PacketCollector.java
/**
*
* Copyright 2003-2007 Jive Software.
*
* 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 java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.TimeUnit;
import org.jivesoftware.smack.SmackException.NoResponseException;
import org.jivesoftware.smack.XMPPException.XMPPErrorException;
import org.jivesoftware.smack.filter.StanzaFilter;
import org.jivesoftware.smack.packet.Stanza;
/**
* 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 StanzaListener} when you need to wait for a specific
* result.<p>
*
* Each packet collector will queue up a configured number of packets for processing before
* older packets are automatically dropped. The default number is retrieved by
* {@link SmackConfiguration#getPacketCollectorSize()}.
*
* @see XMPPConnection#createPacketCollector(StanzaFilter)
* @author Matt Tucker
*/
public class PacketCollector {
private final StanzaFilter packetFilter;
private final ArrayBlockingQueue<Stanza> resultQueue;
/**
* The packet collector which timeout for the next result will get reset once this collector collects a stanza.
*/
private final PacketCollector collectorToReset;
private final XMPPConnection connection;
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 connection the connection the collector is tied to.
* @param configuration the configuration used to construct this collector
*/
protected PacketCollector(XMPPConnection connection, Configuration configuration) {
this.connection = connection;
this.packetFilter = configuration.packetFilter;
this.resultQueue = new ArrayBlockingQueue<>(configuration.size);
this.collectorToReset = configuration.collectorToReset;
}
/**
* 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) {
cancelled = true;
connection.removePacketCollector(this);
}
}
/**
* 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.
* @deprecated use {@link #getStanzaFilter()} instead.
*/
@Deprecated
public StanzaFilter getPacketFilter() {
return getStanzaFilter();
}
/**
* Returns the stanza filter associated with this stanza collector. The stanza
* filter is used to determine what stanzas are queued as results.
*
* @return the stanza filter.
*/
public StanzaFilter getStanzaFilter() {
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.
*/
@SuppressWarnings("unchecked")
public <P extends Stanza> P pollResult() {
return (P) resultQueue.poll();
}
/**
* 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.
* <p>
* Throws an XMPPErrorException in case the polled stanzas did contain an XMPPError.
* </p>
*
* @return the next available packet.
* @throws XMPPErrorException in case an error response.
*/
public <P extends Stanza> P pollResultOrThrow() throws XMPPErrorException {
P result = pollResult();
if (result != null) {
XMPPErrorException.ifHasErrorThenThrow(result);
}
return result;
}
/**
* Returns the next available packet. The method call will block (not return) until a packet is
* available.
*
* @return the next available packet.
* @throws InterruptedException
*/
@SuppressWarnings("unchecked")
public <P extends Stanza> P nextResultBlockForever() throws InterruptedException {
throwIfCancelled();
P res = null;
while (res == null) {
res = (P) resultQueue.take();
}
return res;
}
/**
* Returns the next available packet. The method call will block until the connection's default
* timeout has elapsed.
*
* @return the next available packet.
* @throws InterruptedException
*/
public <P extends Stanza> P nextResult() throws InterruptedException {
return nextResult(connection.getPacketReplyTimeout());
}
private volatile long waitStart;
/**
* Returns the next available packet. The method call will block (not return)
* until a packet is available or the <tt>timeout</tt> has elapsed. If the
* timeout elapses without a result, <tt>null</tt> will be returned.
*
* @param timeout the timeout in milliseconds.
* @return the next available packet.
* @throws InterruptedException
*/
@SuppressWarnings("unchecked")
public <P extends Stanza> P nextResult(long timeout) throws InterruptedException {
throwIfCancelled();
P res = null;
long remainingWait = timeout;
waitStart = System.currentTimeMillis();
do {
res = (P) resultQueue.poll(remainingWait, TimeUnit.MILLISECONDS);
if (res != null) {
return res;
}
remainingWait = timeout - (System.currentTimeMillis() - waitStart);
} while (remainingWait > 0);
return null;
}
/**
* Returns the next available packet. The method call will block until a packet is available or
* the connections reply timeout has elapsed. If the timeout elapses without a result,
* <tt>null</tt> will be returned. This method does also cancel the PacketCollector.
*
* @return the next available packet.
* @throws XMPPErrorException in case an error response.
* @throws NoResponseException if there was no response from the server.
* @throws InterruptedException
*/
public <P extends Stanza> P nextResultOrThrow() throws NoResponseException, XMPPErrorException, InterruptedException {
return nextResultOrThrow(connection.getPacketReplyTimeout());
}
/**
* Returns the next available packet. The method call will block until a packet is available or
* the <tt>timeout</tt> has elapsed. This method does also cancel the PacketCollector.
*
* @param timeout the amount of time to wait for the next packet (in milleseconds).
* @return the next available packet.
* @throws NoResponseException if there was no response from the server.
* @throws XMPPErrorException in case an error response.
* @throws InterruptedException
*/
public <P extends Stanza> P nextResultOrThrow(long timeout) throws NoResponseException, XMPPErrorException, InterruptedException {
P result = nextResult(timeout);
cancel();
if (result == null) {
throw NoResponseException.newWith(connection, this);
}
XMPPErrorException.ifHasErrorThenThrow(result);
return result;
}
/**
* Get the number of collected stanzas this packet collector has collected so far.
*
* @return the count of collected stanzas.
* @since 4.1
*/
public int getCollectedCount() {
return resultQueue.size();
}
/**
* 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 void processPacket(Stanza packet) {
if (packetFilter == null || packetFilter.accept(packet)) {
while (!resultQueue.offer(packet)) {
// Since we know the queue is full, this poll should never actually block.
resultQueue.poll();
}
if (collectorToReset != null) {
collectorToReset.waitStart = System.currentTimeMillis();
}
}
}
private final void throwIfCancelled() {
if (cancelled) {
throw new IllegalStateException("Packet collector already cancelled");
}
}
/**
* Get a new packet collector configuration instance.
*
* @return a new packet collector configuration.
*/
public static Configuration newConfiguration() {
return new Configuration();
}
public static class Configuration {
private StanzaFilter packetFilter;
private int size = SmackConfiguration.getPacketCollectorSize();
private PacketCollector collectorToReset;
private Configuration() {
}
/**
* Set the packet filter used by this collector. If <code>null</code>, then all packets will
* get collected by this collector.
*
* @param packetFilter
* @return a reference to this configuration.
* @deprecated use {@link #setStanzaFilter(StanzaFilter)} instead.
*/
@Deprecated
public Configuration setPacketFilter(StanzaFilter packetFilter) {
return setStanzaFilter(packetFilter);
}
/**
* Set the stanza filter used by this collector. If <code>null</code>, then all stanzas will
* get collected by this collector.
*
* @param stanzaFilter
* @return a reference to this configuration.
*/
public Configuration setStanzaFilter(StanzaFilter stanzaFilter) {
this.packetFilter = stanzaFilter;
return this;
}
/**
* Set the maximum size of this collector, i.e. how many stanzas this collector will collect
* before dropping old ones.
*
* @param size
* @return a reference to this configuration.
*/
public Configuration setSize(int size) {
this.size = size;
return this;
}
/**
* Set the collector which timeout for the next result is reset once this collector collects
* a packet.
*
* @param collector
* @return a reference to this configuration.
*/
public Configuration setCollectorToReset(PacketCollector collector) {
this.collectorToReset = collector;
return this;
}
}
}