Source file src/pkg/sync/atomic/doc.go
1 // Copyright 2011 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 // Package atomic provides low-level atomic memory primitives 6 // useful for implementing synchronization algorithms. 7 // 8 // These functions require great care to be used correctly. 9 // Except for special, low-level applications, synchronization is better 10 // done with channels or the facilities of the sync package. 11 // Share memory by communicating; 12 // don't communicate by sharing memory. 13 // 14 // The compare-and-swap operation, implemented by the CompareAndSwapT 15 // functions, is the atomic equivalent of: 16 // 17 // if *val == old { 18 // *val = new 19 // return true 20 // } 21 // return false 22 // 23 package atomic 24 25 import ( 26 "unsafe" 27 ) 28 29 // BUG(rsc): On ARM, the 64-bit functions use instructions unavailable before ARM 11. 30 // 31 // On x86-32, the 64-bit functions use instructions unavailable before the Pentium MMX. 32 33 // CompareAndSwapInt32 executes the compare-and-swap operation for an int32 value. 34 func CompareAndSwapInt32(val *int32, old, new int32) (swapped bool) 35 36 // CompareAndSwapInt64 executes the compare-and-swap operation for an int64 value. 37 func CompareAndSwapInt64(val *int64, old, new int64) (swapped bool) 38 39 // CompareAndSwapUint32 executes the compare-and-swap operation for a uint32 value. 40 func CompareAndSwapUint32(val *uint32, old, new uint32) (swapped bool) 41 42 // CompareAndSwapUint64 executes the compare-and-swap operation for a uint64 value. 43 func CompareAndSwapUint64(val *uint64, old, new uint64) (swapped bool) 44 45 // CompareAndSwapUintptr executes the compare-and-swap operation for a uintptr value. 46 func CompareAndSwapUintptr(val *uintptr, old, new uintptr) (swapped bool) 47 48 // CompareAndSwapPointer executes the compare-and-swap operation for a unsafe.Pointer value. 49 func CompareAndSwapPointer(val *unsafe.Pointer, old, new unsafe.Pointer) (swapped bool) 50 51 // AddInt32 atomically adds delta to *val and returns the new value. 52 func AddInt32(val *int32, delta int32) (new int32) 53 54 // AddUint32 atomically adds delta to *val and returns the new value. 55 func AddUint32(val *uint32, delta uint32) (new uint32) 56 57 // AddInt64 atomically adds delta to *val and returns the new value. 58 func AddInt64(val *int64, delta int64) (new int64) 59 60 // AddUint64 atomically adds delta to *val and returns the new value. 61 func AddUint64(val *uint64, delta uint64) (new uint64) 62 63 // AddUintptr atomically adds delta to *val and returns the new value. 64 func AddUintptr(val *uintptr, delta uintptr) (new uintptr) 65 66 // LoadInt32 atomically loads *addr. 67 func LoadInt32(addr *int32) (val int32) 68 69 // LoadInt64 atomically loads *addr. 70 func LoadInt64(addr *int64) (val int64) 71 72 // LoadUint32 atomically loads *addr. 73 func LoadUint32(addr *uint32) (val uint32) 74 75 // LoadUint64 atomically loads *addr. 76 func LoadUint64(addr *uint64) (val uint64) 77 78 // LoadUintptr atomically loads *addr. 79 func LoadUintptr(addr *uintptr) (val uintptr) 80 81 // LoadPointer atomically loads *addr. 82 func LoadPointer(addr *unsafe.Pointer) (val unsafe.Pointer) 83 84 // StoreInt32 atomically stores val into *addr. 85 func StoreInt32(addr *int32, val int32) 86 87 // StoreInt64 atomically stores val into *addr. 88 func StoreInt64(addr *int64, val int64) 89 90 // StoreUint32 atomically stores val into *addr. 91 func StoreUint32(addr *uint32, val uint32) 92 93 // StoreUint64 atomically stores val into *addr. 94 func StoreUint64(addr *uint64, val uint64) 95 96 // StoreUintptr atomically stores val into *addr. 97 func StoreUintptr(addr *uintptr, val uintptr) 98 99 // StorePointer atomically stores val into *addr. 100 func StorePointer(addr *unsafe.Pointer, val unsafe.Pointer) 101 102 // Helper for ARM. Linker will discard on other systems 103 func panic64() { 104 panic("sync/atomic: broken 64-bit atomic operations (buggy QEMU)") 105 }