nodestack: add Node::get_parent() function

As I add more complicated backtracking and may-read-from relationships,
each Node might need some structural information to be able to reach its
parent Node.

To support this:
* the NodeStack should provide the parent information via Node constructor
* the Node should provide a get_parent() method

diff --git a/nodestack.cc b/nodestack.cc
index 87b3ee531fbe2d10a7b52f229f23e7ea90196e9d..e7b5f51162b485160f3b4bb20cb06f13df2dc3b6 100644 (file)
--- a/nodestack.cc
+++ b/nodestack.cc
@@ -4,8 +4,9 @@
 #include "model.h"
 
 /** @brief Node constructor */
-Node::Node(ModelAction *act, int nthreads)
+Node::Node(ModelAction *act, Node *par, int nthreads)
        : action(act),
+       parent(par),
        num_threads(nthreads),
        explored_children(num_threads),
        backtrack(num_threads),
@@ -173,7 +174,7 @@ ModelAction * NodeStack::explore_action(ModelAction *act)
 
        /* Record action */
        get_head()->explore_child(act);
-       node_list.push_back(new Node(act, model->get_num_threads()));
+       node_list.push_back(new Node(act, get_head(), model->get_num_threads()));
        total_nodes++;
        iter++;
        return NULL;

diff --git a/nodestack.h b/nodestack.h
index 74ac245f3b3b00331a3328482d7c21c47bdc7cdb..11440e5ae5680af381842c3ef81e637dd0e16ee9 100644 (file)
--- a/nodestack.h
+++ b/nodestack.h
@@ -18,7 +18,7 @@ typedef std::set< ModelAction *, std::less< ModelAction *>, MyAlloc< ModelAction
 
 class Node {
 public:
-       Node(ModelAction *act = NULL, int nthreads = 1);
+       Node(ModelAction *act = NULL, Node *par = NULL, int nthreads = 1);
        ~Node();
        /* return true = thread choice has already been explored */
        bool has_been_explored(thread_id_t tid);
@@ -31,6 +31,10 @@ public:
        bool is_enabled(Thread *t);
        ModelAction * get_action() { return action; }
 
+       /** @return the parent Node to this Node; that is, the action that
+        * occurred previously in the stack. */
+       Node * get_parent() const { return parent; }
+
        void add_read_from(ModelAction *act);
 
        void print();
@@ -40,6 +44,7 @@ private:
        void explore(thread_id_t tid);
 
        ModelAction *action;
+       Node *parent;
        int num_threads;
        std::vector< bool, MyAlloc<bool> > explored_children;
        std::vector< bool, MyAlloc<bool> > backtrack;