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 tonode is also a rmw, don't do this check as the execution is
59 //doomed and we'll catch the problem elsewhere, but we want to allow
60 //for the possibility of sending to's write value to rmwnode
62 if (rmwnode!=NULL&&!to->is_rmw()) {
65 hasCycles=checkReachable(tonode, rmwnode);
67 rollbackvector.push_back(rmwnode);
68 rmwnode->addEdge(tonode);
72 /** Handles special case of a RMW action. The ModelAction rmw reads
73 * from the ModelAction from. The key differences are: (1) no write
74 * can occur in between the rmw and the from action. Only one RMW
75 * action can read from a given write.
77 void CycleGraph::addRMWEdge(const ModelAction *from, const ModelAction *rmw) {
81 CycleNode *fromnode=getNode(from);
82 CycleNode *rmwnode=getNode(rmw);
84 /* Two RMW actions cannot read from the same write. */
85 if (fromnode->setRMW(rmwnode)) {
88 rmwrollbackvector.push_back(fromnode);
91 /* Transfer all outgoing edges from the from node to the rmw node */
92 /* This process should not add a cycle because either:
93 * (1) The rmw should not have any incoming edges yet if it is the
95 * (2) the fromnode is the new node and therefore it should not
96 * have any outgoing edges.
98 std::vector<CycleNode *> * edges=fromnode->getEdges();
99 for(unsigned int i=0;i<edges->size();i++) {
100 CycleNode * tonode=(*edges)[i];
101 if (tonode!=rmwnode) {
102 rollbackvector.push_back(rmwnode);
103 rmwnode->addEdge(tonode);
106 rollbackvector.push_back(fromnode);
109 // With promises we could be setting up a cycle here if we aren't
110 // careful...avoid it..
111 hasCycles=checkReachable(rmwnode, fromnode);
113 fromnode->addEdge(rmwnode);
117 * Checks whether one ModelAction can reach another.
118 * @param from The ModelAction from which to begin exploration
119 * @param to The ModelAction to reach
120 * @return True, @a from can reach @a to; otherwise, false
122 bool CycleGraph::checkReachable(const ModelAction *from, const ModelAction *to) {
123 CycleNode *fromnode = actionToNode.get(from);
124 CycleNode *tonode = actionToNode.get(to);
126 if (!fromnode || !tonode)
129 return checkReachable(fromnode, tonode);
133 * Checks whether one CycleNode can reach another.
134 * @param from The CycleNode from which to begin exploration
135 * @param to The CycleNode to reach
136 * @return True, @a from can reach @a to; otherwise, false
138 bool CycleGraph::checkReachable(CycleNode *from, CycleNode *to) {
139 std::vector<CycleNode *> queue;
140 HashTable<CycleNode *, CycleNode *, uintptr_t, 4> discovered;
142 queue.push_back(from);
143 discovered.put(from, from);
144 while(!queue.empty()) {
145 CycleNode * node=queue.back();
150 for(unsigned int i=0;i<node->getEdges()->size();i++) {
151 CycleNode *next=(*node->getEdges())[i];
152 if (!discovered.contains(next)) {
153 discovered.put(next,next);
154 queue.push_back(next);
161 void CycleGraph::startChanges() {
162 ASSERT(rollbackvector.size()==0);
163 ASSERT(rmwrollbackvector.size()==0);
164 ASSERT(oldCycles==hasCycles);
165 ASSERT(oldRMWViolation==hasRMWViolation);
168 /** Commit changes to the cyclegraph. */
169 void CycleGraph::commitChanges() {
170 rollbackvector.resize(0);
171 rmwrollbackvector.resize(0);
173 oldRMWViolation=hasRMWViolation;
176 /** Rollback changes to the previous commit. */
177 void CycleGraph::rollbackChanges() {
178 for (unsigned int i = 0; i < rollbackvector.size(); i++) {
179 rollbackvector[i]->popEdge();
182 for (unsigned int i = 0; i < rmwrollbackvector.size(); i++) {
183 rmwrollbackvector[i]->clearRMW();
186 hasCycles = oldCycles;
187 hasRMWViolation = oldRMWViolation;
188 rollbackvector.resize(0);
189 rmwrollbackvector.resize(0);
192 /** @returns whether a CycleGraph contains cycles. */
193 bool CycleGraph::checkForCycles() {
197 bool CycleGraph::checkForRMWViolation() {
198 return hasRMWViolation;
202 * Constructor for a CycleNode.
203 * @param modelaction The ModelAction for this node
205 CycleNode::CycleNode(const ModelAction *modelaction) :
211 /** @returns a vector of the edges from a CycleNode. */
212 std::vector<CycleNode *> * CycleNode::getEdges() {
217 * Adds an edge from this CycleNode to another CycleNode.
218 * @param node The node to which we add a directed edge
220 void CycleNode::addEdge(CycleNode *node) {
221 edges.push_back(node);
224 /** @returns the RMW CycleNode that reads from the current CycleNode */
225 CycleNode * CycleNode::getRMW() {
230 * Set a RMW action node that reads from the current CycleNode.
231 * @param node The RMW that reads from the current node
232 * @return True, if this node already was read by another RMW; false otherwise
233 * @see CycleGraph::addRMWEdge
235 bool CycleNode::setRMW(CycleNode *node) {