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-module(mod_global_distrib_outgoing_conns_sup). |
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-behaviour(supervisor). |
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-include("mongoose.hrl"). |
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-export([start_link/0, init/1]). |
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-export([add_server/1, get_connection/1, ensure_server_started/1]). |
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-ignore_xref([add_server/1, start_link/0]). |
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%%-------------------------------------------------------------------- |
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%% API |
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%%-------------------------------------------------------------------- |
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-spec start_link() -> {ok, pid()} | {error, any()}. |
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start_link() -> |
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supervisor:start_link({local, ?MODULE}, ?MODULE, []). |
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-spec add_server(Server :: jid:lserver()) -> ok | {error, any()}. |
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add_server(Server) -> |
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SupName = mod_global_distrib_utils:server_to_sup_name(Server), |
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ServerSupSpec = #{ |
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id => SupName, |
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start => {mod_global_distrib_server_sup, start_link, [Server]}, |
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restart => temporary, |
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shutdown => 5000, |
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type => supervisor, |
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modules => dynamic |
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}, |
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case supervisor:start_child(?MODULE, ServerSupSpec) of |
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{ok, Pid} -> |
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?LOG_INFO(#{what => gd_outgoing_conn_started, |
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:-( |
server => Server, gd_pid => Pid}), |
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ok; |
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{error, {already_started, Pid}} -> |
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?LOG_INFO(#{what => gd_outgoing_conn_already_started, |
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:-( |
server => Server, gd_pid => Pid}), |
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ok; |
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Error -> |
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:-( |
?LOG_ERROR(#{what => gd_outgoing_conn_start_failed, |
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:-( |
server => Server, reason => Error}), |
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:-( |
Error |
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end. |
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%% Call to get_connection blocks until a connection is available. |
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%% Currently the timeout is infinity. |
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%% This function is safe for concurrent calls if the outgoing pool is not present yet. |
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%% The first caller will be the one initiating pool startup and the others are blocked |
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%% in the meantime; then, everyone will use the pool initiated by the first caller. |
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%% TODO: Revise negative cases for this function. |
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-spec get_connection(Server :: jid:lserver()) -> pid(). |
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get_connection(Server) -> |
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get_connection(Server, 5). |
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-spec get_connection(Server :: jid:lserver(), RetriesLeft :: non_neg_integer()) -> |
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pid() | no_return(). |
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get_connection(Server, 0) -> |
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?LOG_ERROR(#{what => gd_cannot_acquire_outgoing_connection, server => Server}), |
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throw({error, {cannot_acquire_outgoing_connection, Server}}); |
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get_connection(Server, RetriesLeft) -> |
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case mod_global_distrib_server_sup:get_connection(Server) of |
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{error, not_available} -> |
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%% add_server is a synchronous call that, if succeeds, |
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%% returns after the outgoing conn layer is ready, |
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%% so we may retry immediately |
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add_server(Server), |
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get_connection(Server, RetriesLeft - 1); |
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{ok, Pid} -> |
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Pid |
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end. |
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-spec ensure_server_started(Server :: jid:lserver()) -> ok | {error, any()}. |
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ensure_server_started(Server) -> |
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case mod_global_distrib_server_sup:is_available(Server) of |
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false -> add_server(Server); |
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true -> ok |
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end. |
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%%-------------------------------------------------------------------- |
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%% supervisor callback |
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%%-------------------------------------------------------------------- |
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init(_) -> |
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SupFlags = #{ strategy => one_for_one, intensity => 5, period => 5 }, |
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{ok, {SupFlags, []}}. |