Smack 1.5.1 + SMACK-73. Branch generated to include TLS support in HEAD.

git-svn-id: http://svn.igniterealtime.org/svn/repos/smack/trunk@2716 b35dd754-fafc-0310-a699-88a17e54d16e

CopyOftrunk/source/org/jivesoftware/smack/PacketCollector.java

@@ -0,0 +1,184 @@
+/**
+ * $RCSfile$
+ * $Revision$
+ * $Date$
+ *
+ * Copyright 2003-2004 Jive Software.
+ *
+ * All rights reserved. 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 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.<p>
+ *
+ * Each packet collector will queue up to 2^16 packets for processing before
+ * older packets are automatically dropped.
+ *
+ * @see XMPPConnection#createPacketCollector(PacketFilter)
+ * @author Matt Tucker
+ */
+public class PacketCollector {
+
+    /**
+     * Max number of packets that any one collector can hold. After the max is
+     * reached, older packets will be automatically dropped from the queue as
+     * new packets are added.
+     */
+    private static final int MAX_PACKETS = 65536;
+
+    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.
+            synchronized (packetReader.collectors) {
+                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 packet 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();
+        }
+    }
+
+    /**
+     * Returns the next available packet. The method call will block (not return)
+     * until a packet is available.
+     *
+     * @return the next available packet.
+     */
+    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();
+    }
+
+    /**
+     * Returns the next available packet. The method call will block (not return)
+     * until a packet is available or the <tt>timeout</tt> has elapased. If the
+     * timeout elapses without a result, <tt>null</tt> will be returned.
+     *
+     * @param timeout the amount of time to wait for the next packet (in milleseconds).
+     * @return the next available packet.
+     */
+    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)) {
+            // If the max number of packets has been reached, remove the oldest one.
+            if (resultQueue.size() == MAX_PACKETS) {
+                resultQueue.removeLast();
+            }
+            // Add the new packet.
+            resultQueue.addFirst(packet);
+            // Notify waiting threads a result is available.
+            notifyAll();
+        }
+    }
+}