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Diffstat (limited to 'src/sync/atomic/doc.go')
| -rw-r--r-- | src/sync/atomic/doc.go | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/src/sync/atomic/doc.go b/src/sync/atomic/doc.go new file mode 100644 index 0000000..c22d115 --- /dev/null +++ b/src/sync/atomic/doc.go @@ -0,0 +1,192 @@ +// 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". +// +// In the terminology of the Go memory model, if the effect of +// an atomic operation A is observed by atomic operation B, +// then A “synchronizes before” B. +// Additionally, all the atomic operations executed in a program +// behave as though executed in some sequentially consistent order. +// This definition provides the same semantics as +// C++'s sequentially consistent atomics and Java's volatile variables. +package atomic + +import ( + "unsafe" +) + +// BUG(rsc): On 386, 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 ARM, 386, and 32-bit MIPS, it is the caller's responsibility to arrange +// for 64-bit alignment of 64-bit words accessed atomically via the primitive +// atomic functions (types [Int64] and [Uint64] are automatically aligned). +// The first word in an allocated struct, array, or slice; in a global +// variable; or in a local variable (because the subject of all atomic operations +// will escape to the heap) can be relied upon to be 64-bit aligned. + +// SwapInt32 atomically stores new into *addr and returns the previous *addr value. +// Consider using the more ergonomic and less error-prone [Int32.Swap] instead. +func SwapInt32(addr *int32, new int32) (old int32) + +// SwapInt64 atomically stores new into *addr and returns the previous *addr value. +// Consider using the more ergonomic and less error-prone [Int64.Swap] instead +// (particularly if you target 32-bit platforms; see the bugs section). +func SwapInt64(addr *int64, new int64) (old int64) + +// SwapUint32 atomically stores new into *addr and returns the previous *addr value. +// Consider using the more ergonomic and less error-prone [Uint32.Swap] instead. +func SwapUint32(addr *uint32, new uint32) (old uint32) + +// SwapUint64 atomically stores new into *addr and returns the previous *addr value. +// Consider using the more ergonomic and less error-prone [Uint64.Swap] instead +// (particularly if you target 32-bit platforms; see the bugs section). +func SwapUint64(addr *uint64, new uint64) (old uint64) + +// SwapUintptr atomically stores new into *addr and returns the previous *addr value. +// Consider using the more ergonomic and less error-prone [Uintptr.Swap] instead. +func SwapUintptr(addr *uintptr, new uintptr) (old uintptr) + +// SwapPointer atomically stores new into *addr and returns the previous *addr value. +// Consider using the more ergonomic and less error-prone [Pointer.Swap] instead. +func SwapPointer(addr *unsafe.Pointer, new unsafe.Pointer) (old unsafe.Pointer) + +// CompareAndSwapInt32 executes the compare-and-swap operation for an int32 value. +// Consider using the more ergonomic and less error-prone [Int32.CompareAndSwap] instead. +func CompareAndSwapInt32(addr *int32, old, new int32) (swapped bool) + +// CompareAndSwapInt64 executes the compare-and-swap operation for an int64 value. +// Consider using the more ergonomic and less error-prone [Int64.CompareAndSwap] instead +// (particularly if you target 32-bit platforms; see the bugs section). +func CompareAndSwapInt64(addr *int64, old, new int64) (swapped bool) + +// CompareAndSwapUint32 executes the compare-and-swap operation for a uint32 value. +// Consider using the more ergonomic and less error-prone [Uint32.CompareAndSwap] instead. +func CompareAndSwapUint32(addr *uint32, old, new uint32) (swapped bool) + +// CompareAndSwapUint64 executes the compare-and-swap operation for a uint64 value. +// Consider using the more ergonomic and less error-prone [Uint64.CompareAndSwap] instead +// (particularly if you target 32-bit platforms; see the bugs section). +func CompareAndSwapUint64(addr *uint64, old, new uint64) (swapped bool) + +// CompareAndSwapUintptr executes the compare-and-swap operation for a uintptr value. +// Consider using the more ergonomic and less error-prone [Uintptr.CompareAndSwap] instead. +func CompareAndSwapUintptr(addr *uintptr, old, new uintptr) (swapped bool) + +// CompareAndSwapPointer executes the compare-and-swap operation for a unsafe.Pointer value. +// Consider using the more ergonomic and less error-prone [Pointer.CompareAndSwap] instead. +func CompareAndSwapPointer(addr *unsafe.Pointer, old, new unsafe.Pointer) (swapped bool) + +// AddInt32 atomically adds delta to *addr and returns the new value. +// Consider using the more ergonomic and less error-prone [Int32.Add] instead. +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)). +// Consider using the more ergonomic and less error-prone [Uint32.Add] instead. +func AddUint32(addr *uint32, delta uint32) (new uint32) + +// AddInt64 atomically adds delta to *addr and returns the new value. +// Consider using the more ergonomic and less error-prone [Int64.Add] instead +// (particularly if you target 32-bit platforms; see the bugs section). +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)). +// Consider using the more ergonomic and less error-prone [Uint64.Add] instead +// (particularly if you target 32-bit platforms; see the bugs section). +func AddUint64(addr *uint64, delta uint64) (new uint64) + +// AddUintptr atomically adds delta to *addr and returns the new value. +// Consider using the more ergonomic and less error-prone [Uintptr.Add] instead. +func AddUintptr(addr *uintptr, delta uintptr) (new uintptr) + +// LoadInt32 atomically loads *addr. +// Consider using the more ergonomic and less error-prone [Int32.Load] instead. +func LoadInt32(addr *int32) (val int32) + +// LoadInt64 atomically loads *addr. +// Consider using the more ergonomic and less error-prone [Int64.Load] instead +// (particularly if you target 32-bit platforms; see the bugs section). +func LoadInt64(addr *int64) (val int64) + +// LoadUint32 atomically loads *addr. +// Consider using the more ergonomic and less error-prone [Uint32.Load] instead. +func LoadUint32(addr *uint32) (val uint32) + +// LoadUint64 atomically loads *addr. +// Consider using the more ergonomic and less error-prone [Uint64.Load] instead +// (particularly if you target 32-bit platforms; see the bugs section). +func LoadUint64(addr *uint64) (val uint64) + +// LoadUintptr atomically loads *addr. +// Consider using the more ergonomic and less error-prone [Uintptr.Load] instead. +func LoadUintptr(addr *uintptr) (val uintptr) + +// LoadPointer atomically loads *addr. +// Consider using the more ergonomic and less error-prone [Pointer.Load] instead. +func LoadPointer(addr *unsafe.Pointer) (val unsafe.Pointer) + +// StoreInt32 atomically stores val into *addr. +// Consider using the more ergonomic and less error-prone [Int32.Store] instead. +func StoreInt32(addr *int32, val int32) + +// StoreInt64 atomically stores val into *addr. +// Consider using the more ergonomic and less error-prone [Int64.Store] instead +// (particularly if you target 32-bit platforms; see the bugs section). +func StoreInt64(addr *int64, val int64) + +// StoreUint32 atomically stores val into *addr. +// Consider using the more ergonomic and less error-prone [Uint32.Store] instead. +func StoreUint32(addr *uint32, val uint32) + +// StoreUint64 atomically stores val into *addr. +// Consider using the more ergonomic and less error-prone [Uint64.Store] instead +// (particularly if you target 32-bit platforms; see the bugs section). +func StoreUint64(addr *uint64, val uint64) + +// StoreUintptr atomically stores val into *addr. +// Consider using the more ergonomic and less error-prone [Uintptr.Store] instead. +func StoreUintptr(addr *uintptr, val uintptr) + +// StorePointer atomically stores val into *addr. +// Consider using the more ergonomic and less error-prone [Pointer.Store] instead. +func StorePointer(addr *unsafe.Pointer, val unsafe.Pointer) |