pooler/src/pooler_sup.erl

-module(pooler_sup).

-behaviour(supervisor).

-export([
    init/1,
    new_pool/1,
    rm_pool/1,
    pool_child_spec/1,
    start_link/0
]).

start_link() ->
    supervisor:start_link({local, ?MODULE}, ?MODULE, []).

init([]) ->
    %% a list of pool configs
    Config =
        case application:get_env(pooler, pools) of
            {ok, C} ->
                C;
            undefined ->
                []
        end,
    {MetricsApi, MetricsMod} = metrics_module(),
    MetricsConfig = [
        {metrics_mod, MetricsMod},
        {metrics_api, MetricsApi}
    ],
    Pools = [pooler_config:list_to_pool(MetricsConfig ++ L) || L <- Config],
    PoolSupSpecs = [pool_sup_spec(Pool) || Pool <- Pools],
    ets:new(pooler_config:group_table(), [set, public, named_table, {write_concurrency, true}]),
    {ok, {{one_for_one, 5, 60}, [starter_sup_spec() | PoolSupSpecs]}}.

%% @doc Create a new pool from proplist pool config `PoolConfig'. The
%% public API for this functionality is {@link pooler:new_pool/1}.
new_pool(PoolConfig) ->
    Spec = pool_child_spec(PoolConfig),
    supervisor:start_child(?MODULE, Spec).

%% @doc Create a child spec for new pool from proplist pool config `PoolConfig'. The
%% public API for this functionality is {@link pooler:pool_child_spec/1}.
pool_child_spec(PoolConfig) ->
    {MetricsApi, MetricsMod} = metrics_module(),
    NewPool = pooler_config:list_to_pool(
        [
            {metrics_mod, MetricsMod},
            {metrics_api, MetricsApi}
        ] ++ PoolConfig
    ),
    pool_sup_spec(NewPool).

%% @doc Shutdown the named pool.
rm_pool(Name) ->
    SupName = pool_sup_name(Name),
    case supervisor:terminate_child(?MODULE, SupName) of
        {error, not_found} ->
            ok;
        ok ->
            supervisor:delete_child(?MODULE, SupName);
        Error ->
            Error
    end.

starter_sup_spec() ->
    {pooler_starter_sup, {pooler_starter_sup, start_link, []}, transient, 5000, supervisor, [pooler_starter_sup]}.

pool_sup_spec(Pool) ->
    SupName = pool_sup_name(pooler_config:get_name(Pool)),
    {SupName, {pooler_pool_sup, start_link, [Pool]}, transient, 5000, supervisor, [pooler_pool_sup]}.

pool_sup_name(Name) ->
    list_to_atom("pooler_" ++ atom_to_list(Name) ++ "_pool_sup").

metrics_module() ->
    case application:get_env(pooler, metrics_module) of
        {ok, Mod} ->
            case application:get_env(pooler, metrics_api) of
                {ok, exometer} ->
                    {exometer, Mod};
                % folsom is the default
                _V ->
                    {folsom, Mod}
            end;
        undefined ->
            {folsom, pooler_no_metrics}
    end.