| /* |
| * |
| * 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 ( |
| "sync" |
| "sync/atomic" |
| "testing" |
| "time" |
| ) |
| |
| // TestOnceFunc tests that a OnceFunc is executed only once even with multiple |
| // simultaneous callers of it. |
| func (s) TestOnceFunc(t *testing.T) { |
| var v int32 |
| inc := OnceFunc(func() { atomic.AddInt32(&v, 1) }) |
| |
| const numWorkers = 100 |
| var wg sync.WaitGroup // Blocks until all workers have called inc. |
| wg.Add(numWorkers) |
| |
| block := NewEvent() // Signal to worker goroutines to call inc |
| |
| for i := 0; i < numWorkers; i++ { |
| go func() { |
| <-block.Done() // Wait for a signal. |
| inc() // Call the OnceFunc. |
| wg.Done() |
| }() |
| } |
| time.Sleep(time.Millisecond) // Allow goroutines to get to the block. |
| block.Fire() // Unblock them. |
| wg.Wait() // Wait for them to complete. |
| if v != 1 { |
| t.Fatalf("OnceFunc() called %v times; want 1", v) |
| } |
| } |