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git-svn-id: http://svn.igniterealtime.org/svn/repos/smack/trunk@1777 b35dd754-fafc-0310-a699-88a17e54d16e

source/org/jivesoftware/smack/PacketCollector.java

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+/**
+ * $RCSfile$
+ * $Revision$
+ * $Date$
+ *
+ * Copyright (C) 2002-2003 Jive Software. All rights reserved.
+ * ====================================================================
+ * The Jive Software License (based on Apache Software License, Version 1.1)
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. The end-user documentation included with the redistribution,
+ *    if any, must include the following acknowledgment:
+ *       "This product includes software developed by
+ *        Jive Software (http://www.jivesoftware.com)."
+ *    Alternately, this acknowledgment may appear in the software itself,
+ *    if and wherever such third-party acknowledgments normally appear.
+ *
+ * 4. The names "Smack" and "Jive Software" must not be used to
+ *    endorse or promote products derived from this software without
+ *    prior written permission. For written permission, please
+ *    contact webmaster@coolservlets.com.
+ *
+ * 5. Products derived from this software may not be called "Smack",
+ *    nor may "Smack" appear in their name, without prior written
+ *    permission of Jive Software.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.  IN NO EVENT SHALL JIVE SOFTWARE OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ * ====================================================================
+ */
+
+package org.jivesoftware.smack;
+
+import org.jivesoftware.smack.packet.Packet;
+import org.jivesoftware.smack.filter.PacketFilter;
+
+import java.util.LinkedList;
+
+/**
+ * Provides a mechanism to collect packets into a result queue that pass a
+ * specified filter. The collector lets you perform blocking and polling
+ * operations on the result queue. So, a PacketCollector is more suitable to
+ * use than a {@link PacketListener} when you need to wait for a specific
+ * result.
+ *
+ * @see PacketReader#createPacketCollector(PacketFilter)
+ * @author Matt Tucker
+ */
+public class PacketCollector {
+
+    private PacketFilter packetFilter;
+    private LinkedList resultQueue;
+    private PacketReader packetReader;
+    private boolean cancelled = false;
+
+    /**
+     * Creates a new packet collector. If the packet filter is <tt>null</tt>, then
+     * all packets will match this collector.
+     *
+     * @param packetReader the packetReader the collector is tied to.
+     * @param packetFilter determines which packets will be returned by this collector.
+     */
+    protected PacketCollector(PacketReader packetReader, PacketFilter packetFilter) {
+        this.packetReader = packetReader;
+        this.packetFilter = packetFilter;
+        this.resultQueue = new LinkedList();
+
+        // Add the collector to the packet reader's list of active collector.
+        synchronized (packetReader.collectors) {
+            packetReader.collectors.add(this);
+        }
+    }
+
+    /**
+     * Explicitly cancels the packet collector so that no more results are
+     * queued up. Once a packet collector has been cancelled, it cannot be
+     * re-enabled. Instead, a new packet collector must be created.
+     */
+    public void cancel() {
+        // If the packet collector has already been cancelled, do nothing.
+        if (cancelled) {
+            return;
+        }
+        else {
+            cancelled = true;
+            // Remove object from collectors list by setting the value in the
+            // list at the correct index to null. The collector thread will
+            // automatically remove the actual list entry when it can.
+            int index = packetReader.collectors.indexOf(this);
+            packetReader.collectors.set(index, null);
+        }
+    }
+
+    /**
+     * Returns the packet filter associated with this packet collector. The packet
+     * filter is used to determine what packets are queued as results.
+     *
+     * @return the packet filter.
+     */
+    public PacketFilter getPacketFilter() {
+        return packetFilter;
+    }
+
+    /**
+     * Polls to see if a result is currently available and returns it, or
+     * immediately returns <tt>null</tt> if no packets are currently in the
+     * result queue.
+     *
+     * @return the next packet result, or <tt>null</tt> if there are no more
+     *      results.
+     */
+    public synchronized Packet pollResult() {
+        if (resultQueue.isEmpty()) {
+            return null;
+        }
+        else {
+            return (Packet)resultQueue.removeLast();
+        }
+    }
+
+    public synchronized Packet nextResult() {
+        // Wait indefinitely until there is a result to return.
+        while (resultQueue.isEmpty()) {
+            try {
+                wait();
+            }
+            catch (InterruptedException ie) { }
+        }
+        return (Packet)resultQueue.removeLast();
+    }
+
+    public synchronized Packet nextResult(long timeout) {
+        // Wait up to the specified amount of time for a result.
+        if (resultQueue.isEmpty()) {
+            try {
+                wait(timeout);
+            }
+            catch (InterruptedException ie) { }
+        }
+        // If still no result, return null.
+        if (resultQueue.isEmpty()) {
+            return null;
+        }
+        else {
+            return (Packet)resultQueue.removeLast();
+        }
+    }
+
+    /**
+     * Processes a packet to see if it meets the criteria for this packet collector.
+     * If so, the packet is added to the result queue.
+     *
+     * @param packet the packet to process.
+     */
+    protected synchronized void processPacket(Packet packet) {
+        if (packet == null) {
+            return;
+        }
+        if (packetFilter == null || packetFilter.accept(packet)) {
+            resultQueue.addFirst(packet);
+            // Notify waiting threads a result is available.
+            notifyAll();
+        }
+    }
+}