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/*
* Copyright (c) 2010-2012, Isode Limited, London, England.
* All rights reserved.
*/
/*
* Copyright (c) 2010 Remko Tronçon
* Licensed under the GNU General Public License v3.
* See Documentation/Licenses/GPLv3.txt for more information.
*/
package com.isode.stroke.eventloop;
import java.util.ArrayList;
import java.util.Vector;
/**
* An event loop is a seemingly infinite loop (runs for the duration of the use
* of the library) that waits for external events
* (e.g. incoming network packets, timers being activated, input happening) to
* happen; when such an event comes in, it notifies interested parties of this
* event, and then continues listening for the next event.
*/
public abstract class EventLoop {
/**
* Create an event loop
*/
public EventLoop() {
}
/**
* Post an event to the loop.
*
* @param callback Callback handler for the event, must not be null. This
* will be called when the event is processed.
*/
public void postEvent(Event.Callback callback) {
postEvent(callback, null);
}
/**
* Post an event to the loop.
*
* @param callback Callback handler for the event, must not be null. This
* will be called when the event is processed.
* @param owner Owner of the event, non-null. This can be used to
* {@link EventLoop#removeEventsFromOwner} later.
*/
public void postEvent(Event.Callback callback, EventOwner owner) {
Event event;
synchronized (eventsMutex_) {
event = new Event(owner, callback, nextEventID_);
nextEventID_++;
events_.add(event);
}
post(event);
}
/**
* Remove all events from the given owner.
* \p
* This does a reference check (==), not calling owner.equals().
*
* @param owner Owner of the event, must not be null
*/
public void removeEventsFromOwner(EventOwner owner) {
synchronized (eventsMutex_) {
ArrayList<Event> matches = new ArrayList<Event>();
for (Event event : events_) {
if (event.owner == owner) {
matches.add(event);
}
}
events_.removeAll(matches);
}
}
/**
* Reimplement this to call handleEvent(event) from the thread in which the
* event loop is residing.
*/
protected abstract void post(Event event);
/**
* When reimplementing, call this from within the {@link EventLoop#post}
* method in the application's event loop (main thread).
*/
protected void handleEvent(Event event) {
if (handlingEvents_) {
// We're being called recursively. Push in the list of events to
// handle in the parent handleEvent()
eventsToHandle_.add(event);
return;
}
boolean doCallback = false;
synchronized (eventsMutex_) {
doCallback = events_.contains(event);
if (doCallback) {
events_.remove(event);
}
}
if (doCallback) {
handlingEvents_ = true;
event.callback.run();
// Process events that were passed to handleEvent during the callback
// (i.e. through recursive calls of handleEvent)
while (!eventsToHandle_.isEmpty()) {
Event nextEvent = eventsToHandle_.firstElement();
eventsToHandle_.remove(0);
nextEvent.callback.run();
}
handlingEvents_ = false;
}
}
// struct HasOwner {
// HasOwner(boost::shared_ptr<EventOwner> owner) : owner(owner) {}
// bool operator()(const Event& event) { return event.owner == owner; }
// boost::shared_ptr<EventOwner> owner;
// };
private final Object eventsMutex_ = new Object();
private int nextEventID_ = 0;
private Vector<Event> events_ = new Vector<Event>();
boolean handlingEvents_ = false;
private Vector<Event> eventsToHandle_ = new Vector<Event>();
}
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