X-Git-Url: http://plrg.eecs.uci.edu/git/?p=model-checker.git;a=blobdiff_plain;f=cyclegraph.cc;h=f519dac93b39975742887746f79a194e63dd12fe;hp=6676f2f0a7ea4a000f2555810cbc4f31f0112263;hb=a0562e0739fd643fdb2108f784f4722482ea5a4f;hpb=37c87f91496ff3e713003c21692c63b8e87d81fb

diff --git a/cyclegraph.cc b/cyclegraph.cc
index 6676f2f..f519dac 100644
--- a/cyclegraph.cc
+++ b/cyclegraph.cc
@@ -1,16 +1,24 @@
 #include "cyclegraph.h"
 #include "action.h"
+#include "common.h"
 
 /** Initializes a CycleGraph object. */
-CycleGraph::CycleGraph() {
-	hasCycles=false;
+CycleGraph::CycleGraph() :
+	hasCycles(false),
+	oldCycles(false)
+{
 }
 
+/** CycleGraph destructor */
 CycleGraph::~CycleGraph() {
 }
 
-/** Returns the CycleNode for a given ModelAction. */
-CycleNode * CycleGraph::getNode(const ModelAction * action) {
+/**
+ * @brief Returns the CycleNode corresponding to a given ModelAction
+ * @param action The ModelAction to find a node for
+ * @return The CycleNode paired with this action
+ */
+CycleNode * CycleGraph::getNode(const ModelAction *action) {
 	CycleNode *node=actionToNode.get(action);
 	if (node==NULL) {
 		node=new CycleNode(action);
@@ -19,41 +27,96 @@ CycleNode * CycleGraph::getNode(const ModelAction * action) {
 	return node;
 }
 
-/** Adds an edge between two ModelActions. */
+/**
+ * Adds an edge between two ModelActions. The ModelAction @a to is ordered
+ * after the ModelAction @a from.
+ * @param to The edge points to this ModelAction
+ * @param from The edge comes from this ModelAction
+ */
 void CycleGraph::addEdge(const ModelAction *from, const ModelAction *to) {
+	ASSERT(from);
+	ASSERT(to);
+
 	CycleNode *fromnode=getNode(from);
 	CycleNode *tonode=getNode(to);
+
 	if (!hasCycles) {
 		// Check for Cycles
 		hasCycles=checkReachable(tonode, fromnode);
 	}
+
+	rollbackvector.push_back(fromnode);
 	fromnode->addEdge(tonode);
+
+	CycleNode * rmwnode=fromnode->getRMW();
+
+	//If the fromnode has a rmwnode that is not the tonode, we
+	//should add an edge between its rmwnode and the tonode
+
+	if (rmwnode!=NULL&&rmwnode!=tonode) {
+		if (!hasCycles) {
+			// Check for Cycles
+			hasCycles=checkReachable(tonode, rmwnode);
+		}
+		rollbackvector.push_back(rmwnode);
+		rmwnode->addEdge(tonode);
+	}
 }
 
+/** Handles special case of a RMW action.  The ModelAction rmw reads
+ *  from the ModelAction from.  The key differences are: (1) no write
+ *  can occur in between the rmw and the from action.  Only one RMW
+ *  action can read from a given write.
+ */
 void CycleGraph::addRMWEdge(const ModelAction *from, const ModelAction *rmw) {
+	ASSERT(from);
+	ASSERT(rmw);
+
 	CycleNode *fromnode=getNode(from);
 	CycleNode *rmwnode=getNode(rmw);
 
 	/* Two RMW actions cannot read from the same write. */
-	if (fromnode->setRMW())
+	if (fromnode->setRMW(rmwnode)) {
 		hasCycles=true;
+	} else {
+		rmwrollbackvector.push_back(fromnode);
+	}
 
 	/* Transfer all outgoing edges from the from node to the rmw node */
 	/* This process cannot add a cycle because rmw should not have any
 		 incoming edges yet.*/
 	std::vector<CycleNode *> * edges=fromnode->getEdges();
-	for(unsigned int i=0;edges->size();i++) {
+	for(unsigned int i=0;i<edges->size();i++) {
 		CycleNode * tonode=(*edges)[i];
+		rollbackvector.push_back(rmwnode);
 		rmwnode->addEdge(tonode);
 	}
-	if (!hasCycles) {
-		hasCycles=checkReachable(rmwnode, fromnode);
-	}
+	rollbackvector.push_back(fromnode);
 	fromnode->addEdge(rmwnode);
 }
 
