io.atomix.raft.utils.Quorum Maven / Gradle / Ivy
/*
* Copyright 2015-present Open Networking Foundation
* Copyright © 2020 camunda services GmbH ([email protected])
*
* 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 io.atomix.raft.utils;
import java.util.function.Consumer;
/**
* Quorum helper. Completes and invokes a callback when the number of {@link #succeed()} or {@link
* #fail()} calls equal the expected quorum count. Not threadsafe.
*/
public class Quorum {
private final int quorum;
private int succeeded = 1;
private int failed;
private Consumer callback;
private boolean complete;
public Quorum(final int quorum, final Consumer callback) {
this.quorum = quorum;
this.callback = callback;
}
/** Indicates that a call in the quorum succeeded. */
public Quorum succeed() {
succeeded++;
checkComplete();
return this;
}
private void checkComplete() {
if (!complete && callback != null) {
if (succeeded >= quorum) {
complete = true;
callback.accept(true);
} else if (failed >= quorum) {
complete = true;
callback.accept(false);
}
}
}
/** Indicates that a call in the quorum failed. */
public Quorum fail() {
failed++;
checkComplete();
return this;
}
/**
* Cancels the quorum. Once this method has been called, the quorum will be marked complete and
* the handler will never be called.
*/
public void cancel() {
callback = null;
complete = true;
}
}