org.elasticsearch.discovery.BlockingClusterStatePublishResponseHandler Maven / Gradle / Ivy

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/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */
package org.elasticsearch.discovery;

import org.elasticsearch.cluster.node.DiscoveryNode;
import org.elasticsearch.common.util.concurrent.ConcurrentCollections;
import org.elasticsearch.core.TimeValue;

import java.util.Collections;
import java.util.Set;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;

/**
 * Handles responses obtained when publishing a new cluster state from master to all non master nodes.
 * Allows to await a reply from all non master nodes, up to a timeout
 */
public class BlockingClusterStatePublishResponseHandler {

    private final CountDownLatch latch;
    private final Set pendingNodes;
    private final Set failedNodes;

    /**
     * Creates a new BlockingClusterStatePublishResponseHandler
     * @param publishingToNodes the set of nodes to which the cluster state will be published and should respond
     */
    public BlockingClusterStatePublishResponseHandler(Set publishingToNodes) {
        this.pendingNodes = ConcurrentCollections.newConcurrentSet();
        this.pendingNodes.addAll(publishingToNodes);
        this.latch = new CountDownLatch(pendingNodes.size());
        this.failedNodes = ConcurrentCollections.newConcurrentSet();
    }

    /**
     * Called for each response obtained from non master nodes
     *
     * @param node the node that replied to the publish event
     */
    public void onResponse(DiscoveryNode node) {
        boolean found = pendingNodes.remove(node);
        assert found : "node [" + node + "] already responded or failed";
        latch.countDown();
    }

    /**
     * Called for each failure obtained from non master nodes
     * @param node the node that replied to the publish event
     */
    public void onFailure(DiscoveryNode node, Exception e) {
        boolean found = pendingNodes.remove(node);
        assert found : "node [" + node + "] already responded or failed";
        boolean added = failedNodes.add(node);
        assert added : "duplicate failures for " + node;
        latch.countDown();
    }

    /**
     * Allows to wait for all non master nodes to reply to the publish event up to a timeout
     * @param timeout the timeout
     * @return true if the timeout expired or not, false otherwise
     */
    public boolean awaitAllNodes(TimeValue timeout) throws InterruptedException {
        boolean success = latch.await(timeout.millis(), TimeUnit.MILLISECONDS);
        assert success == false || pendingNodes.isEmpty() : "response count reached 0 but still waiting for some nodes";
        return success;
    }

    /**
     * returns a list of nodes which didn't respond yet
     */
    public DiscoveryNode[] pendingNodes() {
        // we use a zero length array, because if we try to pre allocate we may need to remove trailing
        // nulls if some nodes responded in the meanwhile
        return pendingNodes.toArray(new DiscoveryNode[0]);
    }

    /**
     * returns a set of nodes for which publication has failed.
     */
    public Set getFailedNodes() {
        return Collections.unmodifiableSet(failedNodes);
    }
}