com.arangodb.internal.net.RoundRobinHostHandler Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of arangodb-java-driver Show documentation

ArangoDB Java Driver

There is a newer version: 7.15.0

/*
 * DISCLAIMER
 *
 * Copyright 2017 ArangoDB GmbH, Cologne, Germany
 *
 * 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.
 *
 * Copyright holder is ArangoDB GmbH, Cologne, Germany
 */

package com.arangodb.internal.net;

import com.arangodb.ArangoDBException;

/**
 * @author Mark Vollmary
 *
 */
public class RoundRobinHostHandler implements HostHandler {

	private final HostResolver resolver;

	private int current;
	private int fails;
	private Host currentHost;

	public RoundRobinHostHandler(final HostResolver resolver) {
		super();
		this.resolver = resolver;
		resolver.resolve(true, false);
		current = 0;
		fails = 0;
	}

	@Override
	public Host get(final HostHandle hostHandle, AccessType accessType) {

		final HostSet hosts = resolver.resolve(false, false);
		final int size = hosts.getHostsList().size();

		if (fails > size) {
			reset();
			throw new ArangoDBException("Cannot contact any host!");
		}

		final int index = (current++) % size;
		Host host = hosts.getHostsList().get(index);
		if (hostHandle != null) {
			final HostDescription hostDescription = hostHandle.getHost();
			if (hostDescription != null) {
				for (int i = index; i < index + size; i++) {
					host = hosts.getHostsList().get(i % size);
					if (hostDescription.equals(host.getDescription())) {
						break;
					}
				}
			} else {
				hostHandle.setHost(host.getDescription());
			}
		}
		currentHost = host;
		return host;
	}

	@Override
	public void success() {
		fails = 0;
	}

	@Override
	public void fail() {
		fails++;
	}

	@Override
	public void reset() {
		fails = 0;
	}

	@Override
	public void confirm() {
	}

	@Override
	public void close() {
		final HostSet hosts = resolver.resolve(false, false);
		hosts.close();
	}

	@Override
	public void closeCurrentOnError() {
		currentHost.closeOnError();
	}

}