mirror of https://github.com/tidwall/tile38.git
54 lines
988 B
Go
54 lines
988 B
Go
// Copyright 2018 Joshua J Baker. All rights reserved.
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// Use of this source code is governed by an MIT-style
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// license that can be found in the LICENSE file.
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package internal
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import (
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"runtime"
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"sync/atomic"
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)
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// this is a good candiate for a lock-free structure.
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type spinlock struct{ lock uintptr }
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func (l *spinlock) Lock() {
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for !atomic.CompareAndSwapUintptr(&l.lock, 0, 1) {
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runtime.Gosched()
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}
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}
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func (l *spinlock) Unlock() {
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atomic.StoreUintptr(&l.lock, 0)
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}
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type noteQueue struct {
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mu spinlock
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notes []interface{}
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}
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func (q *noteQueue) Add(note interface{}) (one bool) {
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q.mu.Lock()
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q.notes = append(q.notes, note)
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n := len(q.notes)
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q.mu.Unlock()
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return n == 1
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}
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func (q *noteQueue) ForEach(iter func(note interface{}) error) error {
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q.mu.Lock()
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if len(q.notes) == 0 {
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q.mu.Unlock()
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return nil
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}
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notes := q.notes
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q.notes = nil
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q.mu.Unlock()
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for _, note := range notes {
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if err := iter(note); err != nil {
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return err
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}
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}
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return nil
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}
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