1 #include "cyclegraph.h"
7 /** Initializes a CycleGraph object. */
8 CycleGraph::CycleGraph() :
9 discovered(new HashTable<const CycleNode *, const CycleNode *, uintptr_t, 4, model_malloc, model_calloc, model_free>(16)),
15 /** CycleGraph destructor */
16 CycleGraph::~CycleGraph()
22 * Add a CycleNode to the graph, corresponding to a store ModelAction
23 * @param act The write action that should be added
24 * @param node The CycleNode that corresponds to the store
26 void CycleGraph::putNode(const ModelAction *act, CycleNode *node)
28 actionToNode.put(act, node);
29 #if SUPPORT_MOD_ORDER_DUMP
30 nodeList.push_back(node);
34 /** @return The corresponding CycleNode, if exists; otherwise NULL */
35 CycleNode * CycleGraph::getNode_noCreate(const ModelAction *act) const
37 return actionToNode.get(act);
40 /** @return The corresponding CycleNode, if exists; otherwise NULL */
41 CycleNode * CycleGraph::getNode_noCreate(const Promise *promise) const
43 return readerToPromiseNode.get(promise->get_action());
47 * @brief Returns the CycleNode corresponding to a given ModelAction
49 * Gets (or creates, if none exist) a CycleNode corresponding to a ModelAction
51 * @param action The ModelAction to find a node for
52 * @return The CycleNode paired with this action
54 CycleNode * CycleGraph::getNode(const ModelAction *action)
56 CycleNode *node = getNode_noCreate(action);
58 node = new CycleNode(action);
59 putNode(action, node);
65 * @brief Returns a CycleNode corresponding to a promise
67 * Gets (or creates, if none exist) a CycleNode corresponding to a promised
70 * @param promise The Promise generated by a reader
71 * @return The CycleNode corresponding to the Promise
73 CycleNode * CycleGraph::getNode(const Promise *promise)
75 const ModelAction *reader = promise->get_action();
76 CycleNode *node = getNode_noCreate(promise);
78 node = new CycleNode(promise);
79 readerToPromiseNode.put(reader, node);
85 * @return false if the resolution results in a cycle; true otherwise
87 bool CycleGraph::resolvePromise(ModelAction *reader, ModelAction *writer,
88 promise_list_t *mustResolve)
90 CycleNode *promise_node = readerToPromiseNode.get(reader);
91 CycleNode *w_node = actionToNode.get(writer);
95 return mergeNodes(w_node, promise_node, mustResolve);
96 /* No existing write-node; just convert the promise-node */
97 promise_node->resolvePromise(writer);
98 readerToPromiseNode.put(reader, NULL); /* erase promise_node */
99 putNode(writer, promise_node);
104 * @brief Merge two CycleNodes that represent the same write
106 * Note that this operation cannot be rolled back.
108 * @param w_node The write ModelAction node with which to merge
109 * @param p_node The Promise node to merge. Will be destroyed after this
111 * @param mustMerge Return (pass-by-reference) any additional Promises that
112 * must also be merged with w_node
114 * @return false if the merge results in a cycle; true otherwise
116 bool CycleGraph::mergeNodes(CycleNode *w_node, CycleNode *p_node,
117 promise_list_t *mustMerge)
119 ASSERT(!w_node->is_promise());
120 ASSERT(p_node->is_promise());
122 const Promise *promise = p_node->getPromise();
123 if (!promise->is_compatible(w_node->getAction())) {
128 /* Transfer the RMW */
129 CycleNode *promise_rmw = p_node->getRMW();
130 if (promise_rmw && promise_rmw != w_node->getRMW() && w_node->setRMW(promise_rmw))
133 /* Transfer back edges to w_node */
134 while (p_node->getNumBackEdges() > 0) {
135 CycleNode *back = p_node->removeBackEdge();
136 if (back != w_node) {
137 if (back->is_promise()) {
138 if (checkReachable(w_node, back)) {
139 /* Edge would create cycle; merge instead */
140 mustMerge->push_back(back->getPromise());
141 if (!mergeNodes(w_node, back, mustMerge))
144 back->addEdge(w_node);
146 addNodeEdge(back, w_node);
150 /* Transfer forward edges to w_node */
151 while (p_node->getNumEdges() > 0) {
152 CycleNode *forward = p_node->removeEdge();
153 if (forward != w_node) {
154 if (forward->is_promise()) {
155 if (checkReachable(forward, w_node)) {
156 mustMerge->push_back(forward->getPromise());
157 if (!mergeNodes(w_node, forward, mustMerge))
160 w_node->addEdge(forward);
162 addNodeEdge(w_node, forward);
167 readerToPromiseNode.put(promise->get_action(), NULL);
174 * Adds an edge between two CycleNodes.
