com.epam.reportportal.utils.queue.BatchExecutor.java Source code

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Here is the source code for com.epam.reportportal.utils.queue.BatchExecutor.java

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/*
 * Copyright 2016 EPAM Systems
 *
 *
 * This file is part of EPAM Report Portal.
 * https://github.com/epam/ReportPortal
 *
 * Report Portal is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Report Portal is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Report Portal.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.epam.reportportal.utils.queue;

import java.io.IOException;
import java.util.Queue;
import java.util.concurrent.Future;

import com.google.common.collect.Lists;

/**
 * Abstract Batch executor. Waits onle {@link #execute(Queue)} is allowed and
 * {@link #executeBatch(Queue)}. Returns {@link Future} since we cannot
 * guarantee that operation will be execute in submit time
 * 
 * @author Andrei Varabyeu
 * 
 * @param
 *          <P>
 * @param <R>
 */
public abstract class BatchExecutor<P, R> {

    /** {@link Queue} delegate */
    private Queue<Parameter<P, R>> batch;

    public BatchExecutor() {
        this.batch = Lists.newLinkedList();
    }

    /**
     * Push to queue. After that flushes queue if needed
     * 
     * @param parameter
     * @throws IOException
     */
    public Result<R> submit(final P parameter) throws IOException {
        final Result<R> result = new Result<R>();
        batch.offer(new Parameter<P, R>(parameter, result));
        if (execute(batch)) {
            executeAndClear();
        }
        return result;

    }

    /**
     * Executes all hold operations and clears batch queue
     * 
     * @throws IOException
     */
    public void executeAndClear() throws IOException {
        Queue<Parameter<P, R>> flushed = batch;
        batch = Lists.newLinkedList();
        if (!flushed.isEmpty())
            executeBatch(flushed);
    }

    /**
     * Executes batch operation for queued parameters. <b>Be aware that the
     * result of execution of each parameter is placed inside {@link Parameter}
     * object and needs to be populated in this method</b>
     * 
     * @param batch
     * @throws IOException
     */
    abstract protected void executeBatch(Queue<Parameter<P, R>> batch) throws IOException;

    /**
     * Whether parameters should be executed in batch or queued. This method are
     * executed after each {@link #submit(Object)} operation
     * 
     * @param batch
     * @throws IOException
     */
    abstract protected boolean execute(Queue<Parameter<P, R>> batch) throws IOException;

    /**
     * Wraps provided parameter and execution result for this parameter
     * 
     * @author Andrei Varabyeu
     * 
     * @param
     *          <P>
     *            - type of parameter
     * @param <R>
     *            - type of result
     */
    protected static final class Parameter<P, R> {
        private final Result<R> result;
        private final P parameter;

        public Parameter(final P parameter, final Result<R> result) {
            this.parameter = parameter;
            this.result = result;
        }

        public P getParameter() {
            return parameter;
        }

        public Result<R> getResult() {
            return result;
        }

        /*
         * (non-Javadoc)
         * 
         * @see java.lang.Object#toString()
         */
        @Override
        public String toString() {
            return "Parameter [result=" + result + ", parameter=" + parameter + "]";
        }

    }

}