106 lines
1.9 KiB
Go
106 lines
1.9 KiB
Go
package sctp
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import (
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"sync"
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"time"
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)
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const (
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ackInterval time.Duration = 200 * time.Millisecond
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)
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// ackTimerObserver is the inteface to an ack timer observer.
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type ackTimerObserver interface {
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onAckTimeout()
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}
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// ackTimer provides the retnransmission timer conforms with RFC 4960 Sec 6.3.1
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type ackTimer struct {
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observer ackTimerObserver
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interval time.Duration
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stopFunc stopAckTimerLoop
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closed bool
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mutex sync.RWMutex
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}
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type stopAckTimerLoop func()
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// newAckTimer creates a new acknowledgement timer used to enable delayed ack.
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func newAckTimer(observer ackTimerObserver) *ackTimer {
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return &ackTimer{
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observer: observer,
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interval: ackInterval,
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}
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}
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// start starts the timer.
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func (t *ackTimer) start() bool {
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t.mutex.Lock()
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defer t.mutex.Unlock()
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// this timer is already closed
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if t.closed {
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return false
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}
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// this is a noop if the timer is already running
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if t.stopFunc != nil {
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return false
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}
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cancelCh := make(chan struct{})
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go func() {
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timer := time.NewTimer(t.interval)
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select {
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case <-timer.C:
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t.stop()
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t.observer.onAckTimeout()
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case <-cancelCh:
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timer.Stop()
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}
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}()
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t.stopFunc = func() {
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close(cancelCh)
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}
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return true
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}
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// stops the timer. this is similar to stop() but subsequent start() call
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// will fail (the timer is no longer usable)
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func (t *ackTimer) stop() {
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t.mutex.Lock()
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defer t.mutex.Unlock()
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if t.stopFunc != nil {
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t.stopFunc()
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t.stopFunc = nil
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}
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}
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// closes the timer. this is similar to stop() but subsequent start() call
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// will fail (the timer is no longer usable)
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func (t *ackTimer) close() {
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t.mutex.Lock()
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defer t.mutex.Unlock()
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if t.stopFunc != nil {
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t.stopFunc()
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t.stopFunc = nil
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}
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t.closed = true
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}
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// isRunning tests if the timer is running.
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// Debug purpose only
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func (t *ackTimer) isRunning() bool {
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t.mutex.RLock()
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defer t.mutex.RUnlock()
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return (t.stopFunc != nil)
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}
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