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	}