farhadi / priority_receive

Prioritized selective receive for Elixir

PriorityReceive

In Erlang/Elixir we can use selective receives to receive higher priority messages first, but it is not possible to receive messages with different priority levels with a single call to receive. Actually to select a message, erlang matches that message against all clauses before going to the next message. Therefore selecting messages with different priorities, needs nested receives. And to avoid deadlocks you have to put all higher priority match clauses in nested lower priority receives.

This module provides priority_receive/1 macro which has the same syntax as receive/1 with the ability to select higher priority messages first, based on given clauses order. So you can receive messages with different priorities with a single call to priority_receive/1. Note that to select a message, all messages in the queue will be scanned and matched against each clause before going to the next clause.

Installation

The package can be installed by adding priority_receive to your list of dependencies in mix.exs:

def deps do
  [
    {:priority_receive, "~> 0.1.0"}
  ]
end

Example usage:

import PriorityReceive

priority_receive do
  {:high, msg} -> process_msg(msg)
  {:normal, msg} -> process_msg(msg)
  {:low, msg} -> process_msg(msg)
after
  1000 -> :timeout
end