| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 org.apache.cassandra.utils.concurrent; |
| |
| import java.util.ArrayList; |
| import java.util.List; |
| import java.util.concurrent.ExecutionException; |
| import java.util.concurrent.ExecutorService; |
| import java.util.concurrent.Executors; |
| import java.util.concurrent.Future; |
| import java.util.concurrent.TimeoutException; |
| |
| import org.junit.Assert; |
| import org.junit.Test; |
| |
| import static java.util.concurrent.TimeUnit.MILLISECONDS; |
| import static java.util.concurrent.TimeUnit.MINUTES; |
| import static org.apache.cassandra.utils.Clock.Global.nanoTime; |
| |
| public class SemaphoreTest |
| { |
| |
| @Test |
| public void testUnfair() throws InterruptedException |
| { |
| Semaphore s = Semaphore.newSemaphore(2); |
| List<Future<Boolean>> fs = start(s); |
| s.release(1); |
| while (s.permits() == 1) Thread.yield(); |
| Assert.assertEquals(1, fs.stream().filter(Future::isDone).count()); |
| s.release(1); |
| while (s.permits() == 1) Thread.yield(); |
| Assert.assertEquals(2, fs.stream().filter(Future::isDone).count()); |
| s.release(1); |
| while (s.permits() == 1) Thread.yield(); |
| Assert.assertEquals(3, fs.stream().filter(Future::isDone).count()); |
| s.release(1); |
| Assert.assertEquals(1, s.permits()); |
| } |
| |
| @Test |
| public void testFair() throws InterruptedException, ExecutionException, TimeoutException |
| { |
| Semaphore s = Semaphore.newFairSemaphore(2); |
| List<Future<Boolean>> fs = start(s); |
| s.release(1); |
| fs.get(0).get(1L, MINUTES); |
| s.release(1); |
| fs.get(1).get(1L, MINUTES); |
| s.release(1); |
| fs.get(2).get(1L, MINUTES); |
| s.release(1); |
| Assert.assertEquals(1, s.permits()); |
| } |
| |
| private List<java.util.concurrent.Future<Boolean>> start(Semaphore s) throws InterruptedException |
| { |
| ExecutorService exec = Executors.newCachedThreadPool(); |
| try |
| { |
| Assert.assertTrue(s.tryAcquire(1)); |
| s.drain(); |
| Assert.assertFalse(s.tryAcquire(1)); |
| Assert.assertFalse(s.tryAcquire(1, 1L, MILLISECONDS)); |
| Thread.currentThread().interrupt(); |
| try { s.acquireThrowUncheckedOnInterrupt(1); Assert.fail(); } catch (UncheckedInterruptedException ignore) { } |
| Thread.currentThread().interrupt(); |
| try { s.tryAcquire(1, 1L, MILLISECONDS); Assert.fail(); } catch (InterruptedException ignore) { } |
| Thread.currentThread().interrupt(); |
| try { s.tryAcquireUntil(1, nanoTime() + MILLISECONDS.toNanos(1L)); Assert.fail(); } catch (InterruptedException ignore) { } |
| List<Future<Boolean>> fs = new ArrayList<>(); |
| fs.add(exec.submit(() -> s.tryAcquire(1, 1L, MINUTES))); |
| while (s instanceof Semaphore.Standard && ((Semaphore.Standard) s).waiting() == 0) Thread.yield(); |
| fs.add(exec.submit(() -> s.tryAcquireUntil(1, System.nanoTime() + MINUTES.toNanos(1L)))); |
| while (s instanceof Semaphore.Standard && ((Semaphore.Standard) s).waiting() == 1) Thread.yield(); |
| fs.add(exec.submit(() -> { s.acquire(1); return true; } )); |
| return fs; |
| } |
| finally |
| { |
| exec.shutdown(); |
| } |
| } |
| |
| } |