51 lines
747 B
Go
51 lines
747 B
Go
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package stream
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import (
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"sync"
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)
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func newThreshold(cutoff int) *threshold {
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t := &threshold{
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threshold: cutoff,
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}
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t.cond.L = &t.mu
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return t
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}
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type threshold struct {
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mu sync.Mutex
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cond sync.Cond
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count int
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threshold int
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}
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// Acquire increments the counter. It will not block.
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func (t *threshold) Acquire() {
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t.mu.Lock()
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t.count++
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t.mu.Unlock()
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}
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// Release decrements the counter.
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func (t *threshold) Release() {
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t.mu.Lock()
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if t.count == 0 {
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panic("negative count")
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}
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if t.threshold == t.count {
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t.cond.Broadcast()
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}
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t.count--
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t.mu.Unlock()
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}
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// Wait waits for the counter to drop below the threshold
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func (t *threshold) Wait() {
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t.mu.Lock()
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for t.count >= t.threshold {
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t.cond.Wait()
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}
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t.mu.Unlock()
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}
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