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net: factor out fdMutex-related methods on netFD

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Also updates documentation.

Change-Id: Idb0fc0feed61407f7f07eab81ce82b55ffde5040
Reviewed-on: https://go-review.googlesource.com/21446
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Mikio Hara 2016-04-04 18:46:13 +09:00
parent 2ae749c13f
commit 86e7a5b92a
4 changed files with 76 additions and 158 deletions
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87
src/net/fd_mutex.go
View file

@ -6,9 +6,9 @@ package net
import "sync/atomic"
// fdMutex is a specialized synchronization primitive
// that manages lifetime of an fd and serializes access
// to Read and Write methods on netFD.
// fdMutex is a specialized synchronization primitive that manages
// lifetime of an fd and serializes access to Read, Write and Close
// methods on netFD.
type fdMutex struct {
state uint64
rsema uint32
@ -35,16 +35,19 @@ const (
)
// Read operations must do rwlock(true)/rwunlock(true).
//
// Write operations must do rwlock(false)/rwunlock(false).
// Misc operations must do incref/decref. Misc operations include functions like
// setsockopt and setDeadline. They need to use incref/decref to ensure that
// they operate on the correct fd in presence of a concurrent close call
// (otherwise fd can be closed under their feet).
// Close operation must do increfAndClose/decref.
// rwlock/incref return whether fd is open.
// rwunlock/decref return whether fd is closed and there are no remaining references.
//
// Misc operations must do incref/decref.
// Misc operations include functions like setsockopt and setDeadline.
// They need to use incref/decref to ensure that they operate on the
// correct fd in presence of a concurrent close call (otherwise fd can
// be closed under their feet).
//
// Close operations must do increfAndClose/decref.
// incref adds a reference to mu.
// It reports whether mu is available for reading or writing.
func (mu *fdMutex) incref() bool {
for {
old := atomic.LoadUint64(&mu.state)
@ -61,6 +64,8 @@ func (mu *fdMutex) incref() bool {
}
}
// increfAndClose sets the state of mu to closed.
// It reports whether there is no remaining reference.
func (mu *fdMutex) increfAndClose() bool {
for {
old := atomic.LoadUint64(&mu.state)
@ -90,6 +95,8 @@ func (mu *fdMutex) increfAndClose() bool {
}
}
// decref removes a reference from mu.
// It reports whether there is no remaining reference.
func (mu *fdMutex) decref() bool {
for {
old := atomic.LoadUint64(&mu.state)
@ -103,6 +110,8 @@ func (mu *fdMutex) decref() bool {
}
}
// lock adds a reference to mu and locks mu.
// It reports whether mu is available for reading or writing.
func (mu *fdMutex) rwlock(read bool) bool {
var mutexBit, mutexWait, mutexMask uint64
var mutexSema *uint32
@ -146,6 +155,8 @@ func (mu *fdMutex) rwlock(read bool) bool {
}
}
// unlock removes a reference from mu and unlocks mu.
// It reports whether there is no remaining reference.
func (mu *fdMutex) rwunlock(read bool) bool {
var mutexBit, mutexWait, mutexMask uint64
var mutexSema *uint32
@ -182,3 +193,57 @@ func (mu *fdMutex) rwunlock(read bool) bool {
// Implemented in runtime package.
func runtime_Semacquire(sema *uint32)
func runtime_Semrelease(sema *uint32)
// incref adds a reference to fd.
// It returns an error when fd cannot be used.
func (fd *netFD) incref() error {
if !fd.fdmu.incref() {
return errClosing
}
return nil
}
// decref removes a reference from fd.
// It also closes fd when the state of fd is set to closed and there
// is no remaining reference.
func (fd *netFD) decref() {
if fd.fdmu.decref() {
fd.destroy()
}
}
// readLock adds a reference to fd and locks fd for reading.
// It returns an error when fd cannot be used for reading.
func (fd *netFD) readLock() error {
if !fd.fdmu.rwlock(true) {
return errClosing
}
return nil
}
// readUnlock removes a reference from fd and unlocks fd for reading.
// It also closes fd when the state of fd is set to closed and there
// is no remaining reference.
func (fd *netFD) readUnlock() {
if fd.fdmu.rwunlock(true) {
fd.destroy()
}
}
// writeLock adds a reference to fd and locks fd for writing.
// It returns an error when fd cannot be used for writing.
func (fd *netFD) writeLock() error {
if !fd.fdmu.rwlock(false) {
return errClosing
}
return nil
}
// writeUnlock removes a reference from fd and unlocks fd for writing.
// It also closes fd when the state of fd is set to closed and there
// is no remaining reference.
func (fd *netFD) writeUnlock() {
if fd.fdmu.rwunlock(false) {
fd.destroy()
}
}

