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);
35 * Add a CycleNode to the graph, corresponding to a Promise
36 * @param promise The Promise that should be added
37 * @param node The CycleNode that corresponds to the Promise
39 void CycleGraph::putNode(const Promise *promise, CycleNode *node)
41 promiseToNode.put(promise, node);
42 #if SUPPORT_MOD_ORDER_DUMP
43 nodeList.push_back(node);
48 * @brief Remove the Promise node from the graph
49 * @param promise The promise to remove from the graph
51 void CycleGraph::erasePromiseNode(const Promise *promise)
53 promiseToNode.put(promise, NULL);
54 #if SUPPORT_MOD_ORDER_DUMP
55 /* Remove the promise node from nodeList */
56 CycleNode *node = getNode_noCreate(promise);
57 for (unsigned int i = 0; i < nodeList.size(); )
58 if (nodeList[i] == node)
59 nodeList.erase(nodeList.begin() + i);
65 /** @return The corresponding CycleNode, if exists; otherwise NULL */
66 CycleNode * CycleGraph::getNode_noCreate(const ModelAction *act) const
68 return actionToNode.get(act);
71 /** @return The corresponding CycleNode, if exists; otherwise NULL */
72 CycleNode * CycleGraph::getNode_noCreate(const Promise *promise) const
74 return promiseToNode.get(promise);
78 * @brief Returns the CycleNode corresponding to a given ModelAction
80 * Gets (or creates, if none exist) a CycleNode corresponding to a ModelAction
82 * @param action The ModelAction to find a node for
83 * @return The CycleNode paired with this action
85 CycleNode * CycleGraph::getNode(const ModelAction *action)
87 CycleNode *node = getNode_noCreate(action);
89 node = new CycleNode(action);
90 putNode(action, node);
96 * @brief Returns a CycleNode corresponding to a promise
98 * Gets (or creates, if none exist) a CycleNode corresponding to a promised
101 * @param promise The Promise generated by a reader
102 * @return The CycleNode corresponding to the Promise
104 CycleNode * CycleGraph::getNode(const Promise *promise)
106 CycleNode *node = getNode_noCreate(promise);
108 node = new CycleNode(promise);
109 putNode(promise, node);
115 * @return false if the resolution results in a cycle; true otherwise
117 bool CycleGraph::resolvePromise(const Promise *promise, ModelAction *writer,
118 promise_list_t *mustResolve)
120 CycleNode *promise_node = promiseToNode.get(promise);
121 CycleNode *w_node = actionToNode.get(writer);
122 ASSERT(promise_node);
125 return mergeNodes(w_node, promise_node, mustResolve);
126 /* No existing write-node; just convert the promise-node */
127 promise_node->resolvePromise(writer);
128 erasePromiseNode(promise_node->getPromise());
129 putNode(writer, promise_node);
134 * @brief Merge two CycleNodes that represent the same write
136 * Note that this operation cannot be rolled back.
138 * @param w_node The write ModelAction node with which to merge
139 * @param p_node The Promise node to merge. Will be destroyed after this
141 * @param mustMerge Return (pass-by-reference) any additional Promises that
142 * must also be merged with w_node
144 * @return false if the merge results in a cycle; true otherwise
146 bool CycleGraph::mergeNodes(CycleNode *w_node, CycleNode *p_node,
147 promise_list_t *mustMerge)
149 ASSERT(!w_node->is_promise());
150 ASSERT(p_node->is_promise());
152 const Promise *promise = p_node->getPromise();
153 if (!promise->is_compatible(w_node->getAction())) {
158 /* Transfer the RMW */
159 CycleNode *promise_rmw = p_node->getRMW();
160 if (promise_rmw && promise_rmw != w_node->getRMW() && w_node->setRMW(promise_rmw)) {
165 /* Transfer back edges to w_node */
166 while (p_node->getNumBackEdges() > 0) {
167 CycleNode *back = p_node->removeBackEdge();
170 if (back->is_promise()) {
171 if (checkReachable(w_node, back)) {
172 /* Edge would create cycle; merge instead */
173 mustMerge->push_back(back->getPromise());
174 if (!mergeNodes(w_node, back, mustMerge))
177 back->addEdge(w_node);
179 addNodeEdge(back, w_node);
182 /* Transfer forward edges to w_node */
183 while (p_node->getNumEdges() > 0) {
184 CycleNode *forward = p_node->removeEdge();
185 if (forward == w_node)
187 if (forward->is_promise()) {
188 if (checkReachable(forward, w_node)) {
189 mustMerge->push_back(forward->getPromise());
190 if (!mergeNodes(w_node, forward, mustMerge))
193 w_node->addEdge(forward);
195 addNodeEdge(w_node, forward);
198 erasePromiseNode(promise);
199 /* Not deleting p_node, to maintain consistency if mergeNodes() fails */
205 * Adds an edge between two CycleNodes.
