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authorRichard Carlsson <[email protected]>2016-05-19 20:29:45 +0200
committerRichard Carlsson <[email protected]>2016-11-25 14:58:03 +0100
commit86fa667f9731c790d6575f31efa156c02cb7984b (patch)
tree8cdbcb4b23aa3c481fddb8601417535facfb6955 /lib/kernel/src/code.erl
parent922b0aa7738d773cf96db03f061b7e940adcdd68 (diff)
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Add code:module_status/1 and modified_modules/0
These functions use the MD5 beam/native checksum to determine whether the code for a module has changed on disk and is a candidate for loading.
Diffstat (limited to 'lib/kernel/src/code.erl')
-rw-r--r--lib/kernel/src/code.erl98
1 files changed, 97 insertions, 1 deletions
diff --git a/lib/kernel/src/code.erl b/lib/kernel/src/code.erl
index 0ad0676f98..5a7ca493cc 100644
--- a/lib/kernel/src/code.erl
+++ b/lib/kernel/src/code.erl
@@ -70,7 +70,9 @@
where_is_file/2,
set_primary_archive/4,
clash/0,
- get_mode/0]).
+ module_status/1,
+ modified_modules/0,
+ get_mode/0]).
-deprecated({rehash,0,next_major_release}).
@@ -895,3 +897,97 @@ load_all_native_1([{Mod,BeamFilename}|T], ChunkTag) ->
load_all_native_1(T, ChunkTag);
load_all_native_1([], _) ->
ok.
+
+%% Returns the status of the module in relation to object file on disk.
+-spec module_status(Module :: module()) -> not_loaded | loaded | modified | removed.
+module_status(Module) ->
+ module_status(Module, code:get_path()).
+
+%% Note that we don't want to go via which/1, since it doesn't look at the
+%% disk contents at all if the module is already loaded.
+module_status(Module, PathFiles) ->
+ case code:is_loaded(Module) of
+ false -> not_loaded;
+ {file, preloaded} -> loaded;
+ {file, cover_compiled} ->
+ %% cover compilation loads directly to memory and does not
+ %% create a beam file, so report 'modified' if a file exists
+ case which(Module, PathFiles) of
+ non_existing -> removed;
+ _File -> modified
+ end;
+ {file, []} -> loaded; % no beam file - generated code
+ {file, OldFile} when is_list(OldFile) ->
+ %% we don't care whether or not the file is in the same location
+ %% as when last loaded, as long as it can be found in the path
+ case which(Module, PathFiles) of
+ non_existing -> removed;
+ Path ->
+ case module_changed_on_disk(Module, Path) of
+ true -> modified;
+ false -> loaded
+ end
+ end
+ end.
+
+%% Detects actual code changes only, e.g. to decide whether a module should
+%% be reloaded; does not care about file timestamps or compilation time
+module_changed_on_disk(Module, Path) ->
+ MD5 = erlang:get_module_info(Module, md5),
+ case erlang:system_info(hipe_architecture) of
+ undefined ->
+ %% straightforward, since native is not supported
+ MD5 =/= beam_file_md5(Path);
+ Architecture ->
+ case code:is_module_native(Module) of
+ true ->
+ %% MD5 is for native code, so we check only the native
+ %% code on disk, ignoring the beam code
+ MD5 =/= beam_file_native_md5(Path, Architecture);
+ _ ->
+ %% MD5 is for beam code, so check only the beam code on
+ %% disk, even if the file contains native code as well
+ MD5 =/= beam_file_md5(Path)
+ end
+ end.
+
+beam_file_md5(Path) ->
+ case beam_lib:md5(Path) of
+ {ok,{_Mod,MD5}} -> MD5;
+ _ -> undefined
+ end.
+
+beam_file_native_md5(Path, Architecture) ->
+ try
+ get_beam_chunk(Path, hipe_unified_loader:chunk_name(Architecture))
+ of
+ NativeCode when is_binary(NativeCode) ->
+ erlang:md5(NativeCode)
+ catch
+ _:_ -> undefined
+ end.
+
+get_beam_chunk(Path, Chunk) ->
+ {ok, {_, [{_, Bin}]}} = beam_lib:chunks(Path, [Chunk]),
+ Bin.
+
+%% Returns a list of all modules modified on disk.
+-spec modified_modules() -> [module()].
+modified_modules() ->
+ PathFiles = path_files(),
+ [M || {M, _} <- code:all_loaded(),
+ module_status(M, PathFiles) =:= modified].
+
+%% prefetch the directory contents of code path directories
+path_files() ->
+ path_files(code:get_path()).
+
+path_files([]) ->
+ [];
+path_files([Path|Tail]) ->
+ case erl_prim_loader:list_dir(Path) of
+ {ok, Files} ->
+ [{Path,Files} | path_files(Tail)];
+ _Error ->
+ path_files(Tail)
+ end.