1 #include "cyclegraph.h"
6 #include "threads-model.h"
8 /** Initializes a CycleGraph object. */
9 CycleGraph::CycleGraph() :
10 discovered(new HashTable<const CycleNode *, const CycleNode *, uintptr_t, 4, model_malloc, model_calloc, model_free>(16)),
16 /** CycleGraph destructor */
17 CycleGraph::~CycleGraph()
23 * Add a CycleNode to the graph, corresponding to a store ModelAction
24 * @param act The write action that should be added
25 * @param node The CycleNode that corresponds to the store
27 void CycleGraph::putNode(const ModelAction *act, CycleNode *node)
29 actionToNode.put(act, node);
30 #if SUPPORT_MOD_ORDER_DUMP
31 nodeList.push_back(node);
36 * Add a CycleNode to the graph, corresponding to a Promise
37 * @param promise The Promise that should be added
38 * @param node The CycleNode that corresponds to the Promise
40 void CycleGraph::putNode(const Promise *promise, CycleNode *node)
42 promiseToNode.put(promise, node);
43 #if SUPPORT_MOD_ORDER_DUMP
44 nodeList.push_back(node);
49 * @brief Remove the Promise node from the graph
50 * @param promise The promise to remove from the graph
52 void CycleGraph::erasePromiseNode(const Promise *promise)
54 promiseToNode.put(promise, NULL);
55 #if SUPPORT_MOD_ORDER_DUMP
56 /* Remove the promise node from nodeList */
57 CycleNode *node = getNode_noCreate(promise);
58 for (unsigned int i = 0; i < nodeList.size(); )
59 if (nodeList[i] == node)
60 nodeList.erase(nodeList.begin() + i);
66 /** @return The corresponding CycleNode, if exists; otherwise NULL */
67 CycleNode * CycleGraph::getNode_noCreate(const ModelAction *act) const
69 return actionToNode.get(act);
72 /** @return The corresponding CycleNode, if exists; otherwise NULL */
73 CycleNode * CycleGraph::getNode_noCreate(const Promise *promise) const
75 return promiseToNode.get(promise);
79 * @brief Returns the CycleNode corresponding to a given ModelAction
81 * Gets (or creates, if none exist) a CycleNode corresponding to a ModelAction
83 * @param action The ModelAction to find a node for
84 * @return The CycleNode paired with this action
86 CycleNode * CycleGraph::getNode(const ModelAction *action)
88 CycleNode *node = getNode_noCreate(action);
90 node = new CycleNode(action);
91 putNode(action, node);
97 * @brief Returns a CycleNode corresponding to a promise
99 * Gets (or creates, if none exist) a CycleNode corresponding to a promised
102 * @param promise The Promise generated by a reader
103 * @return The CycleNode corresponding to the Promise
105 CycleNode * CycleGraph::getNode(const Promise *promise)
107 CycleNode *node = getNode_noCreate(promise);
109 node = new CycleNode(promise);
110 putNode(promise, node);
116 * @return false if the resolution results in a cycle; true otherwise
118 bool CycleGraph::resolvePromise(const Promise *promise, ModelAction *writer,
119 promise_list_t *mustResolve)
121 CycleNode *promise_node = promiseToNode.get(promise);
122 CycleNode *w_node = actionToNode.get(writer);
123 ASSERT(promise_node);
126 return mergeNodes(w_node, promise_node, mustResolve);
127 /* No existing write-node; just convert the promise-node */
128 promise_node->resolvePromise(writer);
129 erasePromiseNode(promise_node->getPromise());
130 putNode(writer, promise_node);
135 * @brief Merge two CycleNodes that represent the same write
137 * Note that this operation cannot be rolled back.
