X-Git-Url: http://plrg.eecs.uci.edu/git/?p=model-checker.git;a=blobdiff_plain;f=nodestack.cc;h=02f5a89ef17fa320a4fed704e95a924fba0b5132;hp=7cef4b670065e21456e2e5758e61aaa0c4a3c854;hb=c7affe0434c47a25fb4b571136aea6089ac75592;hpb=f52c40fdba5d4648020927cfb942518ed02362df

diff --git a/nodestack.cc b/nodestack.cc
index 7cef4b6..02f5a89 100644
--- a/nodestack.cc
+++ b/nodestack.cc
@@ -1,29 +1,46 @@
 #include "nodestack.h"
 #include "action.h"
 #include "common.h"
+#include "model.h"
 
-int Node::total_nodes = 0;
-
-Node::Node(ModelAction *act, Node *parent)
+/**
+ * @brief Node constructor
+ *
+ * Constructs a single Node for use in a NodeStack. Each Node is associated
+ * with exactly one ModelAction (exception: the first Node should be created
+ * as an empty stub, to represent the first thread "choice") and up to one
+ * parent.
+ *
+ * @param act The ModelAction to associate with this Node. May be NULL.
+ * @param par The parent Node in the NodeStack. May be NULL if there is no
+ * parent.
+ * @param nthreads The number of threads which exist at this point in the
+ * execution trace.
+ */
+Node::Node(ModelAction *act, Node *par, int nthreads)
 	: action(act),
-	num_threads(parent ? parent->num_threads : 1),
+	parent(par),
+	num_threads(nthreads),
 	explored_children(num_threads),
-	backtrack(num_threads)
+	backtrack(num_threads),
+	numBacktracks(0),
+	may_read_from(),
+	read_from_index(0),
+	future_values(),
+	future_index(-1)
 {
-	total_nodes++;
-	if (act && act->get_type() == THREAD_CREATE) {
-		num_threads++;
-		explored_children.resize(num_threads);
-		backtrack.resize(num_threads);
-	}
+	if (act)
+		act->set_node(this);
 }
 
+/** @brief Node desctructor */
 Node::~Node()
 {
 	if (action)
 		delete action;
 }
 
+/** Prints debugging info for the ModelAction associated with this Node */
 void Node::print()
 {
 	if (action)
@@ -32,46 +49,152 @@ void Node::print()
 		printf("******** empty action ********\n");
 }
 
+/** @brief Prints info about may_read_from set */
+void Node::print_may_read_from()
+{
+	readfrom_set_t::iterator it;
+	for (it = may_read_from.begin(); it != may_read_from.end(); it++)
+		(*it)->print();
+}
+
+/**
+ * Sets a promise to explore meeting with the given node.
+ * @param i is the promise index.
+ */
+void Node::set_promise(uint32_t i) {
+	if (i>=promises.size())
+		promises.resize(i+1,0);
+	promises[i]=1;
+}
+
+/**
+ * Looks up whether a given promise should be satisfied by this node.
+ * @param i The promise index.
+ * @return true if the promise should be satisfied by the given model action.
+ */
+bool Node::get_promise(uint32_t i) {
+	return (i<promises.size())&&(promises[i]==2);
+}
+
+/**
+ * Increments to the next combination of promises.
+ * @return true if we have a valid combination.
+ */
+bool Node::increment_promise() {
+	for (unsigned int i=0;i<promises.size();i++) {
+		if (promises[i]==1) {
+			promises[i]=2;
+			while (i>0) {
+				i--;
+				if (promises[i]==2)
+					promises[i]=1;
+			}
+			return true;
+		}
+	}
+	return false;
+}
+
+/**
+ * Returns whether the promise set is empty.
+ * @return true if we have explored all promise combinations.
+ */
+bool Node::promise_empty() {
+	for (unsigned int i=0;i<promises.size();i++)
+		if (promises[i]==1)
+			return false;
+	return true;
+}
+
+/**
+ * Adds a value from a weakly ordered future write to backtrack to.
+ * @param value is the value to backtrack to.
+ */
+bool Node::add_future_value(uint64_t value) {
+	for(unsigned int i=0;i<future_values.size();i++)
+		if (future_values[i]==value)
+			return false;
+
+	future_values.push_back(value);
+	return true;
+}
+
+/**
+ * Checks whether the future_values set for this node is empty.
+ * @return true if the future_values set is empty.
+ */
+bool Node::future_value_empty() {
+	return ((future_index+1)>=future_values.size());
+}
+
+/**
+ * Checks if the Thread associated with this thread ID has been explored from
+ * this Node already.
+ * @param tid is the thread ID to check
+ * @return true if this thread choice has been explored already, false
+ * otherwise
+ */
 bool Node::has_been_explored(thread_id_t tid)
 {
 	int id = id_to_int(tid);
 	return explored_children[id];
 }
 
+/**
+ * Checks if the backtracking set is empty.
+ * @return true if the backtracking set is empty
+ */
 bool Node::backtrack_empty()
 {
-	unsigned int i;
-	for (i = 0; i < backtrack.size(); i++)
-		if (backtrack[i] == true)
-			return false;
-	return true;
+	return (numBacktracks == 0);
 }
 
