internal/poll: remove rsa field from Windows' poll.operation

The rsa field was added to the operation structure to avoid allocating
it every time it is needed. We can do better by using a sync.Pool to
reuse allocations across operations and FDs instead of the field.

A side benefit is that FD is now 16 bytes smaller and operation more
stateless.

Change-Id: I3b69a59e36b27f2cdd076cebd8d27a2a350b9c43
Reviewed-on: https://go-review.googlesource.com/c/go/+/698875
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Damien Neil <dneil@google.com>

diff --git a/src/internal/poll/fd_windows.go b/src/internal/poll/fd_windows.go
index 18ccee3cee724695c04d16d4bd3848bc319651ff..7e5ed698560385eb3f90dd65da7608a869b847f9 100644 (file)
--- a/src/internal/poll/fd_windows.go
+++ b/src/internal/poll/fd_windows.go
@@ -78,7 +78,6 @@ type operation struct {
 
        // fields used only by net package
        buf  syscall.WSABuf
-       rsa  *syscall.RawSockaddrAny
        bufs []syscall.WSABuf
 }
 
@@ -187,6 +186,12 @@ func freeWSAMsg(msg *windows.WSAMsg) {
        wsaMsgPool.Put(msg)
 }
 
+var wsaRsaPool = sync.Pool{
+       New: func() any {
+               return new(syscall.RawSockaddrAny)
+       },
+}
+
 // waitIO waits for the IO operation o to complete.
 func (fd *FD) waitIO(o *operation) error {
        if fd.isBlocking {
@@ -693,20 +698,19 @@ func (fd *FD) ReadFrom(buf []byte) (int, syscall.Sockaddr, error) {
        defer fd.readUnlock()
        o := &fd.rop
        o.InitBuf(buf)
+       rsa := wsaRsaPool.Get().(*syscall.RawSockaddrAny)
+       defer wsaRsaPool.Put(rsa)
        n, err := fd.execIO(o, func(o *operation) (qty uint32, err error) {
-               if o.rsa == nil {
-                       o.rsa = new(syscall.RawSockaddrAny)
-               }
-               rsan := int32(unsafe.Sizeof(*o.rsa))
+               rsan := int32(unsafe.Sizeof(*rsa))
                var flags uint32
-               err = syscall.WSARecvFrom(fd.Sysfd, &o.buf, 1, &qty, &flags, o.rsa, &rsan, &o.o, nil)
+               err = syscall.WSARecvFrom(fd.Sysfd, &o.buf, 1, &qty, &flags, rsa, &rsan, &o.o, nil)
                return qty, err
        })
        err = fd.eofError(n, err)
        if err != nil {
                return n, nil, err
        }
-       sa, _ := o.rsa.Sockaddr()
+       sa, _ := rsa.Sockaddr()
        return n, sa, nil
 }
 
@@ -724,20 +728,19 @@ func (fd *FD) ReadFromInet4(buf []byte, sa4 *syscall.SockaddrInet4) (int, error)
        defer fd.readUnlock()
        o := &fd.rop
        o.InitBuf(buf)
+       rsa := wsaRsaPool.Get().(*syscall.RawSockaddrAny)
+       defer wsaRsaPool.Put(rsa)
        n, err := fd.execIO(o, func(o *operation) (qty uint32, err error) {
-               if o.rsa == nil {
-                       o.rsa = new(syscall.RawSockaddrAny)
-               }
-               rsan := int32(unsafe.Sizeof(*o.rsa))
+               rsan := int32(unsafe.Sizeof(*rsa))
                var flags uint32
-               err = syscall.WSARecvFrom(fd.Sysfd, &o.buf, 1, &qty, &flags, o.rsa, &rsan, &o.o, nil)
+               err = syscall.WSARecvFrom(fd.Sysfd, &o.buf, 1, &qty, &flags, rsa, &rsan, &o.o, nil)
                return qty, err
        })
        err = fd.eofError(n, err)
        if err != nil {
                return n, err
        }
-       rawToSockaddrInet4(o.rsa, sa4)
+       rawToSockaddrInet4(rsa, sa4)
        return n, err
 }
 
