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Diffstat (limited to 'src/sync/atomic/doc.go')
| -rw-r--r-- | src/sync/atomic/doc.go | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/src/sync/atomic/doc.go b/src/sync/atomic/doc.go new file mode 100644 index 000000000..10fb8c917 --- /dev/null +++ b/src/sync/atomic/doc.go @@ -0,0 +1,149 @@ +// Copyright 2011 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 atomic provides low-level atomic memory primitives +// useful for implementing synchronization algorithms. +// +// These functions require great care to be used correctly. +// Except for special, low-level applications, synchronization is better +// done with channels or the facilities of the sync package. +// Share memory by communicating; +// don't communicate by sharing memory. +// +// The swap operation, implemented by the SwapT functions, is the atomic +// equivalent of: +// +// old = *addr +// *addr = new +// return old +// +// The compare-and-swap operation, implemented by the CompareAndSwapT +// functions, is the atomic equivalent of: +// +// if *addr == old { +// *addr = new +// return true +// } +// return false +// +// The add operation, implemented by the AddT functions, is the atomic +// equivalent of: +// +// *addr += delta +// return *addr +// +// The load and store operations, implemented by the LoadT and StoreT +// functions, are the atomic equivalents of "return *addr" and +// "*addr = val". +// +package atomic + +import ( + "unsafe" +) + +// BUG(rsc): On x86-32, the 64-bit functions use instructions unavailable before the Pentium MMX. +// +// On non-Linux ARM, the 64-bit functions use instructions unavailable before the ARMv6k core. +// +// On both ARM and x86-32, it is the caller's responsibility to arrange for 64-bit +// alignment of 64-bit words accessed atomically. The first word in a global +// variable or in an allocated struct or slice can be relied upon to be +// 64-bit aligned. + +// SwapInt32 atomically stores new into *addr and returns the previous *addr value. +func SwapInt32(addr *int32, new int32) (old int32) + +// SwapInt64 atomically stores new into *addr and returns the previous *addr value. +func SwapInt64(addr *int64, new int64) (old int64) + +// SwapUint32 atomically stores new into *addr and returns the previous *addr value. +func SwapUint32(addr *uint32, new uint32) (old uint32) + +// SwapUint64 atomically stores new into *addr and returns the previous *addr value. +func SwapUint64(addr *uint64, new uint64) (old uint64) + +// SwapUintptr atomically stores new into *addr and returns the previous *addr value. +func SwapUintptr(addr *uintptr, new uintptr) (old uintptr) + +// SwapPointer atomically stores new into *addr and returns the previous *addr value. +func SwapPointer(addr *unsafe.Pointer, new unsafe.Pointer) (old unsafe.Pointer) + +// CompareAndSwapInt32 executes the compare-and-swap operation for an int32 value. +func CompareAndSwapInt32(addr *int32, old, new int32) (swapped bool) + +// CompareAndSwapInt64 executes the compare-and-swap operation for an int64 value. +func CompareAndSwapInt64(addr *int64, old, new int64) (swapped bool) + +// CompareAndSwapUint32 executes the compare-and-swap operation for a uint32 value. +func CompareAndSwapUint32(addr *uint32, old, new uint32) (swapped bool) + +// CompareAndSwapUint64 executes the compare-and-swap operation for a uint64 value. +func CompareAndSwapUint64(addr *uint64, old, new uint64) (swapped bool) + +// CompareAndSwapUintptr executes the compare-and-swap operation for a uintptr value. +func CompareAndSwapUintptr(addr *uintptr, old, new uintptr) (swapped bool) + +// CompareAndSwapPointer executes the compare-and-swap operation for a unsafe.Pointer value. +func CompareAndSwapPointer(addr *unsafe.Pointer, old, new unsafe.Pointer) (swapped bool) + +// AddInt32 atomically adds delta to *addr and returns the new value. +func AddInt32(addr *int32, delta int32) (new int32) + +// AddUint32 atomically adds delta to *addr and returns the new value. +// To subtract a signed positive constant value c from x, do AddUint32(&x, ^uint32(c-1)). +// In particular, to decrement x, do AddUint32(&x, ^uint32(0)). +func AddUint32(addr *uint32, delta uint32) (new uint32) + +// AddInt64 atomically adds delta to *addr and returns the new value. +func AddInt64(addr *int64, delta int64) (new int64) + +// AddUint64 atomically adds delta to *addr and returns the new value. +// To subtract a signed positive constant value c from x, do AddUint64(&x, ^uint64(c-1)). +// In particular, to decrement x, do AddUint64(&x, ^uint64(0)). +func AddUint64(addr *uint64, delta uint64) (new uint64) + +// AddUintptr atomically adds delta to *addr and returns the new value. +func AddUintptr(addr *uintptr, delta uintptr) (new uintptr) + +// LoadInt32 atomically loads *addr. +func LoadInt32(addr *int32) (val int32) + +// LoadInt64 atomically loads *addr. +func LoadInt64(addr *int64) (val int64) + +// LoadUint32 atomically loads *addr. +func LoadUint32(addr *uint32) (val uint32) + +// LoadUint64 atomically loads *addr. +func LoadUint64(addr *uint64) (val uint64) + +// LoadUintptr atomically loads *addr. +func LoadUintptr(addr *uintptr) (val uintptr) + +// LoadPointer atomically loads *addr. +func LoadPointer(addr *unsafe.Pointer) (val unsafe.Pointer) + +// StoreInt32 atomically stores val into *addr. +func StoreInt32(addr *int32, val int32) + +// StoreInt64 atomically stores val into *addr. +func StoreInt64(addr *int64, val int64) + +// StoreUint32 atomically stores val into *addr. +func StoreUint32(addr *uint32, val uint32) + +// StoreUint64 atomically stores val into *addr. +func StoreUint64(addr *uint64, val uint64) + +// StoreUintptr atomically stores val into *addr. +func StoreUintptr(addr *uintptr, val uintptr) + +// StorePointer atomically stores val into *addr. +func StorePointer(addr *unsafe.Pointer, val unsafe.Pointer) + +// Helper for ARM. Linker will discard on other systems +func panic64() { + panic("sync/atomic: broken 64-bit atomic operations (buggy QEMU)") +} |