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())) {
159 /* Transfer the RMW */
160 CycleNode *promise_rmw = p_node->getRMW();
161 if (promise_rmw && promise_rmw != w_node->getRMW() && w_node->setRMW(promise_rmw)) {
166 /* Transfer back edges to w_node */
167 while (p_node->getNumBackEdges() > 0) {
168 CycleNode *back = p_node->removeBackEdge();
171 if (back->is_promise()) {
172 if (checkReachable(w_node, back)) {
173 /* Edge would create cycle; merge instead */
174 mustMerge->push_back(back->getPromise());
175 if (!mergeNodes(w_node, back, mustMerge))
178 back->addEdge(w_node);
180 addNodeEdge(back, w_node);
183 /* Transfer forward edges to w_node */
184 while (p_node->getNumEdges() > 0) {
185 CycleNode *forward = p_node->removeEdge();
186 if (forward == w_node)
188 if (forward->is_promise()) {
189 if (checkReachable(forward, w_node)) {
190 mustMerge->push_back(forward->getPromise());
191 if (!mergeNodes(w_node, forward, mustMerge))
194 w_node->addEdge(forward);
196 addNodeEdge(w_node, forward);
199 erasePromiseNode(promise);
200 /* Not deleting p_node, to maintain consistency if mergeNodes() fails */
206 * Adds an edge between two CycleNodes.
207 * @param fromnode The edge comes from this CycleNode
208 * @param tonode The edge points to this CycleNode
209 * @return True, if new edge(s) are added; otherwise false
211 bool CycleGraph::addNodeEdge(CycleNode *fromnode, CycleNode *tonode)
216 hasCycles = checkReachable(tonode, fromnode);
218 if ((added = fromnode->addEdge(tonode)))
219 rollbackvector.push_back(fromnode);
222 * If the fromnode has a rmwnode that is not the tonode, we should add
223 * an edge between its rmwnode and the tonode
225 CycleNode *rmwnode = fromnode->getRMW();
226 if (rmwnode && rmwnode != tonode) {
228 hasCycles = checkReachable(tonode, rmwnode);
230 if (rmwnode->addEdge(tonode)) {
231 rollbackvector.push_back(rmwnode);
239 * @brief Add an edge between a write and the RMW which reads from it
241 * Handles special case of a RMW action, where the ModelAction rmw reads from
242 * the ModelAction/Promise from. The key differences are:
243 * (1) no write can occur in between the rmw and the from action.
244 * (2) Only one RMW action can read from a given write.
246 * @param from The edge comes from this ModelAction/Promise
247 * @param rmw The edge points to this ModelAction; this action must read from
248 * the ModelAction/Promise from
250 template <typename T>
251 void CycleGraph::addRMWEdge(const T *from, const ModelAction *rmw)
256 CycleNode *fromnode = getNode(from);
257 CycleNode *rmwnode = getNode(rmw);
259 /* Two RMW actions cannot read from the same write. */
260 if (fromnode->setRMW(rmwnode))
263 rmwrollbackvector.push_back(fromnode);
265 /* Transfer all outgoing edges from the from node to the rmw node */
266 /* This process should not add a cycle because either:
267 * (1) The rmw should not have any incoming edges yet if it is the
269 * (2) the fromnode is the new node and therefore it should not
270 * have any outgoing edges.
272 for (unsigned int i = 0; i < fromnode->getNumEdges(); i++) {
273 CycleNode *tonode = fromnode->getEdge(i);
274 if (tonode != rmwnode) {
275 if (rmwnode->addEdge(tonode))
276 rollbackvector.push_back(rmwnode);
280 addNodeEdge(fromnode, rmwnode);
282 /* Instantiate two forms of CycleGraph::addRMWEdge */
283 template void CycleGraph::addRMWEdge(const ModelAction *from, const ModelAction *rmw);
284 template void CycleGraph::addRMWEdge(const Promise *from, const ModelAction *rmw);
287 * @brief Adds an edge between objects
289 * This function will add an edge between any two objects which can be
290 * associated with a CycleNode. That is, if they have a CycleGraph::getNode
293 * The object to is ordered after the object from.
