mirror of https://github.com/deavmi/eventy.git
585 lines
14 KiB
D
585 lines
14 KiB
D
module eventy.engine;
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import eventy.queues : Queue;
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import eventy.signal : Signal;
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import eventy.event : Event;
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import eventy.config;
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import std.container.dlist;
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import core.sync.mutex : Mutex;
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import core.thread : Thread, dur, Duration;
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import eventy.exceptions;
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import std.stdio;
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// /* TODO: Move elsewhere, this thing thinks it's a delegate in the unit test, idk why */
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// private void runner(Event e)
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// {
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// import std.stdio;
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// writeln("Running event", e.id);
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// }
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unittest
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{
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Engine engine = new Engine();
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engine.start();
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/**
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* Let the event engine know what typeIDs are
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* allowed to be queued
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*/
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engine.addQueue(1);
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engine.addQueue(2);
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/**
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* Create a new Signal Handler that will handles
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* event types `1` and `2` with the given `handler()`
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* function
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*/
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class SignalHandler1 : Signal
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{
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this()
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{
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super([1, 2]);
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}
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public override void handler(Event e)
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{
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import std.stdio;
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writeln("Running event", e.id);
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}
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}
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/**
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* Tell the event engine that I want to register
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* the following handler for its queues `1` and `2`
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*/
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Signal j = new SignalHandler1();
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engine.addSignalHandler(j);
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Event eTest = new Event(1);
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engine.push(eTest);
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eTest = new Event(2);
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engine.push(eTest);
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Thread.sleep(dur!("seconds")(2));
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engine.push(eTest);
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writeln("done with main thread code");
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while(engine.hasPendingEvents()) {}
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/* TODO: Before shutting down, actually test it out (i.e. all events ran) */
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engine.shutdown();
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}
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// unittest
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// {
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// EngineSettings customSettings = {holdOffMode: HoldOffMode.YIELD};
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// Engine engine = new Engine(customSettings);
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// engine.start();
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// /**
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// * Let the event engine know what typeIDs are
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// * allowed to be queued
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// */
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// engine.addQueue(1);
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// engine.addQueue(2);
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// /**
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// * Create a new Signal Handler that will handles
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// * event types `1` and `2` with the given `handler()`
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// * function
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// */
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// class SignalHandler1 : Signal
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// {
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// this()
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// {
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// super([1, 2]);
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// }
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// public override void handler(Event e)
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// {
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// import std.stdio;
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// writeln("Running event", e.id);
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// }
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// }
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// /**
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// * Tell the event engine that I want to register
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// * the following handler for its queues `1` and `2`
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// */
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// Signal j = new SignalHandler1();
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// engine.addSignalHandler(j);
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// Event eTest = new Event(1);
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// engine.push(eTest);
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// eTest = new Event(2);
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// engine.push(eTest);
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// Thread.sleep(dur!("seconds")(2));
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// engine.push(eTest);
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// writeln("done with main thread code");
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// /* TODO: Before shutting down, actually test it out (i.e. all events ran) */
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// engine.shutdown();
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// }
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/**
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* Engine
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*
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* An instance of this represents an engine that
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* can, at any time, handle the delivery of new
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* events, trigger the correct signal handlers
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* for the respective events, remove signal
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* handlers, add signal handlers, among many
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* other things
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*/
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public final class Engine : Thread
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{
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/* TODO: Or use a queue data structure */
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private DList!(Queue) queues;
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private Mutex queueLock;
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/* TODO: Or use a queue data structure */
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private DList!(Signal) handlers;
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private Mutex handlerLock;
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/* Engine configuration */
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private EngineSettings settings;
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private bool running;
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private DList!(DispatchWrapper) threadStore;
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private Mutex threadStoreLock;
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this(EngineSettings settings)
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{
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super(&run);
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queueLock = new Mutex();
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handlerLock = new Mutex();
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threadStoreLock = new Mutex();
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this.settings = settings;
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}
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/**
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* Instantiates a new Eventy engine with the default
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* settings
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*/
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this()
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{
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EngineSettings defaultSettings;
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/* Yield if a lock fails (prevent potential thread starvation) */
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defaultSettings.agressiveTryLock = false;
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/* Make the event engine loop sleep (1) and for 200ms (2) (TODO: Adjust this) */
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defaultSettings.holdOffMode = HoldOffMode.SLEEP;
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defaultSettings.sleepTime = dur!("msecs")(200);
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/* Do not gracefully shutdown */
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defaultSettings.gracefulShutdown = false;
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this(defaultSettings);
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}
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/**
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* Set the event loop sleep time
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*
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* The load average will sky rocket if it is 0,
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* which is just because it is calculated on how
