Add src/hk_browser_session_sup.erl

src/hk_browser_session_sup.erl

@@ -0,0 +1,47 @@
+%%%-------------------------------------------------------------------
+%%% @doc HK-BROWSER :: supervises one `hk_browser_session' child per
+%%% active session.
+%%%
+%%% Sessions are `simple_one_for_one', `transient': a session that
+%%% terminates normally (an explicit `close_session') is not
+%%% restarted, but a session whose Chromium process crashed
+%%% (`hk_browser_session' stops with an abnormal reason, see its
+%%% `handle_info' clause for `exit_status') *is* restarted with the
+%%% same start arguments -- a fresh Chromium process comes up under
+%%% the same `session_id'. This is the concrete demonstration the
+%%% spec asks for: one browser session crashing never takes down
+%%% `hk_agent_sup', `hk_search_sup', or any other session -- and,
+%%% because this pool is its own supervisor nested under
+%%% `hk_browser_sup' rather than sharing a supervisor with the
+%%% session registry, restart storms in the session pool cannot
+%%% (via `hk_browser_sup''s own intensity/period) take the registry
+%%% down with them either.
+%%% @end
+%%%-------------------------------------------------------------------
+-module(hk_browser_session_sup).
+-behaviour(supervisor).
+
+-export([start_link/0, init/1, start_session/1]).
+
+start_link() ->
+    hk_sup_util:start_link_retry(
+        fun() -> supervisor:start_link({local, ?MODULE}, ?MODULE, []) end).
+
+%% @doc Start a new supervised browser session. `Args' is the map
+%% `hk_browser_session:init/1' expects (`session_id', `owner_agent_id',
+%% `profile').
+-spec start_session(map()) -> {ok, pid()} | {error, term()}.
+start_session(Args) ->
+    supervisor:start_child(?MODULE, [Args]).
+
+init([]) ->
+    SupFlags = #{strategy => simple_one_for_one, intensity => 10, period => 60},
+    Children = [
+        #{id => hk_browser_session,
+          start => {hk_browser_session, start_link, []},
+          restart => transient,
+          shutdown => 10000,
+          type => worker,
+          modules => [hk_browser_session]}
+    ],
+    {ok, {SupFlags, Children}}.