X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=model.cc;h=03a0c689431c90720ec56a1020ef21344920ac08;hb=c7f10b7c489c0c186bfe34dd1d87ae8b89d501ff;hp=3fb3758edac8e7a19c6575dfe8cb32d1cdaea416;hpb=0170878f8a8be6aa06af6591e50fffdb2ce54022;p=model-checker.git diff --git a/model.cc b/model.cc index 3fb3758..03a0c68 100644 --- a/model.cc +++ b/model.cc @@ -11,6 +11,7 @@ #include "cyclegraph.h" #include "promise.h" #include "datarace.h" +#include "mutex.h" #define INITIAL_THREAD_ID 0 @@ -19,14 +20,15 @@ ModelChecker *model; /** @brief Constructor */ ModelChecker::ModelChecker(struct model_params params) : /* Initialize default scheduler */ + params(params), scheduler(new Scheduler()), num_executions(0), num_feasible_executions(0), - params(params), diverge(NULL), action_trace(new action_list_t()), thread_map(new HashTable()), obj_map(new HashTable()), + lock_waiters_map(new HashTable()), obj_thrd_map(new HashTable, uintptr_t, 4 >()), promises(new std::vector()), futurevalues(new std::vector()), @@ -55,6 +57,7 @@ ModelChecker::~ModelChecker() delete obj_thrd_map; delete obj_map; + delete lock_waiters_map; delete action_trace; for (unsigned int i = 0; i < promises->size(); i++) @@ -83,19 +86,19 @@ void ModelChecker::reset_to_initial_state() snapshotObject->backTrackBeforeStep(0); } -/** @returns a thread ID for a new Thread */ +/** @return a thread ID for a new Thread */ thread_id_t ModelChecker::get_next_id() { return priv->next_thread_id++; } -/** @returns the number of user threads created during this execution */ +/** @return the number of user threads created during this execution */ int ModelChecker::get_num_threads() { return priv->next_thread_id; } -/** @returns a sequence number for a new ModelAction */ +/** @return a sequence number for a new ModelAction */ modelclock_t ModelChecker::get_next_seq_num() { return ++priv->used_sequence_numbers; @@ -118,12 +121,14 @@ Thread * ModelChecker::get_next_thread(ModelAction *curr) { thread_id_t tid; - /* Do not split atomic actions. */ - if (curr->is_rmwr()) - return thread_current(); - /* The THREAD_CREATE action points to the created Thread */ - else if (curr->get_type() == THREAD_CREATE) - return (Thread *)curr->get_location(); + if (curr!=NULL) { + /* Do not split atomic actions. */ + if (curr->is_rmwr()) + return thread_current(); + /* The THREAD_CREATE action points to the created Thread */ + else if (curr->get_type() == THREAD_CREATE) + return (Thread *)curr->get_location(); + } /* Have we completed exploring the preselected path? */ if (diverge == NULL) @@ -195,9 +200,10 @@ bool ModelChecker::next_execution() ModelAction * ModelChecker::get_last_conflict(ModelAction *act) { - action_type type = act->get_type(); - - if (type==ATOMIC_READ||type==ATOMIC_WRITE||type==ATOMIC_RMW) { + switch (act->get_type()) { + case ATOMIC_READ: + case ATOMIC_WRITE: + case ATOMIC_RMW: { /* linear search: from most recent to oldest */ action_list_t *list = obj_map->get_safe_ptr(act->get_location()); action_list_t::reverse_iterator rit; @@ -206,59 +212,98 @@ ModelAction * ModelChecker::get_last_conflict(ModelAction *act) if (act->is_synchronizing(prev)) return prev; } - } else if (type==ATOMIC_LOCK||type==ATOMIC_TRYLOCK) { + break; + } + case ATOMIC_LOCK: + case ATOMIC_TRYLOCK: { /* linear search: from most recent to oldest */ action_list_t *list = obj_map->get_safe_ptr(act->get_location()); action_list_t::reverse_iterator rit; for (rit = list->rbegin(); rit != list->rend(); rit++) { ModelAction *prev = *rit; - if (prev->is_success_lock()) + if (act->is_conflicting_lock(prev)) return prev; } - } else if (type==ATOMIC_UNLOCK) { + break; + } + case ATOMIC_UNLOCK: { /* linear search: from most recent to oldest */ action_list_t *list = obj_map->get_safe_ptr(act->get_location()); action_list_t::reverse_iterator rit; for (rit = list->rbegin(); rit != list->rend(); rit++) { ModelAction *prev = *rit; - if (prev->is_failed_trylock()) + if (!act->same_thread(prev)&&prev->is_failed_trylock()) return prev; } + break; + } + default: + break; } return NULL; } +/** This method find backtracking points where we should try to + * reorder the parameter ModelAction against. + * + * @param the ModelAction to find backtracking points for. + */ + + void ModelChecker::set_backtracking(ModelAction *act) { - ModelAction *prev; - Node *node; Thread *t = get_thread(act); - - prev = get_last_conflict(act); + ModelAction * prev = get_last_conflict(act); if (prev == NULL) return; - node = prev->get_node()->get_parent(); + Node * node = prev->get_node()->get_parent(); - while (!node->is_enabled(t)) - t = t->get_parent(); + int low_tid, high_tid; + if (node->is_enabled(t)) { + low_tid = id_to_int(act->get_tid()); + high_tid = low_tid+1; + } else { + low_tid = 0; + high_tid = get_num_threads(); + } - /* Check if this has been explored already */ - if (node->has_been_explored(t->get_id())) - return; + for(int i = low_tid; i < high_tid; i++) { + thread_id_t tid = int_to_id(i); + if (!node->is_enabled(tid)) + continue; - /* Cache the latest backtracking point */ - if (!priv->next_backtrack || *prev > *priv->next_backtrack) - priv->next_backtrack = prev; + /* Check if this has been explored already */ + if (node->has_been_explored(tid)) + continue; - /* If this is a new backtracking point, mark the tree */ - if (!node->set_backtrack(t->get_id())) - return; - DEBUG("Setting backtrack: conflict = %d, instead tid = %d\n", - prev->get_tid(), t->get_id()); - if (DBG_ENABLED()) { - prev->print(); - act->print(); + /* See if fairness allows */ + if (model->params.fairwindow != 0 && !node->has_priority(tid)) { + bool unfair=false; + for(int t=0;tget_num_threads();t++) { + thread_id_t tother=int_to_id(t); + if (node->is_enabled(tother) && node->has_priority(tother)) { + unfair=true; + break; + } + } + if (unfair) + continue; + } + + /* Cache the latest backtracking point */ + if (!priv->next_backtrack || *prev > *priv->next_backtrack) + priv->next_backtrack = prev; + + /* If this is a new backtracking point, mark the tree */ + if (!node->set_backtrack(tid)) + continue; + DEBUG("Setting backtrack: conflict = %d, instead tid = %d\n", + prev->get_tid(), t->get_id()); + if (DBG_ENABLED()) { + prev->print(); + act->print(); + } } } @@ -320,6 +365,63 @@ bool ModelChecker::process_read(ModelAction *curr, bool second_part_of_rmw) } } +/** + * Processes a lock, trylock, or unlock model action. @param curr is + * the read model action to process. + * + * The try lock operation checks whether the lock is taken. If not, + * it falls to the normal lock operation case. If so, it returns + * fail. + * + * The lock operation has already been checked that it is enabled, so + * it just grabs the lock and synchronizes with the previous unlock. + * + * The unlock operation has to re-enable all of the threads that are + * waiting on the lock. + */ +void ModelChecker::process_mutex(ModelAction *curr) { + std::mutex *mutex = (std::mutex *)curr->get_location(); + struct std::mutex_state *state = mutex->get_state(); + switch (curr->get_type()) { + case ATOMIC_TRYLOCK: { + bool success = !state->islocked; + curr->set_try_lock(success); + if (!success) { + get_thread(curr)->set_return_value(0); + break; + } + get_thread(curr)->set_return_value(1); + } + //otherwise