206 * @param fromnode The edge comes from this CycleNode
207 * @param tonode The edge points to this CycleNode
208 * @return True, if new edge(s) are added; otherwise false
210 bool CycleGraph::addNodeEdge(CycleNode *fromnode, CycleNode *tonode)
215 hasCycles = checkReachable(tonode, fromnode);
217 if ((added = fromnode->addEdge(tonode)))
218 rollbackvector.push_back(fromnode);
221 * If the fromnode has a rmwnode that is not the tonode, we should add
222 * an edge between its rmwnode and the tonode
224 CycleNode *rmwnode = fromnode->getRMW();
225 if (rmwnode && rmwnode != tonode) {
227 hasCycles = checkReachable(tonode, rmwnode);
229 if (rmwnode->addEdge(tonode)) {
230 rollbackvector.push_back(rmwnode);
238 * @brief Add an edge between a write and the RMW which reads from it
240 * Handles special case of a RMW action, where the ModelAction rmw reads from
241 * the ModelAction/Promise from. The key differences are:
242 * (1) no write can occur in between the rmw and the from action.
243 * (2) Only one RMW action can read from a given write.
245 * @param from The edge comes from this ModelAction/Promise
246 * @param rmw The edge points to this ModelAction; this action must read from
247 * the ModelAction/Promise from
249 template <typename T>
250 void CycleGraph::addRMWEdge(const T *from, const ModelAction *rmw)
255 CycleNode *fromnode = getNode(from);
256 CycleNode *rmwnode = getNode(rmw);
258 /* Two RMW actions cannot read from the same write. */
259 if (fromnode->setRMW(rmwnode))
262 rmwrollbackvector.push_back(fromnode);
264 /* Transfer all outgoing edges from the from node to the rmw node */
265 /* This process should not add a cycle because either:
266 * (1) The rmw should not have any incoming edges yet if it is the
268 * (2) the fromnode is the new node and therefore it should not
269 * have any outgoing edges.
271 for (unsigned int i = 0; i < fromnode->getNumEdges(); i++) {
272 CycleNode *tonode = fromnode->getEdge(i);
273 if (tonode != rmwnode) {
274 if (rmwnode->addEdge(tonode))
275 rollbackvector.push_back(rmwnode);
279 addNodeEdge(fromnode, rmwnode);
281 /* Instantiate two forms of CycleGraph::addRMWEdge */
282 template void CycleGraph::addRMWEdge(const ModelAction *from, const ModelAction *rmw);
283 template void CycleGraph::addRMWEdge(const Promise *from, const ModelAction *rmw);
286 * @brief Adds an edge between objects
288 * This function will add an edge between any two objects which can be
289 * associated with a CycleNode. That is, if they have a CycleGraph::getNode
292 * The object to is ordered after the object from.
