Merge remote-tracking branch 'upstream/master'

1 files changed, 208 insertions, 0 deletions

diff --git a/src/rebar_paths.erl b/src/rebar_paths.erl
new file mode 100644
index 0000000..82c0218
--- /dev/null
+++ b/src/rebar_paths.erl
@@ -0,0 +1,208 @@
+-module(rebar_paths).
+-include("rebar.hrl").
+
+-type target() :: deps | plugins.
+-type targets() :: [target(), ...].
+-export_type([target/0, targets/0]).
+-export([set_paths/2, unset_paths/2]).
+-export([clashing_apps/2]).
+
+-ifdef(TEST).
+-export([misloaded_modules/2]).
+-endif.
+
+-spec set_paths(targets(), rebar_state:t()) -> ok.
+set_paths(UserTargets, State) ->
+    Targets = normalize_targets(UserTargets),
+    GroupPaths = path_groups(Targets, State),
+    Paths = lists:append(lists:reverse([P || {_, P} <- GroupPaths])),
+    code:add_pathsa(Paths),
+    AppGroups = app_groups(Targets, State),
+    purge_and_load(AppGroups, sets:new()),
+    ok.
+
+-spec unset_paths(targets(), rebar_state:t()) -> ok.
+unset_paths(UserTargets, State) ->
+    Targets = normalize_targets(UserTargets),
+    GroupPaths = path_groups(Targets, State),
+    Paths = lists:append([P || {_, P} <- GroupPaths]),
+    [code:del_path(P) || P <- Paths],
+    purge(Paths, code:all_loaded()),
+    ok.
+
+-spec clashing_apps(targets(), rebar_state:t()) -> [{target(), [binary()]}].
+clashing_apps(Targets, State) ->
+    AppGroups = app_groups(Targets, State),
+    AppNames = [{G, sets:from_list(
+                    [rebar_app_info:name(App) || App <- Apps]
+                )} || {G, Apps} <- AppGroups],
+    clashing_app_names(sets:new(), AppNames, []).
+
+%%%%%%%%%%%%%%%
+%%% PRIVATE %%%
+%%%%%%%%%%%%%%%
+
+%% The paths are to be set in the reverse order; i.e. the default
+%% path is always last when possible (minimize cases where a build
+%% tool version clashes with an app's), and put the highest priorities
+%% first.
+-spec normalize_targets(targets()) -> targets().
+normalize_targets(List) ->
+    %% Plan for the eventuality of getting values piped in
+    %% from future versions of rebar3, possibly from plugins and so on,
+    %% which means we'd risk failing kind of violently. We only support
+    %% deps and plugins
+    TmpList = lists:foldl(
+      fun(deps, [deps | _] = Acc) -> Acc;
+         (plugins, [plugins | _] = Acc) -> Acc;
+         (deps, Acc) -> [deps | Acc -- [deps]];
+         (plugins, Acc) -> [plugins | Acc -- [plugins]];
+         (_, Acc) -> Acc
+      end,
+      [],
+      List
+    ),
+    lists:reverse(TmpList).
+
+purge_and_load([], _) ->
+    ok;
+purge_and_load([{_Group, Apps}|Rest], Seen) ->
+    %% We have: a list of all applications in the current priority group,
+    %% a list of all loaded modules with their active path, and a list of
+    %% seen applications.
+    %%
+    %% We do the following:
+    %% 1. identify the apps that have not been solved yet
+    %% 2. find the paths for all apps in the current group
+    %% 3. unload and reload apps that may have changed paths in order
+    %%    to get updated module lists and specs
+    %%    (we ignore started apps and apps that have not run for this)
+    %%    This part turns out to be the bottleneck of this module, so
+    %%    to speed it up, using clash detection proves useful:
+    %%    only reload apps that clashed since others are unlikely to
+    %%    conflict in significant ways
+    %% 4. create a list of modules to check from that app list—only loaded
+    %%    modules make sense to check.
+    %% 5. check the modules to match their currently loaded paths with
+    %%    the path set from the apps in the current group; modules
+    %%    that differ must be purged; others can stay
+
+    %% 1)
+    AppNames = [AppName || App <- Apps,
+                           AppName <- [rebar_app_info:name(App)],
+                           not sets:is_element(AppName, Seen)],
+    GoodApps = [App || AppName <- AppNames,
+                       App <- Apps,
+                       rebar_app_info:name(App) =:= AppName],
+    %% 2)
+    %% (no need for extra_src_dirs since those get put into ebin;
+    %%  also no need for OTP libs; we want to allow overtaking them)
+    GoodAppPaths = [rebar_app_info:ebin_dir(App) || App <- GoodApps],
+    %% 3)
+    [begin
+         AtomApp = binary_to_atom(AppName, utf8),
+         %% blind load/unload won't interrupt an already-running app,
+         %% preventing odd errors, maybe!
