co.cask.cdap.internal.app.runtime.flow.FlowletProgramController.java Source code

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Here is the source code for co.cask.cdap.internal.app.runtime.flow.FlowletProgramController.java

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/*
 * Copyright  2014 Cask Data, Inc.
 *
 * 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 co.cask.cdap.internal.app.runtime.flow;

import co.cask.cdap.internal.app.runtime.AbstractProgramController;
import co.cask.cdap.internal.app.runtime.ProgramOptionConstants;
import com.google.common.base.Preconditions;
import com.google.common.io.Closeables;
import com.google.common.util.concurrent.Service;
import org.apache.twill.common.Threads;
import org.apache.twill.internal.ServiceListenerAdapter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Collection;

/**
 * A {@link co.cask.cdap.app.runtime.ProgramController} for controlling a running flowlet.
 */
final class FlowletProgramController extends AbstractProgramController {

    private static final Logger LOG = LoggerFactory.getLogger(FlowletProgramController.class);

    private final BasicFlowletContext flowletContext;
    private final FlowletRuntimeService driver;
    private final Collection<ProducerSupplier> producerSuppliers;
    private final Collection<ConsumerSupplier<?>> consumerSuppliers;

    /**
     * Constructs an instance. The instance must be constructed before the flowlet driver starts.
     */
    FlowletProgramController(String programName, String flowletName, BasicFlowletContext flowletContext,
            FlowletRuntimeService driver, Collection<ProducerSupplier> producerSuppliers,
            Collection<ConsumerSupplier<?>> consumerSuppliers) {
        super(programName + ":" + flowletName, flowletContext.getRunId());
        this.flowletContext = flowletContext;
        this.driver = driver;
        this.producerSuppliers = producerSuppliers;
        this.consumerSuppliers = consumerSuppliers;
        listenDriveState(driver);
    }

    @Override
    protected void doSuspend() throws Exception {
        LOG.info("Suspending flowlet: " + flowletContext);
        driver.suspend();
        // Close all producers
        for (ProducerSupplier producerSupplier : producerSuppliers) {
            producerSupplier.close();
        }
        // Close all consumers
        for (ConsumerSupplier consumerSupplier : consumerSuppliers) {
            consumerSupplier.close();
        }
        LOG.info("Flowlet suspended: " + flowletContext);
    }

    @Override
    protected void doResume() throws Exception {
        LOG.info("Resuming flowlet: " + flowletContext);
        // Open producers
        for (ProducerSupplier producerSupplier : producerSuppliers) {
            producerSupplier.open();
        }
        // Open consumers
        for (ConsumerSupplier consumerSupplier : consumerSuppliers) {
            consumerSupplier.open(flowletContext.getInstanceCount());
        }
        driver.resume();
        LOG.info("Flowlet resumed: " + flowletContext);
    }

    @Override
    protected void doStop() throws Exception {
        LOG.info("Stopping flowlet: " + flowletContext);
        try {
            driver.stopAndWait();
        } finally {
            // Close all consumers
            for (ConsumerSupplier consumerSupplier : consumerSuppliers) {
                Closeables.closeQuietly(consumerSupplier);
            }
            flowletContext.close();
        }
        LOG.info("Flowlet stopped: " + flowletContext);
    }

    @Override
    protected void doCommand(String name, Object value) throws Exception {
        Preconditions.checkState(getState() == State.SUSPENDED,
                "Cannot change instance count when flowlet is running.");
        if (!ProgramOptionConstants.INSTANCES.equals(name) || !(value instanceof Integer)) {
            return;
        }
        int instances = (Integer) value;
        LOG.info("Change flowlet instance count: " + flowletContext + ", new count is " + instances);
        changeInstanceCount(flowletContext, instances);
        LOG.info("Flowlet instance count changed: " + flowletContext + ", new count is " + instances);
    }

    private void changeInstanceCount(BasicFlowletContext flowletContext, int instanceCount) {
        Preconditions.checkState(getState() == State.SUSPENDED,
                "Cannot change instance count of a flowlet without suspension.");
        flowletContext.setInstanceCount(instanceCount);
    }

    private void listenDriveState(FlowletRuntimeService driver) {
        driver.addListener(new ServiceListenerAdapter() {
            @Override
            public void running() {
                started();
            }

            @Override
            public void failed(Service.State from, Throwable failure) {
                LOG.error("Flowlet terminated with exception", failure);
                error(failure);
            }

            @Override
            public void terminated(Service.State from) {
                if (getState() != State.STOPPING) {
                    LOG.warn("Flowlet terminated by itself");
                    // Close all consumers
                    for (ConsumerSupplier consumerSupplier : consumerSuppliers) {
                        Closeables.closeQuietly(consumerSupplier);
                    }
                }
            }
        }, Threads.SAME_THREAD_EXECUTOR);
    }
}