139 * @param w_node The write ModelAction node with which to merge
140 * @param p_node The Promise node to merge. Will be destroyed after this
142 * @param mustMerge Return (pass-by-reference) any additional Promises that
143 * must also be merged with w_node
145 * @return false if the merge results in a cycle; true otherwise
147 bool CycleGraph::mergeNodes(CycleNode *w_node, CycleNode *p_node,
148 promise_list_t *mustMerge)
150 ASSERT(!w_node->is_promise());
151 ASSERT(p_node->is_promise());
153 const Promise *promise = p_node->getPromise();
154 if (!promise->is_compatible(w_node->getAction()) ||
155 !promise->same_value(w_node->getAction())) {
160 /* Transfer the RMW */
161 CycleNode *promise_rmw = p_node->getRMW();
162 if (promise_rmw && promise_rmw != w_node->getRMW() && w_node->setRMW(promise_rmw)) {
167 /* Transfer back edges to w_node */
168 while (p_node->getNumBackEdges() > 0) {
169 CycleNode *back = p_node->removeBackEdge();
172 if (back->is_promise()) {
173 if (checkReachable(w_node, back)) {
174 /* Edge would create cycle; merge instead */
175 mustMerge->push_back(back->getPromise());
176 if (!mergeNodes(w_node, back, mustMerge))
179 back->addEdge(w_node);
181 addNodeEdge(back, w_node);
184 /* Transfer forward edges to w_node */
185 while (p_node->getNumEdges() > 0) {
186 CycleNode *forward = p_node->removeEdge();
187 if (forward == w_node)
189 if (forward->is_promise()) {
190 if (checkReachable(forward, w_node)) {
191 mustMerge->push_back(forward->getPromise());
192 if (!mergeNodes(w_node, forward, mustMerge))
195 w_node->addEdge(forward);
197 addNodeEdge(w_node, forward);
200 erasePromiseNode(promise);
201 /* Not deleting p_node, to maintain consistency if mergeNodes() fails */
207 * Adds an edge between two CycleNodes.
208 * @param fromnode The edge comes from this CycleNode
209 * @param tonode The edge points to this CycleNode
210 * @return True, if new edge(s) are added; otherwise false
212 bool CycleGraph::addNodeEdge(CycleNode *fromnode, CycleNode *tonode)
217 hasCycles = checkReachable(tonode, fromnode);
219 if ((added = fromnode->addEdge(tonode)))
220 rollbackvector.push_back(fromnode);
223 * If the fromnode has a rmwnode that is not the tonode, we should add
224 * an edge between its rmwnode and the tonode
226 CycleNode *rmwnode = fromnode->getRMW();
227 if (rmwnode && rmwnode != tonode) {
229 hasCycles = checkReachable(tonode, rmwnode);
231 if (rmwnode->addEdge(tonode)) {
232 rollbackvector.push_back(rmwnode);
240 * @brief Add an edge between a write and the RMW which reads from it
242 * Handles special case of a RMW action, where the ModelAction rmw reads from
243 * the ModelAction/Promise from. The key differences are:
244 * (1) no write can occur in between the rmw and the from action.
245 * (2) Only one RMW action can read from a given write.
247 * @param from The edge comes from this ModelAction/Promise
248 * @param rmw The edge points to this ModelAction; this action must read from
249 * the ModelAction/Promise from
251 template <typename T>
252 void CycleGraph::addRMWEdge(const T *from, const ModelAction *rmw)
257 CycleNode *fromnode = getNode(from);
258 CycleNode *rmwnode = getNode(rmw);
260 /* Two RMW actions cannot read from the same write. */
261 if (fromnode->setRMW(rmwnode))
264 rmwrollbackvector.push_back(fromnode);
266 /* Transfer all outgoing edges from the from node to the rmw node */
267 /* This process should not add a cycle because either:
268 * (1) The rmw should not have any incoming edges yet if it is the
270 * (2) the fromnode is the new node and therefore it should not
271 * have any outgoing edges.
273 for (unsigned int i = 0; i < fromnode->getNumEdges(); i++) {
274 CycleNode *tonode = fromnode->getEdge(i);
275 if (tonode != rmwnode) {
276 if (rmwnode->addEdge(tonode))
277 rollbackvector.push_back(rmwnode);
281 addNodeEdge(fromnode, rmwnode);
283 /* Instantiate two forms of CycleGraph::addRMWEdge */
284 template void CycleGraph::addRMWEdge(const ModelAction *from, const ModelAction *rmw);
285 template void CycleGraph::addRMWEdge(const Promise *from, const ModelAction *rmw);
288 * @brief Adds an edge between objects
290 * This function will add an edge between any two objects which can be
291 * associated with a CycleNode. That is, if they have a CycleGraph::getNode
294 * The object to is ordered after the object from.