49
src/net/fd_plan9.go
View file

@ -74,55 +74,6 @@ func (fd *netFD) destroy() {
fd.data = nil
}
// Add a reference to this fd.
// Returns an error if the fd cannot be used.
func (fd *netFD) incref() error {
if !fd.fdmu.incref() {
return errClosing
}
return nil
}
// Remove a reference to this FD and close if we've been asked to do so
// (and there are no references left).
func (fd *netFD) decref() {
if fd.fdmu.decref() {
fd.destroy()
}
}
// Add a reference to this fd and lock for reading.
// Returns an error if the fd cannot be used.
func (fd *netFD) readLock() error {
if !fd.fdmu.rwlock(true) {
return errClosing
}
return nil
}
// Unlock for reading and remove a reference to this FD.
func (fd *netFD) readUnlock() {
if fd.fdmu.rwunlock(true) {
fd.destroy()
}
}
// Add a reference to this fd and lock for writing.
// Returns an error if the fd cannot be used.
func (fd *netFD) writeLock() error {
if !fd.fdmu.rwlock(false) {
return errClosing
}
return nil
}
// Unlock for writing and remove a reference to this FD.
func (fd *netFD) writeUnlock() {
if fd.fdmu.rwunlock(false) {
fd.destroy()
}
}
func (fd *netFD) Read(b []byte) (n int, err error) {
if !fd.ok() || fd.data == nil {
return 0, syscall.EINVAL

49
src/net/fd_unix.go
View file

@ -164,55 +164,6 @@ func (fd *netFD) destroy() {
runtime.SetFinalizer(fd, nil)
}
// Add a reference to this fd.
// Returns an error if the fd cannot be used.
func (fd *netFD) incref() error {
if !fd.fdmu.incref() {
return errClosing
}
return nil
}
// Remove a reference to this FD and close if we've been asked to do so
// (and there are no references left).
func (fd *netFD) decref() {
if fd.fdmu.decref() {
fd.destroy()
}
}
// Add a reference to this fd and lock for reading.
// Returns an error if the fd cannot be used.
func (fd *netFD) readLock() error {
if !fd.fdmu.rwlock(true) {
return errClosing
}
return nil
}
// Unlock for reading and remove a reference to this FD.
func (fd *netFD) readUnlock() {
if fd.fdmu.rwunlock(true) {
fd.destroy()
}
}
// Add a reference to this fd and lock for writing.
// Returns an error if the fd cannot be used.
func (fd *netFD) writeLock() error {
if !fd.fdmu.rwlock(false) {
return errClosing
}
return nil
}
// Unlock for writing and remove a reference to this FD.
func (fd *netFD) writeUnlock() {
if fd.fdmu.rwunlock(false) {
fd.destroy()
}
}
func (fd *netFD) Close() error {
if !fd.fdmu.increfAndClose() {
return errClosing

49
src/net/fd_windows.go
View file

@ -395,55 +395,6 @@ func (fd *netFD) destroy() {
runtime.SetFinalizer(fd, nil)
}
// Add a reference to this fd.
// Returns an error if the fd cannot be used.
func (fd *netFD) incref() error {
if !fd.fdmu.incref() {
return errClosing
}
return nil
}
// Remove a reference to this FD and close if we've been asked to do so
// (and there are no references left).
func (fd *netFD) decref() {
if fd.fdmu.decref() {
fd.destroy()
}
}
// Add a reference to this fd and lock for reading.
// Returns an error if the fd cannot be used.
func (fd *netFD) readLock() error {
if !fd.fdmu.rwlock(true) {
return errClosing
}
return nil
}
// Unlock for reading and remove a reference to this FD.
func (fd *netFD) readUnlock() {
if fd.fdmu.rwunlock(true) {
fd.destroy()
}
}
// Add a reference to this fd and lock for writing.
// Returns an error if the fd cannot be used.
func (fd *netFD) writeLock() error {
if !fd.fdmu.rwlock(false) {
return errClosing
}
return nil
}
// Unlock for writing and remove a reference to this FD.
func (fd *netFD) writeUnlock() {
if fd.fdmu.rwunlock(false) {
fd.destroy()
}
}
func (fd *netFD) Close() error {
if !fd.fdmu.increfAndClose() {
return errClosing