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* full the run queue is, length but also over time
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* and even just one task continousy in it will
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* make the average high
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*
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* Reason why it's always runnable is the process
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* (the "thread") is a tight loop with no sleeps
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* that would dequeue it from the run queue and/or
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* no I/O system calls that would put it into the
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* waiting queue
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*/
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public void setSleep(Duration time)
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{
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// sleepTime = time;
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}
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/**
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* Adds the given Signal handler
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*
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* @param e the Signal handler to add
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*/
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/**
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* Attaches a new signal handler to the engine
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*
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* Params:
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* e = the signal handler to add
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*/
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public void addSignalHandler(Signal e)
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{
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/* Lock the signal-set */
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handlerLock.lock();
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/* Add the new handler */
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handlers ~= e;
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/* Unlock the signal-set */
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handlerLock.unlock();
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}
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/**
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* The main event loop
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*
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* This checks at a certain interval (see HoldOffMode) if
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* there are any events in any of the queues, if so,
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* the dispatcher for said event type is called
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*/
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private void run()
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{
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running = true;
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while (running)
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{
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/**
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* Lock the queue-set
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*
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* Additionally:
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* Don't waste time spinning on mutex,
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* if it is not lockable then yield
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*/
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while (!queueLock.tryLock_nothrow())
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{
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yield();
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}
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foreach (Queue queue; queues)
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{
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/* If the queue has evenets queued */
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if (queue.hasEvents())
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{
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/* TODO: Add different dequeuing techniques */
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/* Pop the first Event */
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Event headEvent = queue.popEvent();
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/* Get all signal-handlers for this event type */
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Signal[] handlersMatched = getSignalsForEvent(headEvent);
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/* Dispatch the signal handlers */
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dispatch(handlersMatched, headEvent);
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}
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}
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/* Unlock the queue set */
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queueLock.unlock();
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/* Activate hold off (dependening on the type) */
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if(settings.holdOffMode == HoldOffMode.YIELD)
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{
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/* Yield to stop mutex starvation */
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yield();
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}
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else if(settings.holdOffMode == HoldOffMode.SLEEP)
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{
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/* Sleep the thread (for given time) to stop mutex starvation */
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sleep(settings.sleepTime);
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}
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else
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{
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/* This should never happen */
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assert(false);
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}
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}
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}
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/**
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* Shuts down the event engine
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*/
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public void shutdown()
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{
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/* TODO: Insert a lock here, that dispatch should adhere too as well */
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/* FIXME: We should prevent adding of queues during shutdown */
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/* FIXME: We should prevent pushing of events during shutdown */
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/* Wait for any pendings events (if configured) */
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if(settings.gracefulShutdown)
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{
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while(hasPendingEvents()) {}
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}
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/* Stop the loop */
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running = false;
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}
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/**
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* Dispatch(Signal[] set, Event e)
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*
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* Creates a new thread per signal and dispatches the event to them
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*
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* TODO: Add ability to dispatch on this thread
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*/
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private void dispatch(Signal[] signalSet, Event e)
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{
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foreach (Signal signal; signalSet)
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{
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/* Create a new Thread */
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// Thread handlerThread = getThread(signal, e);
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DispatchWrapper handlerThread = new DispatchWrapper(signal, e);
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/**
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* TODO
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*
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* When we call `shutdown()` there may very well be a case of
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* where the threadStoreLock unlocks after the clean up
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* loop, but storeThread hangs here during that time,
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* then proceeds to start the thread, we should therefore,
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* either block on running changed (solution 1, not as granular)
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*
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* Solution 2: Block on dispatch being called <- use this method rather
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* But still needs a running check, it must not go ahead if running is now
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* false
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*/
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/* Store the thread */
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storeThread(handlerThread);
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/* Start the thread */
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handlerThread.start();
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}
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}
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/**
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* Store the thread
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*
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* TODO: This can only be implemented if we use
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* wrapper threads that exit, and we can signal
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* removal from thread store then
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*/
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private void storeThread(DispatchWrapper t)
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{
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/* Lock the thread store from editing */
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threadStoreLock.lock();
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/* Add the thread */
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threadStore ~= t;
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/* Unlock the thread store for editing */
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threadStoreLock.unlock();
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}
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/**
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* Removes a thread from the thread store
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*/
