README.md

Erlang Traffic Control

A traffic control library written in Erlang allows you to control the rate of flow using the token bucket algorithm.

Notice

1. The project has been stable for two years, running reliably in our system.
2. I wrote this project when I was an Erlang learner, so the code style may not be optimal...

Two Ways to Use It

The library can be used in either blocking or non-blocking mode. You can find a demonstration in src/demo_worker.erl.

Blocking Demo

start(Pid) ->
start(1000000, Pid).

start(N, Pid) ->
    spawn(fun() ->
        for(N, fun() -> tokens_queue:request_tokens(Pid) end)
    end).

for (0, _Func) ->
    ok;
for (N, Func) ->
    Func(),
    for (N - 1, Func).

Running the Blocking Demo

{ok, Pid} = tokens_queue_manager:new_tokens_queue(100),
demo_worker:start(Pid).

%% show status
tokens_queue:infos(Pid).

Non-Blocking Demo

start_with_callback(Pid) ->
spawn(fun() ->
        Self = self(),
        tokens_queue:set_callback_function(Pid, fun() -> Self ! wakeup end),
        tokens_queue:request_tokens_cast(Pid),
        loop(Pid)
    end).

loop(Pid) ->
    receive
        wakeup ->
            tokens_queue:request_tokens_cast(Pid),
            loop(Pid);
        _Other ->
            io:format("I am fine!~n"),
            loop(Pid)
    end.

Running the Non-Blocking Demo

{ok, Pid} = tokens_queue_manager:new_tokens_queue(100),
UserPid = demo_worker:start_with_callback(Pid).

%% show status
tokens_queue:infos(Pid).

Unified MySQL Platform

This library is used in the proxy module of Unified MySQL Platform by Taobao to control SQL queries per second.

TODO

• Add a comprehensive tutorial.
• Add a license file, preferably a BSD-like license.