action: add get_thread_operand() method

Instead of guessing at the (type-unsafe) storage within
THREAD_{CREATE,JOIN} ModelActions, we can at least code this within a
single method. Note that this method may get more complex, particularly
for THREAD_CREATE.

diff --git a/action.cc b/action.cc
index 84c20eb5c42f0ff9b1fa4f3ef668aa6432b793d5..acecd5a6e20f6b512cef0d9e136db4422d8078d8 100644 (file)
--- a/action.cc
+++ b/action.cc
@@ -238,6 +238,30 @@ void ModelAction::copy_typeandorder(ModelAction * act)
        this->order = act->order;
 }
 
+/**
+ * Get the Thread which is the operand of this action. This is only valid for
+ * THREAD_* operations (currently only for THREAD_CREATE and THREAD_JOIN). Note
+ * that this provides a central place for determining the conventions of Thread
+ * storage in ModelAction, where we generally aren't very type-safe (e.g., we
+ * store object references in a (void *) address.
+ *
+ * For THREAD_CREATE, this yields the Thread which is created.
+ * For THREAD_JOIN, this yields the Thread we are joining with.
+ *
+ * @return The Thread which this action acts on, if exists; otherwise NULL
+ */
+Thread * ModelAction::get_thread_operand() const
+{
+       if (type == THREAD_CREATE)
+               /* THREAD_CREATE uses (Thread *) for location */
+               return (Thread *)get_location();
+       else if (type == THREAD_JOIN)
+               /* THREAD_JOIN uses (Thread *) for location */
+               return (Thread *)get_location();
+       else
+               return NULL;
+}
+
 /** This method changes an existing read part of an RMW action into either:
  *  (1) a full RMW action in case of the completed write or
  *  (2) a READ action in case a failed action.

diff --git a/action.h b/action.h
index 5ec109883118af17cc3abf860594d58383ab0909..f742ddc62854a79fd2f2aff3721914781f115b36 100644 (file)
--- a/action.h
+++ b/action.h
@@ -125,6 +125,8 @@ public:
        bool is_conflicting_lock(const ModelAction *act) const;
        bool could_synchronize_with(const ModelAction *act) const;
 
+       Thread * get_thread_operand() const;
+
        void create_cv(const ModelAction *parent = NULL);
        ClockVector * get_cv() const { return cv; }
        bool synchronize_with(const ModelAction *act);

diff --git a/model.cc b/model.cc
index 14b1aa38b500a146e49b2766e54509afcb029c99..84c42689425f257d594c969df0b758038001ab83 100644 (file)
--- a/model.cc
+++ b/model.cc
@@ -217,9 +217,8 @@ Thread * ModelChecker::get_next_thread(ModelAction *curr)
                /* Do not split atomic actions. */
                if (curr->is_rmwr())
                        return thread_current();
-               /* The THREAD_CREATE action points to the created Thread */
                else if (curr->get_type() == THREAD_CREATE)
-                       return (Thread *)curr->get_location();
+                       return curr->get_thread_operand();
        }
 
        /* Have we completed exploring the preselected path? */
@@ -949,12 +948,12 @@ bool ModelChecker::process_thread_action(ModelAction *curr)
 
        switch (curr->get_type()) {
        case THREAD_CREATE: {
-               Thread *th = (Thread *)curr->get_location();
+               Thread *th = curr->get_thread_operand();
                th->set_creation(curr);
                break;
        }
        case THREAD_JOIN: {
-               Thread *blocking = (Thread *)curr->get_location();
+               Thread *blocking = curr->get_thread_operand();
                ModelAction *act = get_last_action(blocking->get_id());
                curr->synchronize_with(act);
                updated = true; /* trigger rel-seq checks */