Sending notifications between threads

Mutexes are synchronization primitives that can be used to protect access to shared data. However, the standard library provides a synchronization primitive called a condition variable that enables a thread to signal to others that a certain condition has occurred. The thread or the threads that are waiting on the condition variable are blocked until the condition variable is signaled or until a timeout or a spurious wakeup occurs. In this recipe, we will see how to use condition variables to send notifications between thread-producing data and thread-consuming data.

Getting ready

For this recipe, you need to be familiar with threads, mutexes, and locks. Condition variables are available in the std namespace in the <condition_variable> header. 

How to do it...

Use the following pattern for synchronizing threads with notifications on condition variables:

1. Define a condition variable (in the appropriate context):

        std::condition_variable cv;

2. Define...