| // 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() |
| } |
| } |