opt: support writev in eventloop.loopWrite()

errors/errors.go

@@ -58,4 +58,11 @@ var (
 	ErrUnsupportedLength = errors.New("unsupported lengthFieldLength. (expected: 1, 2, 3, 4, or 8)")
 	// ErrTooLessLength occurs when adjusted frame length is less than zero.
 	ErrTooLessLength = errors.New("adjusted frame length is less than zero")
+
+	// ================================================ internal errors ================================================
+
+	// ErrShortWritev occurs when internal/io.Writev fails to send all data.
+	ErrShortWritev = errors.New("short writev")
+	// ErrShortReadv occurs when internal/io.Writev fails to send all data.
+	ErrShortReadv = errors.New("short readv")
 )

eventloop_unix.go

@@ -33,11 +33,13 @@ import (
 	"time"
 	"unsafe"
 
+	"golang.org/x/sys/unix"
+
 	gerrors "github.com/panjf2000/gnet/errors"
+	"github.com/panjf2000/gnet/internal/io"
 	"github.com/panjf2000/gnet/internal/logging"
 	"github.com/panjf2000/gnet/internal/netpoll"
 	"github.com/panjf2000/gnet/internal/socket"
-	"golang.org/x/sys/unix"
 )
 
 type eventloop struct {
@@ -180,24 +182,14 @@ func (el *eventloop) loopWrite(c *conn) error {
 	el.eventHandler.PreWrite()
 
 	head, tail := c.outboundBuffer.LazyReadAll()
-	n, err := unix.Write(c.fd, head)
-	if err != nil {
-		if err == unix.EAGAIN {
-			return nil
-		}
-		return el.loopCloseConn(c, os.NewSyscallError("write", err))
-	}
+	n, err := io.Writev(c.fd, [][]byte{head, tail})
 	c.outboundBuffer.Shift(n)
-
-	if n == len(head) && tail != nil {
-		n, err = unix.Write(c.fd, tail)
-		if err != nil {
-			if err == unix.EAGAIN {
-				return nil
-			}
-			return el.loopCloseConn(c, os.NewSyscallError("write", err))
-		}
-		c.outboundBuffer.Shift(n)
+	switch err {
+	case nil, gerrors.ErrShortWritev: // do nothing, just go on
+	case unix.EAGAIN:
+		return nil
+	default:
+		return el.loopCloseConn(c, os.NewSyscallError("write", err))
 	}
 
 	// All data have been drained, it's no need to monitor the writable events,

gnet_test.go

@@ -35,11 +35,12 @@ import (
 	"testing"
 	"time"
 
+	"go.uber.org/zap"
+	"go.uber.org/zap/zapcore"
+
 	"github.com/panjf2000/gnet/errors"
 	"github.com/panjf2000/gnet/pool/bytebuffer"
 	"github.com/panjf2000/gnet/pool/goroutine"
-	"go.uber.org/zap"
-	"go.uber.org/zap/zapcore"
 )
 
 func TestCodecServe(t *testing.T) {

internal/io/io_bsd.go

@@ -0,0 +1,67 @@
+// Copyright (c) 2021 Andy Pan
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+// +build freebsd dragonfly darwin
+
+package io
+
+import (
+	"golang.org/x/sys/unix"
+
+	"github.com/panjf2000/gnet/errors"
+)
+
+// Writev simply calls write() multiple times cuz writev() on BSD-like OS's is not yet implemented in Go.
+func Writev(fd int, iov [][]byte) (int, error) {
+	var sum int
+	for i := range iov {
+		n, err := unix.Write(fd, iov[i])
+		if err != nil {
+			if sum == 0 {
+				sum = n
+			}
+			return sum, err
+		}
+		sum += n
+		if n < len(iov[i]) {
+			return sum, errors.ErrShortWritev
+		}
+	}
+	return sum, nil
+}
+
+// Readv simply calls read() multiple times cuz readv() on BSD-like OS's is not yet implemented in Go.
+func Readv(fd int, iov [][]byte) (int, error) {
+	var sum int
+	for i := range iov {
+		n, err := unix.Read(fd, iov[i])
+		if err != nil {
+			if sum == 0 {
+				sum = n
+			}
+			return sum, err
+		}
+		sum += n
+		if n < len(iov[i]) {
+			return sum, errors.ErrShortReadv
+		}
+	}
+	return sum, nil
+}

internal/io/io_linux.go

@@ -0,0 +1,35 @@
+// Copyright (c) 2021 Andy Pan
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+// +build linux
+
+package io
+
+import "golang.org/x/sys/unix"
+
+// Writev calls writev() on Linux.
+func Writev(fd int, iov [][]byte) (int, error) {
+	return unix.Writev(fd, iov)
+}
+
+// Readv calls readv() on Linux.
+func Readv(fd int, iov [][]byte) (int, error) {
+	return unix.Readv(fd, iov)
+}