@@ -755,20 +758,19 @@ func (fd *FD) ReadFromInet6(buf []byte, sa6 *syscall.SockaddrInet6) (int, error)
        defer fd.readUnlock()
        o := &fd.rop
        o.InitBuf(buf)
+       rsa := wsaRsaPool.Get().(*syscall.RawSockaddrAny)
+       defer wsaRsaPool.Put(rsa)
        n, err := fd.execIO(o, func(o *operation) (qty uint32, err error) {
-               if o.rsa == nil {
-                       o.rsa = new(syscall.RawSockaddrAny)
-               }
-               rsan := int32(unsafe.Sizeof(*o.rsa))
+               rsan := int32(unsafe.Sizeof(*rsa))
                var flags uint32
-               err = syscall.WSARecvFrom(fd.Sysfd, &o.buf, 1, &qty, &flags, o.rsa, &rsan, &o.o, nil)
+               err = syscall.WSARecvFrom(fd.Sysfd, &o.buf, 1, &qty, &flags, rsa, &rsan, &o.o, nil)
                return qty, err
        })
        err = fd.eofError(n, err)
        if err != nil {
                return n, err
        }
-       rawToSockaddrInet6(o.rsa, sa6)
+       rawToSockaddrInet6(rsa, sa6)
        return n, err
 }
 
@@ -1321,20 +1323,18 @@ func (fd *FD) ReadMsg(p []byte, oob []byte, flags int) (int, int, int, syscall.S
                p = p[:maxRW]
        }
 
-       o := &fd.rop
-       if o.rsa == nil {
-               o.rsa = new(syscall.RawSockaddrAny)
-       }
-       msg := newWSAMsg(p, oob, flags, o.rsa)
+       rsa := wsaRsaPool.Get().(*syscall.RawSockaddrAny)
+       defer wsaRsaPool.Put(rsa)
+       msg := newWSAMsg(p, oob, flags, rsa)
        defer freeWSAMsg(msg)
-       n, err := fd.execIO(o, func(o *operation) (qty uint32, err error) {
+       n, err := fd.execIO(&fd.rop, func(o *operation) (qty uint32, err error) {
                err = windows.WSARecvMsg(fd.Sysfd, msg, &qty, &o.o, nil)
                return qty, err
        })
        err = fd.eofError(n, err)
        var sa syscall.Sockaddr
        if err == nil {
-               sa, err = o.rsa.Sockaddr()
+               sa, err = rsa.Sockaddr()
        }
        return n, int(msg.Control.Len), int(msg.Flags), sa, err
 }
@@ -1350,19 +1350,17 @@ func (fd *FD) ReadMsgInet4(p []byte, oob []byte, flags int, sa4 *syscall.Sockadd
                p = p[:maxRW]
        }
 
-       o := &fd.rop
-       if o.rsa == nil {
-               o.rsa = new(syscall.RawSockaddrAny)
-       }
-       msg := newWSAMsg(p, oob, flags, o.rsa)
+       rsa := wsaRsaPool.Get().(*syscall.RawSockaddrAny)
+       defer wsaRsaPool.Put(rsa)
+       msg := newWSAMsg(p, oob, flags, rsa)
        defer freeWSAMsg(msg)
-       n, err := fd.execIO(o, func(o *operation) (qty uint32, err error) {
+       n, err := fd.execIO(&fd.rop, func(o *operation) (qty uint32, err error) {
                err = windows.WSARecvMsg(fd.Sysfd, msg, &qty, &o.o, nil)
                return qty, err
        })
        err = fd.eofError(n, err)
        if err == nil {
-               rawToSockaddrInet4(o.rsa, sa4)
+               rawToSockaddrInet4(rsa, sa4)
        }
        return n, int(msg.Control.Len), int(msg.Flags), err
 }
@@ -1378,19 +1376,17 @@ func (fd *FD) ReadMsgInet6(p []byte, oob []byte, flags int, sa6 *syscall.Sockadd
                p = p[:maxRW]
        }
 