175 * @param fromnode The edge comes from this CycleNode
176 * @param tonode The edge points to this CycleNode
177 * @return True, if new edge(s) are added; otherwise false
179 bool CycleGraph::addNodeEdge(CycleNode *fromnode, CycleNode *tonode)
184 hasCycles = checkReachable(tonode, fromnode);
186 if ((added = fromnode->addEdge(tonode)))
187 rollbackvector.push_back(fromnode);
190 * If the fromnode has a rmwnode that is not the tonode, we should add
191 * an edge between its rmwnode and the tonode
193 CycleNode *rmwnode = fromnode->getRMW();
194 if (rmwnode && rmwnode != tonode) {
196 hasCycles = checkReachable(tonode, rmwnode);
198 if (rmwnode->addEdge(tonode)) {
199 rollbackvector.push_back(rmwnode);
207 * @brief Add an edge between a write and the RMW which reads from it
209 * Handles special case of a RMW action, where the ModelAction rmw reads from
210 * the ModelAction/Promise from. The key differences are:
211 * (1) no write can occur in between the rmw and the from action.
212 * (2) Only one RMW action can read from a given write.
214 * @param from The edge comes from this ModelAction/Promise
215 * @param rmw The edge points to this ModelAction; this action must read from
216 * the ModelAction/Promise from
218 template <typename T>
219 void CycleGraph::addRMWEdge(const T *from, const ModelAction *rmw)
224 CycleNode *fromnode = getNode(from);
225 CycleNode *rmwnode = getNode(rmw);
227 /* Two RMW actions cannot read from the same write. */
228 if (fromnode->setRMW(rmwnode))
231 rmwrollbackvector.push_back(fromnode);
233 /* Transfer all outgoing edges from the from node to the rmw node */
234 /* This process should not add a cycle because either:
235 * (1) The rmw should not have any incoming edges yet if it is the
237 * (2) the fromnode is the new node and therefore it should not
238 * have any outgoing edges.
240 for (unsigned int i = 0; i < fromnode->getNumEdges(); i++) {
241 CycleNode *tonode = fromnode->getEdge(i);
242 if (tonode != rmwnode) {
243 if (rmwnode->addEdge(tonode))
244 rollbackvector.push_back(rmwnode);
248 addNodeEdge(fromnode, rmwnode);
250 /* Instantiate two forms of CycleGraph::addRMWEdge */
251 template void CycleGraph::addRMWEdge(const ModelAction *from, const ModelAction *rmw);
252 template void CycleGraph::addRMWEdge(const Promise *from, const ModelAction *rmw);
255 * @brief Adds an edge between objects
257 * This function will add an edge between any two objects which can be
258 * associated with a CycleNode. That is, if they have a CycleGraph::getNode
261 * The object to is ordered after the object from.
