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187e158260
poll the result before waiting for a message (with nextResult()), in order to prevent waiting unnecessarily. Add PacketCollector.pollResultOrThrow()
240 lines
8.6 KiB
Java
240 lines
8.6 KiB
Java
/**
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*
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* Copyright 2003-2007 Jive Software.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.jivesoftware.smack;
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import java.util.concurrent.ArrayBlockingQueue;
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import java.util.concurrent.TimeUnit;
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import java.util.logging.Level;
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import java.util.logging.Logger;
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import org.jivesoftware.smack.SmackException.NoResponseException;
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import org.jivesoftware.smack.XMPPException.XMPPErrorException;
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import org.jivesoftware.smack.filter.PacketFilter;
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import org.jivesoftware.smack.packet.Packet;
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/**
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* Provides a mechanism to collect packets into a result queue that pass a
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* specified filter. The collector lets you perform blocking and polling
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* operations on the result queue. So, a PacketCollector is more suitable to
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* use than a {@link PacketListener} when you need to wait for a specific
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* result.<p>
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*
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* Each packet collector will queue up a configured number of packets for processing before
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* older packets are automatically dropped. The default number is retrieved by
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* {@link SmackConfiguration#getPacketCollectorSize()}.
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*
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* @see XMPPConnection#createPacketCollector(PacketFilter)
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* @author Matt Tucker
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*/
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public class PacketCollector {
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private static final Logger LOGGER = Logger.getLogger(PacketCollector.class.getName());
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private final PacketFilter packetFilter;
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private final ArrayBlockingQueue<Packet> resultQueue;
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private final XMPPConnection connection;
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private boolean cancelled = false;
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/**
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* Creates a new packet collector. If the packet filter is <tt>null</tt>, then
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* all packets will match this collector.
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*
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* @param connection the connection the collector is tied to.
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* @param packetFilter determines which packets will be returned by this collector.
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*/
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protected PacketCollector(XMPPConnection connection, PacketFilter packetFilter) {
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this(connection, packetFilter, SmackConfiguration.getPacketCollectorSize());
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}
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/**
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* Creates a new packet collector. If the packet filter is <tt>null</tt>, then
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* all packets will match this collector.
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*
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* @param connection the connection the collector is tied to.
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* @param packetFilter determines which packets will be returned by this collector.
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* @param maxSize the maximum number of packets that will be stored in the collector.
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*/
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protected PacketCollector(XMPPConnection connection, PacketFilter packetFilter, int maxSize) {
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this.connection = connection;
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this.packetFilter = packetFilter;
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this.resultQueue = new ArrayBlockingQueue<Packet>(maxSize);
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}
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/**
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* Explicitly cancels the packet collector so that no more results are
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* queued up. Once a packet collector has been cancelled, it cannot be
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* re-enabled. Instead, a new packet collector must be created.
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*/
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public void cancel() {
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// If the packet collector has already been cancelled, do nothing.
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if (!cancelled) {
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cancelled = true;
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connection.removePacketCollector(this);
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}
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}
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/**
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* Returns the packet filter associated with this packet collector. The packet
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* filter is used to determine what packets are queued as results.
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*
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* @return the packet filter.
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*/
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public PacketFilter getPacketFilter() {
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return packetFilter;
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}
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/**
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* Polls to see if a packet is currently available and returns it, or
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* immediately returns <tt>null</tt> if no packets are currently in the
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* result queue.
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*
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* @return the next packet result, or <tt>null</tt> if there are no more
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* results.
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*/
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@SuppressWarnings("unchecked")
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public <P extends Packet> P pollResult() {
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return (P) resultQueue.poll();
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}
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/**
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* Polls to see if a packet is currently available and returns it, or
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* immediately returns <tt>null</tt> if no packets are currently in the
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* result queue.
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* <p>
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* Throws an XMPPErrorException in case the polled stanzas did contain an XMPPError.
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* </p>
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*
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* @return the next available packet.
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* @throws XMPPErrorException in case an error response.
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*/
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public <P extends Packet> P pollResultOrThrow() throws XMPPErrorException {
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P result = pollResult();
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if (result != null) {
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XMPPErrorException.ifHasErrorThenThrow(result);
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}
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return result;
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}
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/**
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* Returns the next available packet. The method call will block (not return) until a packet is
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* available.
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*
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* @return the next available packet.
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*/
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@SuppressWarnings("unchecked")
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public <P extends Packet> P nextResultBlockForever() {
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P res = null;
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while (res == null) {
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try {
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res = (P) resultQueue.take();
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} catch (InterruptedException e) {
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LOGGER.log(Level.FINE,
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"nextResultBlockForever was interrupted", e);
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}
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}
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return res;
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}
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/**
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* Returns the next available packet. The method call will block until the connection's default
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* timeout has elapsed.
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*
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* @return the next availabe packet.
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*/
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public <P extends Packet> P nextResult() {
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return nextResult(connection.getPacketReplyTimeout());
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}
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/**
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* Returns the next available packet. The method call will block (not return)
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* until a packet is available or the <tt>timeout</tt> has elapsed. If the
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* timeout elapses without a result, <tt>null</tt> will be returned.
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*
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* @return the next available packet.
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*/
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@SuppressWarnings("unchecked")
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public <P extends Packet> P nextResult(long timeout) {
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P res = null;
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long remainingWait = timeout;
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final long waitStart = System.currentTimeMillis();
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while (res == null && remainingWait > 0) {
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try {
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res = (P) resultQueue.poll(remainingWait, TimeUnit.MILLISECONDS);
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remainingWait = timeout - (System.currentTimeMillis() - waitStart);
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} catch (InterruptedException e) {
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LOGGER.log(Level.FINE, "nextResult was interrupted", e);
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}
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}
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return res;
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}
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/**
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* Returns the next available packet. The method call will block until a packet is available or
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* the connections reply timeout has elapsed. If the timeout elapses without a result,
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* <tt>null</tt> will be returned. This method does also cancel the PacketCollector.
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*
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* @return the next available packet.
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* @throws XMPPErrorException in case an error response.
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* @throws NoResponseException if there was no response from the server.
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*/
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public <P extends Packet> P nextResultOrThrow() throws NoResponseException, XMPPErrorException {
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return nextResultOrThrow(connection.getPacketReplyTimeout());
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}
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/**
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* Returns the next available packet. The method call will block until a packet is available or
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* the <tt>timeout</tt> has elapsed. This method does also cancel the PacketCollector.
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*
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* @param timeout the amount of time to wait for the next packet (in milleseconds).
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* @return the next available packet.
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* @throws NoResponseException if there was no response from the server.
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* @throws XMPPErrorException in case an error response.
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*/
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public <P extends Packet> P nextResultOrThrow(long timeout) throws NoResponseException, XMPPErrorException {
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P result = nextResult(timeout);
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cancel();
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if (result == null) {
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throw new NoResponseException(connection);
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}
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XMPPErrorException.ifHasErrorThenThrow(result);
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return result;
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}
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/**
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* Processes a packet to see if it meets the criteria for this packet collector.
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* If so, the packet is added to the result queue.
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*
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* @param packet the packet to process.
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*/
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protected void processPacket(Packet packet) {
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if (packet == null) {
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return;
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}
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if (packetFilter == null || packetFilter.accept(packet)) {
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while (!resultQueue.offer(packet)) {
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// Since we know the queue is full, this poll should never actually block.
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resultQueue.poll();
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}
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}
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}
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}
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