Created
April 7, 2017 11:52
-
-
Save klimisa/c24bf9abae9958a325690f86e50a4fc3 to your computer and use it in GitHub Desktop.
Enhancing the frequency server
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
%% Based on code from | |
%% Erlang Programming | |
%% Francecso Cesarini and Simon Thompson | |
%% O'Reilly, 2008 | |
%% http://oreilly.com/catalog/9780596518189/ | |
%% http://www.erlangprogramming.org/ | |
%% (c) Francesco Cesarini and Simon Thompson | |
-module(frequency). | |
-export([start/0,allocate/0,deallocate/1,stop/0]). | |
-export([init/0]). | |
%% These are the start functions used to create and | |
%% initialize the server. | |
start() -> | |
register(frequency, | |
spawn(frequency, init, [])). | |
init() -> | |
Frequencies = {get_frequencies(), []}, | |
loop(Frequencies). | |
% Hard Coded | |
get_frequencies() -> [10,11,12,13,14,15]. | |
%% The Main Loop | |
loop(Frequencies) -> | |
timer:sleep(10000), | |
receive | |
{request, Pid, allocate} -> | |
{NewFrequencies, Reply} = allocate(Frequencies, Pid), | |
Pid ! {reply, Reply}, | |
loop(NewFrequencies); | |
{request, Pid , {deallocate, Freq}} -> | |
NewFrequencies = deallocate(Frequencies, Freq), | |
Pid ! {reply, ok}, | |
loop(NewFrequencies); | |
{request, Pid, stop} -> | |
Pid ! {reply, stopped} | |
end. | |
%% Functional interface | |
allocate() -> | |
frequency ! {request, self(), allocate}, | |
receive | |
{reply, Reply} -> Reply | |
after 1000 -> | |
clear() | |
end. | |
deallocate(Freq) -> | |
frequency ! {request, self(), {deallocate, Freq}}, | |
receive | |
{reply, Reply} -> Reply | |
after 1000 -> | |
clear() | |
end. | |
stop() -> | |
frequency ! {request, self(), stop}, | |
receive | |
{reply, Reply} -> Reply | |
end. | |
%% The Internal Help Functions used to allocate and | |
%% deallocate frequencies. | |
allocate({[], Allocated}, _Pid) -> | |
{{[], Allocated}, {error, no_frequency}}; | |
allocate({[Freq|Free], Allocated}, Pid) -> | |
{{Free, [{Freq, Pid}|Allocated]}, {ok, Freq}}. | |
deallocate({Free, Allocated}, Freq) -> | |
NewAllocated=lists:keydelete(Freq, 1, Allocated), | |
{[Freq|Free], NewAllocated}. | |
clear() -> | |
receive | |
_Msg -> | |
clear() | |
after 0 -> clear | |
end. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment