Java tutorial
/* * 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.synapse.mediators.eip.aggregator; import org.apache.synapse.MessageContext; import org.apache.synapse.SynapseLog; import org.apache.synapse.core.SynapseEnvironment; import org.apache.synapse.mediators.eip.EIPConstants; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import java.util.List; import java.util.ArrayList; import java.util.TimerTask; /** * An instance of this class is created to manage each aggregation group, and it holds * the aggregation properties and the messages collected during aggregation. This class also * times out itself after the timeout expires it */ public class Aggregate extends TimerTask { private static final Log log = LogFactory.getLog(Aggregate.class); private long timeoutMillis = 0; /** The time in millis at which this aggregation should be considered as expired */ private long expiryTimeMillis = 0; /** The minimum number of messages to be collected to consider this aggregation as complete */ private int minCount = -1; /** The maximum number of messages that should be collected by this aggregation */ private int maxCount = -1; private String correlation = null; /** The AggregateMediator that should be invoked on completion of the aggregation */ private AggregateMediator aggregateMediator = null; private List<MessageContext> messages = new ArrayList<MessageContext>(); private boolean locked = false; private boolean completed = false; private SynapseEnvironment synEnv = null; /** * Save aggregation properties and timeout * * @param corelation representing the corelation name of the messages in the aggregate * @param timeoutMillis the timeout duration in milliseconds * @param min the minimum number of messages to be aggregated * @param max the maximum number of messages to be aggregated * @param mediator */ public Aggregate(SynapseEnvironment synEnv, String corelation, long timeoutMillis, int min, int max, AggregateMediator mediator) { this.synEnv = synEnv; this.correlation = corelation; if (timeoutMillis > 0) { expiryTimeMillis = System.currentTimeMillis() + timeoutMillis; } if (min > 0) { minCount = min; } if (max > 0) { maxCount = max; } this.aggregateMediator = mediator; } /** * Add a message to the interlan message list * * @param synCtx message to be added into this aggregation group * @return true if the message was added or false if not */ public synchronized boolean addMessage(MessageContext synCtx) { if (maxCount <= 0 || (maxCount > 0 && messages.size() < maxCount)) { messages.add(synCtx); return true; } else { return false; } } /** * Has this aggregation group completed? * * @param synLog the Synapse log to use * * @return boolean true if aggregation is complete */ public synchronized boolean isComplete(SynapseLog synLog) { if (!completed) { // if any messages have been collected, check if the completion criteria is met if (!messages.isEmpty()) { // get total messages for this group, from the first message we have collected MessageContext mc = messages.get(0); Object prop = mc.getProperty(EIPConstants.MESSAGE_SEQUENCE + (aggregateMediator.getId() != null ? "." + aggregateMediator.getId() : "")); if (prop != null && prop instanceof String) { String[] msgSequence = prop.toString().split(EIPConstants.MESSAGE_SEQUENCE_DELEMITER); int total = Integer.parseInt(msgSequence[1]); if (synLog.isTraceOrDebugEnabled()) { synLog.traceOrDebug( messages.size() + " messages of " + total + " collected in current aggregation"); } if (messages.size() >= total) { synLog.traceOrDebug("Aggregation complete"); return true; } } } else { synLog.traceOrDebug("No messages collected in current aggregation"); } // if the minimum number of messages has been reached, its complete if (minCount > 0 && messages.size() >= minCount) { if (synLog.isTraceOrDebugEnabled()) { synLog.traceOrDebug( "Aggregation complete - the minimum : " + minCount + " messages has been reached"); } return true; } if (maxCount > 0 && messages.size() >= maxCount) { if (synLog.isTraceOrDebugEnabled()) { synLog.traceOrDebug( "Aggregation complete - the maximum : " + maxCount + " messages has been reached"); } return true; } // else, has this aggregation reached its timeout? if (expiryTimeMillis > 0 && System.currentTimeMillis() >= expiryTimeMillis) { synLog.traceOrDebug("Aggregation complete - the aggregation has timed out"); return true; } } else { synLog.traceOrDebug( "Aggregation already completed - this message will not be processed in aggregation"); } return false; } public MessageContext getLastMessage() { return messages.get(messages.size() - 1); } public long getTimeoutMillis() { return timeoutMillis; } public void setTimeoutMillis(long timeoutMillis) { this.timeoutMillis = timeoutMillis; } public int getMinCount() { return minCount; } public void setMinCount(int minCount) { this.minCount = minCount; } public int getMaxCount() { return maxCount; } public void setMaxCount(int maxCount) { this.maxCount = maxCount; } public String getCorrelation() { return correlation; } public void setCorrelation(String correlation) { this.correlation = correlation; } public synchronized List<MessageContext> getMessages() { return new ArrayList<MessageContext>(messages); } public void setMessages(List<MessageContext> messages) { this.messages = messages; } public long getExpiryTimeMillis() { return expiryTimeMillis; } public void setExpiryTimeMillis(long expiryTimeMillis) { this.expiryTimeMillis = expiryTimeMillis; } public void run() { while (true) { if (completed) { break; } if (getLock()) { if (log.isDebugEnabled()) { log.debug("Time : " + System.currentTimeMillis() + " and this aggregator " + "expired at : " + expiryTimeMillis); } synEnv.getExecutorService().execute(new AggregateTimeout(this)); break; } } } /** * Clear references in Aggregate Timer Task * * This need to be called when aggregation is completed. * Task is not eligible for gc until it reach the execution time, * even though it is cancelled. So we need to remove references from task to other objects to * allow them to be garbage collected * */ public void clear() { messages = null; } private class AggregateTimeout implements Runnable { private Aggregate aggregate = null; AggregateTimeout(Aggregate aggregate) { this.aggregate = aggregate; } public void run() { aggregateMediator.completeAggregate(aggregate); log.warn("Aggregate Mediator Time out occured."); } } public synchronized boolean getLock() { return !locked; } public void releaseLock() { locked = false; } public boolean isCompleted() { return completed; } public void setCompleted(boolean completed) { this.completed = completed; } }