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/*
*
* Copyright 2022 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package grpcsync
import (
"context"
"sync"
"testing"
"time"
"github.com/google/go-cmp/cmp"
)
const (
defaultTestTimeout = 5 * time.Second
defaultTestShortTimeout = 10 * time.Millisecond // For events expected to *not* happen.
)
// TestCallbackSerializer_Schedule_FIFO verifies that callbacks are executed in
// the same order in which they were scheduled.
func (s) TestCallbackSerializer_Schedule_FIFO(t *testing.T) {
ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
cs := NewCallbackSerializer(ctx)
defer cancel()
// We have two channels, one to record the order of scheduling, and the
// other to record the order of execution. We spawn a bunch of goroutines
// which record the order of scheduling and call the actual Schedule()
// method as well. The callbacks record the order of execution.
//
// We need to grab a lock to record order of scheduling to guarantee that
// the act of recording and the act of calling Schedule() happen atomically.
const numCallbacks = 100
var mu sync.Mutex
scheduleOrderCh := make(chan int, numCallbacks)
executionOrderCh := make(chan int, numCallbacks)
for i := 0; i < numCallbacks; i++ {
go func(id int) {
mu.Lock()
defer mu.Unlock()
scheduleOrderCh <- id
cs.Schedule(func(ctx context.Context) {
select {
case <-ctx.Done():
return
case executionOrderCh <- id:
}
})
}(i)
}
// Spawn a couple of goroutines to capture the order or scheduling and the
// order of execution.
scheduleOrder := make([]int, numCallbacks)
executionOrder := make([]int, numCallbacks)
var wg sync.WaitGroup
wg.Add(2)
go func() {
defer wg.Done()
for i := 0; i < numCallbacks; i++ {
select {
case <-ctx.Done():
return
case id := <-scheduleOrderCh:
scheduleOrder[i] = id
}
}
}()
go func() {
defer wg.Done()
for i := 0; i < numCallbacks; i++ {
select {
case <-ctx.Done():
return
case id := <-executionOrderCh:
executionOrder[i] = id
}
}
}()
wg.Wait()
if diff := cmp.Diff(executionOrder, scheduleOrder); diff != "" {
t.Fatalf("Callbacks are not executed in scheduled order. diff(-want, +got):\n%s", diff)
}
}
// TestCallbackSerializer_Schedule_Concurrent verifies that all concurrently
// scheduled callbacks get executed.
func (s) TestCallbackSerializer_Schedule_Concurrent(t *testing.T) {
ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
cs := NewCallbackSerializer(ctx)
defer cancel()
// Schedule callbacks concurrently by calling Schedule() from goroutines.
// The execution of the callbacks call Done() on the waitgroup, which
// eventually unblocks the test and allows it to complete.
const numCallbacks = 100
var wg sync.WaitGroup
wg.Add(numCallbacks)
for i := 0; i < numCallbacks; i++ {
go func() {
cs.Schedule(func(context.Context) {
wg.Done()
})
}()
}
// We call Wait() on the waitgroup from a goroutine so that we can select on
// the Wait() being unblocked and the overall test deadline expiring.
done := make(chan struct{})
go func() {
wg.Wait()
close(done)
}()
select {
case <-ctx.Done():
t.Fatal("Timeout waiting for all scheduled callbacks to be executed")
case <-done:
}
}
// TestCallbackSerializer_Schedule_Close verifies that callbacks in the queue
// are not executed once Close() returns.
func (s) TestCallbackSerializer_Schedule_Close(t *testing.T) {
ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
defer cancel()
serializerCtx, serializerCancel := context.WithTimeout(context.Background(), defaultTestTimeout)
cs := NewCallbackSerializer(serializerCtx)
// Schedule a callback which blocks until the context passed to it is
// canceled. It also closes a channel to signal that it has started.
firstCallbackStartedCh := make(chan struct{})
cs.Schedule(func(ctx context.Context) {
close(firstCallbackStartedCh)
<-ctx.Done()
})
// Schedule a bunch of callbacks. These should be exeuted since the are
// scheduled before the serializer is closed.
const numCallbacks = 10
callbackCh := make(chan int, numCallbacks)
for i := 0; i < numCallbacks; i++ {
num := i
if !cs.Schedule(func(context.Context) { callbackCh <- num }) {
t.Fatal("Schedule failed to accept a callback when the serializer is yet to be closed")
}
}
// Ensure that none of the newer callbacks are executed at this point.
select {
case <-time.After(defaultTestShortTimeout):
case <-callbackCh:
t.Fatal("Newer callback executed when older one is still executing")
}
// Wait for the first callback to start before closing the scheduler.
<-firstCallbackStartedCh
// Cancel the context which will unblock the first callback. All of the
// other callbacks (which have not started executing at this point) should
// be executed after this.
serializerCancel()
// Ensure that the newer callbacks are executed.
for i := 0; i < numCallbacks; i++ {
select {
case <-ctx.Done():
t.Fatal("Timeout when waiting for callback scheduled before close to be executed")
case num := <-callbackCh:
if num != i {
t.Fatalf("Executing callback %d, want %d", num, i)
}
}
}
<-cs.Done
done := make(chan struct{})
if cs.Schedule(func(context.Context) { close(done) }) {
t.Fatal("Scheduled a callback after closing the serializer")
}
// Ensure that the lates callback is executed at this point.
select {
case <-time.After(defaultTestShortTimeout):
case <-done:
t.Fatal("Newer callback executed when scheduled after closing serializer")
}
}
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