SynchronizationPoint.java
/**
*
* Copyright © 2014-2015 Florian Schmaus
*
* 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.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import org.jivesoftware.smack.SmackException.NoResponseException;
import org.jivesoftware.smack.SmackException.NotConnectedException;
import org.jivesoftware.smack.packet.Nonza;
import org.jivesoftware.smack.packet.Stanza;
import org.jivesoftware.smack.packet.TopLevelStreamElement;
public class SynchronizationPoint<E extends Exception> {
private final AbstractXMPPConnection connection;
private final Lock connectionLock;
private final Condition condition;
private final String waitFor;
// Note that there is no need to make 'state' and 'failureException' volatile. Since 'lock' and 'unlock' have the
// same memory synchronization effects as synchronization block enter and leave.
private State state;
private E failureException;
/**
* Construct a new synchronization point for the given connection.
*
* @param connection the connection of this synchronization point.
* @param waitFor a description of the event this synchronization point handles.
*/
public SynchronizationPoint(AbstractXMPPConnection connection, String waitFor) {
this.connection = connection;
this.connectionLock = connection.getConnectionLock();
this.condition = connection.getConnectionLock().newCondition();
this.waitFor = waitFor;
init();
}
/**
* Initialize (or reset) this synchronization point.
*/
public void init() {
connectionLock.lock();
state = State.Initial;
failureException = null;
connectionLock.unlock();
}
/**
* Send the given top level stream element and wait for a response.
*
* @param request the plain stream element to send.
* @throws NoResponseException if no response was received.
* @throws NotConnectedException if the connection is not connected.
* @throws InterruptedException if the connection is interrupted.
* @return <code>null</code> if synchronization point was successful, or the failure Exception.
*/
public E sendAndWaitForResponse(TopLevelStreamElement request) throws NoResponseException,
NotConnectedException, InterruptedException {
assert (state == State.Initial);
connectionLock.lock();
try {
if (request != null) {
if (request instanceof Stanza) {
connection.sendStanza((Stanza) request);
}
else if (request instanceof Nonza) {
connection.sendNonza((Nonza) request);
} else {
throw new IllegalStateException("Unsupported element type");
}
state = State.RequestSent;
}
waitForConditionOrTimeout();
}
finally {
connectionLock.unlock();
}
return checkForResponse();
}
/**
* Send the given plain stream element and wait for a response.
*
* @param request the plain stream element to send.
* @throws E if an failure was reported.
* @throws NoResponseException if no response was received.
* @throws NotConnectedException if the connection is not connected.
* @throws InterruptedException if the connection is interrupted.
*/
public void sendAndWaitForResponseOrThrow(Nonza request) throws E, NoResponseException,
NotConnectedException, InterruptedException {
sendAndWaitForResponse(request);
switch (state) {
case Failure:
if (failureException != null) {
throw failureException;
}
break;
default:
// Success, do nothing
}
}
/**
* Check if this synchronization point is successful or wait the connections reply timeout.
* @throws NoResponseException if there was no response marking the synchronization point as success or failed.
* @throws E if there was a failure
* @throws InterruptedException if the connection is interrupted.
*/
public void checkIfSuccessOrWaitOrThrow() throws NoResponseException, E, InterruptedException {
checkIfSuccessOrWait();
if (state == State.Failure) {
throw failureException;
}
}
/**
* Check if this synchronization point is successful or wait the connections reply timeout.
* @throws NoResponseException if there was no response marking the synchronization point as success or failed.
* @throws InterruptedException
* @return <code>null</code> if synchronization point was successful, or the failure Exception.
*/
public E checkIfSuccessOrWait() throws NoResponseException, InterruptedException {
connectionLock.lock();
try {
switch (state) {
// Return immediately on success or failure
case Success:
return null;
case Failure:
return failureException;
default:
// Do nothing
break;
}
waitForConditionOrTimeout();
} finally {
connectionLock.unlock();
}
return checkForResponse();
}
/**
* Report this synchronization point as successful.
*/
public void reportSuccess() {
connectionLock.lock();
try {
state = State.Success;
condition.signalAll();
}
finally {
connectionLock.unlock();
}
}
/**
* Deprecated.
* @deprecated use {@link #reportFailure(Exception)} instead.
*/
@Deprecated
public void reportFailure() {
reportFailure(null);
}
/**
* Report this synchronization point as failed because of the given exception. The {@code failureException} must be set.
*
* @param failureException the exception causing this synchronization point to fail.
*/
public void reportFailure(E failureException) {
assert failureException != null;
connectionLock.lock();
try {
state = State.Failure;
this.failureException = failureException;
condition.signalAll();
}
finally {
connectionLock.unlock();
}
}
/**
* Check if this synchronization point was successful.
*
* @return true if the synchronization point was successful, false otherwise.
*/
public boolean wasSuccessful() {
connectionLock.lock();
try {
return state == State.Success;
}
finally {
connectionLock.unlock();
}
}
/**
* Check if this synchronization point has its request already sent.
*
* @return true if the request was already sent, false otherwise.
*/
public boolean requestSent() {
connectionLock.lock();
try {
return state == State.RequestSent;
}
finally {
connectionLock.unlock();
}
}
public E getFailureException() {
connectionLock.lock();
try {
return failureException;
}
finally {
connectionLock.unlock();
}
}
/**
* Wait for the condition to become something else as {@link State#RequestSent} or {@link State#Initial}.
* {@link #reportSuccess()}, {@link #reportFailure()} and {@link #reportFailure(Exception)} will either set this
* synchronization point to {@link State#Success} or {@link State#Failure}. If none of them is set after the
* connections reply timeout, this method will set the state of {@link State#NoResponse}.
* @throws InterruptedException
*/
private void waitForConditionOrTimeout() throws InterruptedException {
long remainingWait = TimeUnit.MILLISECONDS.toNanos(connection.getReplyTimeout());
while (state == State.RequestSent || state == State.Initial) {
if (remainingWait <= 0) {
state = State.NoResponse;
break;
}
remainingWait = condition.awaitNanos(remainingWait);
}
}
/**
* Check for a response and throw a {@link NoResponseException} if there was none.
* <p>
* The exception is thrown, if state is one of 'Initial', 'NoResponse' or 'RequestSent'
* </p>
* @return <code>true</code> if synchronization point was successful, <code>false</code> on failure.
* @throws NoResponseException
*/
private E checkForResponse() throws NoResponseException {
switch (state) {
case Initial:
case NoResponse:
case RequestSent:
throw NoResponseException.newWith(connection, waitFor);
case Success:
return null;
case Failure:
return failureException;
default:
throw new AssertionError("Unknown state " + state);
}
}
private enum State {
Initial,
RequestSent,
NoResponse,
Success,
Failure,
}
}