/afs/cern.ch/work/a/aaltunda/public/www/CMSSW_5_3_14/src/EventFilter/ResourceBroker/src/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_);
}