X-Git-Url: http://plrg.eecs.uci.edu/git/?p=model-checker.git;a=blobdiff_plain;f=model.cc;h=fb2423f3dfe12a29090ae647194b8a2adbc5bfc6;hp=44e1a2dd06e944aec3e70fbfe80704baf3d3072e;hb=31081494669effd19d6b4e502129db6397722f28;hpb=6761199295a062ec89e8f3de2f79503e7105e715 diff --git a/model.cc b/model.cc index 44e1a2d..6ec6080 100644 --- a/model.cc +++ b/model.cc @@ -1,4 +1,5 @@ #include +#include #include "model.h" #include "action.h" @@ -9,6 +10,8 @@ #include "clockvector.h" #include "cyclegraph.h" #include "promise.h" +#include "datarace.h" +#include "mutex.h" #define INITIAL_THREAD_ID 0 @@ -17,26 +20,32 @@ ModelChecker *model; /** @brief Constructor */ ModelChecker::ModelChecker(struct model_params params) : /* Initialize default scheduler */ + params(params), scheduler(new Scheduler()), - /* First thread created will have id INITIAL_THREAD_ID */ - next_thread_id(INITIAL_THREAD_ID), - used_sequence_numbers(0), num_executions(0), - params(params), - current_action(NULL), + num_feasible_executions(0), diverge(NULL), - nextThread(THREAD_ID_T_NONE), + earliest_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()), + pending_acq_rel_seq(new std::vector()), thrd_last_action(new std::vector(1)), node_stack(new NodeStack()), - next_backtrack(NULL), mo_graph(new CycleGraph()), - failed_promise(false) + failed_promise(false), + too_many_reads(false), + asserted(false), + bad_synchronization(false) { + /* Allocate this "size" on the snapshotting heap */ + priv = (struct model_snapshot_members *)calloc(1, sizeof(*priv)); + /* First thread created will have id INITIAL_THREAD_ID */ + priv->next_thread_id = INITIAL_THREAD_ID; } /** @brief Destructor */ @@ -48,12 +57,15 @@ 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++) delete (*promises)[i]; delete promises; + delete pending_acq_rel_seq; + delete thrd_last_action; delete node_stack; delete scheduler; @@ -68,73 +80,68 @@ void ModelChecker::reset_to_initial_state() { DEBUG("+++ Resetting to initial state +++\n"); node_stack->reset_execution(); - current_action = NULL; - next_thread_id = INITIAL_THREAD_ID; - used_sequence_numbers = 0; - nextThread = 0; - next_backtrack = NULL; failed_promise = false; + too_many_reads = false; + bad_synchronization = false; + reset_asserted(); 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 next_thread_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 next_thread_id; + 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 ++used_sequence_numbers; + return ++priv->used_sequence_numbers; } /** - * Performs the "scheduling" for the model-checker. That is, it checks if the - * model-checker has selected a "next thread to run" and returns it, if - * available. This function should be called from the Scheduler routine, where - * the Scheduler falls back to a default scheduling routine if needed. + * @brief Choose the next thread to execute. * - * @return The next thread chosen by the model-checker. If the model-checker - * makes no selection, retuns NULL. + * This function chooses the next thread that should execute. It can force the + * adjacency of read/write portions of a RMW action, force THREAD_CREATE to be + * followed by a THREAD_START, or it can enforce execution replay/backtracking. + * The model-checker may have no preference regarding the next thread (i.e., + * when exploring a new execution ordering), in which case this will return + * NULL. + * @param curr The current ModelAction. This action might guide the choice of + * next thread. + * @return The next thread to run. If the model-checker has no preference, NULL. */ -Thread * ModelChecker::schedule_next_thread() -{ - Thread *t; - if (nextThread == THREAD_ID_T_NONE) - return NULL; - t = thread_map->get(id_to_int(nextThread)); - - ASSERT(t != NULL); - - return t; -} - -/** - * Choose the next thread in the replay sequence. - * - * If the replay sequence has reached the 'diverge' point, returns a thread - * from the backtracking set. Otherwise, simply returns