296 * @param to The edge points to this object, of type T
297 * @param from The edge comes from this object, of type U
298 * @return True, if new edge(s) are added; otherwise false
300 template <typename T, typename U>
301 bool CycleGraph::addEdge(const T *from, const U *to)
306 CycleNode *fromnode = getNode(from);
307 CycleNode *tonode = getNode(to);
309 return addNodeEdge(fromnode, tonode);
311 /* Instantiate four forms of CycleGraph::addEdge */
312 template bool CycleGraph::addEdge(const ModelAction *from, const ModelAction *to);
313 template bool CycleGraph::addEdge(const ModelAction *from, const Promise *to);
314 template bool CycleGraph::addEdge(const Promise *from, const ModelAction *to);
315 template bool CycleGraph::addEdge(const Promise *from, const Promise *to);
317 #if SUPPORT_MOD_ORDER_DUMP
319 static void print_node(FILE *file, const CycleNode *node, int label)
321 if (node->is_promise()) {
322 const Promise *promise = node->getPromise();
323 int idx = model->get_promise_number(promise);
324 fprintf(file, "P%u", idx);
327 fprintf(file, " [label=\"P%d, T", idx);
328 for (unsigned int i = 0 ; i < model->get_num_threads(); i++)
329 if (promise->thread_is_available(int_to_id(i))) {
330 fprintf(file, "%s%u", first ? "": ",", i);
333 fprintf(file, "\"]");
336 const ModelAction *act = node->getAction();
337 modelclock_t idx = act->get_seq_number();
338 fprintf(file, "N%u", idx);
340 fprintf(file, " [label=\"N%u, T%u\"]", idx, act->get_tid());
344 static void print_edge(FILE *file, const CycleNode *from, const CycleNode *to, const char *prop)
346 print_node(file, from, 0);
347 fprintf(file, " -> ");
348 print_node(file, to, 0);
349 if (prop && strlen(prop))
350 fprintf(file, " [%s]", prop);
351 fprintf(file, ";\n");
354 void CycleGraph::dot_print_node(FILE *file, const ModelAction *act)
356 print_node(file, getNode(act), 1);
359 template <typename T, typename U>
360 void CycleGraph::dot_print_edge(FILE *file, const T *from, const U *to, const char *prop)
362 CycleNode *fromnode = getNode(from);
363 CycleNode *tonode = getNode(to);
365 print_edge(file, fromnode, tonode, prop);
367 /* Instantiate two forms of CycleGraph::dot_print_edge */
368 template void CycleGraph::dot_print_edge(FILE *file, const Promise *from, const ModelAction *to, const char *prop);
369 template void CycleGraph::dot_print_edge(FILE *file, const ModelAction *from, const ModelAction *to, const char *prop);
371 void CycleGraph::dumpNodes(FILE *file) const
373 for (unsigned int i = 0; i < nodeList.size(); i++) {
374 CycleNode *n = nodeList[i];
375 print_node(file, n, 1);
376 fprintf(file, ";\n");
378 print_edge(file, n, n->getRMW(), "style=dotted");
379 for (unsigned int j = 0; j < n->getNumEdges(); j++)
380 print_edge(file, n, n->getEdge(j), NULL);
384 void CycleGraph::dumpGraphToFile(const char *filename) const
387 sprintf(buffer, "%s.dot", filename);
388 FILE *file = fopen(buffer, "w");
389 fprintf(file, "digraph %s {\n", filename);
391 fprintf(file, "}\n");
397 * Checks whether one CycleNode can reach another.
398 * @param from The CycleNode from which to begin exploration
399 * @param to The CycleNode to reach
400 * @return True, @a from can reach @a to; otherwise, false
402 bool CycleGraph::checkReachable(const CycleNode *from, const CycleNode *to) const
404 std::vector< const CycleNode *, ModelAlloc<const CycleNode *> > queue;
407 queue.push_back(from);
408 discovered->put(from, from);
409 while (!queue.empty()) {
410 const CycleNode *node = queue.back();
415 for (unsigned int i = 0; i < node->getNumEdges(); i++) {
416 CycleNode *next = node->getEdge(i);
417 if (!discovered->contains(next)) {
418 discovered->put(next, next);
419 queue.push_back(next);
427 * Checks whether one ModelAction/Promise can reach another ModelAction/Promise
428 * @param from The ModelAction or Promise from which to begin exploration
429 * @param to The ModelAction or Promise to reach
430 * @return True, @a from can reach @a to; otherwise, false
432 template <typename T, typename U>
433 bool CycleGraph::checkReachable(const T *from, const U *to) const
435 CycleNode *fromnode = getNode_noCreate(from);
436 CycleNode *tonode = getNode_noCreate(to);
438 if (!fromnode || !tonode)
441 return checkReachable(fromnode, tonode);
443 /* Instantiate three forms of CycleGraph::checkReachable */
444 template bool CycleGraph::checkReachable(const ModelAction *from,
445 const ModelAction *to) const;
446 template bool CycleGraph::checkReachable(const ModelAction *from,
