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/*
* Copyright (c) 2010 Soren Dreijer
* Licensed under the simplified BSD license.
* See Documentation/Licenses/BSD-simplified.txt for more information.
*/
/*
* Copyright (c) 2015 Tarun Gupta.
* Licensed under the simplified BSD license.
* See Documentation/Licenses/BSD-simplified.txt for more information.
*/
package com.isode.stroke.eventloop;
import com.isode.stroke.eventloop.EventLoop;
import java.util.Vector;
import java.util.Collection;
import java.util.ArrayList;
// DESCRIPTION:
//
// All interaction with Swiften should happen on the same thread, such as the main GUI thread,
// since the library isn't thread-safe.
// For applications that don't have a main loop, such as WPF and MFC applications, we need a
// different approach to process events from Swiften.
//
// The SingleThreadedEventLoop class implements an event loop that can be used from such applications.
//
// USAGE:
//
// Spawn a new thread in the desired framework and call SingleThreadedEventLoop::waitForEvents(). The method
// blocks until a new event has arrived at which time it'll return, or until the wait is canceled
// at which time it throws EventLoopCanceledException.
//
// When a new event has arrived and SingleThreadedEventLoop::waitForEvents() returns, the caller should then
// call SingleThreadedEventLoop::handleEvents() on the main GUI thread. For WPF applications, for instance,
// the Dispatcher class can be used to execute the call on the GUI thread.
//
public class SingleThreadedEventLoop extends EventLoop {
public class EventLoopCanceledException extends Exception {
public EventLoopCanceledException(String message) {
super(message);
}
}
private boolean shouldShutDown_;
private Vector<Event> events_ = new Vector<Event>();
private Object eventsMutex_ = new Object();
public SingleThreadedEventLoop() {
shouldShutDown_ = false;
}
/**
* Blocks while waiting for new events and returns when new events are available.
* @throws EventLoopCanceledException when the wait is canceled.
*/
public void waitForEvents() throws EventLoopCanceledException {
synchronized(eventsMutex_) {
while (events_.isEmpty() && !shouldShutDown_) {
try {
eventsMutex_.wait();
} catch (InterruptedException e) {
}
}
}
if (shouldShutDown_) {
throw new EventLoopCanceledException("");
}
}
public void handleEvents() {
// Make a copy of the list of events so we don't block any threads that post
// events while we process them.
Vector<Event> events = new Vector<Event>();
synchronized(eventsMutex_) {
swapCollectionContents(events, events_);
}
// Loop through all the events and handle them
for(Event event : events) {
handleEvent(event);
}
}
static <T> void swapCollectionContents(Collection<T> coll1, Collection<T> coll2) {
Collection<T> temp = new ArrayList<T>(coll1);
coll1.clear();
coll1.addAll(coll2);
coll2.clear();
coll2.addAll(temp);
}
public void stop() {
synchronized(eventsMutex_) {
shouldShutDown_ = true;
eventsMutex_.notifyAll();
}
}
public void post(final Event event) {
synchronized(eventsMutex_) {
events_.add(event);
eventsMutex_.notifyAll();
}
}
}
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