fall into the lock case + case ATOMIC_LOCK: { + if (curr->get_cv()->getClock(state->alloc_tid) <= state->alloc_clock) { + printf("Lock access before initialization\n"); + set_assert(); + } + state->islocked = true; + ModelAction *unlock = get_last_unlock(curr); + //synchronize with the previous unlock statement + if (unlock != NULL) + curr->synchronize_with(unlock); + break; + } + case ATOMIC_UNLOCK: { + //unlock the lock + state->islocked = false; + //wake up the other threads + action_list_t *waiters = lock_waiters_map->get_safe_ptr(curr->get_location()); + //activate all the waiting threads + for (action_list_t::iterator rit = waiters->begin(); rit != waiters->end(); rit++) { + scheduler->add_thread(get_thread((*rit)->get_tid())); + } + waiters->clear(); + break; + } + default: + ASSERT(0); + } +} + /** * Process a write ModelAction * @param curr The ModelAction to process @@ -331,7 +433,7 @@ bool ModelChecker::process_write(ModelAction *curr) bool updated_promises = resolve_promises(curr); if (promises->size() == 0) { - for (unsigned int i = 0; isize(); i++) { + for (unsigned int i = 0; i < futurevalues->size(); i++) { struct PendingFutureValue pfv = (*futurevalues)[i]; if (pfv.act->get_node()->add_future_value(pfv.value, pfv.expiration) && (!priv->next_backtrack || *pfv.act > *priv->next_backtrack)) @@ -367,13 +469,15 @@ ModelAction * ModelChecker::initialize_curr_action(ModelAction *curr) return newcurr; } - newcurr = node_stack->explore_action(curr); + newcurr = node_stack->explore_action(curr, scheduler->get_enabled()); if (newcurr) { /* First restore type and order in case of RMW operation */ if (curr->is_rmwr()) newcurr->copy_typeandorder(curr); - ASSERT(curr->get_location()==newcurr->get_location()); + ASSERT(curr->get_location() == newcurr->get_location()); + newcurr->copy_from_new(curr); + /* Discard duplicate ModelAction; use action from NodeStack */ delete curr; @@ -393,6 +497,28 @@ ModelAction * ModelChecker::initialize_curr_action(ModelAction *curr) return newcurr; } +/** + * This method checks whether a model action is enabled at the given point. + * At this point, it checks whether a lock operation would be successful at this point. + * If not, it puts the thread in a waiter list. + * @param curr is the ModelAction to check whether it is enabled. + * @return a bool that indicates whether the action is enabled. + */ + +bool ModelChecker::check_action_enabled(ModelAction *curr) { + if (curr->is_lock()) { + std::mutex * lock = (std::mutex *)curr->get_location(); + struct std::mutex_state * state = lock->get_state(); + if (state->islocked) { + //Stick the action in the appropriate waiting queue + lock_waiters_map->get_safe_ptr(curr->get_location())->push_back(curr); + return false; + } + } + + return true; +} + /** * This is the heart of the model checker routine. It performs model-checking * actions corresponding to a given "current action." Among other processes, it @@ -411,6 +537,14 @@ Thread * ModelChecker::check_current_action(ModelAction *curr) bool second_part_of_rmw = curr->is_rmwc() || curr->is_rmw(); + if (!check_action_enabled(curr)) { + //we'll make the execution look like we chose to run this action + //much later...when a lock is actually available to relese + get_current_thread()->set_pending(curr); + remove_thread(get_current_thread()); + return get_next_thread(NULL); + } + ModelAction *newcurr = initialize_curr_action(curr); /* Add the action to lists before any other model-checking tasks */ @@ -476,6 +610,9 @@ Thread * ModelChecker::check_current_action(ModelAction *curr) if (act->is_write() && process_write(act)) updated = true; + if (act->is_mutex_op()) + process_mutex(act); + if (updated) work_queue.push_back(CheckRelSeqWorkEntry(act->get_location())); break; @@ -551,18 +688,18 @@ bool ModelChecker::promises_expired() { return false; } -/** @returns whether the current partial trace must be a prefix of a +/** @return whether the current partial trace must be a prefix of a * feasible trace. */ bool ModelChecker::isfeasibleprefix() { return promises->size() == 0 && *lazy_sync_size == 0; } -/** @returns whether the current partial trace is feasible. */ +/** @return whether the current partial trace is feasible. */ bool ModelChecker::isfeasible() { return !mo_graph->checkForRMWViolation() && isfeasibleotherthanRMW(); } -/** @returns whether the current partial trace is feasible other than +/** @return whether the current partial trace is feasible other than * multiple RMW reading from the same store. */ bool ModelChecker::isfeasibleotherthanRMW() { if (DBG_ENABLED()) { @@ -694,7 +831,7 @@ void ModelChecker::check_recency(ModelAction *curr) { /** * Updates the mo_graph with the constraints imposed from the current - * read. + * read. * * Basic idea is the following: Go through each other thread and find * the lastest action that happened before our read. Two cases: @@ -753,7 +890,7 @@ bool ModelChecker::r_modification_order(ModelAction *curr, const ModelAction *rf * promises. The basic problem is that actions that occur after the * read curr could not property add items to the modification order * for our read. - * + * * So for each thread, we find the earliest item that happens after * the read curr. This is the item we have to fix up with additional * constraints. If that action is write, we add a MO edge between @@ -889,7 +1026,7 @@ bool ModelChecker::w_modification_order(ModelAction *curr) */ if (thin_air_constraint_may_allow(curr, act)) { if (isfeasible() || - (curr->is_rmw() && act->is_rmw() && curr->get_reads_from()==act->get_reads_from() && isfeasibleotherthanRMW())) { + (curr->is_rmw() && act->is_rmw() && curr->get_reads_from() == act->get_reads_from() && isfeasibleotherthanRMW())) { struct PendingFutureValue pfv = {curr->get_value(),curr->get_seq_number()+params.maxfuturedelay,act}; futurevalues->push_back(pfv); } @@ -913,7 +1050,7 @@ bool ModelChecker::thin_air_constraint_may_allow(const ModelAction * writer, con return true; for (const ModelAction *search = writer->get_reads_from(); search != NULL; search = search->get_reads_from()) { - if (search==reader) + if (search == reader) return false; if (search->get_tid() == reader->get_tid() && search->happens_before(reader)) @@ -1000,10 +1137,12 @@ bool ModelChecker::release_seq_head(const ModelAction *rf, rel_heads_list_t *rel * the release seq? */ bool future_ordered = false; + ModelAction *last = get_last_action(int_to_id(i)); + if (last && rf->happens_before(last)) + future_ordered = true; + for (rit = list->rbegin(); rit != list->rend(); rit++) { const ModelAction *act = *rit; - if (!act->is_write()) - continue; /* Reach synchronization -> this thread is complete */ if (act->happens_before(release)) break; @@ -1012,6 +1151,10 @@ bool ModelChecker::release_seq_head(const ModelAction *rf, rel_heads_list_t *rel continue; } + /* Only writes can break release sequences */ + if (!act->is_write()) + continue; + /* Check modification order */ if (mo_graph->checkReachable(rf, act)) { /* rf --mo--> act */ @@ -1104,7 +1247,7 @@ bool ModelChecker::resolve_release_sequences(void *location, work_queue_t *work_ /* propagate synchronization to later actions */ action_list_t::reverse_iterator