cyclegraph: support rolling back changes

diff --git a/cyclegraph.cc b/cyclegraph.cc
index 3168923a8c0f260c137755e7775f99a643ab96a5..967b0763abbdcdba0ec35cdd2608cb0fa94caa13 100644 (file)
--- a/cyclegraph.cc
+++ b/cyclegraph.cc
@@ -3,7 +3,8 @@
 
 /** Initializes a CycleGraph object. */
 CycleGraph::CycleGraph() :
-       hasCycles(false)
+       hasCycles(false),
+       oldCycles(false)
 {
 }
 
@@ -39,6 +40,8 @@ void CycleGraph::addEdge(const ModelAction *from, const ModelAction *to) {
                // Check for Cycles
                hasCycles=checkReachable(tonode, fromnode);
        }
+
+       rollbackvector.push_back(fromnode);
        fromnode->addEdge(tonode);
 
        CycleNode * rmwnode=fromnode->getRMW();
@@ -51,6 +54,7 @@ void CycleGraph::addEdge(const ModelAction *from, const ModelAction *to) {
                        // Check for Cycles
                        hasCycles=checkReachable(tonode, rmwnode);
                }
+               rollbackvector.push_back(rmwnode);
                rmwnode->addEdge(tonode);
        }
 }
@@ -67,6 +71,8 @@ void CycleGraph::addRMWEdge(const ModelAction *from, const ModelAction *rmw) {
        /* Two RMW actions cannot read from the same write. */
        if (fromnode->setRMW(rmwnode)) {
                hasCycles=true;
+       } else {
+               rmwrollbackvector.push_back(fromnode);
        }
 
        /* Transfer all outgoing edges from the from node to the rmw node */
@@ -75,9 +81,10 @@ void CycleGraph::addRMWEdge(const ModelAction *from, const ModelAction *rmw) {
        std::vector<CycleNode *> * edges=fromnode->getEdges();
        for(unsigned int i=0;i<edges->size();i++) {
                CycleNode * tonode=(*edges)[i];
+               rollbackvector.push_back(rmwnode);
                rmwnode->addEdge(tonode);
        }
-
+       rollbackvector.push_back(fromnode);
        fromnode->addEdge(rmwnode);
 }
 
@@ -126,6 +133,28 @@ bool CycleGraph::checkReachable(CycleNode *from, CycleNode *to) {
        return false;
 }
 
+/** 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;
@@ -166,7 +195,8 @@ CycleNode * CycleNode::getRMW() {
  * @see CycleGraph::addRMWEdge
  */
 bool CycleNode::setRMW(CycleNode *node) {
-       CycleNode * oldhasRMW=hasRMW;
+       if (hasRMW!=NULL)
+               return true;
        hasRMW=node;
-       return (oldhasRMW!=NULL);
+       return false;
 }

diff --git a/cyclegraph.h b/cyclegraph.h
index 2e523d7950b28c5b91830217414eebbc459d2972..0bb01c4c15ec608aa06a1892103635c4973ed039 100644 (file)
--- a/cyclegraph.h
+++ b/cyclegraph.h
@@ -22,6 +22,8 @@ class CycleGraph {
        void addRMWEdge(const ModelAction *from, const ModelAction *rmw);
 
        bool checkReachable(const ModelAction *from, const ModelAction *to);
+       void commitChanges();
+       void rollbackChanges();
 
  private:
        CycleNode * getNode(const ModelAction *);
@@ -33,6 +35,11 @@ class CycleGraph {
 
        /** @brief A flag: true if this graph contains cycles */
        bool hasCycles;
+
+       bool oldCycles;
+
+       std::vector<CycleNode *> rollbackvector;
+       std::vector<CycleNode *> rmwrollbackvector;
 };
 
 /** @brief A node within a CycleGraph; corresponds to one ModelAction */
@@ -43,6 +50,12 @@ class CycleNode {
        std::vector<CycleNode *> * getEdges();
        bool setRMW(CycleNode *);
        CycleNode* getRMW();
+       void popEdge() {
+               edges.pop_back();
+       };
+       void clearRMW() {
+               hasRMW=NULL;
+       }
 
  private:
        /** @brief The ModelAction that this node represents */