Changeset 4306

Timestamp:

06/09/08 09:01:54 (4 months ago)

Author:

pmoura

Message:

Corrected a bug in the implementation of the built-in meta-predicate threaded/1 when canceling individual threads that resultd from a leak of thread results between calls to the threaded/1 predicate.

Location:

trunk

Files:

• compiler/logtalk.pl (modified) (12 diffs)
• RELEASE_NOTES.txt (modified) (1 diff)

trunk/compiler/logtalk.pl

@@ -13203 +13203 @@
 
 
-'$lgt_mt_threaded_and_exit'(terminate, _, Ids, _) :-
-    '$lgt_mt_threaded_call_cancel'(Ids),
+'$lgt_mt_threaded_and_exit'(terminate, _, Ids, Results) :-
+    '$lgt_mt_threaded_call_cancel'(Ids, Results),
     throw('$lgt_terminated').
 
+% messages can arrive out-of-order; if that's the case we need to keep looking for the
+% thread result that lead to the termination of the other threads
+
 '$lgt_mt_threaded_and_exit'(exception(Error), Id, Ids, Results) :-
+    '$lgt_mt_threaded_record_result'(Results, Id, exception(Error)),
     (   Error == '$lgt_terminated' ->
         '$lgt_mt_threaded_and_exit'(Ids, Results)
-    ;   '$lgt_mt_threaded_call_cancel'(Ids, Id),
+    ;   '$lgt_mt_threaded_call_cancel'(Ids, Results, Id),
         throw(Error)
     ).
@@ -13218 +13222 @@
     '$lgt_mt_threaded_and_add_result'(Results, Id, TGoal, Continue),
     (   Continue == false ->
-        '$lgt_mt_threaded_call_join'(Ids)
+        '$lgt_mt_threaded_call_join'(Ids, Results)
     ;   '$lgt_mt_threaded_and_exit'(Ids, Results)
     ).
 
-'$lgt_mt_threaded_and_exit'(false, Id, Ids, _) :-
-    '$lgt_mt_threaded_call_cancel'(Ids, Id),
+'$lgt_mt_threaded_and_exit'(false, Id, Ids, Results) :-
+    '$lgt_mt_threaded_record_result'(Results, Id, false),
+    '$lgt_mt_threaded_call_cancel'(Ids, Results, Id),
     fail.
 
@@ -13242 +13247 @@
     (   var(Done) ->
         Continue = true     % we found a thread whose result is still pending
-    ;   true                % otherwise continue examining the reamaining thread results
+    ;   true                % otherwise continue examining the remaining thread results
     ),
     '$lgt_mt_threaded_and_add_result'(Results, Id, TGoal, Continue).
@@ -13269 +13274 @@
 
 
-'$lgt_mt_threaded_or_exit'(terminate, _, Ids, _) :-
-    '$lgt_mt_threaded_call_cancel'(Ids),
+'$lgt_mt_threaded_or_exit'(terminate, _, Ids, Results) :-
+    '$lgt_mt_threaded_call_cancel'(Ids, Results),
     throw('$lgt_terminated').
 
+% messages can arrive out-of-order; if that's the case we need to keep looking for the
+% thread result that lead to the termination of the other threads
+
 '$lgt_mt_threaded_or_exit'(exception(Error), Id, Ids, Results) :-
+    '$lgt_mt_threaded_record_result'(Results, Id, exception(Error)),
     (   Error == '$lgt_terminated' ->
         '$lgt_mt_threaded_or_exit'(Ids, Results)
-    ;   '$lgt_mt_threaded_call_cancel'(Ids, Id),
+    ;   '$lgt_mt_threaded_call_cancel'(Ids, Results, Id),
         throw(Error)
     ).
@@ -13282 +13291 @@
 '$lgt_mt_threaded_or_exit'(true, Id, Ids, Results) :-
     thread_get_message('$lgt_result'(Id, TGoal)),
-    '$lgt_mt_threaded_call_cancel'(Ids, Id),
+    '$lgt_mt_threaded_record_result'(Results, Id, true),
+    '$lgt_mt_threaded_call_cancel'(Ids, Results, Id),
     '$lgt_mt_threaded_or_exit_unify'(Results, Id, TGoal).
 