+/**
+ * Checks whether one ModelAction can reach another.
+ * @param from The ModelAction from which to begin exploration
+ * @param to The ModelAction to reach
+ * @return True, @a from can reach @a to; otherwise, false
+ */
+bool CycleGraph::checkReachable(const ModelAction *from, const ModelAction *to) {
+	CycleNode *fromnode = actionToNode.get(from);
+	CycleNode *tonode = actionToNode.get(to);
+
+	if (!fromnode || !tonode)
+		return false;
 
-/** Checks whether the first CycleNode can reach the second one. */
+	return checkReachable(fromnode, tonode);
+}
+
+/**
+ * Checks whether one CycleNode can reach another.
+ * @param from The CycleNode from which to begin exploration
+ * @param to The CycleNode to reach
+ * @return True, @a from can reach @a to; otherwise, false
+ */
 bool CycleGraph::checkReachable(CycleNode *from, CycleNode *to) {
 	std::vector<CycleNode *> queue;
 	HashTable<CycleNode *, CycleNode *, uintptr_t, 4> discovered;
@@ -77,28 +140,76 @@ bool CycleGraph::checkReachable(CycleNode *from, CycleNode *to) {
 	return false;
 }
 
-/** Returns whether a CycleGraph contains cycles. */
+void CycleGraph::startChanges() {
+	ASSERT(rollbackvector.size()==0);
+	ASSERT(rmwrollbackvector.size()==0);
+	ASSERT(oldCycles==hasCycles);
+}
+
+/** Commit changes to the cyclegraph. */
+void CycleGraph::commitChanges() {
+	rollbackvector.resize(0);
+	rmwrollbackvector.resize(0);
+	oldCycles=hasCycles;
+}
+
+/** Rollback changes to the previous commit. */
+void CycleGraph::rollbackChanges() {
+	for (unsigned int i = 0; i < rollbackvector.size(); i++) {
+		rollbackvector[i]->popEdge();
+	}
+
+	for (unsigned int i = 0; i < rmwrollbackvector.size(); i++) {
+		rmwrollbackvector[i]->clearRMW();
+	}
+
+	hasCycles = oldCycles;
+	rollbackvector.resize(0);
+	rmwrollbackvector.resize(0);
+}
+
+/** @returns whether a CycleGraph contains cycles. */
 bool CycleGraph::checkForCycles() {
 	return hasCycles;
 }
 
-/** Constructor for a CycleNode. */
-CycleNode::CycleNode(const ModelAction *modelaction) {
-	action=modelaction;
+/**
+ * Constructor for a CycleNode.
+ * @param modelaction The ModelAction for this node
+ */
+CycleNode::CycleNode(const ModelAction *modelaction) :
+	action(modelaction),
+	hasRMW(NULL)
+{
 }
 
-/** Returns a vector of the edges from a CycleNode. */
+/** @returns a vector of the edges from a CycleNode. */
 std::vector<CycleNode *> * CycleNode::getEdges() {
 	return &edges;
 }
 
-/** Adds an edge to a CycleNode. */
-void CycleNode::addEdge(CycleNode * node) {
+/**
+ * Adds an edge from this CycleNode to another CycleNode.
+ * @param node The node to which we add a directed edge
+ */
+void CycleNode::addEdge(CycleNode *node) {
 	edges.push_back(node);
 }
 
-bool CycleNode::setRMW() {
-	bool oldhasRMW=hasRMW;
-	hasRMW=true;
-	return oldhasRMW;
+/** @returns the RMW CycleNode that reads from the current CycleNode */
+CycleNode * CycleNode::getRMW() {
+	return hasRMW;
+}
+
+/**
+ * Set a RMW action node that reads from the current CycleNode.
+ * @param node The RMW that reads from the current node
+ * @return True, if this node already was read by another RMW; false otherwise
+ * @see CycleGraph::addRMWEdge
+ */
+bool CycleNode::setRMW(CycleNode *node) {
+	if (hasRMW!=NULL)
+		return true;
+	hasRMW=node;
+	return false;
 }