org.apache.hadoop.gateway.ha.dispatch.DefaultHaDispatch.java Source code

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Here is the source code for org.apache.hadoop.gateway.ha.dispatch.DefaultHaDispatch.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.gateway.ha.dispatch;

import org.apache.hadoop.gateway.config.Configure;
import org.apache.hadoop.gateway.config.Optional;
import org.apache.hadoop.gateway.dispatch.DefaultDispatch;
import org.apache.hadoop.gateway.filter.AbstractGatewayFilter;
import org.apache.hadoop.gateway.ha.dispatch.i18n.HaDispatchMessages;
import org.apache.hadoop.gateway.ha.provider.HaProvider;
import org.apache.hadoop.gateway.ha.provider.HaServiceConfig;
import org.apache.hadoop.gateway.ha.provider.impl.HaServiceConfigConstants;
import org.apache.hadoop.gateway.i18n.messages.MessagesFactory;
import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpRequestBase;
import org.apache.http.client.methods.HttpUriRequest;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.net.URI;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * Default HA dispatch class that has a very basic failover mechanism
 */
public class DefaultHaDispatch extends DefaultDispatch {

    protected static final String FAILOVER_COUNTER_ATTRIBUTE = "dispatch.ha.failover.counter";

    private static final HaDispatchMessages LOG = MessagesFactory.get(HaDispatchMessages.class);

    private int maxFailoverAttempts = HaServiceConfigConstants.DEFAULT_MAX_FAILOVER_ATTEMPTS;

    private int failoverSleep = HaServiceConfigConstants.DEFAULT_FAILOVER_SLEEP;

    private HaProvider haProvider;

    @Optional
    @Configure
    private String serviceRole;

    @Override
    public void init() {
        super.init();
        LOG.initializingForResourceRole(getServiceRole());
        if (haProvider != null) {
            HaServiceConfig serviceConfig = haProvider.getHaDescriptor().getServiceConfig(getServiceRole());
            maxFailoverAttempts = serviceConfig.getMaxFailoverAttempts();
            failoverSleep = serviceConfig.getFailoverSleep();
        }
    }

    public String getServiceRole() {
        return serviceRole;
    }

    public void setServiceRole(String serviceRole) {
        this.serviceRole = serviceRole;
    }

    public HaProvider getHaProvider() {
        return haProvider;
    }

    @Configure
    public void setHaProvider(HaProvider haProvider) {
        this.haProvider = haProvider;
    }

    @Override
    protected void executeRequest(HttpUriRequest outboundRequest, HttpServletRequest inboundRequest,
            HttpServletResponse outboundResponse) throws IOException {
        HttpResponse inboundResponse = null;
        try {
            inboundResponse = executeOutboundRequest(outboundRequest);
            writeOutboundResponse(outboundRequest, inboundRequest, outboundResponse, inboundResponse);
        } catch (IOException e) {
            LOG.errorConnectingToServer(outboundRequest.getURI().toString(), e);
            failoverRequest(outboundRequest, inboundRequest, outboundResponse, inboundResponse, e);
        }
    }

    private void failoverRequest(HttpUriRequest outboundRequest, HttpServletRequest inboundRequest,
            HttpServletResponse outboundResponse, HttpResponse inboundResponse, Exception exception)
            throws IOException {
        LOG.failingOverRequest(outboundRequest.getURI().toString());
        AtomicInteger counter = (AtomicInteger) inboundRequest.getAttribute(FAILOVER_COUNTER_ATTRIBUTE);
        if (counter == null) {
            counter = new AtomicInteger(0);
        }
        inboundRequest.setAttribute(FAILOVER_COUNTER_ATTRIBUTE, counter);
        if (counter.incrementAndGet() <= maxFailoverAttempts) {
            haProvider.markFailedURL(getServiceRole(), outboundRequest.getURI().toString());
            //null out target url so that rewriters run again
            inboundRequest.setAttribute(AbstractGatewayFilter.TARGET_REQUEST_URL_ATTRIBUTE_NAME, null);
            URI uri = getDispatchUrl(inboundRequest);
            ((HttpRequestBase) outboundRequest).setURI(uri);
            if (failoverSleep > 0) {
                try {
                    Thread.sleep(failoverSleep);
                } catch (InterruptedException e) {
                    LOG.failoverSleepFailed(getServiceRole(), e);
                }
            }
            executeRequest(outboundRequest, inboundRequest, outboundResponse);
        } else {
            LOG.maxFailoverAttemptsReached(maxFailoverAttempts, getServiceRole());
            if (inboundResponse != null) {
                writeOutboundResponse(outboundRequest, inboundRequest, outboundResponse, inboundResponse);
            } else {
                throw new IOException(exception);
            }
        }
    }

}