+         case application:unload(AtomApp) of
+             ok -> application:load(AtomApp);
+             _ -> ok
+         end
+     end || AppName <- AppNames,
+            %% Shouldn't unload ourselves; rebar runs without ever
+            %% being started and unloading breaks logging!
+            AppName =/= <<"rebar">>],
+
+    %% 4)
+    CandidateMods = lists:append(
+        %% Start by asking the currently loaded app (if loaded)
+        %% since it would be the primary source of conflicting modules
+        [case application:get_key(AppName, modules) of
+             {ok, Mods} ->
+                 Mods;
+             undefined ->
+                 %% if not found, parse the app file on disk, in case
+                 %% the app's modules are used without it being loaded
+                 case rebar_app_info:app_details(App) of
+                     [] -> [];
+                     Details -> proplists:get_value(modules, Details, [])
+                 end
+         end || App <- GoodApps,
+                AppName <- [binary_to_atom(rebar_app_info:name(App), utf8)]]
+    ),
+    ModPaths = [{Mod,Path} || Mod <- CandidateMods,
+                              erlang:function_exported(Mod, module_info, 0),
+                              {file, Path} <- [code:is_loaded(Mod)]],
+
+    %% 5)
+    Mods = misloaded_modules(GoodAppPaths, ModPaths),
+    [purge_mod(Mod) || Mod <- Mods],
+
+    purge_and_load(Rest, sets:union(Seen, sets:from_list(AppNames))).
+
+purge(Paths, ModPaths) ->
+    SortedPaths = lists:sort(Paths),
+    lists:map(fun purge_mod/1,
+              [Mod || {Mod, Path} <- ModPaths,
+                      is_list(Path), % not 'preloaded' or mocked
+                      any_prefix(Path, SortedPaths)]
+             ).
+
+misloaded_modules(GoodAppPaths, ModPaths) ->
+    %% Identify paths that are invalid; i.e. app paths that cover an
+    %% app in the desired group, but are not in the desired group.
+    lists:usort(
+        [Mod || {Mod, Path} <- ModPaths,
+                is_list(Path), % not 'preloaded' or mocked
+                not any_prefix(Path, GoodAppPaths)]
+    ).
+
+any_prefix(Path, Paths) ->
+    lists:any(fun(P) -> lists:prefix(P, Path) end, Paths).
+
+%% assume paths currently set are good; only unload a module so next call
+%% uses the correctly set paths
+purge_mod(Mod) ->
+    code:soft_purge(Mod) andalso code:delete(Mod).
+
+
+%% This is a tricky O(n²) check since we want to
+%% know whether an app clashes with any of the top priority groups.
+%%
+%% For example, let's say we have `[deps, plugins]', then we want
+%% to find the plugins that clash with deps:
+%%
+%% `[{deps, [ClashingPlugins]}, {plugins, []}]'
+%%
+%% In case we'd ever have alternative or additional types, we can
+%% find all clashes from other 'groups'.
+clashing_app_names(_, [], Acc) ->
+    lists:reverse(Acc);
+clashing_app_names(PrevNames, [{G,AppNames} | Rest], Acc) ->
+    CurrentNames = sets:subtract(AppNames, PrevNames),
+    NextNames = sets:subtract(sets:union([A || {_, A} <- Rest]), PrevNames),
+    Clashes = sets:intersection(CurrentNames, NextNames),
+    NewAcc = [{G, sets:to_list(Clashes)} | Acc],
+    clashing_app_names(sets:union(PrevNames, CurrentNames), Rest, NewAcc).
+
+path_groups(Targets, State) ->
+    [{Target, get_paths(Target, State)} || Target <- Targets].
+
+app_groups(Targets, State) ->
+    [{Target, get_apps(Target, State)} || Target <- Targets].
+
+get_paths(deps, State) ->
+    rebar_state:code_paths(State, all_deps);
+get_paths(plugins, State) ->
+    rebar_state:code_paths(State, all_plugin_deps).
+
+get_apps(deps, State) ->
+    %% The code paths for deps also include the top level apps
+    %% and the extras, which we don't have here; we have to
+    %% add the apps by hand
+    case rebar_state:project_apps(State) of
+        undefined -> [];
+        List -> List
+    end ++
+    rebar_state:all_deps(State);
+get_apps(plugins, State) ->
+    rebar_state:all_plugin_deps(State).