@OverrideMustInvoke
@Activate
protected void activate(Map<String, Object> props) {
// configuring the buffer
Integer bufferSize = Integer.valueOf(200);
if (props.containsKey(BUFFER_SIZE)) {
bufferSize = (Integer) props.get(BUFFER_SIZE);
}
this.fifo = BufferUtils.synchronizedBuffer(new CircularFifoBuffer(bufferSize));
}
/** * This class manages worker threads. Its main responsibility is to create / remove worker threads * and distribute tasks among them. This is an effort to hide complexity of threading logic from the * rest of toolkit. Worker manager receives processing requests from external tools and assigns them * to free worker threads. If there's no free worker thread left manager puts item in queue. When * worker thread finishes its job it asks for next job using <code>JobSource</code> callback * interface. If there is at least one job in queue manager assigns it to worker. If not then worker * goes to rest until manager has something to assign. * * <p>Worker manager uses instance of <code>WorkerThreadFactoryIF</code> specified on creation to * create new worker threads. Client application should use it to create and initialize * task-specific workers, which will be started as independent threads. * * <p>It's possible to tune number of threads working at a given time using <code> * setWorkerThreads(int)</code> method call. Right after the number of threads will change manager * will stop unnecessary threads (only after running task completion) or create new worker threads. * * @author Aleksey Gureev ([email protected]) */ public class WorkersManager { private static final int DEFAULT_WORKER_THREADS = 5; private static final int DEFAULT_QUEUE_LIMIT = 25; private List<WorkerThread> workers = new ArrayList<>(); // This code intentionally uses deprecated classes! Old commons library was 150 Kb and // current is 550 Kb. Many applications (including BlogBridge) will be enforced to replace // small lib with giantic new one if we start using new classes instead these. // When support of these will be finished, please replace: // PriorityQueue -> Buffer // SynchronizedPriorityQueue -> SynchronizedBuffer // BinaryHeap -> PriorityBuffer private Buffer queue = BufferUtils.blockingBuffer(new BinaryHeap(DEFAULT_QUEUE_LIMIT, new PriorityComparator())); private WorkerThreadFactoryIF workerThreadsFactory; /** * Creates worker manager with default number of worker threads. * * @param factory worker threads factory. */ public WorkersManager(WorkerThreadFactoryIF factory) { this(factory, DEFAULT_WORKER_THREADS); } /** * Creates worker manager. * * @param factory worker threads factory. * @param workerThreads number of worker threads. */ public WorkersManager(WorkerThreadFactoryIF factory, int workerThreads) { this.workerThreadsFactory = factory; // Protect ourselves from incorrect parameters. if (workerThreads <= 0) { workerThreads = DEFAULT_WORKER_THREADS; } setWorkerThreads(workerThreads); } /** * Changes number of worker threads. * * @param count new number of worker threads. */ public final void setWorkerThreads(int count) { synchronized (workers) { // If we have more than specified number of working threads then terminate unwanted. int curWorkerThreads = workers.size(); for (int i = curWorkerThreads - 1; i >= count; i--) { final WorkerThread worker = workers.get(i); worker.terminate(); workers.remove(worker); } // If we have less than specified number of thread then add some. curWorkerThreads = workers.size(); for (int i = curWorkerThreads; i < count; i++) { // Create new worker using custom factory. final WorkerThread worker = workerThreadsFactory.create(); worker.setQueue(queue); // Add worker to the list and start. workers.add(worker); worker.start(); } } } /** Terminates all worker threads. */ public final void terminateAll() { synchronized (workers) { int count = workers.size(); for (int i = count - 1; i >= 0; i--) { workers.get(i).terminate(); workers.remove(i); } } } /** * Put the record in processing. * * @param record record to process. */ public final void process(ChannelRecord record) { if (!isInProcess(record)) { putRecordInQueue(record); } } /** * Checks if the channel is not currently in processing. * * @param record channel record. * @return TRUE if is in processing. */ private boolean isInProcess(ChannelRecord record) { boolean found = false; synchronized (workers) { Iterator<WorkerThread> i = workers.iterator(); while (!found && i.hasNext()) { WorkerThread worker = i.next(); found = worker.getChannelInProcess() == record; } } return found; } /** * Put task in processing queue. During putting the task algorythm analyzes the priority of * insertion and evaluates index of new item in queue. * * @param record record to put in queue. */ @SuppressWarnings("unchecked") private void putRecordInQueue(ChannelRecord record) { queue.add(record); } }
