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authorBjörn Gustavsson <[email protected]>2016-09-05 16:16:23 +0200
committerBjörn Gustavsson <[email protected]>2016-09-14 12:54:54 +0200
commitc70ca686fe269db6079a2ca1c7e09cdfc0cfa903 (patch)
treefa9d97ff6a1f50a7532f4ebe38f70937bc035359 /erts/preloaded/src/erts_code_purger.erl
parent176b7c94e4146a65ccd2bd729d58487098dddd9c (diff)
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Don't leak old code when loading a modules with an on_load function
Normally, calling code:delete/1 before re-loading the code for a module is unnecessary but causes no problem. But there will be be problems if the new code has an on_load function. Code with an on_load function will always be loaded as old code to allowed it to be easily purged if the on_load function would fail. If the on_load function succeeds, the old and current code will be swapped. So in the scenario where code:delete/1 has been called explicitly, there is old code but no current code. Loading code with an on_load function will cause the reference to the old code to be overwritten. That will at best cause a memory leak, and at worst an emulator crash (especially if NIFs are involved). To avoid that situation, we will put the code with the on_load function in a special, third slot in Module. ERL-240
Diffstat (limited to 'erts/preloaded/src/erts_code_purger.erl')
-rw-r--r--erts/preloaded/src/erts_code_purger.erl37
1 files changed, 36 insertions, 1 deletions
diff --git a/erts/preloaded/src/erts_code_purger.erl b/erts/preloaded/src/erts_code_purger.erl
index ee4fcedd2d..28d71fd07e 100644
--- a/erts/preloaded/src/erts_code_purger.erl
+++ b/erts/preloaded/src/erts_code_purger.erl
@@ -22,7 +22,8 @@
%% Purpose : Implement system process erts_code_purger
%% to handle code module purging.
--export([start/0, purge/1, soft_purge/1, pending_purge_lambda/3]).
+-export([start/0, purge/1, soft_purge/1, pending_purge_lambda/3,
+ finish_after_on_load/2]).
-spec start() -> term().
start() ->
@@ -40,6 +41,11 @@ loop() ->
Res = do_soft_purge(Mod),
From ! {reply, soft_purge, Res, Ref};
+ {finish_after_on_load,{Mod,Keep},From,Ref}
+ when is_atom(Mod), is_pid(From) ->
+ Res = do_finish_after_on_load(Mod, Keep),
+ From ! {reply, finish_after_on_load, Res, Ref};
+
{test_purge, Mod, From, Type, Ref} when is_atom(Mod), is_pid(From) ->
do_test_purge(Mod, From, Type, Ref);
@@ -129,6 +135,35 @@ do_soft_purge(Mod) ->
end)
end.
+%% finish_after_on_load(Module, Keep)
+%% Finish after running on_load function. If Keep is false,
+%% purge the code for the on_load function.
+
+finish_after_on_load(Mod, Keep) ->
+ Ref = make_ref(),
+ erts_code_purger ! {finish_after_on_load, {Mod,Keep}, self(), Ref},
+ receive
+ {reply, finish_after_on_load, Result, Ref} ->
+ Result
+ end.
+
+do_finish_after_on_load(Mod, Keep) ->
+ erlang:finish_after_on_load(Mod, Keep),
+ case Keep of
+ true ->
+ ok;
+ false ->
+ case erts_internal:purge_module(Mod, prepare_on_load) of
+ false ->
+ true;
+ true ->
+ _ = check_proc_code(erlang:processes(), Mod, true),
+ true = erts_internal:purge_module(Mod, complete)
+ end
+ end.
+
+
+
%%
%% check_proc_code(Pids, Mod, Hard) - Send asynchronous
%% requests to all processes to perform a check_process_code