81 lines
1.7 KiB
Go
81 lines
1.7 KiB
Go
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// Copied from the go standard library.
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//
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// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE-BSD file.
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package multiplex
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import (
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"sync"
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"time"
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)
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// pipeDeadline is an abstraction for handling timeouts.
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type pipeDeadline struct {
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mu sync.Mutex // Guards timer and cancel
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timer *time.Timer
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cancel chan struct{} // Must be non-nil
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}
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func makePipeDeadline() pipeDeadline {
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return pipeDeadline{cancel: make(chan struct{})}
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}
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// set sets the point in time when the deadline will time out.
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// A timeout event is signaled by closing the channel returned by waiter.
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// Once a timeout has occurred, the deadline can be refreshed by specifying a
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// t value in the future.
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//
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// A zero value for t prevents timeout.
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func (d *pipeDeadline) set(t time.Time) {
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d.mu.Lock()
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defer d.mu.Unlock()
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if d.timer != nil && !d.timer.Stop() {
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<-d.cancel // Wait for the timer callback to finish and close cancel
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}
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d.timer = nil
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// Time is zero, then there is no deadline.
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closed := isClosedChan(d.cancel)
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if t.IsZero() {
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if closed {
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d.cancel = make(chan struct{})
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}
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return
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}
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// Time in the future, setup a timer to cancel in the future.
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if dur := time.Until(t); dur > 0 {
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if closed {
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d.cancel = make(chan struct{})
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}
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d.timer = time.AfterFunc(dur, func() {
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close(d.cancel)
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})
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return
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}
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// Time in the past, so close immediately.
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if !closed {
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close(d.cancel)
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}
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}
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// wait returns a channel that is closed when the deadline is exceeded.
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func (d *pipeDeadline) wait() chan struct{} {
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d.mu.Lock()
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defer d.mu.Unlock()
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return d.cancel
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}
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func isClosedChan(c <-chan struct{}) bool {
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select {
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case <-c:
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return true
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default:
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return false
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}
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}
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