Awesome
Load-Balancer
Process for spreading Erlang messages to Erlang process(es) or port(s).
Download
~ $ git clone https://github.com/Pouriya-Jahanbakhsh/lb.git
Compile
~ $ cd lb
rebar
~/lb $ rebar compile
==> lb (compile)
Compiled src/lb.erl
rebar3
~/lb $ rebar3 compile
===> Verifying dependencies...
===> Compiling lb
How to use?
If you need a real example, I recommend to see this post.
You need to start a Load-Balancer and your process which wants to receive Erlang messages from Load-Balancer should subscribe to Load-Balancer:
Erlang/OTP 19 [erts-8.3] [source-d5c06c6] [64-bit] [smp:8:8] [async-threads:0] [hipe] [kernel-poll:false]
Eshell V8.3 (abort with ^G)
%% you can use start_link/1 & start_link/2, read the doc
1> {ok, LB} = lb:start_link().
{ok,<0.106.0>}
%% subscribe caller (self()) for receiving messages.
2> lb:subscribe(LB).
ok
%% subscribe self twic
3> lb:subscribe(LB, erlang:self()).
ok
%% one of subscribers will receive message foo, request is synchronous.
4> lb:send_sync(LB, foo, one_for_one).
ok
5> flush().
Shell got foo
ok
%% next subscriber will receive message "bar", request is asynchronous.
6> lb:send_async(LB, "bar", one_for_one).
ok
7> flush().
Shell got "bar"
ok
%% all subscribers will receive message <<"baz">>.
8> lb:send_sync(LB, <<"baz">>, one_for_all).
ok
9> flush().
Shell got <<"baz">>
Shell got <<"baz">>
ok
%% fetching all available subscribers.
%% You can use lb:get_object(LB) for fetching one subscriber, in next call you will get next subscriber and so on.
10> lb:get_objects(LB).
[<0.103.0>,<0.103.0>]
%% unsubscribe caller (self())
11> lb:unsubscribe(LB).
ok
12> lb:get_objects(LB).
[<0.103.0>]
%% unsubscribe specific pid or port
15> lb:unsubscribe(LB, erlang:self()).
ok
16> lb:get_object(LB).
{error,empty}
17> lb:send_sync(LB, oops, one_for_one).
{error,{empty,[{send_type,one_for_one},{message,oops}]}}
Debugging
Erlang/OTP 19 [erts-8.3] [source-d5c06c6] [64-bit] [smp:8:8] [async-threads:0] [hipe] [kernel-poll:false]
Eshell V8.3 (abort with ^G)
1> lb:start_link({local, load_balancer}, [{debug, [trace]}]).
{ok,<0.105.0>}
2> lb:subscribe(load_balancer).
*DBG* lb "load_balancer" got subscribe for "<0.102.0>" from "<0.102.0>" with tag "#Ref<0.0.3.875>"
*DBG* lb "load_balancer" sent reply "ok" to "<0.102.0>" with tag "#Ref<0.0.3.875>"
ok
3> lb:send_sync(load_balancer, hello, one_for_one).
*DBG* lb "load_balancer" got synchronous "one_for_one" message "hello" from "<0.102.0>" with tag "#Ref<0.0.3.883>"
*DBG* lb "load_balancer" sent message "hello" to "<0.102.0>"
*DBG* lb "load_balancer" sent reply "ok" to "<0.102.0>" with tag "#Ref<0.0.3.883>"
ok
4> lb:subscribe(load_balancer).
*DBG* lb "load_balancer" got subscribe for "<0.102.0>" from "<0.102.0>" with tag "#Ref<0.0.3.891>"
*DBG* lb "load_balancer" sent reply "ok" to "<0.102.0>" with tag "#Ref<0.0.3.891>"
ok
5> lb:send_sync(load_balancer, hi, one_for_all).
*DBG* lb "load_balancer" got synchronous "one_for_all" message "hi" from "<0.102.0>" with tag "#Ref<0.0.3.898>"
*DBG* lb "load_balancer" sent message "hi" to "<0.102.0>"
*DBG* lb "load_balancer" sent message "hi" to "<0.102.0>"
*DBG* lb "load_balancer" sent reply "ok" to "<0.102.0>" with tag "#Ref<0.0.3.898>"
ok
6> lb:get_object(load_balancer).
*DBG* lb "load_balancer" got request for getting one object from "<0.102.0>" with tag "#Ref<0.0.3.907>"
*DBG* lb "load_balancer" sent reply "{ok,<0.102.0>}" to "<0.102.0>" with tag "#Ref<0.0.3.907>"
{ok,<0.102.0>}
7> lb:get_objects(load_balancer).
*DBG* lb "load_balancer" got request for getting all objects from "<0.102.0>" with tag "#Ref<0.0.3.914>"
*DBG* lb "load_balancer" sent reply "[<0.102.0>,<0.102.0>]" to "<0.102.0>" with tag "#Ref<0.0.3.914>"
[<0.102.0>,<0.102.0>]
8> lb:unsubscribe(load_balancer).
*DBG* lb "load_balancer" got unsubscribe for "<0.102.0>" from "<0.102.0>" with tag "#Ref<0.0.3.921>"
*DBG* lb "load_balancer" sent reply "ok" to "<0.102.0>" with tag "#Ref<0.0.3.921>"
ok
License
BSD 3-Clause
Links
Github
This documentation is availible in http://docs.codefather.org/lb too.