Add bounded frequency runner
This lib manages runs of a function to have min and max frequencies.
This commit is contained in:
Tim Hockin
332
pkg/util/async/bounded_frequency_runner_test.go
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332
pkg/util/async/bounded_frequency_runner_test.go
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/*
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Copyright 2017 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package async
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import (
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"sync"
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"testing"
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"time"
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)
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// Track calls to the managed function.
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type receiver struct {
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lock sync.Mutex
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run bool
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}
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func (r *receiver) F() {
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r.lock.Lock()
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defer r.lock.Unlock()
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r.run = true
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}
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func (r *receiver) reset() bool {
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r.lock.Lock()
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defer r.lock.Unlock()
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was := r.run
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r.run = false
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return was
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}
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// A single change event in the fake timer.
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type timerUpdate struct {
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active bool
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next time.Duration // iff active == true
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}
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// Fake time.
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type fakeTimer struct {
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c chan time.Time
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lock sync.Mutex
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now time.Time
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active bool
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updated chan timerUpdate
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}
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func newFakeTimer() *fakeTimer {
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ft := &fakeTimer{
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c: make(chan time.Time),
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updated: make(chan timerUpdate),
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}
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return ft
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}
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func (ft *fakeTimer) C() <-chan time.Time {
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return ft.c
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}
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func (ft *fakeTimer) Reset(in time.Duration) bool {
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ft.lock.Lock()
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defer ft.lock.Unlock()
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was := ft.active
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ft.active = true
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ft.updated <- timerUpdate{
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active: true,
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next: in,
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}
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return was
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}
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func (ft *fakeTimer) Stop() bool {
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ft.lock.Lock()
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defer ft.lock.Unlock()
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was := ft.active
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ft.active = false
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ft.updated <- timerUpdate{
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active: false,
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}
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return was
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}
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func (ft *fakeTimer) Now() time.Time {
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ft.lock.Lock()
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defer ft.lock.Unlock()
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return ft.now
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}
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func (ft *fakeTimer) Since(t time.Time) time.Duration {
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ft.lock.Lock()
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defer ft.lock.Unlock()
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return ft.now.Sub(t)
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}
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func (ft *fakeTimer) Sleep(d time.Duration) {
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ft.lock.Lock()
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defer ft.lock.Unlock()
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ft.advance(d)
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}
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// advance the current time.
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func (ft *fakeTimer) advance(d time.Duration) {
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ft.lock.Lock()
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defer ft.lock.Unlock()
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ft.now = ft.now.Add(d)
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}
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// send a timer tick.
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func (ft *fakeTimer) tick() {
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ft.lock.Lock()
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defer ft.lock.Unlock()
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ft.active = false
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ft.c <- ft.now
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}
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// return the calling line number (for printing)
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// test the timer's state
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func checkTimer(name string, t *testing.T, upd timerUpdate, active bool, next time.Duration) {
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if upd.active != active {
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t.Fatalf("%s: expected timer active=%v", name, active)
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}
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if active && upd.next != next {
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t.Fatalf("%s: expected timer to be %v, got %v", name, next, upd.next)
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}
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}
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// test and reset the receiver's state
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func checkReceiver(name string, t *testing.T, receiver *receiver, expected bool) {
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triggered := receiver.reset()
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if expected && !triggered {
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t.Fatalf("%s: function should have been called", name)
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} else if !expected && triggered {
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t.Fatalf("%s: function should not have been called", name)
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}
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}
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// Durations embedded in test cases depend on these.
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var minInterval = 1 * time.Second
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var maxInterval = 10 * time.Second
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func waitForReset(name string, t *testing.T, timer *fakeTimer, obj *receiver, expectCall bool, expectNext time.Duration) {
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upd := <-timer.updated // wait for stop
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checkReceiver(name, t, obj, expectCall)
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checkReceiver(name, t, obj, false) // prove post-condition
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checkTimer(name, t, upd, false, 0)
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upd = <-timer.updated // wait for reset
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checkTimer(name, t, upd, true, expectNext)
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}
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func waitForRun(name string, t *testing.T, timer *fakeTimer, obj *receiver) {
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waitForReset(name, t, timer, obj, true, maxInterval)
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}
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func waitForDefer(name string, t *testing.T, timer *fakeTimer, obj *receiver, expectNext time.Duration) {
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waitForReset(name, t, timer, obj, false, expectNext)
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}
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func Test_BoundedFrequencyRunnerNoBurst(t *testing.T) {
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obj := &receiver{}
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timer := newFakeTimer()
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runner := construct("test-runner", obj.F, minInterval, maxInterval, 1, timer)
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stop := make(chan struct{})
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var upd timerUpdate
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// Start.
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go runner.Loop(stop)
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upd = <-timer.updated // wait for initial time to be set to max
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checkTimer("init", t, upd, true, maxInterval)
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checkReceiver("init", t, obj, false)
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// Run once, immediately.
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// rel=0ms
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runner.Run()
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waitForRun("first run", t, timer, obj)
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// Run again, before minInterval expires.
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timer.advance(500 * time.Millisecond) // rel=500ms
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runner.Run()
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waitForDefer("too soon after first", t, timer, obj, 500*time.Millisecond)
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// Run again, before minInterval expires.
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timer.advance(499 * time.Millisecond) // rel=999ms
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runner.Run()
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waitForDefer("still too soon after first", t, timer, obj, 1*time.Millisecond)
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// Run again, once minInterval has passed (race with timer).
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timer.advance(1 * time.Millisecond) // rel=1000ms
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runner.Run()
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waitForRun("second run", t, timer, obj)
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// Run again, before minInterval expires.
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// rel=0ms
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runner.Run()
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waitForDefer("too soon after second", t, timer, obj, 1*time.Second)
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// Run again, before minInterval expires.
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timer.advance(1 * time.Millisecond) // rel=1ms
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runner.Run()
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waitForDefer("still too soon after second", t, timer, obj, 999*time.Millisecond)
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// Let the timer tick prematurely.
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timer.advance(998 * time.Millisecond) // rel=999ms
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timer.tick()
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waitForDefer("premature tick", t, timer, obj, 1*time.Millisecond)
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// Let the timer tick.
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timer.advance(1 * time.Millisecond) // rel=1000ms
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timer.tick()
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waitForRun("first tick", t, timer, obj)
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// Let the timer tick.
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timer.advance(10 * time.Second) // rel=10000ms
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timer.tick()
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waitForRun("second tick", t, timer, obj)
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// Run again, before minInterval expires.
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timer.advance(1 * time.Millisecond) // rel=1ms
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runner.Run()
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waitForDefer("too soon after tick", t, timer, obj, 999*time.Millisecond)
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// Let the timer tick.
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timer.advance(999 * time.Millisecond) // rel=1000ms
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timer.tick()
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waitForRun("third tick", t, timer, obj)
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// Clean up.
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stop <- struct{}{}
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}
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func Test_BoundedFrequencyRunnerBurst(t *testing.T) {
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obj := &receiver{}
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timer := newFakeTimer()
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runner := construct("test-runner", obj.F, minInterval, maxInterval, 2, timer)
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stop := make(chan struct{})
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var upd timerUpdate
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// Start.
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go runner.Loop(stop)
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upd = <-timer.updated // wait for initial time to be set to max
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checkTimer("init", t, upd, true, maxInterval)
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checkReceiver("init", t, obj, false)
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// Run once, immediately.
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// abs=0ms, rel=0ms
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runner.Run()
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waitForRun("first run", t, timer, obj)
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// Run again, before minInterval expires, with burst.
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timer.advance(1 * time.Millisecond) // abs=1ms, rel=1ms
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runner.Run()
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waitForRun("second run", t, timer, obj)
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// Run again, before minInterval expires.
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timer.advance(498 * time.Millisecond) // abs=499ms, rel=498ms
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runner.Run()
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waitForDefer("too soon after second", t, timer, obj, 502*time.Millisecond)
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// Run again, before minInterval expires.
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timer.advance(1 * time.Millisecond) // abs=500ms, rel=499ms
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runner.Run()
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waitForDefer("too soon after second 2", t, timer, obj, 501*time.Millisecond)
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// Run again, before minInterval expires.
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timer.advance(1 * time.Millisecond) // abs=501ms, rel=500ms
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runner.Run()
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waitForDefer("too soon after second 3", t, timer, obj, 500*time.Millisecond)
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// Run again, once burst has replenished.
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timer.advance(499 * time.Millisecond) // abs=1000ms, rel=999ms
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runner.Run()
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waitForRun("third run", t, timer, obj)
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// Run again, before minInterval expires.
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timer.advance(1 * time.Millisecond) // abs=1001ms, rel=1ms
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runner.Run()
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waitForDefer("too soon after third", t, timer, obj, 999*time.Millisecond)
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// Run again, before minInterval expires.
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timer.advance(998 * time.Millisecond) // abs=1999ms, rel=999ms
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runner.Run()
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waitForDefer("too soon after third 2", t, timer, obj, 1*time.Millisecond)
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// Run again, once burst has replenished.
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timer.advance(1 * time.Millisecond) // abs=2000ms, rel=1000ms
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runner.Run()
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waitForRun("fourth run", t, timer, obj)
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// Run again, once burst has fully replenished.
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timer.advance(2 * time.Second) // abs=4000ms, rel=2000ms
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runner.Run()
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waitForRun("fifth run", t, timer, obj)
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runner.Run()
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waitForRun("sixth run", t, timer, obj)
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runner.Run()
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waitForDefer("too soon after sixth", t, timer, obj, 1*time.Second)
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// Let the timer tick.
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timer.advance(1 * time.Second) // abs=5000ms, rel=1000ms
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timer.tick()
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waitForRun("first tick", t, timer, obj)
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// Let the timer tick.
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timer.advance(10 * time.Second) // abs=15000ms, rel=10000ms
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timer.tick()
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waitForRun("second tick", t, timer, obj)
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// Clean up.
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stop <- struct{}{}
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}
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