atomic

package
Version: v0.0.0-...-e6da185 Latest Latest
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Published: Jul 30, 2021 License: MIT Imports: 1 Imported by: 0

Documentation

Overview

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".

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func AddInt32

func AddInt32(addr *int32, delta int32) (new int32)

AddInt32 atomically adds delta to *addr and returns the new value.

func AddInt64

func AddInt64(addr *int64, delta int64) (new int64)

AddInt64 atomically adds delta to *addr and returns the new value.

func AddUint32

func AddUint32(addr *uint32, delta uint32) (new uint32)

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 AddUint64

func AddUint64(addr *uint64, delta uint64) (new uint64)

AddUint64 自动将 delta 加到 *addr 并返回一个新值 为了从 x 减去有符号的常量值 c,可以使用 AddUint64(&x, ^uint64(c-1)) 特别地,递减 x 可以使用 AddUint64(&x, ^uint64(0))

func AddUintptr

func AddUintptr(addr *uintptr, delta uintptr) (new uintptr)

AddUintptr atomically adds delta to *addr and returns the new value.

func CompareAndSwapInt32

func CompareAndSwapInt32(addr *int32, old, new int32) (swapped bool)

CompareAndSwapInt32 executes the compare-and-swap operation for an int32 value.

func CompareAndSwapInt64

func CompareAndSwapInt64(addr *int64, old, new int64) (swapped bool)

CompareAndSwapInt64 executes the compare-and-swap operation for an int64 value.

func CompareAndSwapPointer

func CompareAndSwapPointer(addr *unsafe.Pointer, old, new unsafe.Pointer) (swapped bool)

CompareAndSwapPointer executes the compare-and-swap operation for a unsafe.Pointer value.

func CompareAndSwapUint32

func CompareAndSwapUint32(addr *uint32, old, new uint32) (swapped bool)

CompareAndSwapUint32 executes the compare-and-swap operation for a uint32 value.

func CompareAndSwapUint64

func CompareAndSwapUint64(addr *uint64, old, new uint64) (swapped bool)

CompareAndSwapUint64 executes the compare-and-swap operation for a uint64 value.

func CompareAndSwapUintptr

func CompareAndSwapUintptr(addr *uintptr, old, new uintptr) (swapped bool)

CompareAndSwapUintptr executes the compare-and-swap operation for a uintptr value.

func LoadInt32

func LoadInt32(addr *int32) (val int32)

LoadInt32 atomically loads *addr.

func LoadInt64

func LoadInt64(addr *int64) (val int64)

LoadInt64 atomically loads *addr.

func LoadPointer

func LoadPointer(addr *unsafe.Pointer) (val unsafe.Pointer)

LoadPointer atomically loads *addr.

func LoadUint32

func LoadUint32(addr *uint32) (val uint32)

LoadUint32 atomically loads *addr.

func LoadUint64

func LoadUint64(addr *uint64) (val uint64)

LoadUint64 atomically loads *addr.

func LoadUintptr

func LoadUintptr(addr *uintptr) (val uintptr)

LoadUintptr atomically loads *addr.

func StoreInt32

func StoreInt32(addr *int32, val int32)

StoreInt32 atomically stores val into *addr.

func StoreInt64

func StoreInt64(addr *int64, val int64)

StoreInt64 atomically stores val into *addr.

func StorePointer

func StorePointer(addr *unsafe.Pointer, val unsafe.Pointer)

StorePointer 将 val 原子的存入 *addr 中

func StoreUint32

func StoreUint32(addr *uint32, val uint32)

StoreUint32 atomically stores val into *addr.

func StoreUint64

func StoreUint64(addr *uint64, val uint64)

StoreUint64 atomically stores val into *addr.

func StoreUintptr

func StoreUintptr(addr *uintptr, val uintptr)

StoreUintptr atomically stores val into *addr.

func SwapInt32

func SwapInt32(addr *int32, new int32) (old int32)

SwapInt32 atomically stores new into *addr and returns the previous *addr value.

func SwapInt64

func SwapInt64(addr *int64, new int64) (old int64)

SwapInt64 atomically stores new into *addr and returns the previous *addr value.

func SwapPointer

func SwapPointer(addr *unsafe.Pointer, new unsafe.Pointer) (old unsafe.Pointer)

SwapPointer atomically stores new into *addr and returns the previous *addr value.

func SwapUint32

func SwapUint32(addr *uint32, new uint32) (old uint32)

SwapUint32 atomically stores new into *addr and returns the previous *addr value.

func SwapUint64

func SwapUint64(addr *uint64, new uint64) (old uint64)

SwapUint64 atomically stores new into *addr and returns the previous *addr value.

func SwapUintptr

func SwapUintptr(addr *uintptr, new uintptr) (old uintptr)

SwapUintptr atomically stores new into *addr and returns the previous *addr value.

Types

type Value

type Value struct {
	// contains filtered or unexported fields
}

Value 提供了相同类型值的原子 load 和 store 操作 零值的 Load 会返回 nil 一旦 Store 被调用,Value 不能被复制

func (*Value) Load

func (v *Value) Load() (x interface{})

Load 返回最近存储的值集合 如果已经没有 Value 调用 Store 则会返回 nil

func (*Value) Store

func (v *Value) Store(x interface{})

Store 将 Value 的值设置为 x Store 的 Value x 必须为相同的类型 Store 不同类型会导致 panic,nil 也是如此

Notes

Bugs

  • 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 ARM, x86-32, and 32-bit MIPS, it is the caller's responsibility to arrange for 64-bit alignment of 64-bit words accessed atomically. The first word in a variable or in an allocated struct, array, or slice can be relied upon to be 64-bit aligned.

Source Files

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