263 * @param to The edge points to this object, of type T
264 * @param from The edge comes from this object, of type U
265 * @return True, if new edge(s) are added; otherwise false
267 template <typename T, typename U>
268 bool CycleGraph::addEdge(const T *from, const U *to)
273 CycleNode *fromnode = getNode(from);
274 CycleNode *tonode = getNode(to);
276 return addNodeEdge(fromnode, tonode);
278 /* Instantiate three forms of CycleGraph::addEdge */
279 template bool CycleGraph::addEdge(const ModelAction *from, const ModelAction *to);
280 template bool CycleGraph::addEdge(const ModelAction *from, const Promise *to);
281 template bool CycleGraph::addEdge(const Promise *from, const ModelAction *to);
283 #if SUPPORT_MOD_ORDER_DUMP
284 void CycleGraph::dumpNodes(FILE *file) const
286 for (unsigned int i = 0; i < nodeList.size(); i++) {
287 CycleNode *cn = nodeList[i];
288 const ModelAction *action = cn->getAction();
289 fprintf(file, "N%u [label=\"%u, T%u\"];\n", action->get_seq_number(), action->get_seq_number(), action->get_tid());
290 if (cn->getRMW() != NULL) {
291 fprintf(file, "N%u -> N%u[style=dotted];\n", action->get_seq_number(), cn->getRMW()->getAction()->get_seq_number());
293 for (unsigned int j = 0; j < cn->getNumEdges(); j++) {
294 CycleNode *dst = cn->getEdge(j);
295 const ModelAction *dstaction = dst->getAction();
296 fprintf(file, "N%u -> N%u;\n", action->get_seq_number(), dstaction->get_seq_number());
301 void CycleGraph::dumpGraphToFile(const char *filename) const
304 sprintf(buffer, "%s.dot", filename);
305 FILE *file = fopen(buffer, "w");
306 fprintf(file, "digraph %s {\n", filename);
308 fprintf(file, "}\n");
314 * Checks whether one CycleNode can reach another.
315 * @param from The CycleNode from which to begin exploration
316 * @param to The CycleNode to reach
317 * @return True, @a from can reach @a to; otherwise, false
319 bool CycleGraph::checkReachable(const CycleNode *from, const CycleNode *to) const
321 std::vector< const CycleNode *, ModelAlloc<const CycleNode *> > queue;
324 queue.push_back(from);
325 discovered->put(from, from);
326 while (!queue.empty()) {
327 const CycleNode *node = queue.back();
332 for (unsigned int i = 0; i < node->getNumEdges(); i++) {
333 CycleNode *next = node->getEdge(i);
334 if (!discovered->contains(next)) {
335 discovered->put(next, next);
336 queue.push_back(next);
344 * Checks whether one ModelAction can reach another ModelAction/Promise
345 * @param from The ModelAction from which to begin exploration
346 * @param to The ModelAction or Promise to reach
347 * @return True, @a from can reach @a to; otherwise, false
349 template <typename T>
350 bool CycleGraph::checkReachable(const ModelAction *from, const T *to) const
352 CycleNode *fromnode = getNode_noCreate(from);
353 CycleNode *tonode = getNode_noCreate(to);
355 if (!fromnode || !tonode)
358 return checkReachable(fromnode, tonode);
360 /* Instantiate two forms of CycleGraph::checkReachable */
361 template bool CycleGraph::checkReachable(const ModelAction *from,
362 const ModelAction *to) const;
363 template bool CycleGraph::checkReachable(const ModelAction *from,
364 const Promise *to) const;
366 /** @return True, if the promise has failed; false otherwise */
367 bool CycleGraph::checkPromise(const ModelAction *fromact, Promise *promise) const
369 std::vector< CycleNode *, ModelAlloc<CycleNode *> > queue;
371 CycleNode *from = actionToNode.get(fromact);
373 queue.push_back(from);
374 discovered->put(from, from);
375 while (!queue.empty()) {
376 CycleNode *node = queue.back();
379 if (!node->is_promise() &&
380 promise->eliminate_thread(node->getAction()->get_tid()))
383 for (unsigned int i = 0; i < node->getNumEdges(); i++) {
384 CycleNode *next = node->getEdge(i);
