package consensus
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import (
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"context"
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"time"
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"github.com/tendermint/tendermint/libs/log"
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"github.com/tendermint/tendermint/libs/service"
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)
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var (
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tickTockBufferSize = 10
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)
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// TimeoutTicker is a timer that schedules timeouts
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// conditional on the height/round/step in the timeoutInfo.
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// The timeoutInfo.Duration may be non-positive.
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type TimeoutTicker interface {
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Start(context.Context) error
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Stop()
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IsRunning() bool
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Chan() <-chan timeoutInfo // on which to receive a timeout
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ScheduleTimeout(ti timeoutInfo) // reset the timer
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}
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// timeoutTicker wraps time.Timer,
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// scheduling timeouts only for greater height/round/step
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// than what it's already seen.
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// Timeouts are scheduled along the tickChan,
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// and fired on the tockChan.
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type timeoutTicker struct {
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service.BaseService
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logger log.Logger
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timer *time.Timer
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tickChan chan timeoutInfo // for scheduling timeouts
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tockChan chan timeoutInfo // for notifying about them
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}
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// NewTimeoutTicker returns a new TimeoutTicker.
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func NewTimeoutTicker(logger log.Logger) TimeoutTicker {
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tt := &timeoutTicker{
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logger: logger,
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timer: time.NewTimer(0),
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tickChan: make(chan timeoutInfo, tickTockBufferSize),
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tockChan: make(chan timeoutInfo, tickTockBufferSize),
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}
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tt.BaseService = *service.NewBaseService(logger, "TimeoutTicker", tt)
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tt.stopTimer() // don't want to fire until the first scheduled timeout
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return tt
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}
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// OnStart implements service.Service. It starts the timeout routine.
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func (t *timeoutTicker) OnStart(ctx context.Context) error {
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go t.timeoutRoutine(ctx)
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return nil
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}
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// OnStop implements service.Service. It stops the timeout routine.
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func (t *timeoutTicker) OnStop() { t.stopTimer() }
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// Chan returns a channel on which timeouts are sent.
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func (t *timeoutTicker) Chan() <-chan timeoutInfo {
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return t.tockChan
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}
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// ScheduleTimeout schedules a new timeout by sending on the internal tickChan.
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// The timeoutRoutine is always available to read from tickChan, so this won't block.
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// The scheduling may fail if the timeoutRoutine has already scheduled a timeout for a later height/round/step.
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func (t *timeoutTicker) ScheduleTimeout(ti timeoutInfo) {
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t.tickChan <- ti
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}
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//-------------------------------------------------------------
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// stop the timer and drain if necessary
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func (t *timeoutTicker) stopTimer() {
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// Stop() returns false if it was already fired or was stopped
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if !t.timer.Stop() {
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select {
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case <-t.timer.C:
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default:
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}
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}
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}
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// send on tickChan to start a new timer.
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// timers are interupted and replaced by new ticks from later steps
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// timeouts of 0 on the tickChan will be immediately relayed to the tockChan
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func (t *timeoutTicker) timeoutRoutine(ctx context.Context) {
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var ti timeoutInfo
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for {
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select {
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case newti := <-t.tickChan:
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t.logger.Debug("Received tick", "old_ti", ti, "new_ti", newti)
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// ignore tickers for old height/round/step
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if newti.Height < ti.Height {
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continue
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} else if newti.Height == ti.Height {
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if newti.Round < ti.Round {
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continue
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} else if newti.Round == ti.Round {
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if ti.Step > 0 && newti.Step <= ti.Step {
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continue
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}
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}
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}
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// stop the last timer
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t.stopTimer()
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// update timeoutInfo and reset timer
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// NOTE time.Timer allows duration to be non-positive
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ti = newti
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t.timer.Reset(ti.Duration)
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t.logger.Debug("Scheduled timeout", "dur", ti.Duration, "height", ti.Height, "round", ti.Round, "step", ti.Step)
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case <-t.timer.C:
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t.logger.Info("Timed out", "dur", ti.Duration, "height", ti.Height, "round", ti.Round, "step", ti.Step)
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// go routine here guarantees timeoutRoutine doesn't block.
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// Determinism comes from playback in the receiveRoutine.
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// We can eliminate it by merging the timeoutRoutine into receiveRoutine
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// and managing the timeouts ourselves with a millisecond ticker
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go func(toi timeoutInfo) {
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select {
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case t.tockChan <- toi:
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case <-ctx.Done():
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}
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}(ti)
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case <-ctx.Done():
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return
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}
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}
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}
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