-       o := &fd.rop
-       if o.rsa == nil {
-               o.rsa = new(syscall.RawSockaddrAny)
-       }
-       msg := newWSAMsg(p, oob, flags, o.rsa)
+       rsa := wsaRsaPool.Get().(*syscall.RawSockaddrAny)
+       defer wsaRsaPool.Put(rsa)
+       msg := newWSAMsg(p, oob, flags, rsa)
        defer freeWSAMsg(msg)
-       n, err := fd.execIO(o, func(o *operation) (qty uint32, err error) {
+       n, err := fd.execIO(&fd.rop, func(o *operation) (qty uint32, err error) {
                err = windows.WSARecvMsg(fd.Sysfd, msg, &qty, &o.o, nil)
                return qty, err
        })
        err = fd.eofError(n, err)
        if err == nil {
-               rawToSockaddrInet6(o.rsa, sa6)
+               rawToSockaddrInet6(rsa, sa6)
        }
        return n, int(msg.Control.Len), int(msg.Flags), err
 }
@@ -1406,20 +1402,21 @@ func (fd *FD) WriteMsg(p []byte, oob []byte, sa syscall.Sockaddr) (int, int, err
        }
        defer fd.writeUnlock()
 
-       o := &fd.wop
-       if sa != nil && o.rsa == nil {
-               o.rsa = new(syscall.RawSockaddrAny)
+       var rsa *syscall.RawSockaddrAny
+       if sa != nil {
+               rsa = wsaRsaPool.Get().(*syscall.RawSockaddrAny)
+               defer wsaRsaPool.Put(rsa)
        }
-       msg := newWSAMsg(p, oob, 0, o.rsa)
+       msg := newWSAMsg(p, oob, 0, rsa)
        defer freeWSAMsg(msg)
        if sa != nil {
                var err error
-               msg.Namelen, err = sockaddrToRaw(o.rsa, sa)
+               msg.Namelen, err = sockaddrToRaw(rsa, sa)
                if err != nil {
                        return 0, 0, err
                }
        }
-       n, err := fd.execIO(o, func(o *operation) (qty uint32, err error) {
+       n, err := fd.execIO(&fd.wop, func(o *operation) (qty uint32, err error) {
                err = windows.WSASendMsg(fd.Sysfd, msg, 0, nil, &o.o, nil)
                return qty, err
        })
@@ -1437,16 +1434,17 @@ func (fd *FD) WriteMsgInet4(p []byte, oob []byte, sa *syscall.SockaddrInet4) (in
        }
        defer fd.writeUnlock()
 
-       o := &fd.wop
-       if sa != nil && o.rsa == nil {
-               o.rsa = new(syscall.RawSockaddrAny)
+       var rsa *syscall.RawSockaddrAny
+       if sa != nil {
+               rsa = wsaRsaPool.Get().(*syscall.RawSockaddrAny)
+               defer wsaRsaPool.Put(rsa)
        }
-       msg := newWSAMsg(p, oob, 0, o.rsa)
+       msg := newWSAMsg(p, oob, 0, rsa)
        defer freeWSAMsg(msg)
        if sa != nil {
-               msg.Namelen = sockaddrInet4ToRaw(o.rsa, sa)
+               msg.Namelen = sockaddrInet4ToRaw(rsa, sa)
        }
-       n, err := fd.execIO(o, func(o *operation) (qty uint32, err error) {
+       n, err := fd.execIO(&fd.wop, func(o *operation) (qty uint32, err error) {
                err = windows.WSASendMsg(fd.Sysfd, msg, 0, nil, &o.o, nil)
                return qty, err
        })
@@ -1464,16 +1462,17 @@ func (fd *FD) WriteMsgInet6(p []byte, oob []byte, sa *syscall.SockaddrInet6) (in
        }
        defer fd.writeUnlock()
 
-       o := &fd.wop
-       if sa != nil && o.rsa == nil {
-               o.rsa = new(syscall.RawSockaddrAny)
+       var rsa *syscall.RawSockaddrAny
+       if sa != nil {
+               rsa = wsaRsaPool.Get().(*syscall.RawSockaddrAny)
+               defer wsaRsaPool.Put(rsa)
        }
-       msg := newWSAMsg(p, oob, 0, o.rsa)
+       msg := newWSAMsg(p, oob, 0, rsa)
        defer freeWSAMsg(msg)
        if sa != nil {
-               msg.Namelen = sockaddrInet6ToRaw(o.rsa, sa)
+               msg.Namelen = sockaddrInet6ToRaw(rsa, sa)
        }
-       n, err := fd.execIO(o, func(o *operation) (qty uint32, err error) {
+       n, err := fd.execIO(&fd.wop, func(o *operation) (qty uint32, err error) {
                err = windows.WSASendMsg(fd.Sysfd, msg, 0, nil, &o.o, nil)
                return qty, err
        })