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authorAnthony Ramine <[email protected]>2013-05-06 20:09:39 +0200
committerFredrik Gustafsson <[email protected]>2013-05-28 12:19:34 +0200
commitacb8ef5d18cc3976bf580a8e6925cb5641acd401 (patch)
tree6118529820acda1f779935cde6c03c935f5a6d1e /lib/stdlib
parent80c02173c9fc1d76ac1b404a05e2706817a4c308 (diff)
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Fix receive support in erl_eval with a BEAM module
Using the low-level BEAM instructions, we can loop over each message in the process queue and removes the first message that matches, without receiving them all to later send them back to itself. The function prim_eval:'receive'/2 is equivalent to the following pseudo-code: 'receive'(F, T) -> RESET MESSAGE QUEUE POINTER, LOOP: case PEEK CURRENT MESSAGE WITH TIMEOUT T of {ok,Msg} -> case F(Msg) of nomatch -> DECREMENT TIMEOUT T, ADVANCE MESSAGE QUEUE POINTER, GOTO LOOP; Result -> RESET MESSAGE QUEUE POINTER, Result end; timeout -> RESET MESSAGE QUEUE POINTER, timeout end. To not break Dialyzer and other tools, we use a stub Erlang module which abstract code is forcefully inserted into prim_inet.erl afterwards compilation.
Diffstat (limited to 'lib/stdlib')
-rw-r--r--lib/stdlib/doc/src/erl_eval.xml5
-rw-r--r--lib/stdlib/src/erl_eval.erl64
2 files changed, 12 insertions, 57 deletions
diff --git a/lib/stdlib/doc/src/erl_eval.xml b/lib/stdlib/doc/src/erl_eval.xml
index d0622594d9..24940f8396 100644
--- a/lib/stdlib/doc/src/erl_eval.xml
+++ b/lib/stdlib/doc/src/erl_eval.xml
@@ -288,10 +288,7 @@ Func(FuncSpec, Arguments) </code>
<section>
<title>Bugs</title>
- <p>The evaluator is not complete. <c>receive</c> cannot be
- handled properly.
- </p>
- <p>Any undocumented functions in <c>erl_eval</c> should not be used.</p>
+ <p>Undocumented functions in <c>erl_eval</c> should not be used.</p>
</section>
</erlref>
diff --git a/lib/stdlib/src/erl_eval.erl b/lib/stdlib/src/erl_eval.erl
index 0b57af1b6d..73b8da335a 100644
--- a/lib/stdlib/src/erl_eval.erl
+++ b/lib/stdlib/src/erl_eval.erl
@@ -245,10 +245,10 @@ expr({'case',_,E,Cs}, Bs0, Lf, Ef, RBs) ->
expr({'try',_,B,Cases,Catches,AB}, Bs, Lf, Ef, RBs) ->
try_clauses(B, Cases, Catches, AB, Bs, Lf, Ef, RBs);
expr({'receive',_,Cs}, Bs, Lf, Ef, RBs) ->
- receive_clauses(Cs, Bs, Lf, Ef, [], RBs);
+ receive_clauses(Cs, Bs, Lf, Ef, RBs);
expr({'receive',_, Cs, E, TB}, Bs0, Lf, Ef, RBs) ->
{value,T,Bs} = expr(E, Bs0, Lf, Ef, none),
- receive_clauses(T, Cs, {TB,Bs}, Bs0, Lf, Ef, [], RBs);
+ receive_clauses(T, Cs, {TB,Bs}, Bs0, Lf, Ef, RBs);
expr({'fun',_Line,{function,Mod0,Name0,Arity0}}, Bs0, Lf, Ef, RBs) ->
{[Mod,Name,Arity],Bs} = expr_list([Mod0,Name0,Arity0], Bs0, Lf, Ef),
F = erlang:make_fun(Mod, Name, Arity),
@@ -807,66 +807,24 @@ case_clauses(Val, Cs, Bs, Lf, Ef, RBs) ->
end.
%%
-%% receive_clauses(Clauses, Bindings, LocalFuncHnd,ExtFuncHnd, Messages, RBs)
+%% receive_clauses(Clauses, Bindings, LocalFuncHnd,ExtFuncHnd, RBs)
%%
-receive_clauses(Cs, Bs, Lf, Ef, Ms, RBs) ->
- receive
- Val ->
- case match_clause(Cs, [Val], Bs, Lf, Ef) of
- {B, Bs1} ->
- merge_queue(Ms),
- exprs(B, Bs1, Lf, Ef, RBs);
- nomatch ->
- receive_clauses(Cs, Bs, Lf, Ef, [Val|Ms], RBs)
- end
- end.
+receive_clauses(Cs, Bs, Lf, Ef, RBs) ->
+ receive_clauses(infinity, Cs, unused, Bs, Lf, Ef, RBs).
%%
%% receive_clauses(TimeOut, Clauses, TimeoutBody, Bindings,
%% ExternalFuncHandler, LocalFuncHandler, RBs)
%%
-receive_clauses(T, Cs, TB, Bs, Lf, Ef, Ms, RBs) ->
- {_,_} = statistics(runtime),
- receive
- Val ->
- case match_clause(Cs, [Val], Bs, Lf, Ef) of
- {B, Bs1} ->
- merge_queue(Ms),
- exprs(B, Bs1, Lf, Ef, RBs);
- nomatch ->
- {_,T1} = statistics(runtime),
- if
- T =:= infinity ->
- receive_clauses(T, Cs, TB,Bs,Lf,Ef,[Val|Ms],RBs);
- T-T1 =< 0 ->
- receive_clauses(0, Cs, TB,Bs,Lf,Ef,[Val|Ms],RBs);
- true ->
- receive_clauses(T-T1, Cs,TB,Bs,Lf,Ef,[Val|Ms],RBs)
- end
- end
- after T ->
- merge_queue(Ms),
+receive_clauses(T, Cs, TB, Bs, Lf, Ef, RBs) ->
+ F = fun (M) -> match_clause(Cs, [M], Bs, Lf, Ef) end,
+ case prim_eval:'receive'(F, T) of
+ {B, Bs1} ->
+ exprs(B, Bs1, Lf, Ef, RBs);
+ timeout ->
{B, Bs1} = TB,
exprs(B, Bs1, Lf, Ef, RBs)
end.
-merge_queue([]) ->
- true;
-merge_queue(Ms) ->
- send_all(recv_all(Ms), self()).
-
-recv_all(Xs) ->
- receive
- X -> recv_all([X|Xs])
- after 0 ->
- reverse(Xs)
- end.
-
-send_all([X|Xs], Self) ->
- Self ! X,
- send_all(Xs, Self);
-send_all([], _) -> true.
-
-
%% match_clause -> {Body, Bindings} or nomatch
-spec(match_clause(Clauses, ValueList, Bindings, LocalFunctionHandler) ->