@@ -24,4 +25,39 @@ In the template you have an implementation of a program that counts the prime nu
***Note:*** Be aware, that each thread must only access his entry of the `results` array and that the `main`thread must only access those results after the threads have been joined.
What speedup can you achieve?
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What speedup can you achieve?
# 2. TESTAT 3: `BoundedQueue` with Timed Operations
In this exercise you will wrap your `BoundedBuffer` in a thread-safe `BoundedQueue`.
Please form groups of 3 students for testat hand-in:
* Send an email to [Felix Morgner](mailto:felix.morgner@hsr.ch)
Your `BoundedQueue` shall provide the following functionality:
*`push(T)` - Both copy and move / or forwarding. This operation blocks if the `BoundedQueue` is full.
*`T pop()` - Always returns the popped value. This operation blocks if the `BoundedQueue`is empty.
*`bool try_push(T const &)` - Tries to put a `T` into the queue. If the queue is not full and put operation has been successful it returns `true`, otherwise it returns `false`.
*`bool try_pop(T&)` - Tries to pop a `T` from the queue. If the queue is not empty and the pop operation has been suffessful it returns `true` and the popped value is in the out parameter, otherwise it returns `false`.
*`size()`, `empty()` and `full()`
* copy/move operations
*`bool try_push_for(T const &, std::chrono::duration)` - The same as `try_push`, but if the operation would block longer than the given duration it returns `false` too. The operation is not performed then.
*`bool try_pop_for(T &, std::chrono::duration)` - The same as `try_pop`, but if the operation would block longer than the given duration it returns `false` too. The operation is not performed then.
In order to avoid duplicating the whole implementation of `BoundedBuffer` you should write `BoundedQueue` as a wrapper for `BoundedBuffer` and delegate the functionality of the queue to it.
* Use strategized locking for your `BoundedQueue`. The used mutex and condition variable types shall be template parameters. Use `std::mutex` and `std::condition_variable` as default arguments.
* Make sure that exceptions do not keep the mutex locked. Use an appropriate standard wrapper type.
## b. Theory Questions
* Why does it not make sense to use `front()` and `back()` member functions for a thread-safe container?
* Why is it difficult to provide iterators for a thread-safe container?
* Why is `BoundedQueue::pop()` returning a `T` by value compared to the `void` return type of `BoundedBuffer::pop()`.
