org.apache.hadoop.hbase.client.ConnectionUtils.java Source code

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Here is the source code for org.apache.hadoop.hbase.client.ConnectionUtils.java

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/**
 * 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 org.apache.hadoop.hbase.client;

import java.io.IOException;
import java.util.Random;

import org.apache.commons.logging.Log;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.ServerName;
import org.apache.hadoop.hbase.protobuf.generated.AdminProtos.AdminService;
import org.apache.hadoop.hbase.protobuf.generated.ClientProtos.ClientService;

/**
 * Utility used by client connections.
 */
@InterfaceAudience.Private
public class ConnectionUtils {

    private static final Random RANDOM = new Random();

    /**
     * Calculate pause time.
     * Built on {@link HConstants#RETRY_BACKOFF}.
     * @param pause
     * @param tries
     * @return How long to wait after <code>tries</code> retries
     */
    public static long getPauseTime(final long pause, final int tries) {
        int ntries = tries;
        if (ntries >= HConstants.RETRY_BACKOFF.length) {
            ntries = HConstants.RETRY_BACKOFF.length - 1;
        }

        long normalPause = pause * HConstants.RETRY_BACKOFF[ntries];
        long jitter = (long) (normalPause * RANDOM.nextFloat() * 0.01f); // 1% possible jitter
        return normalPause + jitter;
    }

    /**
     * Adds / subs a 10% jitter to a pause time. Minimum is 1.
     * @param pause the expected pause.
     * @param jitter the jitter ratio, between 0 and 1, exclusive.
     */
    public static long addJitter(final long pause, final float jitter) {
        float lag = pause * (RANDOM.nextFloat() - 0.5f) * jitter;
        long newPause = pause + (long) lag;
        if (newPause <= 0) {
            return 1;
        }
        return newPause;
    }

    /**
     * @param conn The connection for which to replace the generator.
     * @param cnm Replaces the nonce generator used, for testing.
     * @return old nonce generator.
     */
    public static NonceGenerator injectNonceGeneratorForTesting(HConnection conn, NonceGenerator cnm) {
        return ConnectionManager.injectNonceGeneratorForTesting(conn, cnm);
    }

    /**
     * Changes the configuration to set the number of retries needed when using HConnection
     * internally, e.g. for  updating catalog tables, etc.
     * Call this method before we create any Connections.
     * @param c The Configuration instance to set the retries into.
     * @param log Used to log what we set in here.
     */
    public static void setServerSideHConnectionRetriesConfig(final Configuration c, final String sn,
            final Log log) {
        int hcRetries = c.getInt(HConstants.HBASE_CLIENT_RETRIES_NUMBER,
                HConstants.DEFAULT_HBASE_CLIENT_RETRIES_NUMBER);
        // Go big.  Multiply by 10.  If we can't get to meta after this many retries
        // then something seriously wrong.
        int serversideMultiplier = c.getInt("hbase.client.serverside.retries.multiplier", 10);
        int retries = hcRetries * serversideMultiplier;
        c.setInt(HConstants.HBASE_CLIENT_RETRIES_NUMBER, retries);
        log.info(sn + " server-side HConnection retries=" + retries);
    }

    /**
     * Adapt a HConnection so that it can bypass the RPC layer (serialization,
     * deserialization, networking, etc..) when it talks to a local server.
     * @param conn the connection to adapt
     * @param serverName the local server name
     * @param admin the admin interface of the local server
     * @param client the client interface of the local server
     * @return an adapted/decorated HConnection
     */
    public static HConnection createShortCircuitHConnection(final HConnection conn, final ServerName serverName,
            final AdminService.BlockingInterface admin, final ClientService.BlockingInterface client) {
        return new ConnectionAdapter(conn) {
            @Override
            public AdminService.BlockingInterface getAdmin(ServerName sn, boolean getMaster) throws IOException {
                return serverName.equals(sn) ? admin : super.getAdmin(sn, getMaster);
            }

            @Override
            public ClientService.BlockingInterface getClient(ServerName sn) throws IOException {
                return serverName.equals(sn) ? client : super.getClient(sn);
            }
        };
    }
}