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/*
 * Copyright (c) 2010-2016 Isode Limited.
 * All rights reserved.
 * See the COPYING file for more information.
 */

#include <Swiften/EventLoop/EventLoop.h>

#include <algorithm>
#include <cassert>

#include <boost/bind.hpp>
#include <boost/lambda/bind.hpp>
#include <boost/lambda/lambda.hpp>
#include <boost/optional.hpp>
#include <boost/thread/locks.hpp>

#include <Swiften/Base/Log.h>
#include <Swiften/Base/foreach.h>

namespace lambda = boost::lambda;

namespace Swift {

inline void invokeCallback(const Event& event) {
	try {
		assert(!event.callback.empty());
		event.callback();
	}
	catch (const std::exception& e) {
		SWIFT_LOG(error) << "Uncaught exception in event loop: " << e.what() << std::endl;
	}
	catch (...) {
		SWIFT_LOG(error) << "Uncaught non-exception in event loop" << std::endl;
	}
}

EventLoop::EventLoop() : nextEventID_(0), handlingEvents_(false) {
}

EventLoop::~EventLoop() {
}

void EventLoop::handleNextEvents() {
	const int eventsBatched = 100;
	// If handleNextEvents is already in progress, e.g. in case of a recursive call due to
	// the event loop implementation, then do no handle further events. Instead call
	// eventPosted() to continue event handling later.
	bool callEventPosted = handlingEvents_;
	if (!handlingEvents_) {
		handlingEvents_ = true;
		boost::recursive_mutex::scoped_lock lock(removeEventsMutex_);
		{
			std::vector<Event> nextEvents;
			{
				boost::recursive_mutex::scoped_lock lock(eventsMutex_);
				for (int n = 0; ((n < eventsBatched) && !events_.empty()); n++) {
					nextEvents.push_back(events_.front());
					events_.pop_front();
				}
				callEventPosted = !events_.empty();
			}
			if (!nextEvents.empty()) {
				foreach (const Event& event, nextEvents) {
					invokeCallback(event);
				}
			}
		}
		handlingEvents_ = false;
	}

	if (callEventPosted) {
		eventPosted();
	}
}

void EventLoop::postEvent(boost::function<void ()> callback, boost::shared_ptr<EventOwner> owner) {
	Event event(owner, callback);
	bool callEventPosted = false;
	{
		boost::recursive_mutex::scoped_lock lock(eventsMutex_);

		callEventPosted = events_.empty();

		event.id = nextEventID_;
		nextEventID_++;
		events_.push_back(event);
	}
	if (callEventPosted) {
		eventPosted();
	}
}

void EventLoop::removeEventsFromOwner(boost::shared_ptr<EventOwner> owner) {
	boost::recursive_mutex::scoped_lock removeLock(removeEventsMutex_);
	boost::recursive_mutex::scoped_lock lock(eventsMutex_);
	events_.remove_if(lambda::bind(&Event::owner, lambda::_1) == owner);
}

}