129 lines
2.6 KiB
Go
129 lines
2.6 KiB
Go
package lookup_test
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// This file contains simple time simulation tools for testing
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// and measuring time-aware algorithms
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import (
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"sync"
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"time"
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)
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// Timer tracks information about a simulated timer
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type Timer struct {
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deadline time.Time
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signal chan time.Time
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id int
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}
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// Stopwatch measures simulated execution time and manages simulated timers
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type Stopwatch struct {
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t time.Time
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resolution time.Duration
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timers map[int]*Timer
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timerCounter int
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stopSignal chan struct{}
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lock sync.RWMutex
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}
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// NewStopwatch returns a simulated clock that ticks on `resolution` intervals
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func NewStopwatch(resolution time.Duration) *Stopwatch {
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s := &Stopwatch{
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resolution: resolution,
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}
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s.Reset()
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return s
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}
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// Reset clears all timers and sents the stopwatch to zero
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func (s *Stopwatch) Reset() {
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s.t = time.Time{}
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s.timers = make(map[int]*Timer)
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s.Stop()
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}
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// Tick advances simulated time by the stopwatch's resolution and triggers
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// all due timers
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func (s *Stopwatch) Tick() {
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s.t = s.t.Add(s.resolution)
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s.lock.Lock()
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defer s.lock.Unlock()
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for id, timer := range s.timers {
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if s.t.After(timer.deadline) || s.t.Equal(timer.deadline) {
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timer.signal <- s.t
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close(timer.signal)
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delete(s.timers, id)
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}
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}
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}
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// NewTimer returns a new timer that will trigger after `duration` elapses in the
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// simulation
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func (s *Stopwatch) NewTimer(duration time.Duration) <-chan time.Time {
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s.lock.Lock()
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defer s.lock.Unlock()
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s.timerCounter++
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timer := &Timer{
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deadline: s.t.Add(duration),
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signal: make(chan time.Time, 1),
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id: s.timerCounter,
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}
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s.timers[timer.id] = timer
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return timer.signal
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}
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// TimeAfter returns a simulated timer factory that can replace `time.After`
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func (s *Stopwatch) TimeAfter() func(d time.Duration) <-chan time.Time {
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return func(d time.Duration) <-chan time.Time {
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return s.NewTimer(d)
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}
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}
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// Elapsed returns the time that has passed in the simulation
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func (s *Stopwatch) Elapsed() time.Duration {
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return s.t.Sub(time.Time{})
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}
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// Run starts the time simulation
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func (s *Stopwatch) Run() {
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go func() {
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stopSignal := make(chan struct{})
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s.lock.Lock()
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if s.stopSignal != nil {
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close(s.stopSignal)
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}
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s.stopSignal = stopSignal
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s.lock.Unlock()
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for {
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select {
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case <-time.After(1 * time.Millisecond):
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s.Tick()
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case <-stopSignal:
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return
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}
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}
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}()
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}
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// Stop stops the time simulation
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func (s *Stopwatch) Stop() {
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s.lock.Lock()
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defer s.lock.Unlock()
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if s.stopSignal != nil {
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close(s.stopSignal)
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s.stopSignal = nil
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}
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}
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func (s *Stopwatch) Measure(measuredFunc func()) time.Duration {
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s.Reset()
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s.Run()
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defer s.Stop()
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measuredFunc()
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return s.Elapsed()
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}
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