295 * @param to The edge points to this object, of type T
296 * @param from The edge comes from this object, of type U
297 * @return True, if new edge(s) are added; otherwise false
299 template <typename T, typename U>
300 bool CycleGraph::addEdge(const T *from, const U *to)
305 CycleNode *fromnode = getNode(from);
306 CycleNode *tonode = getNode(to);
308 return addNodeEdge(fromnode, tonode);
310 /* Instantiate four forms of CycleGraph::addEdge */
311 template bool CycleGraph::addEdge(const ModelAction *from, const ModelAction *to);
312 template bool CycleGraph::addEdge(const ModelAction *from, const Promise *to);
313 template bool CycleGraph::addEdge(const Promise *from, const ModelAction *to);
314 template bool CycleGraph::addEdge(const Promise *from, const Promise *to);
316 #if SUPPORT_MOD_ORDER_DUMP
318 static void print_node(FILE *file, const CycleNode *node, int label)
320 if (node->is_promise()) {
321 const Promise *promise = node->getPromise();
322 int idx = model->get_promise_number(promise);
323 fprintf(file, "P%d", idx);
326 fprintf(file, " [label=\"P%d, 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 modelclock_t idx = act->get_seq_number();
337 fprintf(file, "N%u", idx);
339 fprintf(file, " [label=\"N%u, T%u\"]", idx, act->get_tid());
343 static void print_edge(FILE *file, const CycleNode *from, const CycleNode *to, const char *prop)
345 print_node(file, from, 0);
346 fprintf(file, " -> ");
347 print_node(file, to, 0);
348 if (prop && strlen(prop))
349 fprintf(file, " [%s]", prop);
350 fprintf(file, ";\n");
353 void CycleGraph::dumpNodes(FILE *file) const
355 for (unsigned int i = 0; i < nodeList.size(); i++) {
356 CycleNode *n = nodeList[i];
357 print_node(file, n, 1);
358 fprintf(file, ";\n");
360 print_edge(file, n, n->getRMW(), "style=dotted");
361 for (unsigned int j = 0; j < n->getNumEdges(); j++)
362 print_edge(file, n, n->getEdge(j), NULL);
366 void CycleGraph::dumpGraphToFile(const char *filename) const
369 sprintf(buffer, "%s.dot", filename);
370 FILE *file = fopen(buffer, "w");
371 fprintf(file, "digraph %s {\n", filename);
373 fprintf(file, "}\n");
379 * Checks whether one CycleNode can reach another.
380 * @param from The CycleNode from which to begin exploration
381 * @param to The CycleNode to reach
382 * @return True, @a from can reach @a to; otherwise, false
384 bool CycleGraph::checkReachable(const CycleNode *from, const CycleNode *to) const
386 std::vector< const CycleNode *, ModelAlloc<const CycleNode *> > queue;
389 queue.push_back(from);
390 discovered->put(from, from);
391 while (!queue.empty()) {
392 const CycleNode *node = queue.back();
397 for (unsigned int i = 0; i < node->getNumEdges(); i++) {
398 CycleNode *next = node->getEdge(i);
399 if (!discovered->contains(next)) {
400 discovered->put(next, next);
401 queue.push_back(next);
409 * Checks whether one ModelAction/Promise can reach another ModelAction/Promise
410 * @param from The ModelAction or Promise from which to begin exploration
411 * @param to The ModelAction or Promise to reach
412 * @return True, @a from can reach @a to; otherwise, false
414 template <typename T, typename U>
415 bool CycleGraph::checkReachable(const T *from, const U *to) const
417 CycleNode *fromnode = getNode_noCreate(from);
418 CycleNode *tonode = getNode_noCreate(to);
420 if (!fromnode || !tonode)
423 return checkReachable(fromnode, tonode);
425 /* Instantiate three forms of CycleGraph::checkReachable */
426 template bool CycleGraph::checkReachable(const ModelAction *from,
427 const ModelAction *to) const;
428 template bool CycleGraph::checkReachable(const ModelAction *from,
429 const Promise *to) const;
430 template bool CycleGraph::checkReachable(const Promise *from,
431 const ModelAction *to) const;
433 /** @return True, if the promise has failed; false otherwise */
434 bool CycleGraph::checkPromise(const ModelAction *fromact, Promise *promise) const
436 std::vector< CycleNode *, ModelAlloc<CycleNode *> > queue;
438 CycleNode *from = actionToNode.get(fromact);
440 queue.push_back(from);
