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// Copyright 2018 The gVisor 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 sync
import (
"context"
"runtime"
"sync/atomic"
"testing"
"time"
)
func TestGateBasic(t *testing.T) {
var g Gate
if !g.Enter() {
t.Fatalf("Enter failed before Close")
}
g.Leave()
g.Close()
if g.Enter() {
t.Fatalf("Enter succeeded after Close")
}
}
func TestGateConcurrent(t *testing.T) {
// Each call to testGateConcurrentOnce tests behavior around a single call
// to Gate.Close, so run many short tests to increase the probability of
// flushing out any issues.
totalTime := 5 * time.Second
timePerTest := 20 * time.Millisecond
numTests := int(totalTime / timePerTest)
for i := 0; i < numTests; i++ {
testGateConcurrentOnce(t, timePerTest)
}
}
func testGateConcurrentOnce(t *testing.T, d time.Duration) {
const numGoroutines = 1000
ctx, cancel := context.WithCancel(context.Background())
var wg WaitGroup
defer func() {
cancel()
wg.Wait()
}()
var g Gate
closeState := int32(0) // set to 1 before g.Close() and 2 after it returns
// Start a large number of goroutines that repeatedly attempt to enter the
// gate and get the expected result.
for i := 0; i < numGoroutines; i++ {
wg.Add(1)
go func() {
defer wg.Done()
for ctx.Err() == nil {
closedBeforeEnter := atomic.LoadInt32(&closeState) == 2
if g.Enter() {
closedBeforeLeave := atomic.LoadInt32(&closeState) == 2
g.Leave()
if closedBeforeEnter {
t.Errorf("Enter succeeded after Close")
return
}
if closedBeforeLeave {
t.Errorf("Close returned before Leave")
return
}
} else {
if atomic.LoadInt32(&closeState) == 0 {
t.Errorf("Enter failed before Close")
return
}
}
// Go does not preempt busy loops until Go 1.14.
runtime.Gosched()
}
}()
}
// Allow goroutines to enter the gate successfully for half of the test's
// duration, then close the gate and allow goroutines to fail to enter the
// gate for the remaining half.
time.Sleep(d / 2)
atomic.StoreInt32(&closeState, 1)
g.Close()
atomic.StoreInt32(&closeState, 2)
time.Sleep(d / 2)
}
func BenchmarkGateEnterLeave(b *testing.B) {
var g Gate
for i := 0; i < b.N; i++ {
g.Enter()
g.Leave()
}
}
func BenchmarkGateClose(b *testing.B) {
for i := 0; i < b.N; i++ {
var g Gate
g.Close()
}
}
func BenchmarkGateEnterLeaveAsyncClose(b *testing.B) {
for i := 0; i < b.N; i++ {
var g Gate
g.Enter()
go func() {
g.Leave()
}()
g.Close()
}
}
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