tasks/common/clock/event_time_source_test.go

// 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_test

import (
	"fmt"
	"testing"
	"time"

	"github.com/stretchr/testify/assert"
	"go.temporal.io/server/common/clock"
)

// event is a helper to verify how many times a callback was triggered. Because callbacks are triggered synchronously
// with calls to EventTimeSource.Advance, we don't need any further synchronization.
type event struct {
	t     *testing.T
	count int
}

// Fire is the callback to be triggered.
func (e *event) Fire() {
	e.count++
}

// AssertFiredOnce asserts that the callback was triggered exactly once.
func (e *event) AssertFiredOnce(msg string) {
	e.t.Helper()
	assert.Equal(e.t, 1, e.count, msg)
}

// AssertNotFired asserts that the callback was not triggered.
func (e *event) AssertNotFired(msg string) {
	e.t.Helper()
	assert.Zero(e.t, e.count, msg)
}

func ExampleEventTimeSource() {
	// Create a new fake timeSource.
	source := clock.NewEventTimeSource()

	// Create a timer which fires after 1 second.
	source.AfterFunc(time.Second, func() {
		fmt.Println("timer fired")
	})

	// Advance the time source by 1 second.
	fmt.Println("advancing time source by 1 second")
	source.Advance(time.Second)
	fmt.Println("time source advanced")

	// Output:
	// advancing time source by 1 second
	// timer fired
	// time source advanced
}

func TestEventTimeSource_AfterFunc(t *testing.T) {
	t.Parallel()

	// Create a new fake time source and an event to fire.
	source := clock.NewEventTimeSource()
	ev := event{t: t}

	// Create a timer which fires after 2ns.
	source.AfterFunc(2, ev.Fire)

	// Advance the time source by 1ns.
	source.Advance(1)
	ev.AssertNotFired(
		"Advancing the time source should not fire the timer if its deadline still has not been reached",
	)

	// Advance the time source by 1ns more.
	source.Advance(1)
	ev.AssertFiredOnce("Advancing a time source past a timer's deadline should fire the timer")
}

func TestEventTimeSource_AfterFunc_Reset(t *testing.T) {
	t.Parallel()

	// Create a new fake time source and two events to fire.
	source := clock.NewEventTimeSource()
	ev1 := event{t: t}
	ev2 := event{t: t}

	// Create a timer for each event which fires after 2ns.
	timer := source.AfterFunc(2, ev1.Fire)
	source.AfterFunc(2, ev2.Fire)

	// Advance the time source by 1ns and verify that neither timer has fired.
	source.Advance(1)
	ev1.AssertNotFired("Timer should not fire before deadline")
	ev2.AssertNotFired("Timer should not fire before deadline")

	// Reset the first timer to fire after an additional 2ns.
	assert.True(t, timer.Reset(2), "`Reset` should return true if the timer was not already stopped")

	// Advance the time source by 1ns and verify that the first timer has not fired but the second timer has.
	source.Advance(1)
	ev1.AssertNotFired("Timer which was reset should not fire after original deadline but before new deadline")
	ev2.AssertFiredOnce("Timer which was not reset should fire after deadline")

	// Advance the time source by 1ns more and verify that the reset timer has fired.
	source.Advance(1)
	ev1.AssertFiredOnce("The reset timer should fire after its new deadline")

	// Reset the first timer and advance the time source past the new deadline to verify that the timer does not fire
	// again.
	assert.False(t, timer.Reset(1), "`Reset` should return false if the timer was already stopped")
	source.Advance(1)
	ev1.AssertFiredOnce("The timer should never fire twice, even if it was reset")
}

func TestEventTimeSource_AfterFunc_Stop(t *testing.T) {
	t.Parallel()

	// Create a new fake time source and two events to fire.
	source := clock.NewEventTimeSource()
	ev1 := event{t: t}
	ev2 := event{t: t}

	// Create a timer for each event which fires after 1ns.
	timer := source.AfterFunc(1, ev1.Fire)
	source.AfterFunc(1, ev2.Fire)

	// Stop the first timer.
	assert.True(t, timer.Stop(), "`Stop` should return true if the timer was not already stopped")

	// Advance the time source by 1ns and verify that the first timer has not fired and the second timer has.
	source.Advance(1)
	ev1.AssertNotFired("A timer should not fire if it was already stopped")
	ev2.AssertFiredOnce("A timer which was not stopped should fire after its deadline")

	// Verify that subsequent calls to `Stop` return false.
	assert.False(t, timer.Stop(), "`Stop` return false if the timer was already stopped")
}

func TestEventTimeSource_AfterFunc_NegativeDelay(t *testing.T) {
	t.Parallel()

	// Create a new fake time source and one event to fire.
	source := clock.NewEventTimeSource()
	ev1 := event{t: t}

	// Create a timer which fires after -1ns. This should fire immediately.
	timer := source.AfterFunc(-1, ev1.Fire)

	// Verify that the timer has fired.
	ev1.AssertFiredOnce("A timer with a negative delay should fire immediately")

	// Verify that the timer is stopped.
	assert.False(t, timer.Stop(), "`Stop` should return false if the timer was already stopped")
}

func TestEventTimeSource_Update(t *testing.T) {
	t.Parallel()

	// Create a new fake time source and two events to fire.
	source := clock.NewEventTimeSource()
	ev1 := event{t: t}
	ev2 := event{t: t}

	// Create a timer for each event which fires after 1ns.
	source.AfterFunc(1, ev1.Fire)
	source.AfterFunc(1, ev2.Fire)

	// Verify that the time source starts at Unix epoch.
	assert.Equal(
		t, time.Unix(0, 0), source.Now(), "The fake time source should start at the unix epoch",
	)

	// Update to move the time source forward by 1ns.
	source.Update(time.Unix(0, 1))
	assert.Equal(t, time.Unix(0, 1), source.Now())
	ev1.AssertFiredOnce("Timer should fire after deadline")
	ev2.AssertFiredOnce("Timer should fire after deadline")
}