001/*
002 * Copyright (C) 2014 Jörg Prante
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package org.xbib.elasticsearch.plugin.jdbc;
017
018import org.elasticsearch.common.logging.ESLogger;
019import org.elasticsearch.common.logging.ESLoggerFactory;
020import org.xbib.elasticsearch.plugin.jdbc.pipeline.Pipeline;
021import org.xbib.elasticsearch.plugin.jdbc.pipeline.element.ContextPipelineElement;
022import org.xbib.elasticsearch.river.jdbc.RiverContext;
023import org.xbib.elasticsearch.river.jdbc.RiverFlow;
024
025import java.util.Queue;
026
027/**
028 * A river pipeline is a collection of threads that can be executed in parallel during a river run
029 */
030public class RiverPipeline implements Pipeline<Boolean, ContextPipelineElement> {
031
032    private final static ESLogger logger = ESLoggerFactory.getLogger("river.jdbc.RiverPipeline");
033
034    private final RiverFlow riverFlow;
035
036    private RiverContext riverContext;
037
038    private volatile boolean interrupted;
039
040    public RiverPipeline(RiverFlow riverFlow) {
041        this.riverFlow = riverFlow;
042    }
043
044    public void setInterrupted(boolean interrupted) {
045        this.interrupted = interrupted;
046    }
047
048    public boolean isInterrupted() {
049        return interrupted;
050    }
051
052    /**
053     * Call this thread. Iterate over all request and pass them to request listeners.
054     * At least, this pipeline itself can listen to requests and handle errors.
055     * Only PipelineExceptions are handled for each listener. Other execptions will quit the
056     * pipeline request executions.
057     *
058     * @return a metric about the pipeline request executions.
059     * @throws Exception if pipeline execution was sborted by a non-PipelineException
060     */
061    @Override
062    public Boolean call() throws Exception {
063        interrupted = false;
064        while (hasNext() && !interrupted) {
065            ContextPipelineElement r = next();
066            request(this, r);
067        }
068        riverFlow.logMetrics(riverContext, "pipeline " + this + " complete");
069        logger.debug("releasing river context");
070        riverContext.release();
071        return true;
072    }
073
074    /**
075     * Removing pipeline requests is not supported.
076     */
077    @Override
078    public void remove() {
079        throw new UnsupportedOperationException("remove not supported");
080    }
081
082    private void request(Pipeline<Boolean, ContextPipelineElement> pipeline, ContextPipelineElement request) {
083        try {
084            if (riverContext != null) {
085                riverFlow.logMetrics(riverContext, "next request for pipeline " + this);
086            }
087            this.riverContext = request.get();
088            riverFlow.execute(riverContext);
089        } catch (Exception e) {
090            logger.error(e.getMessage(), e);
091        }
092    }
093
094    @Override
095    public boolean hasNext() {
096        return !riverFlow.getQueue().isEmpty();
097    }
098
099    @Override
100    public ContextPipelineElement next() {
101        Queue<RiverContext> queue = riverFlow.getQueue();
102        return new ContextPipelineElement().set(queue.poll());
103    }
104
105    public RiverContext getRiverContext() {
106        return riverContext;
107    }
108
109}