58 lines
1.1 KiB
Go
58 lines
1.1 KiB
Go
//go:build !386
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/*
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* Copyright (C) THL A29 Limited, a Tencent company. All rights reserved.
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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*/
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package lockfree
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import "sync/atomic"
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type e[T any] struct {
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c uint64
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val T
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}
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// ringBuffer 具体对象的存放区域，通过数组（定长切片）实现环状数据结构
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// 其中e为具体对象，非指针，这样可以一次性进行内存申请
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type ringBuffer[T any] struct {
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// 增加默认的对象以便于return，处理data race问题
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tDefault T
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buf []e[T]
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capMask uint64
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}
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func newRingBuffer[T any](cap int) *ringBuffer[T] {
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x := ringBuffer[T]{
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capMask: uint64(cap) - 1,
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buf: make([]e[T], cap),
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}
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return &x
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}
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func (r *ringBuffer[T]) write(c uint64, v T) {
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x := &r.buf[c&r.capMask]
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x.val = v
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atomic.StoreUint64(&x.c, c+1)
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}
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func (r *ringBuffer[T]) element(c uint64) e[T] {
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return r.buf[c&r.capMask]
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}
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func (r *ringBuffer[T]) contains(c uint64) (T, *uint64, bool) {
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x := &r.buf[c&r.capMask]
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if atomic.LoadUint64(&x.c) == c+1 {
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v := x.val
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return v, &x.c, true
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}
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return r.tDefault, &x.c, false
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}
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func (r *ringBuffer[T]) cap() uint64 {
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return r.capMask + 1
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}
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