such as connection pool for asynchronous communication
*
* Performance:
* - The longer the business is, the more obvious the performance improvement.
* If the service is executed for 1ms each time, the performance is improved by about 4 times;
* If the business is executed for 10ms each time, the performance is improved by about 28 times
* - The average time spent on each operation will not change significantly,
* but the overall throughput is greatly improved
*/
type (
// Worker woker interface
// Note: Worker can not be implemented using empty structures(struct{})!
Worker interface {
Health() bool
Close() error
}
// Workshop working workshop
Workshop struct {
addFn func() (*workerInfo, error)
maxQuota int
maxIdleDuration time.Duration
infos map[Worker]*workerInfo
minLoadInfo *workerInfo
stats *WorkshopStats
statsReader atomic.Value
lock sync.Mutex
wg sync.WaitGroup
closeCh chan struct{}
closeLock sync.Mutex
}
workerInfo struct {
worker Worker
jobNum int32
idleExpire time.Time
}
// WorkshopStats workshop stats
WorkshopStats struct {
Worker int32 // The current total number of workers
Idle int32 // The current total number of idle workers
Created uint64 // Total created workers
Doing int32 // The total number of tasks in progress
Done uint64 // The total number of tasks completed
MaxLoad int32 // In the current load balancing, the maximum number of tasks
MinLoad int32 // In the current load balancing, the minimum number of tasks
}
)
const (
defaultWorkerMaxQuota = 64
defaultWorkerMaxIdleDuration = 3 * time.Minute
)
var (
// ErrWorkshopClosed error: 'workshop is closed'
ErrWorkshopClosed = fmt.Errorf("%s", "workshop is closed")
)
// NewWorkshop creates a new workshop(non-blocking asynchronous multiplex resource pool).
// If maxQuota<=0, will use default value.
// If maxIdleDuration<=0, will use default value.
// Note: Worker can not be implemented using empty structures(struct{})!
func NewWorkshop(maxQuota int, maxIdleDuration time.Duration, newWorkerFunc func() (Worker, error)) *Workshop {
if maxQuota <= 0 {
maxQuota = defaultWorkerMaxQuota
}
if maxIdleDuration <= 0 {
maxIdleDuration = defaultWorkerMaxIdleDuration
}
w := new(Workshop)
w.stats = new(WorkshopStats)
w.reportStatsLocked()
w.maxQuota = maxQuota
w.maxIdleDuration = maxIdleDuration
w.infos = make(map[Worker]*workerInfo, maxQuota)
w.closeCh = make(chan struct{})
w.addFn = func() (info *workerInfo, err error) {
defer func() {
if p := recover(); p != nil {
err = fmt.Errorf("%v", p)
}
}()
worker, err := newWorkerFunc()
if err != nil {
return nil, err
}
info = &workerInfo{
worker: worker,
}
w.infos[worker] = info
w.stats.Created++
w.stats.Worker++
return info, nil
}
go w.gc()
return w
}
// Callback assigns a healthy worker to execute the function.
func (w *Workshop) Callback(fn func(Worker) error) (err error) {
select {
case <-w.closeCh:
return ErrWorkshopClosed
default:
}
w.lock.Lock()
info, err := w.hireLocked()
w.lock.Unlock()
if err != nil {
return err
}
worker := info.worker
defer func() {
if p := recover(); p != nil {
err = fmt.Errorf("%v", p)
}
w.lock.Lock()
_, ok := w.infos[worker]
if !ok {
worker.Close()
} else {
w.fireLocked(info)
}
w.lock.Unlock()
}()
return fn(worker)
}
// Close wait for all the work to be completed and close the workshop.
func (w *Workshop) Close() {
w.closeLock.Lock()
defer w.closeLock.Unlock()
select {
case <-w.closeCh:
return
default:
close(w.closeCh)
}
w.wg.Wait()
w.lock.Lock()
defer w.lock.Unlock()
for _, info := range w.infos {
info.worker.Close()
}
w.infos = nil
w.stats.Idle = 0
w.stats.Worker = 0
w.refreshLocked(true)
}
// Fire marks the worker to reduce a job.