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private void removeThread(DispatchWrapper t)
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{
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/* Lock the thread store from editing */
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threadStoreLock.lock();
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/* Remove the thread */
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threadStore.linearRemoveElement(t);
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/* Unlock the thread store for editing */
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threadStoreLock.unlock();
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}
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/**
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* DispatchWrapper
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*
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* Effectively a thread but with the Signal,
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* Event included with clean-up routines
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*/
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private class DispatchWrapper : Thread
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{
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private Signal signal;
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private Event e;
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this(Signal signal, Event e)
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{
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super(&run);
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this.signal = signal;
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this.e = e;
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}
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private void run()
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{
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/* Run the signal handler */
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signal.handler(e);
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/* Remove myself from the thread store */
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removeThread(this);
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}
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}
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/**
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* returns all signal(s) responsible for
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* handling the type of Event provided
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*
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* @param e the Event type to match to
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* @returns Signal[] the list of signal
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* handlers that handle event e
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*/
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public Signal[] getSignalsForEvent(Event e)
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{
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/* Matched handlers */
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Signal[] matchedHandlers;
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/* Lock the signal-set */
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handlerLock.lock();
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/* Find all handlers matching */
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foreach (Signal signal; handlers)
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{
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if (signal.handles(e.id))
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{
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matchedHandlers ~= signal;
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}
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}
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/* Unlock the signal-set */
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handlerLock.unlock();
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return matchedHandlers;
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}
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/**
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* Checks if there is a signal handler that handles
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* the given event id
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* Params:
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* id = the event ID to check
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* Returns:
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*/
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public bool isSignalExists(ulong id)
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{
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return getSignalsForEvent(new Event(id)).length != 0;
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}
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/**
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* push(Event e)
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*
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* Provided an Event, `e`, this will enqueue the event
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* to
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*/
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public void push(Event e)
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{
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Queue matchedQueue = findQueue(e.id);
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if (matchedQueue)
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{
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/* Append to the queue */
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matchedQueue.add(e);
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}
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}
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/**
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* Creates a new queue with the given id
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* and then adds it
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*
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* @param id the id of the new queue to add
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* @throws EventyException if a queue with
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* the given id already exists
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*/
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public void addQueue(ulong id)
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{
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/* Create a new queue with the given id */
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Queue newQueue = new Queue(id);
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/* Lock the queue collection */
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queueLock.lock();
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/* If no such queue exists then add it (recursive mutex used) */
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if (!findQueue(id))
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{
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/* Add the queue */
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queues ~= newQueue;
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}
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else
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{
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throw new EventyException("Failure to add queue with ID already in use");
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}
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/* Unlock the queue collection */
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queueLock.unlock();
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}
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/**
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* Given an id, this will return
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* the Queue associated with said
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* id
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*
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* @param id the id of the Queue
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* @returns The Queue if found but
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* null otherwise
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*/
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public Queue findQueue(ulong id)
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{
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/* Lock the queue collection */
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queueLock.lock();
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/* Find the matching queue */
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Queue matchedQueue;
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foreach (Queue queue; queues)
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{
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if (queue.id == id)
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{
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matchedQueue = queue;
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break;
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}
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}
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/* Unlock the queue collection */
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queueLock.unlock();
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return matchedQueue;
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}
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/* TODO: Add coumentation */
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public ulong[] getTypes()
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{
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/* TODO: Implement me */
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return null;
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}
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/**
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* Checks if any of the queues in the event engine
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* have any pending events in them waiting dispatch
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*
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* Returns: <code>true</code> if there are pending events,
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* <code>false</code> otherwise
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*/
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public bool hasPendingEvents()
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{
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bool isPending = false;
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/* Lock the queues */
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queueLock.lock();
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foreach (Queue queue; queues)
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{
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if (queue.hasEvents())
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{
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isPending = true;
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break;
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}
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}
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/* Unlock the queues */
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queueLock.unlock();
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return isPending;
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}
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} |