441 discovered->put(from, from);
442 while (!queue.empty()) {
443 CycleNode *node = queue.back();
446 if (node->getPromise() == promise)
448 if (!node->is_promise() &&
449 promise->eliminate_thread(node->getAction()->get_tid()))
452 for (unsigned int i = 0; i < node->getNumEdges(); i++) {
453 CycleNode *next = node->getEdge(i);
454 if (!discovered->contains(next)) {
455 discovered->put(next, next);
456 queue.push_back(next);
463 void CycleGraph::startChanges()
465 ASSERT(rollbackvector.empty());
466 ASSERT(rmwrollbackvector.empty());
467 ASSERT(oldCycles == hasCycles);
470 /** Commit changes to the cyclegraph. */
471 void CycleGraph::commitChanges()
473 rollbackvector.clear();
474 rmwrollbackvector.clear();
475 oldCycles = hasCycles;
478 /** Rollback changes to the previous commit. */
479 void CycleGraph::rollbackChanges()
481 for (unsigned int i = 0; i < rollbackvector.size(); i++)
482 rollbackvector[i]->removeEdge();
484 for (unsigned int i = 0; i < rmwrollbackvector.size(); i++)
485 rmwrollbackvector[i]->clearRMW();
487 hasCycles = oldCycles;
488 rollbackvector.clear();
489 rmwrollbackvector.clear();
492 /** @returns whether a CycleGraph contains cycles. */
493 bool CycleGraph::checkForCycles() const
499 * @brief Constructor for a CycleNode
500 * @param act The ModelAction for this node
502 CycleNode::CycleNode(const ModelAction *act) :
510 * @brief Constructor for a Promise CycleNode
511 * @param promise The Promise which was generated
513 CycleNode::CycleNode(const Promise *promise) :
521 * @param i The index of the edge to return
522 * @returns The a CycleNode edge indexed by i
524 CycleNode * CycleNode::getEdge(unsigned int i) const
529 /** @returns The number of edges leaving this CycleNode */
530 unsigned int CycleNode::getNumEdges() const
535 CycleNode * CycleNode::getBackEdge(unsigned int i) const
537 return back_edges[i];
540 unsigned int CycleNode::getNumBackEdges() const
542 return back_edges.size();
546 * @brief Remove an element from a vector
547 * @param v The vector
548 * @param n The element to remove
549 * @return True if the element was found; false otherwise
551 template <typename T>
552 static bool vector_remove_node(std::vector<T, SnapshotAlloc<T> >& v, const T n)
554 for (unsigned int i = 0; i < v.size(); i++) {
556 v.erase(v.begin() + i);
564 * @brief Remove a (forward) edge from this CycleNode
565 * @return The CycleNode which was popped, if one exists; otherwise NULL
567 CycleNode * CycleNode::removeEdge()
572 CycleNode *ret = edges.back();
574 vector_remove_node(ret->back_edges, this);
579 * @brief Remove a (back) edge from this CycleNode
580 * @return The CycleNode which was popped, if one exists; otherwise NULL
582 CycleNode * CycleNode::removeBackEdge()
584 if (back_edges.empty())
587 CycleNode *ret = back_edges.back();
588 back_edges.pop_back();
589 vector_remove_node(ret->edges, this);
594 * Adds an edge from this CycleNode to another CycleNode.
595 * @param node The node to which we add a directed edge
596 * @return True if this edge is a new edge; false otherwise
598 bool CycleNode::addEdge(CycleNode *node)
600 for (unsigned int i = 0; i < edges.size(); i++)
601 if (edges[i] == node)
603 edges.push_back(node);
604 node->back_edges.push_back(this);
608 /** @returns the RMW CycleNode that reads from the current CycleNode */
609 CycleNode * CycleNode::getRMW() const
615 * Set a RMW action node that reads from the current CycleNode.
616 * @param node The RMW that reads from the current node
617 * @return True, if this node already was read by another RMW; false otherwise
618 * @see CycleGraph::addRMWEdge
620 bool CycleNode::setRMW(CycleNode *node)
629 * Convert a Promise CycleNode into a concrete-valued CycleNode. Should only be
630 * used when there's no existing ModelAction CycleNode for this write.
632 * @param writer The ModelAction which wrote the future value represented by
635 void CycleNode::resolvePromise(const ModelAction *writer)
637 ASSERT(is_promise());
638 ASSERT(promise->is_compatible(writer));
641 ASSERT(!is_promise());