294 * @param to The edge points to this object, of type T
295 * @param from The edge comes from this object, of type U
296 * @return True, if new edge(s) are added; otherwise false
298 template <typename T, typename U>
299 bool CycleGraph::addEdge(const T *from, const U *to)
304 CycleNode *fromnode = getNode(from);
305 CycleNode *tonode = getNode(to);
307 return addNodeEdge(fromnode, tonode);
309 /* Instantiate four forms of CycleGraph::addEdge */
310 template bool CycleGraph::addEdge(const ModelAction *from, const ModelAction *to);
311 template bool CycleGraph::addEdge(const ModelAction *from, const Promise *to);
312 template bool CycleGraph::addEdge(const Promise *from, const ModelAction *to);
313 template bool CycleGraph::addEdge(const Promise *from, const Promise *to);
315 #if SUPPORT_MOD_ORDER_DUMP
317 static void print_node(const CycleNode *node, FILE *file, int label)
320 if (node->is_promise()) {
321 const Promise *promise = node->getPromise();
322 idx = promise->get_action()->get_seq_number();
323 fprintf(file, "P%u", idx);
326 fprintf(file, " [label=\"P%u, T", idx);
327 for (unsigned int i = 0 ; i < model->get_num_threads(); i++)
328 if (promise->thread_is_available(int_to_id(i))) {
329 fprintf(file, "%s%u", first ? "": ",", i);
332 fprintf(file, "\"]");
335 const ModelAction *act = node->getAction();
336 idx = act->get_seq_number();
337 fprintf(file, "N%u", idx);
339 fprintf(file, " [label=\"N%u, T%u\"]", idx, act->get_tid());
343 void CycleGraph::dumpNodes(FILE *file) const
345 for (unsigned int i = 0; i < nodeList.size(); i++) {
346 CycleNode *n = nodeList[i];
347 print_node(n, file, 1);
348 fprintf(file, ";\n");
349 if (n->getRMW() != NULL) {
350 print_node(n, file, 0);
351 fprintf(file, " -> ");
352 print_node(n->getRMW(), file, 0);
353 fprintf(file, "[style=dotted];\n");
355 for (unsigned int j = 0; j < n->getNumEdges(); j++) {
356 print_node(n, file, 0);
357 fprintf(file, " -> ");
358 print_node(n->getEdge(j), file, 0);
359 fprintf(file, ";\n");
364 void CycleGraph::dumpGraphToFile(const char *filename) const
367 sprintf(buffer, "%s.dot", filename);
368 FILE *file = fopen(buffer, "w");
369 fprintf(file, "digraph %s {\n", filename);
371 fprintf(file, "}\n");
377 * Checks whether one CycleNode can reach another.
378 * @param from The CycleNode from which to begin exploration
379 * @param to The CycleNode to reach
380 * @return True, @a from can reach @a to; otherwise, false
382 bool CycleGraph::checkReachable(const CycleNode *from, const CycleNode *to) const
384 std::vector< const CycleNode *, ModelAlloc<const CycleNode *> > queue;
387 queue.push_back(from);
388 discovered->put(from, from);
389 while (!queue.empty()) {
390 const CycleNode *node = queue.back();
395 for (unsigned int i = 0; i < node->getNumEdges(); i++) {
396 CycleNode *next = node->getEdge(i);
397 if (!discovered->contains(next)) {
398 discovered->put(next, next);
399 queue.push_back(next);
407 * Checks whether one ModelAction/Promise can reach another ModelAction/Promise
408 * @param from The ModelAction or Promise from which to begin exploration
409 * @param to The ModelAction or Promise to reach
410 * @return True, @a from can reach @a to; otherwise, false
412 template <typename T, typename U>
413 bool CycleGraph::checkReachable(const T *from, const U *to) const
415 CycleNode *fromnode = getNode_noCreate(from);
416 CycleNode *tonode = getNode_noCreate(to);
418 if (!fromnode || !tonode)
421 return checkReachable(fromnode, tonode);
423 /* Instantiate three forms of CycleGraph::checkReachable */
424 template bool CycleGraph::checkReachable(const ModelAction *from,
425 const ModelAction *to) const;
426 template bool CycleGraph::checkReachable(const ModelAction *from,
427 const Promise *to) const;
428 template bool CycleGraph::checkReachable(const Promise *from,
429 const ModelAction *to) const;
431 /** @return True, if the promise has failed; false otherwise */
432 bool CycleGraph::checkPromise(const ModelAction *fromact, Promise *promise) const
434 std::vector< CycleNode *, ModelAlloc<CycleNode *> > queue;
436 CycleNode *from = actionToNode.get(fromact);