385 if (!discovered->contains(next)) {
386 discovered->put(next, next);
387 queue.push_back(next);
394 void CycleGraph::startChanges()
396 ASSERT(rollbackvector.empty());
397 ASSERT(rmwrollbackvector.empty());
398 ASSERT(oldCycles == hasCycles);
401 /** Commit changes to the cyclegraph. */
402 void CycleGraph::commitChanges()
404 rollbackvector.clear();
405 rmwrollbackvector.clear();
406 oldCycles = hasCycles;
409 /** Rollback changes to the previous commit. */
410 void CycleGraph::rollbackChanges()
412 for (unsigned int i = 0; i < rollbackvector.size(); i++)
413 rollbackvector[i]->removeEdge();
415 for (unsigned int i = 0; i < rmwrollbackvector.size(); i++)
416 rmwrollbackvector[i]->clearRMW();
418 hasCycles = oldCycles;
419 rollbackvector.clear();
420 rmwrollbackvector.clear();
423 /** @returns whether a CycleGraph contains cycles. */
424 bool CycleGraph::checkForCycles() const
430 * @brief Constructor for a CycleNode
431 * @param act The ModelAction for this node
433 CycleNode::CycleNode(const ModelAction *act) :
441 * @brief Constructor for a Promise CycleNode
442 * @param promise The Promise which was generated
444 CycleNode::CycleNode(const Promise *promise) :
452 * @param i The index of the edge to return
453 * @returns The a CycleNode edge indexed by i
455 CycleNode * CycleNode::getEdge(unsigned int i) const
460 /** @returns The number of edges leaving this CycleNode */
461 unsigned int CycleNode::getNumEdges() const
466 CycleNode * CycleNode::getBackEdge(unsigned int i) const
468 return back_edges[i];
471 unsigned int CycleNode::getNumBackEdges() const
473 return back_edges.size();
477 * @brief Remove an element from a vector
478 * @param v The vector
479 * @param n The element to remove
480 * @return True if the element was found; false otherwise
482 template <typename T>
483 static bool vector_remove_node(std::vector<T, SnapshotAlloc<T> >& v, const T n)
485 for (unsigned int i = 0; i < v.size(); i++) {
487 v.erase(v.begin() + i);
495 * @brief Remove a (forward) edge from this CycleNode
496 * @return The CycleNode which was popped, if one exists; otherwise NULL
498 CycleNode * CycleNode::removeEdge()
503 CycleNode *ret = edges.back();
505 vector_remove_node(ret->back_edges, this);
510 * @brief Remove a (back) edge from this CycleNode
511 * @return The CycleNode which was popped, if one exists; otherwise NULL
513 CycleNode * CycleNode::removeBackEdge()
515 if (back_edges.empty())
518 CycleNode *ret = back_edges.back();
519 back_edges.pop_back();
520 vector_remove_node(ret->edges, this);
525 * Adds an edge from this CycleNode to another CycleNode.
526 * @param node The node to which we add a directed edge
527 * @return True if this edge is a new edge; false otherwise
529 bool CycleNode::addEdge(CycleNode *node)
531 for (unsigned int i = 0; i < edges.size(); i++)
532 if (edges[i] == node)
534 edges.push_back(node);
535 node->back_edges.push_back(this);
539 /** @returns the RMW CycleNode that reads from the current CycleNode */
540 CycleNode * CycleNode::getRMW() const
546 * Set a RMW action node that reads from the current CycleNode.
547 * @param node The RMW that reads from the current node
548 * @return True, if this node already was read by another RMW; false otherwise
549 * @see CycleGraph::addRMWEdge
551 bool CycleNode::setRMW(CycleNode *node)
560 * Convert a Promise CycleNode into a concrete-valued CycleNode. Should only be
561 * used when there's no existing ModelAction CycleNode for this write.
563 * @param writer The ModelAction which wrote the future value represented by
566 void CycleNode::resolvePromise(const ModelAction *writer)
568 ASSERT(is_promise());
569 ASSERT(promise->is_compatible(writer));
572 ASSERT(!is_promise());