CommandQueue.cc

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//
// CommandQueue.cc
// -------
//
//  Created on: Dec 13, 2011
//                                          Andrei Spataru : aspataru@cern.ch

#include "EventFilter/ResourceBroker/interface/CommandQueue.h"

#include <iostream>

using namespace evf::rb_statemachine;

using std::cout;
using std::endl;

CommandQueue::CommandQueue() {
    sem_init(&lock_, 0, 1);
    // commands semaphore initialized to 0
    // no commands on the queue initially
    sem_init(&commandsSem_, 0, 0);
}

CommandQueue::~CommandQueue() {
}

void CommandQueue::enqEvent(EventPtr evType) {
    lock();
    eventQueue_.push(evType);
    sem_post(&commandsSem_);
    unlock();
}

EventPtr CommandQueue::deqEvent() {
    sem_wait(&commandsSem_);
    EventPtr eventPtr;

    lock();
    eventPtr = eventQueue_.front();
    eventQueue_.pop();
    unlock();

    return eventPtr;
}

void CommandQueue::lock() {
    while (0 != sem_wait(&lock_)) {
        cout << "SMEventScheduler: cannot obtain lock!" << endl;
        sleep(1);
    }
}

void CommandQueue::unlock() {
    sem_post(&lock_);
}