+/**
+ * Checks whether the readsfrom set for this node is empty.
+ * @return true if the readsfrom set is empty.
+ */
+bool Node::read_from_empty() {
+	return ((read_from_index+1)>=may_read_from.size());
+}
+
+/**
+ * Mark the appropriate backtracking information for exploring a thread choice.
+ * @param act The ModelAction to explore
+ */
 void Node::explore_child(ModelAction *act)
 {
-	act->set_node(this);
 	explore(act->get_tid());
 }
 
+/**
+ * Records a backtracking reference for a thread choice within this Node.
+ * Provides feedback as to whether this thread choice is already set for
+ * backtracking.
+ * @return false if the thread was already set to be backtracked, true
+ * otherwise
+ */
 bool Node::set_backtrack(thread_id_t id)
 {
 	int i = id_to_int(id);
 	if (backtrack[i])
 		return false;
 	backtrack[i] = true;
+	numBacktracks++;
 	return true;
 }
 
 thread_id_t Node::get_next_backtrack()
 {
-	/* TODO: find next backtrack */
+	/** @todo Find next backtrack */
 	unsigned int i;
 	for (i = 0; i < backtrack.size(); i++)
 		if (backtrack[i] == true)
 			break;
-	if (i >= backtrack.size())
-		return THREAD_ID_T_NONE;
+	/* Backtrack set was empty? */
+	ASSERT(i != backtrack.size());
+
 	backtrack[i] = false;
+	numBacktracks--;
 	return int_to_id(i);
 }
 
@@ -80,15 +203,67 @@ bool Node::is_enabled(Thread *t)
 	return id_to_int(t->get_id()) < num_threads;
 }
 
+/**
+ * Add an action to the may_read_from set.
+ * @param act is the action to add
+ */
+void Node::add_read_from(const ModelAction *act)
+{
+	may_read_from.push_back(act);
+}
+
+/**
+ * Gets the next 'future_value' value from this Node. Only valid for a node
+ * where this->action is a 'read'.
+ * @return The first element in future_values
+ */
+uint64_t Node::get_future_value() {
+	ASSERT(future_index<future_values.size());
+	return future_values[future_index];
+}
+
+/**
+ * Gets the next 'may_read_from' action from this Node. Only valid for a node
+ * where this->action is a 'read'.
+ * @return The first element in may_read_from
+ */
+const ModelAction * Node::get_read_from() {
+	if (read_from_index<may_read_from.size())
+		return may_read_from[read_from_index];
+	else
+		return NULL;
+}
+
+/**
+ * Increments the index into the readsfrom set to explore the next item.
+ * @return Returns false if we have explored all items.
+ */
+bool Node::increment_read_from() {
+	read_from_index++;
+	return (read_from_index<may_read_from.size());
+}
+
+/**
+ * Increments the index into the future_values set to explore the next item.
+ * @return Returns false if we have explored all values.
+ */
+bool Node::increment_future_value() {
+	future_index++;
+	return (future_index<future_values.size());
+}
+
 void Node::explore(thread_id_t tid)
 {
 	int i = id_to_int(tid);
-	backtrack[i] = false;
+	if (backtrack[i]) {
+		backtrack[i] = false;
+		numBacktracks--;
+	}
 	explored_children[i] = true;
 }
 
 static void clear_node_list(node_list_t *list, node_list_t::iterator start,
-					       node_list_t::iterator end)
+                                               node_list_t::iterator end)
 {
 	node_list_t::iterator it;
 
@@ -98,8 +273,10 @@ static void clear_node_list(node_list_t *list, node_list_t::iterator start,
 }
 
 NodeStack::NodeStack()
+	: total_nodes(0)
 {
 	node_list.push_back(new Node());
+	total_nodes++;
 	iter = node_list.begin();
 }
 
@@ -124,25 +301,39 @@ void NodeStack::print()
 ModelAction * NodeStack::explore_action(ModelAction *act)
 {
 	DBG();
-	if (node_list.empty()) {
-		node_list.push_back(new Node(act));
-		iter = node_list.begin();
-	} else if (get_head()->has_been_explored(act->get_tid())) {
-		/* Discard duplicate ModelAction */
-		delete act;
-		iter++;
-	} else { /* Diverging from previous execution */
-		/* Clear out remainder of list */
-		node_list_t::iterator it = iter;
-		it++;
-		clear_node_list(&node_list, it, node_list.end());
 
-		/* Record action */
-		get_head()->explore_child(act);
-		node_list.push_back(new Node(act, get_head()));
+	ASSERT(!node_list.empty());
+	node_list_t::iterator it=iter;
+	it++;
+
+	if (it != node_list.end()) {
 		iter++;
+		return (*iter)->get_action();
 	}
-	return (*iter)->get_action();
+
+	/* Record action */
+	get_head()->explore_child(act);
+	node_list.push_back(new Node(act, get_head(), model->get_num_threads()));
+	total_nodes++;
+	iter++;
+	return NULL;
+}
+
+/**
+ * Empties the stack of all trailing nodes after a given position and calls the
+ * destructor for each. This function is provided an offset which determines
+ * how many nodes (relative to the current replay state) to save before popping
+ * the stack.
+ * @param numAhead gives the number of Nodes (including this Node) to skip over
+ * before removing nodes.
+ */
+void NodeStack::pop_restofstack(int numAhead)
+{
+	/* Diverging from previous execution; clear out remainder of list */
+	node_list_t::iterator it = iter;
+	while (numAhead--)
+		it++;
+	clear_node_list(&node_list, it, node_list.end());
 }
 
 Node * NodeStack::get_head()