the next thread in the - * sequence that is being replayed. - */ -thread_id_t ModelChecker::get_next_replay_thread() +Thread * ModelChecker::get_next_thread(ModelAction *curr) { thread_id_t tid; + 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) - return THREAD_ID_T_NONE; + return NULL; /* Else, we are trying to replay an execution */ ModelAction *next = node_stack->get_next()->get_action(); if (next == diverge) { + if (earliest_diverge == NULL || *diverge < *earliest_diverge) + earliest_diverge=diverge; + Node *nextnode = next->get_node(); /* Reached divergence point */ if (nextnode->increment_promise()) { @@ -154,14 +161,19 @@ thread_id_t ModelChecker::get_next_replay_thread() Node *node = nextnode->get_parent(); tid = node->get_next_backtrack(); node_stack->pop_restofstack(1); + if (diverge==earliest_diverge) { + earliest_diverge=node->get_action(); + } } DEBUG("*** Divergence point ***\n"); + diverge = NULL; } else { tid = next->get_tid(); } DEBUG("*** ModelChecker chose next thread = %d ***\n", tid); - return tid; + ASSERT(tid != THREAD_ID_T_NONE); + return thread_map->get(id_to_int(tid)); } /** @@ -177,10 +189,24 @@ bool ModelChecker::next_execution() num_executions++; + if (isfinalfeasible()) { + printf("Earliest divergence point since last feasible execution:\n"); + if (earliest_diverge) + earliest_diverge->print(false); + else + printf("(Not set)\n"); + + earliest_diverge = NULL; + num_feasible_executions++; + } + + DEBUG("Number of acquires waiting on pending release sequences: %lu\n", + pending_acq_rel_seq->size()); + if (isfinalfeasible() || DBG_ENABLED()) print_summary(); - if ((diverge = model->get_next_backtrack()) == NULL) + if ((diverge = get_next_backtrack()) == NULL) return false; if (DBG_ENABLED()) { @@ -188,64 +214,114 @@ bool ModelChecker::next_execution() diverge->print(); } - model->reset_to_initial_state(); + reset_to_initial_state(); return true; } ModelAction * ModelChecker::get_last_conflict(ModelAction *act) { - action_type type = act->get_type(); - - switch (type) { - case ATOMIC_READ: - case ATOMIC_WRITE: - case ATOMIC_RMW: - break; - default: - return NULL; + 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; + for (rit = list->rbegin(); rit != list->rend(); rit++) { + ModelAction *prev = *rit; + if (act->is_synchronizing(prev)) + return prev; + } + break; } - /* 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 (act->is_synchronizing(prev)) - return prev; + 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 (act->is_conflicting_lock(prev)) + return prev; + } + 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 (!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->get_tid()); - - prev = get_last_conflict(act); + Thread *t = get_thread(act); + ModelAction * prev = get_last_conflict(act); if (prev == NULL) return; - node = prev->get_node()->get_parent(); - - while (!node->is_enabled(t)) - t = t->get_parent(); + Node * node = prev->get_node()->get_parent(); - /* Check if this has been explored already */ - if (node->has_been_explored(t->get_id())) - return; + 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(); + } - /* Cache the latest backtracking point */ - if (!next_backtrack || *prev > *next_backtrack) - next_backtrack = prev; + for(int i = low_tid; i < high_tid; i++) { + thread_id_t tid = int_to_id(i); + if (!node->is_enabled(tid)) + continue; + + /* Check if this has been explored already */ + if (node->has_been_explored(tid)) + continue; + + /* 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; + } - /* 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(); + /* 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(); + } } } @@ -256,120 +332,456 @@ void ModelChecker::set_backtracking(ModelAction *act) */ ModelAction * ModelChecker::get_next_backtrack() { - ModelAction *next = next_backtrack; - next_backtrack = NULL; + ModelAction *next = priv->next_backtrack; + priv->next_backtrack = NULL; return next; } -void ModelChecker::check_current_action(void) +/** + * Processes a read or rmw model action. + * @param curr is the read model action to process. + * @param second_part_of_rmw is boolean that is true is this is the second action of a rmw. + * @return True if processing this read updates the mo_graph. + */ +bool ModelChecker::process_read(ModelAction *curr, bool second_part_of_rmw) { - ModelAction *curr = this->current_action; - bool already_added = false; - this->current_action = NULL; - if (!curr) { - DEBUG("trying to push NULL action...