it = action_trace->rbegin(); - while ((*it) != act) { + for (; (*it) != act; it++) { ModelAction *propagate = *it; if (act->happens_before(propagate)) { propagate->synchronize_with(act); @@ -1152,10 +1295,15 @@ void ModelChecker::add_action_to_lists(ModelAction *act) (*thrd_last_action)[tid] = act; } -ModelAction * ModelChecker::get_last_action(thread_id_t tid) +/** + * @brief Get the last action performed by a particular Thread + * @param tid The thread ID of the Thread in question + * @return The last action in the thread + */ +ModelAction * ModelChecker::get_last_action(thread_id_t tid) const { - int threadid=id_to_int(tid); - if (threadid<(int)thrd_last_action->size()) + int threadid = id_to_int(tid); + if (threadid < (int)thrd_last_action->size()) return (*thrd_last_action)[id_to_int(tid)]; else return NULL; @@ -1169,7 +1317,7 @@ ModelAction * ModelChecker::get_last_action(thread_id_t tid) * check * @return The last seq_cst write */ -ModelAction * ModelChecker::get_last_seq_cst(ModelAction *curr) +ModelAction * ModelChecker::get_last_seq_cst(ModelAction *curr) const { void *location = curr->get_location(); action_list_t *list = obj_map->get_safe_ptr(location); @@ -1181,6 +1329,26 @@ ModelAction * ModelChecker::get_last_seq_cst(ModelAction *curr) return NULL; } +/** + * Gets the last unlock operation performed on a particular mutex (i.e., memory + * location). This function identifies the mutex according to the current + * action, which is presumed to perform on the same mutex. + * @param curr The current ModelAction; also denotes the object location to + * check + * @return The last unlock operation + */ +ModelAction * ModelChecker::get_last_unlock(ModelAction *curr) const +{ + void *location = curr->get_location(); + action_list_t *list = obj_map->get_safe_ptr(location); + /* Find: max({i in dom(S) | isUnlock(t_i) && samevar(t_i, t)}) */ + action_list_t::reverse_iterator rit; + for (rit = list->rbegin(); rit != list->rend(); rit++) + if ((*rit)->is_unlock()) + return *rit; + return NULL; +} + ModelAction * ModelChecker::get_parent_action(thread_id_t tid) { ModelAction *parent = get_last_action(tid); @@ -1310,7 +1478,7 @@ void ModelChecker::build_reads_from_past(ModelAction *curr) continue; /* Don't consider more than one seq_cst write if we are a seq_cst read. */ - if (!curr->is_seqcst()|| (!act->is_seqcst() && (last_seq_cst==NULL||!act->happens_before(last_seq_cst))) || act == last_seq_cst) { + if (!curr->is_seqcst() || (!act->is_seqcst() && (last_seq_cst == NULL || !act->happens_before(last_seq_cst))) || act == last_seq_cst) { DEBUG("Adding action to may_read_from:\n"); if (DBG_ENABLED()) { act->print(); @@ -1366,7 +1534,7 @@ void ModelChecker::print_summary() #if SUPPORT_MOD_ORDER_DUMP scheduler->print(); char buffername[100]; - sprintf(buffername, "exec%u",num_executions); + sprintf(buffername, "exec%04u", num_executions); mo_graph->dumpGraphToFile(buffername); #endif @@ -1387,6 +1555,11 @@ void ModelChecker::add_thread(Thread *t) scheduler->add_thread(t); } +/** + * Removes a thread from the scheduler. + * @param the thread to remove. + */ + void ModelChecker::remove_thread(Thread *t) { scheduler->remove_thread(t); @@ -1443,6 +1616,15 @@ bool ModelChecker::take_step() { /* next == NULL -> don't take any more steps */ if (!next) return false; + + if ( next->get_pending() != NULL ) { + //restart a pending action + set_current_action(next->get_pending()); + next->set_pending(NULL); + next->set_state(THREAD_READY); + return true; + } + /* Return false only if swap fails with an error */ return (Thread::swap(&system_context, next) == 0); }