From: Brian Norris <banorris@uci.edu>
Date: Wed, 3 Oct 2012 01:48:05 +0000 (-0700)
Subject: (bug) revert JOIN/LOCK simplification
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=c11tester.git;a=commitdiff_plain;h=381e2769f94f7e41c1c90d3ab633a37136fa24b0

(bug) revert JOIN/LOCK simplification

A test case throws an assertion when these changes are included. Maybe
I'll make a proper fix later, but for now, I mostly revert these.

Revert "model: remove obsolete ModelChecker::do_complete_join()"
This reverts commit cef10a2b49af5da16ffe59c5b9ddd210c668fbac.

Revert "model: unify JOIN- and LOCK-related sleep/wake code"
This reverts commit 620ae95ce4fed006d18a41b6ccfd949d7e77f677.
---

diff --git a/model.cc b/model.cc
index 38f40e5c..d0dc0271 100644
--- a/model.cc
+++ b/model.cc
@@ -488,17 +488,26 @@ bool ModelChecker::process_thread_action(ModelAction *curr)
 		break;
 	}
 	case THREAD_JOIN: {
-		Thread *blocking = (Thread *)curr->get_location();
-		ModelAction *act = get_last_action(blocking->get_id());
-		curr->synchronize_with(act);
-		updated = true; /* trigger rel-seq checks */
+		Thread *waiting, *blocking;
+		waiting = get_thread(curr);
+		blocking = (Thread *)curr->get_location();
+		if (!blocking->is_complete()) {
+			blocking->push_wait_list(curr);
+			scheduler->sleep(waiting);
+		} else {
+			do_complete_join(curr);
+			updated = true; /* trigger rel-seq checks */
+		}
 		break;
 	}
 	case THREAD_FINISH: {
 		Thread *th = get_thread(curr);
 		while (!th->wait_list_empty()) {
 			ModelAction *act = th->pop_wait_list();
-			scheduler->wake(get_thread(act));
+			Thread *wake = get_thread(act);
+			scheduler->wake(wake);
+			do_complete_join(act);
+			updated = true; /* trigger rel-seq checks */
 		}
 		th->complete();
 		updated = true; /* trigger rel-seq checks */
@@ -571,12 +580,9 @@ ModelAction * ModelChecker::initialize_curr_action(ModelAction *curr)
 }
 
 /**
- * @brief Check whether a model action is enabled.
- *
- * Checks whether a lock or join operation would be successful (i.e., is the
- * lock already locked, or is the joined thread already complete). If not, put
- * the action in a waiter list.
- *
+ * This method checks whether a model action is enabled at the given point.
+ * At this point, it checks whether a lock operation would be successful at this point.
+ * If not, it puts the thread in a waiter list.
  * @param curr is the ModelAction to check whether it is enabled.
  * @return a bool that indicates whether the action is enabled.
  */
@@ -589,12 +595,6 @@ bool ModelChecker::check_action_enabled(ModelAction *curr) {
 			lock_waiters_map->get_safe_ptr(curr->get_location())->push_back(curr);
 			return false;
 		}
-	} else if (curr->get_type() == THREAD_JOIN) {
-		Thread *blocking = (Thread *)curr->get_location();
-		if (!blocking->is_complete()) {
-			blocking->push_wait_list(curr);
-			return false;
-		}
 	}
 
 	return true;
@@ -620,7 +620,7 @@ Thread * ModelChecker::check_current_action(ModelAction *curr)
 
 	if (!check_action_enabled(curr)) {
 		/* Make the execution look like we chose to run this action
-		 * much later, when a lock/join can succeed */
+		 * much later, when a lock is actually available to release */
 		get_current_thread()->set_pending(curr);
 		scheduler->sleep(get_current_thread());
 		return get_next_thread(NULL);
@@ -704,6 +704,19 @@ Thread * ModelChecker::check_current_action(ModelAction *curr)
 	return get_next_thread(curr);
 }
 
+/**
+ * Complete a THREAD_JOIN operation, by synchronizing with the THREAD_FINISH
+ * operation from the Thread it is joining with. Must be called after the
+ * completion of the Thread in question.
+ * @param join The THREAD_JOIN action
+ */
+void ModelChecker::do_complete_join(ModelAction *join)
+{
+	Thread *blocking = (Thread *)join->get_location();
+	ModelAction *act = get_last_action(blocking->get_id());
+	join->synchronize_with(act);
+}
+
 void ModelChecker::check_curr_backtracking(ModelAction * curr) {
 	Node *currnode = curr->get_node();
 	Node *parnode = currnode->get_parent();
diff --git a/model.h b/model.h
index d6d6f090..a2d33432 100644
--- a/model.h
+++ b/model.h
@@ -153,6 +153,7 @@ private:
 	bool w_modification_order(ModelAction *curr);
 	bool release_seq_head(const ModelAction *rf, rel_heads_list_t *release_heads) const;
 	bool resolve_release_sequences(void *location, work_queue_t *work_queue);
+	void do_complete_join(ModelAction *join);
 
 	ModelAction *diverge;
 	ModelAction *earliest_diverge;