1 #include "cyclegraph.h"
5 /** Initializes a CycleGraph object. */
6 CycleGraph::CycleGraph() :
9 hasRMWViolation(false),
10 oldRMWViolation(false)
14 /** CycleGraph destructor */
15 CycleGraph::~CycleGraph() {
19 * @brief Returns the CycleNode corresponding to a given ModelAction
20 * @param action The ModelAction to find a node for
21 * @return The CycleNode paired with this action
23 CycleNode * CycleGraph::getNode(const ModelAction *action) {
24 CycleNode *node=actionToNode.get(action);
26 node=new CycleNode(action);
27 actionToNode.put(action, node);
33 * Adds an edge between two ModelActions. The ModelAction @a to is ordered
34 * after the ModelAction @a from.
35 * @param to The edge points to this ModelAction
36 * @param from The edge comes from this ModelAction
38 void CycleGraph::addEdge(const ModelAction *from, const ModelAction *to) {
42 CycleNode *fromnode=getNode(from);
43 CycleNode *tonode=getNode(to);
47 hasCycles=checkReachable(tonode, fromnode);
50 rollbackvector.push_back(fromnode);
51 fromnode->addEdge(tonode);
53 CycleNode * rmwnode=fromnode->getRMW();
55 //If the fromnode has a rmwnode that is not the tonode, we
56 //should add an edge between its rmwnode and the tonode
58 if (rmwnode!=NULL&&rmwnode!=tonode) {
61 hasCycles=checkReachable(tonode, rmwnode);
63 rollbackvector.push_back(rmwnode);
64 rmwnode->addEdge(tonode);
68 /** Handles special case of a RMW action. The ModelAction rmw reads
69 * from the ModelAction from. The key differences are: (1) no write
70 * can occur in between the rmw and the from action. Only one RMW
71 * action can read from a given write.
73 void CycleGraph::addRMWEdge(const ModelAction *from, const ModelAction *rmw) {
77 CycleNode *fromnode=getNode(from);
78 CycleNode *rmwnode=getNode(rmw);
80 /* Two RMW actions cannot read from the same write. */
81 if (fromnode->setRMW(rmwnode)) {
84 rmwrollbackvector.push_back(fromnode);
87 /* Transfer all outgoing edges from the from node to the rmw node */
88 /* This process should not add a cycle because either:
89 * (1) The rmw should not have any incoming edges yet if it is the
91 * (2) the fromnode is the new node and therefore it should not
92 * have any outgoing edges.
94 std::vector<CycleNode *> * edges=fromnode->getEdges();
95 for(unsigned int i=0;i<edges->size();i++) {
96 CycleNode * tonode=(*edges)[i];
97 rollbackvector.push_back(rmwnode);
98 rmwnode->addEdge(tonode);
100 rollbackvector.push_back(fromnode);
103 // With promises we could be setting up a cycle here if we aren't
104 // careful...avoid it..
105 hasCycles=checkReachable(rmwnode, fromnode);
107 fromnode->addEdge(rmwnode);
111 * Checks whether one ModelAction can reach another.
112 * @param from The ModelAction from which to begin exploration
113 * @param to The ModelAction to reach
114 * @return True, @a from can reach @a to; otherwise, false
116 bool CycleGraph::checkReachable(const ModelAction *from, const ModelAction *to) {
117 CycleNode *fromnode = actionToNode.get(from);
118 CycleNode *tonode = actionToNode.get(to);
120 if (!fromnode || !tonode)
123 return checkReachable(fromnode, tonode);
127 * Checks whether one CycleNode can reach another.
128 * @param from The CycleNode from which to begin exploration
129 * @param to The CycleNode to reach
130 * @return True, @a from can reach @a to; otherwise, false
132 bool CycleGraph::checkReachable(CycleNode *from, CycleNode *to) {
133 std::vector<CycleNode *> queue;
134 HashTable<CycleNode *, CycleNode *, uintptr_t, 4> discovered;
136 queue.push_back(from);
137 discovered.put(from, from);
138 while(!queue.empty()) {
139 CycleNode * node=queue.back();
144 for(unsigned int i=0;i<node->getEdges()->size();i++) {
145 CycleNode *next=(*node->getEdges())[i];
146 if (!discovered.contains(next)) {
147 discovered.put(next,next);
148 queue.push_back(next);
155 void CycleGraph::startChanges() {
156 ASSERT(rollbackvector.size()==0);
157 ASSERT(rmwrollbackvector.size()==0);
158 ASSERT(oldCycles==hasCycles);
159 ASSERT(oldRMWViolation==hasRMWViolation);
162 /** Commit changes to the cyclegraph. */
163 void CycleGraph::commitChanges() {
164 rollbackvector.resize(0);
165 rmwrollbackvector.resize(0);
167 oldRMWViolation=hasRMWViolation;
170 /** Rollback changes to the previous commit. */
171 void CycleGraph::rollbackChanges() {
172 for (unsigned int i = 0; i < rollbackvector.size(); i++) {
173 rollbackvector[i]->popEdge();
176 for (unsigned int i = 0; i < rmwrollbackvector.size(); i++) {
177 rmwrollbackvector[i]->clearRMW();
180 hasCycles = oldCycles;
181 hasRMWViolation = oldRMWViolation;
182 rollbackvector.resize(0);
183 rmwrollbackvector.resize(0);
186 /** @returns whether a CycleGraph contains cycles. */
187 bool CycleGraph::checkForCycles() {
191 bool CycleGraph::checkForRMWViolation() {
192 return hasRMWViolation;
196 * Constructor for a CycleNode.
197 * @param modelaction The ModelAction for this node
199 CycleNode::CycleNode(const ModelAction *modelaction) :
205 /** @returns a vector of the edges from a CycleNode. */
206 std::vector<CycleNode *> * CycleNode::getEdges() {
211 * Adds an edge from this CycleNode to another CycleNode.
212 * @param node The node to which we add a directed edge
214 void CycleNode::addEdge(CycleNode *node) {
215 edges.push_back(node);
218 /** @returns the RMW CycleNode that reads from the current CycleNode */
219 CycleNode * CycleNode::getRMW() {
224 * Set a RMW action node that reads from the current CycleNode.
225 * @param node The RMW that reads from the current node
226 * @return True, if this node already was read by another RMW; false otherwise
227 * @see CycleGraph::addRMWEdge
229 bool CycleNode::setRMW(CycleNode *node) {