org.camunda.bpm.engine.impl.util.SingleConsumerCondition Maven / Gradle / Ivy
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* Copyright Camunda Services GmbH and/or licensed to Camunda Services GmbH
* under one or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information regarding copyright
* ownership. Camunda licenses this file to you under the Apache License,
* Version 2.0; 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.camunda.bpm.engine.impl.util;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.LockSupport;
/**
* MPSC Condition implementation.
*
* Implementation Notes:
*
* - {@link #await(long)} may spuriously return before the deadline is reached.
* - if {@link #signal()} is called before the consumer thread calls {@link #await(long)},
* the next call to {@link #await(long)} returns immediately.
*
*/
public class SingleConsumerCondition {
// note: making this private & final because it cannot be subclassed
// and replaced in a meaningful way without breaking the implementation
private final Thread consumer;
public SingleConsumerCondition(Thread consumer) {
if (consumer == null) {
throw new IllegalArgumentException("Consumer thread cannot be null");
}
this.consumer = consumer;
}
public void signal() {
LockSupport.unpark(consumer);
}
public void await(long millis) {
if (Thread.currentThread() != consumer) {
throw new RuntimeException("Wrong usage of SingleConsumerCondition: can only await in consumer thread.");
}
// NOTE: may spuriously return before deadline
LockSupport.parkNanos(TimeUnit.MILLISECONDS.toNanos(millis));
}
}
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