net: refactor poller into new internal/poll package

This will make it possible to use the poller with the os package.

This is a lot of code movement but the behavior is intended to be
unchanged.

Update #6817.
Update #7903.
Update #15021.
Update #18507.

Change-Id: I1413685928017c32df5654ded73a2643820977ae
Reviewed-on: https://go-review.googlesource.com/36799
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

1 files changed, 4 insertions, 70 deletions

diff --git a/src/net/writev_unix.go b/src/net/writev_unix.go
index 174e6bc51e..bf0fbf8a13 100644
--- a/src/net/writev_unix.go
+++ b/src/net/writev_unix.go
@@ -7,10 +7,8 @@
 package net
 
 import (
-	"io"
-	"os"
+	"runtime"
 	"syscall"
-	"unsafe"
 )
 
 func (c *conn) writeBuffers(v *Buffers) (int64, error) {
@@ -25,71 +23,7 @@ func (c *conn) writeBuffers(v *Buffers) (int64, error) {
 }
 
 func (fd *netFD) writeBuffers(v *Buffers) (n int64, err error) {
-	if err := fd.writeLock(); err != nil {
-		return 0, err
-	}
-	defer fd.writeUnlock()
-	if err := fd.pd.prepareWrite(); err != nil {
-		return 0, err
-	}
-
-	var iovecs []syscall.Iovec
-	if fd.iovecs != nil {
-		iovecs = *fd.iovecs
-	}
-	// TODO: read from sysconf(_SC_IOV_MAX)? The Linux default is
-	// 1024 and this seems conservative enough for now. Darwin's
-	// UIO_MAXIOV also seems to be 1024.
-	maxVec := 1024
-
-	for len(*v) > 0 {
-		iovecs = iovecs[:0]
-		for _, chunk := range *v {
-			if len(chunk) == 0 {
-				continue
-			}
-			iovecs = append(iovecs, syscall.Iovec{Base: &chunk[0]})
-			if fd.isStream && len(chunk) > 1<<30 {
-				iovecs[len(iovecs)-1].SetLen(1 << 30)
-				break // continue chunk on next writev
-			}
-			iovecs[len(iovecs)-1].SetLen(len(chunk))
-			if len(iovecs) == maxVec {
-				break
-			}
-		}
-		if len(iovecs) == 0 {
-			break
-		}
-		fd.iovecs = &iovecs // cache
-
-		wrote, _, e0 := syscall.Syscall(syscall.SYS_WRITEV,
-			uintptr(fd.sysfd),
-			uintptr(unsafe.Pointer(&iovecs[0])),
-			uintptr(len(iovecs)))
-		if wrote == ^uintptr(0) {
-			wrote = 0
-		}
-		testHookDidWritev(int(wrote))
-		n += int64(wrote)
-		v.consume(int64(wrote))
-		if e0 == syscall.EAGAIN {
-			if err = fd.pd.waitWrite(); err == nil {
-				continue
-			}
-		} else if e0 != 0 {
-			err = syscall.Errno(e0)
-		}
-		if err != nil {
-			break
-		}
-		if n == 0 {
-			err = io.ErrUnexpectedEOF
-			break
-		}
-	}
-	if _, ok := err.(syscall.Errno); ok {
-		err = os.NewSyscallError("writev", err)
-	}
-	return n, err
+	n, err = fd.pfd.Writev((*[][]byte)(v))
+	runtime.KeepAlive(fd)
+	return n, wrapSyscallError("writev", err)
 }