In the preceding code, we see a prime example of the way an RLock works within our single-threaded program. We have defined a class called myWorker, which features four functions, these are the constructors which initialize our Rlock and our a and b variables.
We then go on to define two functions that both modify a and b respectively. These both first acquire the classes Rlock using the with statement, and then perform any necessary modifications to our internal variables.
Finally, we have our modifyBoth function, which performs the initial Rlock acquisition before calling the modifyA and modifyB functions.
At each step of the way, we print out the state of our Rlock. We see that after it has been acquired within the modifyBoth function, its owner is set to the main thread, and its count is incremented to one. When we next call modifyA, the Rlocks counter is again incremented by one, and the necessary calculations are made before modifyA then releases the Rlock. Upon the modifyA function release of the Rlock, we see the counter decrement to 1 before being immediately incremented to 2 again by our modifyB function.
Finally, when modifyB completes its execution, it releases the Rlock, and then, so does our modifyBoth function. When we do a final print out of our Rlock object, we see that the owner has been set to 0, and that our count has also been set to 0. It is only at this point in time that another thread could, in theory, obtain this lock.