447 const Promise *to) const;
448 template bool CycleGraph::checkReachable(const Promise *from,
449 const ModelAction *to) const;
451 /** @return True, if the promise has failed; false otherwise */
452 bool CycleGraph::checkPromise(const ModelAction *fromact, Promise *promise) const
454 std::vector< CycleNode *, ModelAlloc<CycleNode *> > queue;
456 CycleNode *from = actionToNode.get(fromact);
458 queue.push_back(from);
459 discovered->put(from, from);
460 while (!queue.empty()) {
461 CycleNode *node = queue.back();
464 if (node->getPromise() == promise)
466 if (!node->is_promise() &&
467 promise->eliminate_thread(node->getAction()->get_tid()))
470 for (unsigned int i = 0; i < node->getNumEdges(); i++) {
471 CycleNode *next = node->getEdge(i);
472 if (!discovered->contains(next)) {
473 discovered->put(next, next);
474 queue.push_back(next);
481 void CycleGraph::startChanges()
483 ASSERT(rollbackvector.empty());
484 ASSERT(rmwrollbackvector.empty());
485 ASSERT(oldCycles == hasCycles);
488 /** Commit changes to the cyclegraph. */
489 void CycleGraph::commitChanges()
491 rollbackvector.clear();
492 rmwrollbackvector.clear();
493 oldCycles = hasCycles;
496 /** Rollback changes to the previous commit. */
497 void CycleGraph::rollbackChanges()
499 for (unsigned int i = 0; i < rollbackvector.size(); i++)
500 rollbackvector[i]->removeEdge();
502 for (unsigned int i = 0; i < rmwrollbackvector.size(); i++)
503 rmwrollbackvector[i]->clearRMW();
505 hasCycles = oldCycles;
506 rollbackvector.clear();
507 rmwrollbackvector.clear();
510 /** @returns whether a CycleGraph contains cycles. */
511 bool CycleGraph::checkForCycles() const
517 * @brief Constructor for a CycleNode
518 * @param act The ModelAction for this node
520 CycleNode::CycleNode(const ModelAction *act) :
528 * @brief Constructor for a Promise CycleNode
529 * @param promise The Promise which was generated
531 CycleNode::CycleNode(const Promise *promise) :
539 * @param i The index of the edge to return
540 * @returns The a CycleNode edge indexed by i
542 CycleNode * CycleNode::getEdge(unsigned int i) const
547 /** @returns The number of edges leaving this CycleNode */
548 unsigned int CycleNode::getNumEdges() const
553 CycleNode * CycleNode::getBackEdge(unsigned int i) const
555 return back_edges[i];
558 unsigned int CycleNode::getNumBackEdges() const
560 return back_edges.size();
564 * @brief Remove an element from a vector
565 * @param v The vector
566 * @param n The element to remove
567 * @return True if the element was found; false otherwise
569 template <typename T>
570 static bool vector_remove_node(std::vector<T, SnapshotAlloc<T> >& v, const T n)
572 for (unsigned int i = 0; i < v.size(); i++) {
574 v.erase(v.begin() + i);
582 * @brief Remove a (forward) edge from this CycleNode
583 * @return The CycleNode which was popped, if one exists; otherwise NULL
585 CycleNode * CycleNode::removeEdge()
590 CycleNode *ret = edges.back();
592 vector_remove_node(ret->back_edges, this);
597 * @brief Remove a (back) edge from this CycleNode
598 * @return The CycleNode which was popped, if one exists; otherwise NULL
600 CycleNode * CycleNode::removeBackEdge()
602 if (back_edges.empty())
605 CycleNode *ret = back_edges.back();
606 back_edges.pop_back();
607 vector_remove_node(ret->edges, this);
612 * Adds an edge from this CycleNode to another CycleNode.
613 * @param node The node to which we add a directed edge
614 * @return True if this edge is a new edge; false otherwise
616 bool CycleNode::addEdge(CycleNode *node)
618 for (unsigned int i = 0; i < edges.size(); i++)
619 if (edges[i] == node)
621 edges.push_back(node);
622 node->back_edges.push_back(this);
626 /** @returns the RMW CycleNode that reads from the current CycleNode */
627 CycleNode * CycleNode::getRMW() const
633 * Set a RMW action node that reads from the current CycleNode.
634 * @param node The RMW that reads from the current node
635 * @return True, if this node already was read by another RMW; false otherwise
636 * @see CycleGraph::addRMWEdge
638 bool CycleNode::setRMW(CycleNode *node)
647 * Convert a Promise CycleNode into a concrete-valued CycleNode. Should only be
648 * used when there's no existing ModelAction CycleNode for this write.
650 * @param writer The ModelAction which wrote the future value represented by
653 void CycleNode::resolvePromise(const ModelAction *writer)
655 ASSERT(is_promise());
656 ASSERT(promise->is_compatible(writer));
659 ASSERT(!is_promise());