| /* |
| * Copyright 2000-2013 JetBrains s.r.o. |
| * |
| * 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 com.intellij.util.concurrency; |
| |
| import com.intellij.openapi.progress.ProcessCanceledException; |
| |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.locks.AbstractQueuedSynchronizer; |
| |
| public class Semaphore { |
| private static final class Sync extends AbstractQueuedSynchronizer { |
| @Override |
| public int tryAcquireShared(int acquires) { |
| return getState() == 0 ? 1 : -1; |
| } |
| |
| @Override |
| public boolean tryReleaseShared(int releases) { |
| // Decrement count; signal when transition to zero |
| while (true) { |
| int c = getState(); |
| if (c == 0) return false; |
| int nextc = c - 1; |
| if (compareAndSetState(c, nextc)) return nextc == 0; |
| } |
| } |
| |
| final void down() { |
| while (true) { |
| int current = getState(); |
| int next = current + 1; |
| if (compareAndSetState(current, next)) return; |
| } |
| } |
| } |
| |
| private final Sync sync = new Sync(); |
| |
| public void up() { |
| tryUp(); |
| } |
| |
| public boolean tryUp() { |
| return sync.releaseShared(1); |
| } |
| |
| public void down() { |
| sync.down(); |
| } |
| |
| public void waitFor() { |
| try { |
| waitForUnsafe(); |
| } |
| catch (InterruptedException e) { |
| throw new ProcessCanceledException(e); |
| } |
| } |
| |
| public void waitForUnsafe() throws InterruptedException { |
| sync.acquireSharedInterruptibly(1); |
| } |
| |
| public boolean waitFor(final long msTimeout) { |
| try { |
| return waitForUnsafe(msTimeout); |
| } |
| catch (InterruptedException e) { |
| throw new ProcessCanceledException(e); |
| } |
| } |
| |
| public boolean waitForUnsafe(long msTimeout) throws InterruptedException { |
| if (sync.tryAcquireShared(1) >= 0) return true; |
| return sync.tryAcquireSharedNanos(1, TimeUnit.MILLISECONDS.toNanos(msTimeout)); |
| } |
| |
| } |