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%%% @doc Runs a process that holds a rebar3 state and can be used
%%% to statefully maintain loaded project state into a running VM.
-module(rebar_agent).
-export([start_link/1, do/1, do/2]).
-export([init/1,
handle_call/3, handle_cast/2, handle_info/2,
code_change/3, terminate/2]).
-include("rebar.hrl").
-record(state, {state,
cwd,
show_warning=true}).
%% @doc boots an agent server; requires a full rebar3 state already.
%% By default (within rebar3), this isn't called; `rebar_prv_shell'
%% enters and transforms into this module
-spec start_link(rebar_state:t()) -> {ok, pid()}.
start_link(State) ->
gen_server:start_link({local, ?MODULE}, ?MODULE, State, []).
%% @doc runs a given command in the agent's context.
-spec do(atom()) -> ok | {error, term()}.
do(Command) when is_atom(Command) ->
gen_server:call(?MODULE, {cmd, Command}, infinity).
%% @doc runs a given command in the agent's context, under a given
%% namespace.
-spec do(atom(), atom()) -> ok | {error, term()}.
do(Namespace, Command) when is_atom(Namespace), is_atom(Command) ->
gen_server:call(?MODULE, {cmd, Namespace, Command}, infinity).
%%%%%%%%%%%%%%%%%
%%% CALLBACKS %%%
%%%%%%%%%%%%%%%%%
%% @private
init(State) ->
Cwd = rebar_dir:get_cwd(),
{ok, #state{state=State, cwd=Cwd}}.
%% @private
handle_call({cmd, Command}, _From, State=#state{state=RState, cwd=Cwd}) ->
MidState = maybe_show_warning(State),
{Res, NewRState} = run(default, Command, RState, Cwd),
{reply, Res, MidState#state{state=NewRState}, hibernate};
handle_call({cmd, Namespace, Command}, _From, State = #state{state=RState, cwd=Cwd}) ->
MidState = maybe_show_warning(State),
{Res, NewRState} = run(Namespace, Command, RState, Cwd),
{reply, Res, MidState#state{state=NewRState}, hibernate};
handle_call(_Call, _From, State) ->
{noreply, State}.
%% @private
handle_cast(_Cast, State) ->
{noreply, State}.
%% @private
handle_info(_Info, State) ->
{noreply, State}.
%% @private
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
%% @private
terminate(_Reason, _State) ->
ok.
%%%%%%%%%%%%%%%
%%% PRIVATE %%%
%%%%%%%%%%%%%%%
%% @private runs the actual command and maintains the state changes
-spec run(atom(), atom(), rebar_state:t(), file:filename()) ->
{ok, rebar_state:t()} | {{error, term()}, rebar_state:t()}.
run(Namespace, Command, RState, Cwd) ->
try
case rebar_dir:get_cwd() of
Cwd ->
Args = [atom_to_list(Namespace), atom_to_list(Command)],
CmdState0 = refresh_state(RState, Cwd),
CmdState1 = rebar_state:set(CmdState0, task, atom_to_list(Command)),
CmdState = rebar_state:set(CmdState1, caller, api),
case rebar3:run(CmdState, Args) of
{ok, TmpState} ->
refresh_paths(TmpState),
{ok, CmdState};
{error, Err} when is_list(Err) ->
refresh_paths(CmdState),
{{error, lists:flatten(Err)}, CmdState};
{error, Err} ->
refresh_paths(CmdState),
{{error, Err}, CmdState}
end;
_ ->
{{error, cwd_changed}, RState}
end
catch
Type:Reason ->
?DEBUG("Agent Stacktrace: ~p", [erlang:get_stacktrace()]),
{{error, {Type, Reason}}, RState}
end.
%% @private function to display a warning for the feature only once
-spec maybe_show_warning(#state{}) -> #state{}.
maybe_show_warning(S=#state{show_warning=true}) ->
?WARN("This feature is experimental and may be modified or removed at any time.", []),
S#state{show_warning=false};
maybe_show_warning(State) ->
State.
%% @private based on a rebar3 state term, reload paths in a way
%% that makes sense.
-spec refresh_paths(rebar_state:t()) -> ok.
refresh_paths(RState) ->
ToRefresh = (rebar_state:code_paths(RState, all_deps)
++ [filename:join([rebar_app_info:out_dir(App), "test"])
|| App <- rebar_state:project_apps(RState)]
%% make sure to never reload self; halt()s the VM
) -- [filename:dirname(code:which(?MODULE))],
%% Modules from apps we can't reload without breaking functionality
Blacklist = [ec_cmd_log, providers, cf, cth_readable],
%% Similar to rebar_utils:update_code/1, but also forces a reload
%% of used modules. Also forces to reload all of ebin/ instead
%% of just the modules in the .app file, because 'extra_src_dirs'
%% allows to load and compile files that are not to be kept
%% in the app file.
lists:foreach(fun(Path) ->
Name = filename:basename(Path, "/ebin"),
Files = filelib:wildcard(filename:join([Path, "*.beam"])),
Modules = [list_to_atom(filename:basename(F, ".beam"))
|| F <- Files],
App = list_to_atom(Name),
application:load(App),
case application:get_key(App, modules) of
undefined ->
code:add_patha(Path),
ok;
{ok, Mods} ->
case {length(Mods), length(Mods -- Blacklist)} of
{X,X} ->
?DEBUG("reloading ~p from ~s", [Modules, Path]),
code:replace_path(App, Path),
reload_modules(Modules);
{_,_} ->
?DEBUG("skipping app ~p, stable copy required", [App])
end
end
end, ToRefresh).
%% @private from a disk config, reload and reapply with the current
%% profiles; used to find changes in the config from a prior run.
-spec refresh_state(rebar_state:t(), file:filename()) -> rebar_state:t().
refresh_state(RState, _Dir) ->
lists:foldl(
fun(F, State) -> F(State) end,
rebar3:init_config(),
[fun(S) -> rebar_state:apply_profiles(S, rebar_state:current_profiles(RState)) end]
).
%% @private takes a list of modules and reloads them
-spec reload_modules([module()]) -> term().
reload_modules([]) -> noop;
reload_modules(Modules) ->
reload_modules(Modules, erlang:function_exported(code, prepare_loading, 1)).
%% @private reloading modules, when there are modules to actually reload
reload_modules(Modules, true) ->
%% OTP 19 and later -- use atomic loading and ignore unloadable mods
case code:prepare_loading(Modules) of
{ok, Prepared} ->
[code:purge(M) || M <- Modules],
code:finish_loading(Prepared);
{error, ModRsns} ->
Blacklist =
lists:foldr(fun({ModError, Error}, Acc) ->
case Error of
% perhaps cover other cases of failure?
on_load_not_allowed ->
reload_modules([ModError], false),
[ModError|Acc];
_ ->
?DEBUG("Module ~p failed to atomic load because ~p", [ModError, Error]),
[ModError|Acc]
end
end,
[], ModRsns
),
reload_modules(Modules -- Blacklist, true)
end;
reload_modules(Modules, false) ->
%% Older versions, use a more ad-hoc mechanism.
lists:foreach(fun(M) ->
code:delete(M),
code:purge(M),
case code:load_file(M) of
{module, M} -> ok;
{error, Error} ->
?DEBUG("Module ~p failed to load because ~p", [M, Error])
end
end, Modules
).
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