Critical Patterns
OTP GenServer (REQUIRED)
-module(counter).
-behaviour(gen_server).
-export([start_link/0, increment/0, get/0]).
-export([init/1, handle_call/3, handle_cast/2]).
start_link() ->
gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
init([]) -> {ok, 0}.
handle_call(get, _From, State) ->
{reply, State, State}.
handle_cast(increment, State) ->
{noreply, State + 1}.
Supervisor (REQUIRED)
-module(my_sup).
-behaviour(supervisor).
-export([start_link/0, init/1]).
start_link() ->
supervisor:start_link({local, ?MODULE}, ?MODULE, []).
init([]) ->
SupFlags = #{strategy => one_for_one, intensity => 5, period => 10},
Children = [
#{id => worker, start => {my_worker, start_link, []}}
],
{ok, {SupFlags, Children}}.
Decision Tree
Need request/response? → Use gen_server call
Need fire-and-forget? → Use gen_server cast
Need supervision? → Use supervisor behavior
Need state machine? → Use gen_statem
Need event handling? → Use gen_event
Commands
erl # Start REPL
erlc module.erl # Compile
rebar3 compile # Build project
rebar3 shell # Interactive shell
Resources
- Concurrent Programming: concurrent-programming.md
- Fault Tolerance: fault-tolerance.md
- OTP Patterns: otp-patterns.md
odjaramillo