status-go/vendor/github.com/libp2p/go-mplex/deadline.go

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2019-06-09 07:24:20 +00:00
// Copied from the go standard library.
//
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE-BSD file.
package multiplex
import (
"sync"
"time"
)
// pipeDeadline is an abstraction for handling timeouts.
type pipeDeadline struct {
mu sync.Mutex // Guards timer and cancel
timer *time.Timer
cancel chan struct{} // Must be non-nil
}
func makePipeDeadline() pipeDeadline {
return pipeDeadline{cancel: make(chan struct{})}
}
// set sets the point in time when the deadline will time out.
// A timeout event is signaled by closing the channel returned by waiter.
// Once a timeout has occurred, the deadline can be refreshed by specifying a
// t value in the future.
//
// A zero value for t prevents timeout.
func (d *pipeDeadline) set(t time.Time) {
d.mu.Lock()
defer d.mu.Unlock()
// deadline closed
if d.cancel == nil {
return
}
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if d.timer != nil && !d.timer.Stop() {
<-d.cancel // Wait for the timer callback to finish and close cancel
}
d.timer = nil
// Time is zero, then there is no deadline.
closed := isClosedChan(d.cancel)
if t.IsZero() {
if closed {
d.cancel = make(chan struct{})
}
return
}
// Time in the future, setup a timer to cancel in the future.
if dur := time.Until(t); dur > 0 {
if closed {
d.cancel = make(chan struct{})
}
d.timer = time.AfterFunc(dur, func() {
close(d.cancel)
})
return
}
// Time in the past, so close immediately.
if !closed {
close(d.cancel)
}
}
// wait returns a channel that is closed when the deadline is exceeded.
func (d *pipeDeadline) wait() chan struct{} {
d.mu.Lock()
defer d.mu.Unlock()
return d.cancel
}
// close closes, the deadline. Any future calls to `set` will do nothing.
func (d *pipeDeadline) close() {
d.mu.Lock()
defer d.mu.Unlock()
if d.timer != nil && !d.timer.Stop() {
<-d.cancel // Wait for the timer callback to finish and close cancel
}
d.timer = nil
d.cancel = nil
}
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func isClosedChan(c <-chan struct{}) bool {
select {
case <-c:
return true
default:
return false
}
}