Imported Upstream version 1.4upstream/1.4

1 files changed, 0 insertions, 184 deletions

diff --git a/src/pkg/net/fd_mutex.go b/src/pkg/net/fd_mutex.go
deleted file mode 100644
index 6d5509d7f..000000000
--- a/src/pkg/net/fd_mutex.go
+++ /dev/null
@@ -1,184 +0,0 @@
-// Copyright 2013 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-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.
-type fdMutex struct {
-	state uint64
-	rsema uint32
-	wsema uint32
-}
-
-// fdMutex.state is organized as follows:
-// 1 bit - whether netFD is closed, if set all subsequent lock operations will fail.
-// 1 bit - lock for read operations.
-// 1 bit - lock for write operations.
-// 20 bits - total number of references (read+write+misc).
-// 20 bits - number of outstanding read waiters.
-// 20 bits - number of outstanding write waiters.
-const (
-	mutexClosed  = 1 << 0
-	mutexRLock   = 1 << 1
-	mutexWLock   = 1 << 2
-	mutexRef     = 1 << 3
-	mutexRefMask = (1<<20 - 1) << 3
-	mutexRWait   = 1 << 23
-	mutexRMask   = (1<<20 - 1) << 23
-	mutexWWait   = 1 << 43
-	mutexWMask   = (1<<20 - 1) << 43
-)
-
-// 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.
-
-func (mu *fdMutex) Incref() bool {
-	for {
-		old := atomic.LoadUint64(&mu.state)
-		if old&mutexClosed != 0 {
-			return false
-		}
-		new := old + mutexRef
-		if new&mutexRefMask == 0 {
-			panic("net: inconsistent fdMutex")
-		}
-		if atomic.CompareAndSwapUint64(&mu.state, old, new) {
-			return true
-		}
-	}
-}
-
-func (mu *fdMutex) IncrefAndClose() bool {
-	for {
-		old := atomic.LoadUint64(&mu.state)
-		if old&mutexClosed != 0 {
-			return false
-		}
-		// Mark as closed and acquire a reference.
-		new := (old | mutexClosed) + mutexRef
-		if new&mutexRefMask == 0 {
-			panic("net: inconsistent fdMutex")
-		}
-		// Remove all read and write waiters.
-		new &^= mutexRMask | mutexWMask
-		if atomic.CompareAndSwapUint64(&mu.state, old, new) {
-			// Wake all read and write waiters,
-			// they will observe closed flag after wakeup.
-			for old&mutexRMask != 0 {
-				old -= mutexRWait
-				runtime_Semrelease(&mu.rsema)
-			}
-			for old&mutexWMask != 0 {
-				old -= mutexWWait
-				runtime_Semrelease(&mu.wsema)
-			}
-			return true
-		}
-	}
-}
-
-func (mu *fdMutex) Decref() bool {
-	for {
-		old := atomic.LoadUint64(&mu.state)
-		if old&mutexRefMask == 0 {
-			panic("net: inconsistent fdMutex")
-		}
-		new := old - mutexRef
-		if atomic.CompareAndSwapUint64(&mu.state, old, new) {
-			return new&(mutexClosed|mutexRefMask) == mutexClosed
-		}
-	}
-}
-
-func (mu *fdMutex) RWLock(read bool) bool {
-	var mutexBit, mutexWait, mutexMask uint64
-	var mutexSema *uint32
-	if read {
-		mutexBit = mutexRLock
-		mutexWait = mutexRWait
-		mutexMask = mutexRMask
-		mutexSema = &mu.rsema
-	} else {
-		mutexBit = mutexWLock
-		mutexWait = mutexWWait
-		mutexMask = mutexWMask
-		mutexSema = &mu.wsema
-	}
-	for {
-		old := atomic.LoadUint64(&mu.state)
-		if old&mutexClosed != 0 {
-			return false
-		}
-		var new uint64
-		if old&mutexBit == 0 {
-			// Lock is free, acquire it.
-			new = (old | mutexBit) + mutexRef
-			if new&mutexRefMask == 0 {
-				panic("net: inconsistent fdMutex")
-			}
-		} else {
-			// Wait for lock.
-			new = old + mutexWait
-			if new&mutexMask == 0 {
-				panic("net: inconsistent fdMutex")
-			}
-		}
-		if atomic.CompareAndSwapUint64(&mu.state, old, new) {
-			if old&mutexBit == 0 {
-				return true
-			}
-			runtime_Semacquire(mutexSema)
-			// The signaller has subtracted mutexWait.
-		}
-	}
-}
-
-func (mu *fdMutex) RWUnlock(read bool) bool {
-	var mutexBit, mutexWait, mutexMask uint64
-	var mutexSema *uint32
-	if read {
-		mutexBit = mutexRLock
-		mutexWait = mutexRWait
-		mutexMask = mutexRMask
-		mutexSema = &mu.rsema
-	} else {
-		mutexBit = mutexWLock
-		mutexWait = mutexWWait
-		mutexMask = mutexWMask
-		mutexSema = &mu.wsema
-	}
-	for {
-		old := atomic.LoadUint64(&mu.state)
-		if old&mutexBit == 0 || old&mutexRefMask == 0 {
-			panic("net: inconsistent fdMutex")
-		}
-		// Drop lock, drop reference and wake read waiter if present.
-		new := (old &^ mutexBit) - mutexRef
-		if old&mutexMask != 0 {
-			new -= mutexWait
-		}
-		if atomic.CompareAndSwapUint64(&mu.state, old, new) {
-			if old&mutexMask != 0 {
-				runtime_Semrelease(mutexSema)
-			}
-			return new&(mutexClosed|mutexRefMask) == mutexClosed
-		}
-	}
-}
-
-// Implemented in runtime package.
-func runtime_Semacquire(sema *uint32)
-func runtime_Semrelease(sema *uint32)