39 lines
882 B
Go
39 lines
882 B
Go
/*
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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 (
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"sync/atomic"
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)
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// sequencer 序号产生器，维护读和写两个状态，写状态具体由内部游标（cursor）维护。
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// 读取状态由自身维护，变量read即可
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type sequencer struct {
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rc uint64 // 读取游标，因为该值仅会被一个g修改，所以不需要使用cursor
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capacity uint64
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wc *cursor
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}
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func newSequencer(capacity int) *sequencer {
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return &sequencer{
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wc: newCursor(),
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rc: 1,
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capacity: uint64(capacity),
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}
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}
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// nextRead 获取下个要读取的位置
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// 使用原子操作解决data race问题
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func (s *sequencer) nextRead() uint64 {
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return atomic.LoadUint64(&s.rc)
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}
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func (s *sequencer) readIncrement() uint64 {
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return atomic.AddUint64(&s.rc, 1)
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}
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