priority

Priority

Reading material

• Learn You Some Erlang: More On Multiprocessing
• Erlang Manual: processes
• Erlang Manual: receive expression

Exercise

For this exercise we will process messages according to priorities from the erlang message box without using any data structure.
Messages with priority vip should be processed as soon as they enter the priority_loop. Carefully consider how messages are processed by a receive block, and how you can combine more than one block to match clauses in a certain order. Hints on how to solve this exercise found here.

You will write 3 functions for the priority module:

• start/0: This will create the process that will receive the messages (using priority_loop/1) and return its PID.
• get_messages/1: Given the PID will return all the messages stored in the receive loop state.
• priority_loop/1: This function will hold a list of messages received and read incoming messages. Remeber, messages need to be read according to their priority.

Notes:

• Messages are of the form {Priority, Message}.
• Priority is either vip or normal.
• priority_loop/1 may receive other things to perform certain actions needed.

You can check your answer by doing make concurrent/priority from the root directory of your erlings folder. If you wish you can also check our proposed solution.