sleeping_threads_list.cpp

#include "sleeping_threads_list.h"

SleepingThreadsList::SleepingThreadsList() {
}


/*
 * Description: This method adds a new element to the list of sleeping
 * threads. It gets the thread's id, and the time when it needs to wake up.
 * The wakeup_tv is a struct timeval (as specified in <sys/time.h>) which
 * contains the number of seconds and microseconds since the Epoch.
 * The method keeps the list sorted by the threads' wake up time.
*/
void SleepingThreadsList::add(int thread_id, timeval wakeup_tv) {

	wake_up_info new_thread;
	new_thread.id = thread_id;
	new_thread.awaken_tv = wakeup_tv;

	if(sleeping_threads.empty()){
		sleeping_threads.push_front(new_thread);
	} 
	else {
		for (deque<wake_up_info>::iterator it = sleeping_threads.begin(); it != sleeping_threads.end(); ++it){
			if(timercmp(&it->awaken_tv, &wakeup_tv, >=)){
				sleeping_threads.insert(it, new_thread);
				return;
			}
		}
		sleeping_threads.push_back(new_thread);
	}
}

/*
 * Description: This method removes the thread at the top of this list.
 * If the list is empty, it does nothing.
*/
void SleepingThreadsList::pop() {
	if(!sleeping_threads.empty())
		sleeping_threads.pop_front();
}

/*
 * Description: This method returns the information about the thread (id and time it needs to wake up)
 * at the top of this list without removing it from the list.
 * If the list is empty, it returns null.
*/
wake_up_info* SleepingThreadsList::peek(){
	if (sleeping_threads.empty())
		return nullptr;
	return &sleeping_threads.at(0);
}

/**
     * erase specific element in deque.
     * @param id id of element
     */
void SleepingThreadsList::erase(int id){
    for (auto it = sleeping_threads.begin(); it != sleeping_threads.end(); it++){
        if (it->id == id){
            sleeping_threads.erase(it);
            break;
        }
    }
}