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