The following pseudo code represents access by a single producer and a single consumer to a shared, N-slot, cyclic buffer, items is a semaphore initialized to 0. spaces is a semaphore initialized to the buffer size, N.

producer repeats consumer repeats

produce data WAIT(items)

WAIT(spaces) remove data from buffer

insert data in buffer SIGNAL(spaces)

SINGAL(items) consume data

(a) Explain in detail how the semaphores are being used to synchronize concurrency control.

(b) Extend the code fragments for multiple producers and multiple consumers, explaining how your solution implements concurrency control.