// If the worker does not belong to the workshop, close the worker.
func (w *Workshop) Fire(worker Worker) {
w.lock.Lock()
info, ok := w.infos[worker]
if !ok {
if worker != nil {
worker.Close()
}
w.lock.Unlock()
return
}
w.fireLocked(info)
w.lock.Unlock()
}
// Hire hires a healthy worker and marks the worker to add a job.
func (w *Workshop) Hire() (Worker, error) {
select {
case <-w.closeCh:
return nil, ErrWorkshopClosed
default:
}
w.lock.Lock()
info, err := w.hireLocked()
if err != nil {
w.lock.Unlock()
return nil, err
}
w.lock.Unlock()
return info.worker, nil
}
// Stats returns the current workshop stats.
func (w *Workshop) Stats() WorkshopStats {
return w.statsReader.Load().(WorkshopStats)
}
func (w *Workshop) fireLocked(info *workerInfo) {
{
w.stats.Doing--
w.stats.Done++
info.jobNum--
w.wg.Add(-1)
}
jobNum := info.jobNum
if jobNum == 0 {
info.idleExpire = coarsetime.CeilingTimeNow().Add(w.maxIdleDuration)
w.stats.Idle++
}
if jobNum+1 >= w.stats.MaxLoad {
w.refreshLocked(true)
return
}
if !w.checkInfoLocked(info) {
if info == w.minLoadInfo {
w.refreshLocked(true)
}
return
}
if jobNum < w.stats.MinLoad {
w.stats.MinLoad = jobNum
w.minLoadInfo = info
}
w.reportStatsLocked()
}
func (w *Workshop) hireLocked() (*workerInfo, error) {
var info *workerInfo
GET:
info = w.minLoadInfo
if len(w.infos) >= w.maxQuota || (info != nil && info.jobNum == 0) {
if !w.checkInfoLocked(info) {
w.refreshLocked(false)
goto GET
}
if info.jobNum == 0 {
w.stats.Idle--
}
info.jobNum++
w.setMinLoadInfoLocked()
w.stats.MinLoad = w.minLoadInfo.jobNum
if w.stats.MaxLoad < info.jobNum {
w.stats.MaxLoad = info.jobNum
}
} else {
var err error
info, err = w.addFn()
if err != nil {
return nil, err
}
info.jobNum = 1
w.stats.MinLoad = 1
if w.stats.MaxLoad == 0 {
w.stats.MaxLoad = 1
}
w.minLoadInfo = info
}
w.wg.Add(1)
w.stats.Doing++
w.reportStatsLocked()
return info, nil
}
func (w *Workshop) gc() {
for {
select {
case <-w.closeCh:
return
default:
time.Sleep(w.maxIdleDuration)
w.lock.Lock()
w.refreshLocked(true)
w.lock.Unlock()
}
}
}
func (w *Workshop) setMinLoadInfoLocked() {
if len(w.infos) == 0 {
w.minLoadInfo = nil
return
}
var minLoadInfo *workerInfo
for _, info := range w.infos {
if minLoadInfo != nil && info.jobNum >= minLoadInfo.jobNum {
continue
}
minLoadInfo = info
}
w.minLoadInfo = minLoadInfo
}
// Remove the expired or unhealthy idle workers.
// The time complexity is O(n).
func (w *Workshop) refreshLocked(reportStats bool) {
var max, min, tmp int32
min = math.MaxInt32
var minLoadInfo *workerInfo
for _, info := range w.infos {
if !w.checkInfoLocked(info) {
continue
}
tmp = info.jobNum
if tmp > max {
max = tmp
}
if tmp < min {
min = tmp
}
if minLoadInfo != nil && tmp >= minLoadInfo.jobNum {
continue
}
minLoadInfo = info
}
if min == math.MaxInt32 {
min = 0
}
w.stats.MinLoad = min
w.stats.MaxLoad = max
if reportStats {
w.reportStatsLocked()
}
w.minLoadInfo = minLoadInfo
}
func (w *Workshop) checkInfoLocked(info *workerInfo) bool {
if !info.worker.Health() ||
(info.jobNum == 0 && coarsetime.FloorTimeNow().After(info.idleExpire)) {
delete(w.infos, info.worker)
info.worker.Close()
w.stats.Worker--
if info.jobNum == 0 {
w.stats.Idle--
} else {
w.wg.Add(-int(info.jobNum))
w.stats.Doing -= info.jobNum
w.stats.Done += uint64(info.jobNum)
}
return false
}
return true
}
func (w *Workshop) reportStatsLocked() {
w.statsReader.Store(*w.stats)
}