Alexey Khit
72 lines
996 B
Go
72 lines
996 B
Go
package core
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import (
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"sync"
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)
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// Waiter support:
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// - autotart on first Wait
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// - block new waiters after last Done
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// - safe Done after finish
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type Waiter struct {
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sync.WaitGroup
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mu sync.Mutex
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state int // state < 0 means finish
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}
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func (w *Waiter) Add(delta int) {
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w.mu.Lock()
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if w.state >= 0 {
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w.state += delta
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w.WaitGroup.Add(delta)
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}
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w.mu.Unlock()
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}
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func (w *Waiter) Wait() {
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w.mu.Lock()
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// first wait auto start waiter
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if w.state == 0 {
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w.state++
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w.WaitGroup.Add(1)
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}
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w.mu.Unlock()
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w.WaitGroup.Wait()
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}
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func (w *Waiter) Done() {
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w.mu.Lock()
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// safe run Done only when have tasks
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if w.state > 0 {
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w.state--
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w.WaitGroup.Done()
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}
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// block waiter for any operations after last done
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if w.state == 0 {
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w.state = -1
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}
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w.mu.Unlock()
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}
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func (w *Waiter) WaitChan() <-chan struct{} {
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var ch chan struct{}
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w.mu.Lock()
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if w.state >= 0 {
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ch = make(chan struct{})
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go func() {
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w.Wait()
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ch <- struct{}{}
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}()
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}
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w.mu.Unlock()
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return ch
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}
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