| /* |
| * 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.concurrent.atomic.AtomicLong; |
| import java.util.concurrent.locks.ReentrantReadWriteLock; |
| |
| import com.google.common.annotations.VisibleForTesting; |
| |
| import org.apache.cassandra.utils.TimeSource; |
| |
| /** |
| * This class extends ReentrantReadWriteLock to provide a write lock that can only be acquired at provided intervals. |
| */ |
| public class IntervalLock extends ReentrantReadWriteLock |
| { |
| private final AtomicLong lastAcquire = new AtomicLong(); |
| private final TimeSource timeSource; |
| |
| public IntervalLock(TimeSource timeSource) |
| { |
| this.timeSource = timeSource; |
| } |
| |
| /** |
| * Try acquiring a write lock if the given interval is passed since the last call to this method. |
| * |
| * @param interval In millis. |
| * @return True if acquired and locked, false otherwise. |
| */ |
| public boolean tryIntervalLock(long interval) |
| { |
| long now = timeSource.currentTimeMillis(); |
| boolean acquired = (now - lastAcquire.get() >= interval) && writeLock().tryLock(); |
| if (acquired) |
| lastAcquire.set(now); |
| |
| return acquired; |
| } |
| |
| /** |
| * Release the last acquired interval lock. |
| */ |
| public void releaseIntervalLock() |
| { |
| writeLock().unlock(); |
| } |
| |
| @VisibleForTesting |
| public long getLastIntervalAcquire() |
| { |
| return lastAcquire.get(); |
| } |
| } |