com.hazelcast.org.apache.calcite.util.CancelFlag Maven / Gradle / Ivy
/*
* 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 com.hazelcast.org.apache.calcite.util;
import com.hazelcast.org.apache.calcite.plan.Context;
import com.hazelcast.org.apache.calcite.plan.RelOptPlanner;
import java.util.Objects;
import java.util.concurrent.atomic.AtomicBoolean;
/**
* CancelFlag is used to post and check cancellation requests.
*
* Pass it to {@link RelOptPlanner} by putting it into a {@link Context}.
*/
public class CancelFlag {
//~ Instance fields --------------------------------------------------------
/** The flag that holds the cancel state.
* Feel free to use the flag directly. */
public final AtomicBoolean atomicBoolean;
public CancelFlag(AtomicBoolean atomicBoolean) {
this.atomicBoolean = Objects.requireNonNull(atomicBoolean, "atomicBoolean");
}
//~ Methods ----------------------------------------------------------------
/** Returns whether a cancellation has been requested. */
public boolean isCancelRequested() {
return atomicBoolean.get();
}
/**
* Requests a cancellation.
*/
public void requestCancel() {
atomicBoolean.compareAndSet(false, true);
}
/**
* Clears any pending cancellation request.
*/
public void clearCancel() {
atomicBoolean.compareAndSet(true, false);
}
}