/**
* Copyright 2012 Comcast Corporation
*
* 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 com.comcast.cqs.controller;
import java.io.IOException;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Random;
import javax.servlet.AsyncContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.json.JSONException;
import com.comcast.cmb.common.model.User;
import com.comcast.cmb.common.persistence.PersistenceFactory;
import com.comcast.cmb.common.util.CMBErrorCodes;
import com.comcast.cmb.common.util.CMBException;
import com.comcast.cmb.common.util.CMBProperties;
import com.comcast.cmb.common.util.PersistenceException;
import com.comcast.cqs.io.CQSMessagePopulator;
import com.comcast.cqs.model.CQSMessage;
import com.comcast.cqs.model.CQSQueue;
import com.comcast.cqs.util.CQSConstants;
import com.comcast.cqs.util.Util;
/**
* Peek message in queue
* @author bwolf
*
*/
public class CQSPeekMessageAction extends CQSAction {
private static final Random rand = new Random();
public CQSPeekMessageAction() {
super("PeekMessage");
}
@Override
public boolean doAction(User user, AsyncContext asyncContext) throws Exception {
HttpServletRequest request = (HttpServletRequest)asyncContext.getRequest();
HttpServletResponse response = (HttpServletResponse)asyncContext.getResponse();
CQSQueue queue = CQSCache.getCachedQueue(user, request);
List<CQSMessage> messageList = getMessages(request, true, queue);
Map<String, String[]> requestParams = request.getParameterMap();
List<String> filterAttributes = new ArrayList<String>();
for (String k: requestParams.keySet()) {
if (k.contains(CQSConstants.ATTRIBUTE_NAME)) {
filterAttributes.add(requestParams.get(k)[0]);
}
}
String out = CQSMessagePopulator.getReceiveMessageResponseAfterSerializing(messageList, filterAttributes);
writeResponse(out, response);
return messageList == null ? false : true;
}
protected List<CQSMessage> getMessages(HttpServletRequest request, boolean useParams, CQSQueue queue) throws PersistenceException, CMBException, IOException, NoSuchAlgorithmException, InterruptedException, JSONException {
String previousReceiptHandle = request.getParameter("PreviousReceiptHandle");
String nextReceiptHandle = request.getParameter("NextReceiptHandle");
String shardNumber = request.getParameter("Shard");
int shard = 0;
if (previousReceiptHandle != null) {
shard = Util.getShardFromReceiptHandle(previousReceiptHandle);
} else if (nextReceiptHandle != null) {
shard = Util.getShardFromReceiptHandle(nextReceiptHandle);
} else if (shardNumber != null) {
shard = Integer.parseInt(shardNumber);
} else if (queue.getNumberOfShards() > 1) {
shard = rand.nextInt(queue.getNumberOfShards());
}
if (shard < 0 || shard >= queue.getNumberOfShards()) {
throw new CMBException(CMBErrorCodes.InvalidParameterValue, "Shard number " + shard +" exceeds number of available shards in queue (" + queue.getNumberOfShards() + ").");
}
int maxNumberOfMessages = CMBProperties.getInstance().getCQSMaxReceiveMessageCount();
if (useParams && request.getParameter(CQSConstants.MAX_NUMBER_OF_MESSAGES) != null) {
maxNumberOfMessages = Integer.parseInt(request.getParameter(CQSConstants.MAX_NUMBER_OF_MESSAGES));
if (maxNumberOfMessages < 1 || maxNumberOfMessages > CMBProperties.getInstance().getCQSMaxReceiveMessageCount()) {
throw new CMBException(CMBErrorCodes.InvalidParameterValue, "The value for MaxNumberOfMessages is not valid (must be from 1 to " + CMBProperties.getInstance().getCQSMaxReceiveMessageCount() + ").");
}
}
List<CQSMessage> messageList = PersistenceFactory.getCQSMessagePersistence().peekQueue(queue.getRelativeUrl(), shard, previousReceiptHandle, nextReceiptHandle, maxNumberOfMessages);
return messageList;
}
}