co.cask.cdap.internal.app.queue.BasicInputDatum.java Source code

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Here is the source code for co.cask.cdap.internal.app.queue.BasicInputDatum.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.queue;

import co.cask.cdap.api.flow.flowlet.InputContext;
import co.cask.cdap.app.queue.InputDatum;
import co.cask.cdap.common.queue.QueueName;
import co.cask.cdap.data2.queue.DequeueResult;
import com.google.common.base.Function;
import com.google.common.base.Objects;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;

import java.util.Iterator;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * An implementation for {@link InputDatum} for common operations across queue and stream
 *
 * @param <T> Type of input.
 */
final class BasicInputDatum<S, T> implements InputDatum<T> {

    private final DequeueResult<S> result;
    private final AtomicInteger retry;
    private final InputContext inputContext;
    private final QueueName queueName;
    private final Iterable<T> events;

    BasicInputDatum(final QueueName queueName, DequeueResult<S> result, Function<S, T> decoder) {
        this.result = result;
        this.retry = new AtomicInteger(0);
        this.queueName = queueName;
        // Memorize the transformed Iterable so that decoder would only invoked once for each event no matter
        // how many times iterator() is called. This is to save time as well as a need for the case where
        // metrics has been logged inside the decoder.
        this.events = result.isEmpty() ? ImmutableList.<T>of()
                : ImmutableList.copyOf(Iterables.transform(result, decoder));
        this.inputContext = new InputContext() {
            @Override
            public String getOrigin() {
                return queueName.getSimpleName();
            }

            @Override
            public int getRetryCount() {
                return retry.get();
            }

            @Override
            public String toString() {
                return Objects.toStringHelper(InputContext.class).add("queue", queueName).toString();
            }
        };
    }

    @Override
    public boolean needProcess() {
        return !result.isEmpty();
    }

    @Override
    public Iterator<T> iterator() {
        return events.iterator();
    }

    @Override
    public void incrementRetry() {
        retry.incrementAndGet();
    }

    @Override
    public int getRetry() {
        return retry.get();
    }

    @Override
    public InputContext getInputContext() {
        return inputContext;
    }

    @Override
    public QueueName getQueueName() {
        return queueName;
    }

    @Override
    public void reclaim() {
        result.reclaim();
    }

    @Override
    public int size() {
        return result.size();
    }

    @Override
    public String toString() {
        return String.format("%s %d", result, retry.get());
    }
}