I have 2 questions :

Q1) Can i implement an asynchronous timer in a single threaded application i.e i want a functionality like this.

```
....
Timer mytimer(5,timeOutHandler)

.... //this thread is doing some other task

...
and after 5 seconds, the timeOutHandler function is invoked.

```

As far as i can think this cannot be done for a single threaded application(correct me if i am wrong). I don't know if it can be done using select as the demultiplexer, but even if select could be used, the event loop would require one thread ? Isn't it ?

I also want to know whether i can implement a timer(not timeout) using select.
Select only waits on set of file descriptors, but i want to have a list of timers in ascending order of their expiry timeouts and want select to tell me when the first timer expires and so on. So the question boils down to can a asynchronous timer be implemented using select/poll or some other event demultiplexer ?

Q2) Now lets come to my second question. **This is my main question.**
Now i am using a dedicated thread for checking timeouts i.e i have a min heap of timers(expiry times) and this thread sleeps till the first timer expires and then invokes the callback.
i.e code looks something like this

1. lock the mutex
2. check the time of the first timer
3. condition timed wait for that time(and wake up if some other thread inserts a timer with expiry time less than the first timer) Condition wait unlocks the lock.
4. After the condition wait ends we have the lock. So unlock it, remove the timer from the heap and invoke the callback function.
5. go to 1

I want the time complexity of such asynchronous timer. From what i see 

1. Insertion is lg(n)
2. Expiry is lg(n)
3. Cancellation

:( this is what makes me dizzy ) the problem is that i have a min heap of timers according to their times and when i insert a timer i get a unique id. So when i need to cancel the timer, i need to provide this timer id and searching for this timer id in the heap would take in the worst case O(n)

Am i wrong ?

Can cancellation be done in O(lg n)

Please do take care of some multithreading issues. I would elaborate on what i mean by my previous sentence once i get some responses.