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|
package fasthttp
import (
"net"
"runtime"
"runtime/debug"
"strings"
"sync"
"time"
)
// workerPool serves incoming connections via a pool of workers
// in FILO order, i.e. the most recently stopped worker will serve the next
// incoming connection.
//
// Such a scheme keeps CPU caches hot (in theory).
type workerPool struct {
// Function for serving server connections.
// It must leave c unclosed.
WorkerFunc func(c net.Conn) error
MaxWorkersCount int
LogAllErrors bool
Logger Logger
lock sync.Mutex
workersCount int
mustStop bool
ready []*workerChan
stopCh chan struct{}
workerChanPool sync.Pool
}
type workerChan struct {
lastUseTime time.Time
ch chan net.Conn
}
func (wp *workerPool) Start() {
if wp.stopCh != nil {
panic("BUG: workerPool already started")
}
wp.stopCh = make(chan struct{})
stopCh := wp.stopCh
go func() {
var scratch []*workerChan
for {
select {
case <-stopCh:
return
default:
time.Sleep(10 * time.Second)
}
wp.clean(&scratch)
}
}()
}
func (wp *workerPool) Stop() {
if wp.stopCh == nil {
panic("BUG: workerPool wasn't started")
}
close(wp.stopCh)
wp.stopCh = nil
// Stop all the workers waiting for incoming connections.
// Do not wait for busy workers - they will stop after
// serving the connection and noticing wp.mustStop = true.
wp.lock.Lock()
for _, ch := range wp.ready {
ch.ch <- nil
}
wp.ready = nil
wp.mustStop = true
wp.lock.Unlock()
}
const maxIdleWorkerDuration = 60 * time.Second
func (wp *workerPool) clean(scratch *[]*workerChan) {
// Clean least recently used workers if they didn't serve connections
// for more than maxIdleWorkerDuration.
currentTime := time.Now()
wp.lock.Lock()
ready := wp.ready
n := len(ready)
i := 0
for i < n && currentTime.Sub(ready[i].lastUseTime) > maxIdleWorkerDuration {
i++
}
if i > 0 {
wp.workersCount -= i
*scratch = append((*scratch)[:0], ready[:i]...)
m := copy(ready, ready[i:])
for i = m; i < n; i++ {
ready[i] = nil
}
wp.ready = ready[:m]
}
wp.lock.Unlock()
// Notify obsolete workers to stop.
// This notification must be outside the wp.lock, since ch.ch
// may be blocking and may consume a lot of time if many workers
// are located on non-local CPUs.
for _, ch := range *scratch {
ch.ch <- nil
}
}
func (wp *workerPool) Serve(c net.Conn) bool {
ch := wp.getCh()
if ch == nil {
return false
}
ch.ch <- c
return true
}
var workerChanCap = func() int {
// Use blocking workerChan if GOMAXPROCS=1.
// This immediately switches Serve to WorkerFunc, which results
// in higher performance (under go1.5 at least).
if runtime.GOMAXPROCS(0) == 1 {
return 0
}
// Use non-blocking workerChan if GOMAXPROCS>1,
// since otherwise the Serve caller (Acceptor) may lag accepting
// new connections if WorkerFunc is CPU-bound.
return 1
}()
func (wp *workerPool) getCh() *workerChan {
var ch *workerChan
createWorker := false
wp.lock.Lock()
ready := wp.ready
n := len(ready) - 1
if n < 0 {
if wp.workersCount < wp.MaxWorkersCount {
createWorker = true
wp.workersCount++
}
} else {
ch = ready[n]
wp.ready = ready[:n]
}
wp.lock.Unlock()
if ch == nil {
if !createWorker {
return nil
}
vch := wp.workerChanPool.Get()
if vch == nil {
vch = &workerChan{
ch: make(chan net.Conn, workerChanCap),
}
}
ch = vch.(*workerChan)
go func() {
wp.workerFunc(ch)
wp.workerChanPool.Put(vch)
}()
}
return ch
}
func (wp *workerPool) release(ch *workerChan) bool {
ch.lastUseTime = time.Now()
wp.lock.Lock()
if wp.mustStop {
wp.lock.Unlock()
return false
}
wp.ready = append(wp.ready, ch)
wp.lock.Unlock()
return true
}
func (wp *workerPool) workerFunc(ch *workerChan) {
var c net.Conn
var err error
defer func() {
if r := recover(); r != nil {
wp.Logger.Printf("panic: %s\nStack trace:\n%s", r, debug.Stack())
}
if c != nil {
c.Close()
wp.release(ch)
}
}()
for c = range ch.ch {
if c == nil {
break
}
if err = wp.WorkerFunc(c); err != nil && err != errHijacked {
errStr := err.Error()
if wp.LogAllErrors || !(strings.Contains(errStr, "broken pipe") ||
strings.Contains(errStr, "reset by peer") ||
strings.Contains(errStr, "i/o timeout")) {
wp.Logger.Printf("error when serving connection %q<->%q: %s", c.LocalAddr(), c.RemoteAddr(), err)
}
}
if err != errHijacked {
c.Close()
}
c = nil
if !wp.release(ch) {
break
}
}
}
|