438 queue.push_back(from);
439 discovered->put(from, from);
440 while (!queue.empty()) {
441 CycleNode *node = queue.back();
444 if (node->getPromise() == promise)
446 if (!node->is_promise() &&
447 promise->eliminate_thread(node->getAction()->get_tid()))
450 for (unsigned int i = 0; i < node->getNumEdges(); i++) {
451 CycleNode *next = node->getEdge(i);
452 if (!discovered->contains(next)) {
453 discovered->put(next, next);
454 queue.push_back(next);
461 void CycleGraph::startChanges()
463 ASSERT(rollbackvector.empty());
464 ASSERT(rmwrollbackvector.empty());
465 ASSERT(oldCycles == hasCycles);
468 /** Commit changes to the cyclegraph. */
469 void CycleGraph::commitChanges()
471 rollbackvector.clear();
472 rmwrollbackvector.clear();
473 oldCycles = hasCycles;
476 /** Rollback changes to the previous commit. */
477 void CycleGraph::rollbackChanges()
479 for (unsigned int i = 0; i < rollbackvector.size(); i++)
480 rollbackvector[i]->removeEdge();
482 for (unsigned int i = 0; i < rmwrollbackvector.size(); i++)
483 rmwrollbackvector[i]->clearRMW();
485 hasCycles = oldCycles;
486 rollbackvector.clear();
487 rmwrollbackvector.clear();
490 /** @returns whether a CycleGraph contains cycles. */
491 bool CycleGraph::checkForCycles() const
497 * @brief Constructor for a CycleNode
498 * @param act The ModelAction for this node
500 CycleNode::CycleNode(const ModelAction *act) :
508 * @brief Constructor for a Promise CycleNode
509 * @param promise The Promise which was generated
511 CycleNode::CycleNode(const Promise *promise) :
519 * @param i The index of the edge to return
520 * @returns The a CycleNode edge indexed by i
522 CycleNode * CycleNode::getEdge(unsigned int i) const
527 /** @returns The number of edges leaving this CycleNode */
528 unsigned int CycleNode::getNumEdges() const
533 CycleNode * CycleNode::getBackEdge(unsigned int i) const
535 return back_edges[i];
538 unsigned int CycleNode::getNumBackEdges() const
540 return back_edges.size();
544 * @brief Remove an element from a vector
545 * @param v The vector
546 * @param n The element to remove
547 * @return True if the element was found; false otherwise
549 template <typename T>
550 static bool vector_remove_node(std::vector<T, SnapshotAlloc<T> >& v, const T n)
552 for (unsigned int i = 0; i < v.size(); i++) {
554 v.erase(v.begin() + i);
562 * @brief Remove a (forward) edge from this CycleNode
563 * @return The CycleNode which was popped, if one exists; otherwise NULL
565 CycleNode * CycleNode::removeEdge()
570 CycleNode *ret = edges.back();
572 vector_remove_node(ret->back_edges, this);
577 * @brief Remove a (back) edge from this CycleNode
578 * @return The CycleNode which was popped, if one exists; otherwise NULL
580 CycleNode * CycleNode::removeBackEdge()
582 if (back_edges.empty())
585 CycleNode *ret = back_edges.back();
586 back_edges.pop_back();
587 vector_remove_node(ret->edges, this);
592 * Adds an edge from this CycleNode to another CycleNode.
593 * @param node The node to which we add a directed edge
594 * @return True if this edge is a new edge; false otherwise
596 bool CycleNode::addEdge(CycleNode *node)
598 for (unsigned int i = 0; i < edges.size(); i++)
599 if (edges[i] == node)
601 edges.push_back(node);
602 node->back_edges.push_back(this);
606 /** @returns the RMW CycleNode that reads from the current CycleNode */
607 CycleNode * CycleNode::getRMW() const
613 * Set a RMW action node that reads from the current CycleNode.
614 * @param node The RMW that reads from the current node
615 * @return True, if this node already was read by another RMW; false otherwise
616 * @see CycleGraph::addRMWEdge
618 bool CycleNode::setRMW(CycleNode *node)
627 * Convert a Promise CycleNode into a concrete-valued CycleNode. Should only be
628 * used when there's no existing ModelAction CycleNode for this write.
630 * @param writer The ModelAction which wrote the future value represented by
633 void CycleNode::resolvePromise(const ModelAction *writer)
635 ASSERT(is_promise());
636 ASSERT(promise->is_compatible(writer));
639 ASSERT(!is_promise());