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event_time_source.go
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event_time_source.go
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// The MIT License
//
// Copyright (c) 2020 Temporal Technologies Inc. All rights reserved.
//
// Copyright (c) 2020 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package clock
import (
"sync"
"time"
)
type (
// EventTimeSource is a fake TimeSource. Unlike other fake clock implementations, the methods are synchronous, so
// when you call Advance or Update, all triggered timers from AfterFunc will fire before the method returns, in the
// same goroutine.
EventTimeSource struct {
mu sync.RWMutex
now time.Time
timers []*fakeTimer
}
// fakeTimer is a fake implementation of [Timer].
fakeTimer struct {
// need a link to the parent timeSource for synchronization
timeSource *EventTimeSource
// deadline for when the timer should fire
deadline time.Time
// callback to call when the timer fires
callback func()
// done is true if the timer has fired or been stopped
done bool
// index of the timer in the parent timeSource
index int
}
)
// NewEventTimeSource returns a EventTimeSource with the current time set to Unix zero: 1970-01-01 00:00:00 +0000 UTC.
func NewEventTimeSource() *EventTimeSource {
return &EventTimeSource{
now: time.Unix(0, 0),
}
}
// Now return the current time.
func (ts *EventTimeSource) Now() time.Time {
ts.mu.RLock()
defer ts.mu.RUnlock()
return ts.now
}
// AfterFunc return a timer that will fire after the specified duration. It is important to note that the timeSource is
// locked while the callback is called. This means that you must be cautious about calling any other mutating methods on
// the timeSource from within the callback. Doing so will probably result in a deadlock. To avoid this, you may want to
// wrap all such calls in a goroutine. If the duration is non-positive, the callback will fire immediately before
// AfterFunc returns.
func (ts *EventTimeSource) AfterFunc(d time.Duration, f func()) Timer {
ts.mu.Lock()
defer ts.mu.Unlock()
if d < 0 {
d = 0
}
t := &fakeTimer{timeSource: ts, deadline: ts.now.Add(d), callback: f}
t.index = len(ts.timers)
ts.timers = append(ts.timers, t)
ts.fireTimers()
return t
}
// Update the fake current time. It returns the timeSource so that you can chain calls like this:
// timeSource := NewEventTimeSource().Update(time.Now())
func (ts *EventTimeSource) Update(now time.Time) *EventTimeSource {
ts.mu.Lock()
defer ts.mu.Unlock()
ts.now = now
ts.fireTimers()
return ts
}
// Advance the timer by the specified duration.
func (ts *EventTimeSource) Advance(d time.Duration) {
ts.mu.Lock()
defer ts.mu.Unlock()
ts.now = ts.now.Add(d)
ts.fireTimers()
}
// fireTimers fires all timers that are ready.
func (ts *EventTimeSource) fireTimers() {
n := 0
for _, t := range ts.timers {
if t.deadline.After(ts.now) {
ts.timers[n] = t
t.index = n
n++
} else {
t.callback()
t.done = true
}
}
ts.timers = ts.timers[:n]
}
// Reset the timer to fire after the specified duration. Returns true if the timer was active.
func (t *fakeTimer) Reset(d time.Duration) bool {
t.timeSource.mu.Lock()
defer t.timeSource.mu.Unlock()
if t.done {
return false
}
t.deadline = t.timeSource.now.Add(d)
t.timeSource.fireTimers()
return true
}
// Stop the timer. Returns true if the timer was active.
func (t *fakeTimer) Stop() bool {
t.timeSource.mu.Lock()
defer t.timeSource.mu.Unlock()
if t.done {
return false
}
i := t.index
timers := t.timeSource.timers
timers[i] = timers[len(timers)-1] // swap with last timer
timers[i].index = i // update index of swapped timer
timers = timers[:len(timers)-1] // shrink list
t.timeSource.timers = timers
t.done = true // ensure that the timer is not reused
return true
}