code: Add functions that can load multiple modules

Add functions to 'code' to allow loading of multiple modules
at once.

code:atomic_load(Modules) will load all modules at once, or fail
having loaded none of them. Since we cannot guarantee the atomicity if
there are modules with -on_load functions, the list of modules must
not contain any modules with an -on_load function.

Also, to make it possible to put an application into an inactive state
for as short time as possible, also add code:prepare_loading/1 and
code:finish_loading/1. They are used like this:

  {ok,Prepared} = code:prepare_loading(Modules)
    .
    .
    .
  ok = code:finish_loading(Prepared)

code:ensure_modules_loaded/1 is useful as a pure optimization to
ensure that modules that will be needed soon have indeed been
loaded. It will not reload modules that have already been loaded and
it *will* accept modules that have an on_load function. Therefore, it
does not make sense to give any atomicity guarantees.

I did consider overloading the existing code:ensure_loaded/1
function, but rejected it because the return value is very
different. Having different forms of return values depending
on the types of arguments is confusing.

1 files changed, 3 insertions, 1 deletions

diff --git a/lib/kernel/test/code_SUITE.erl b/lib/kernel/test/code_SUITE.erl
index cf8863fcd0..00f29aa8ed 100644
--- a/lib/kernel/test/code_SUITE.erl
+++ b/lib/kernel/test/code_SUITE.erl
@@ -798,7 +798,7 @@ analyse2(MFA={_,_,_}, Path, Visited0) ->
     analyse(FL, [MFA|Path], my_usort([MFA|Visited0]), 0).
 
 %%%% We need to check these manually...
-% fun's are ok as long as they are defined locally.
+%% fun's are ok as long as they are defined locally.
 check_funs({'$M_EXPR','$F_EXPR',_},
 	   [{unicode,characters_to_binary_int,3},
 	    {unicode,characters_to_binary,3},
@@ -870,6 +870,8 @@ check_funs({'$M_EXPR','$F_EXPR',1},
 	    {hipe_unified_loader,get_refs_from,2}| _]) -> 0;
 check_funs({'$M_EXPR',warning_msg,2},
 	   [{code_server,finish_on_load_report,2} | _]) -> 0;
+check_funs({'$M_EXPR','$F_EXPR',1},
+	   [{code_server,run,2}|_]) -> 0;
 %% This is cheating! /raimo
 %%
 %% check_funs(This = {M,_,_}, Path) ->