@@ -13290 +13300 @@
         '$lgt_mt_threaded_or_exit'(Ids, Results)
     ;   % all goals failed
-        '$lgt_mt_threaded_call_join'(Ids),
+        '$lgt_mt_threaded_call_join'(Ids, Results),
         fail
     ).
@@ -13298 +13308 @@
 % unifies the successful thread goal result with the original call
 
-'$lgt_mt_threaded_or_exit_unify'([id(Id, TGoal, _)| _], Id, TGoal) :-
+'$lgt_mt_threaded_or_exit_unify'([id(Id, TGoal, true)| _], Id, TGoal) :-
     !.
 
@@ -13306 +13316 @@
 
 
+% '$lgt_mt_threaded_record_result'(+list, +thread_identifier, +callable)
+%
+% records a thread goal result:
+
+'$lgt_mt_threaded_record_result'([id(Id, _, Result)| _], Id, Result) :-
+    !.
+
+'$lgt_mt_threaded_record_result'([_| Results], Id, Result) :-
+    '$lgt_mt_threaded_record_result'(Results, Id, Result).
+
+
+
 % '$lgt_mt_threaded_or_record_failure'(+list, +thread_identifier, -atom)
 %
-% records a goal failure and checks if all other goals have failed:
+% records a thread goal failure and checks if all other thread goals have failed:
 
 '$lgt_mt_threaded_or_record_failure'([id(Id, _, fail)| Results], Id, Continue) :-
@@ -13320 +13342 @@
     (   var(Done) ->
         Continue = true     % we found a thread whose result is still pending
-    ;   true                % otherwise continue examining the reamaining thread results
+    ;   true                % otherwise continue examining the remaining thread results
     ),
     '$lgt_mt_threaded_or_record_failure'(Results, Id, Continue).
@@ -13337 +13359 @@
 
 
-% '$lgt_mt_threaded_call_cancel'(+list(thread_identifier), thread_identifier)
+% '$lgt_mt_threaded_call_cancel'(+list(thread_identifier), +list, +thread_identifier)
 %
 % aborts a threaded call by aborting and joining all individual threads;
 % we must use catch/3 as some threads may already be terminated
 
-'$lgt_mt_threaded_call_cancel'(Ids, ProtectedId) :-
+'$lgt_mt_threaded_call_cancel'(Ids, Results, ProtectedId) :-
     '$lgt_mt_threaded_call_abort'(Ids, ProtectedId),
-    '$lgt_mt_threaded_call_join'(Ids).
+    '$lgt_mt_threaded_call_join'(Ids, Results).
 
 
@@ -13361 +13383 @@
 
 
-'$lgt_mt_threaded_call_cancel'(Ids) :-
+'$lgt_mt_threaded_call_cancel'(Ids, Results) :-
     '$lgt_mt_threaded_call_abort'(Ids),
-    '$lgt_mt_threaded_call_join'(Ids).
+    '$lgt_mt_threaded_call_join'(Ids, Results).
 
 
@@ -13376 +13398 @@
 
 
-'$lgt_mt_threaded_call_join'([]).
-
-'$lgt_mt_threaded_call_join'([Id| Ids]) :-
+'$lgt_mt_threaded_call_join'([], []).
+
+'$lgt_mt_threaded_call_join'([Id| Ids], [id(Id, _, Result)| Results]) :-
+    (   var(Result) ->
+        thread_get_message('$lgt_status'(Id, Result)),
+        (   Result == true ->
+            thread_get_message('$lgt_result'(Id, _))
+        ;   true
+        )
+    ;   true
+    ),
     catch(thread_join(Id, _), _, true),
-    '$lgt_mt_threaded_call_join'(Ids).
+    '$lgt_mt_threaded_call_join'(Ids, Results).
 
 

trunk/RELEASE_NOTES.txt

@@ -23 +23 @@
     exception terms. Thanks to Joerg Schuster for the bug report.
 
-    Corrected a bug in the implementation of the built-in meta-predicate 
-    threaded/1 when canceling individual threads when one of them terminates 
-    with an exception or a failure.
+    Corrected two bugs in the implementation of the built-in meta-predicate 
+    threaded/1 when canceling individual threads. The first bug resulted from 
+    out-of-order thread status messages. The second bug resultd from a leak 
+    of thread results between calls to the threaded/1 predicate.
 
     Added a new default compiler option, multifile_directive, to all config