opt: improve the buffered channels

gnet.go

@@ -321,15 +321,19 @@ func sniffErrorAndLog(err error) {
 }
 
 // channelBuffer determines whether the channel should be a buffered channel to get the best performance.
-func channelBuffer(preset int) int {
+var channelBuffer = func() int {
 	// Use blocking channel if GOMAXPROCS=1.
 	// This switches context from sender to receiver immediately,
-	// which results in higher performance (under go1.5 at least).
-	if runtime.GOMAXPROCS(0) == 1 {
+	// which results in higher performance.
+	var n int
+	if n = runtime.GOMAXPROCS(0); n == 1 {
 		return 0
 	}
 
-	// Use non-blocking workerChan if GOMAXPROCS>1,
-	// since otherwise the sender might be dragged down if the receiver is CPU-bound.
-	return preset
-}
+	// Make channel non-blocking and set up its capacity with GOMAXPROCS if GOMAXPROCS>1,
+	// otherwise the sender might be dragged down if the receiver is CPU-bound.
+	//
+	// GOMAXPROCS determines how many goroutines can run in parallel,
+	// which makes it the best choice as the channel capacity,
+	return n
+}()

server_unix.go

@@ -241,7 +241,7 @@ func serve(eventHandler EventHandler, listener *listener, options *Options, prot
 	}
 
 	svr.cond = sync.NewCond(&sync.Mutex{})
-	svr.ticktock = make(chan time.Duration, channelBuffer(1))
+	svr.ticktock = make(chan time.Duration, channelBuffer)
 	svr.logger = logging.DefaultLogger
 	svr.codec = func() ICodec {
 		if options.Codec == nil {

server_windows.go

@@ -32,11 +32,6 @@ import (
 	"github.com/panjf2000/gnet/internal/logging"
 )
 
-// commandBufferSize represents the buffer size of event-loop command channel on Windows.
-const (
-	commandBufferSize = 128
-)
-
 var errCloseAllConns = errors.New("close all connections in event-loop")
 
 type server struct {
@@ -96,7 +91,7 @@ func (svr *server) startListener() {
 func (svr *server) startEventLoops(numEventLoop int) {
 	for i := 0; i < numEventLoop; i++ {
 		el := new(eventloop)
-		el.ch = make(chan interface{}, channelBuffer(commandBufferSize))
+		el.ch = make(chan interface{}, channelBuffer)
 		el.svr = svr
 		el.connections = make(map[*stdConn]struct{})
 		el.eventHandler = svr.eventHandler