\n"); - return; + uint64_t value; + bool updated = false; + while (true) { + const ModelAction *reads_from = curr->get_node()->get_read_from(); + if (reads_from != NULL) { + mo_graph->startChanges(); + + value = reads_from->get_value(); + bool r_status = false; + + if (!second_part_of_rmw) { + check_recency(curr, reads_from); + r_status = r_modification_order(curr, reads_from); + } + + + if (!second_part_of_rmw&&!isfeasible()&&(curr->get_node()->increment_read_from()||curr->get_node()->increment_future_value())) { + mo_graph->rollbackChanges(); + too_many_reads = false; + continue; + } + + curr->read_from(reads_from); + mo_graph->commitChanges(); + updated |= r_status; + } else if (!second_part_of_rmw) { + /* Read from future value */ + value = curr->get_node()->get_future_value(); + modelclock_t expiration = curr->get_node()->get_future_value_expiration(); + curr->read_from(NULL); + Promise *valuepromise = new Promise(curr, value, expiration); + promises->push_back(valuepromise); + } + get_thread(curr)->set_return_value(value); + return updated; } +} + +/** + * 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. + * + * @return True if synchronization was updated; false otherwise + */ +bool 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); + return true; + } + 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->wake(get_thread(*rit)); + } + waiters->clear(); + break; + } + default: + ASSERT(0); + } + return false; +} + +/** + * Process a write ModelAction + * @param curr The ModelAction to process + * @return True if the mo_graph was updated or promises were resolved + */ +bool ModelChecker::process_write(ModelAction *curr) +{ + bool updated_mod_order = w_modification_order(curr); + bool updated_promises = resolve_promises(curr); + + if (promises->size() == 0) { + 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)) + priv->next_backtrack = pfv.act; + } + futurevalues->resize(0); + } + + mo_graph->commitChanges(); + get_thread(curr)->set_return_value(VALUE_NONE); + return updated_mod_order || updated_promises; +} + +/** + * @brief Process the current action for thread-related activity + * + * Performs current-action processing for a THREAD_* ModelAction. Proccesses + * may include setting Thread status, completing THREAD_FINISH/THREAD_JOIN + * synchronization, etc. This function is a no-op for non-THREAD actions + * (e.g., ATOMIC_{READ,WRITE,RMW,LOCK}, etc.) + * + * @param curr The current action + * @return True if synchronization was updated or a thread completed + */ +bool ModelChecker::process_thread_action(ModelAction *curr) +{ + bool updated = false; + + switch (curr->get_type()) { + case THREAD_CREATE: { + Thread *th = (Thread *)curr->get_location(); + th->set_creation(curr); + break; + } + case THREAD_JOIN: { + Thread *waiting, *blocking; + waiting = get_thread(curr); + blocking = (Thread *)curr->get_location(); + if (!blocking->is_complete()) { + blocking->push_wait_list(curr); + scheduler->sleep(waiting); + } else { + do_complete_join(curr); + updated = true; /* trigger rel-seq checks */ + } + break; + } + case THREAD_FINISH: { + Thread *th = get_thread(curr); + while (!th->wait_list_empty()) { + ModelAction *act = th->pop_wait_list(); + Thread *wake = get_thread(act); + scheduler->wake(wake); + do_complete_join(act); + updated = true; /* trigger rel-seq checks */ + } + th->complete(); + updated = true; /* trigger rel-seq checks */ + break; + } + case THREAD_START: { + check_promises(NULL, curr->get_cv()); + break; + } + default: + break; + } + + return updated; +} + +/** + * Initialize the current action by performing one or more of the following + * actions, as appropriate: merging RMWR and RMWC/RMW actions, stepping forward + * in the NodeStack, manipulating backtracking sets, allocating and + * initializing clock vectors, and computing the promises to fulfill. + * + * @param curr The current action, as passed from the user context; may be + * freed/invalidated after the execution of this function + * @return The current action, as processed by the ModelChecker. Is only the + * same as the parameter @a curr if this is a newly-explored action. + */ +ModelAction * ModelChecker::initialize_curr_action(ModelAction *curr) +{ + ModelAction *newcurr; if (curr->is_rmwc() || curr->is_rmw()) { - ModelAction *tmp = process_rmw(curr); - already_added = true; + newcurr = process_rmw(curr); delete curr; - curr = tmp; + + if (newcurr->is_rmw()) + compute_promises(newcurr); + return newcurr; + } + + curr->set_seq_number(get_next_seq_num()); + + 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()); + newcurr->copy_from_new(curr); + + /* Discard duplicate ModelAction; use action from NodeStack */ + delete curr; + + /* Always compute new clock vector */ + newcurr->create_cv(get_parent_action(newcurr->get_tid())); } else { - ModelAction *tmp = node_stack->explore_action(curr); - if (tmp) { - /* Discard duplicate ModelAction; use action from NodeStack */ - /* First restore type and order in case of RMW operation */ - if (curr->is_rmwr()) - tmp->copy_typeandorder(curr); - - /* If we have diverged, we need to reset the clock vector. */ - if (diverge == NULL) - tmp->create_cv(get_parent_action(tmp->get_tid())); - - delete curr; - curr = tmp; - } else { - /* - * Perform one-time actions when pushing new ModelAction onto - * NodeStack - */ - curr->create_cv(get_parent_action(curr->get_tid())); - /* Build may_read_from set */ - if (curr->is_read()) - build_reads_from_past(curr); - if (curr->is_write()) - compute_promises(curr); + newcurr = curr; + + /* Always compute new clock vector */ + newcurr->create_cv(get_parent_action(newcurr->get_tid())); + /* + * Perform one-time actions when pushing new ModelAction onto + * NodeStack + */ + if (newcurr->is_write()) + compute_promises(newcurr); + } + 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; } } - /* Assign 'creation' parent */ - if (curr->get_type() == THREAD_CREATE) { - Thread *th = (Thread *)curr->get_location(); - th->set_creation(curr); + 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 + * calculates reads-from relationships, updates synchronization clock vectors, + * forms a memory_order constraints graph, and handles replay/backtrack + * execution when running permutations of previously-observed executions. + * + * @param curr The current action to process + * @return The next Thread that must be executed. May be NULL if ModelChecker + * makes no choice (e.g., according to replay execution, combining RMW actions, + * etc.) + */ +Thread * ModelChecker::check_current_action(ModelAction *curr) +{ + ASSERT(curr); + + bool second_part_of_rmw = curr->is_rmwc() || curr->is_rmw(); + + if (!check_action_enabled(curr)) { + /* Make the execution look like we chose to run this action + * much later, when a lock is actually available to release */ + get_current_thread()->set_pending(curr); + scheduler->sleep(get_current_thread()); + return get_next_thread(NULL); } - /* Deal with new thread */ - if (curr->get_type() == THREAD_START) - check_promises(NULL, curr->get_cv()); + ModelAction *newcurr = initialize_curr_action(curr); - /* Assign reads_from values */ - Thread *th = get_thread(curr->get_tid()); - uint64_t value = VALUE_NONE; - if (curr->is_read()) { - const ModelAction *reads_from = curr->get_node()->get_read_from(); - if (reads_from != NULL) { - value = reads_from->get_value(); - /* Assign reads_from, perform release/acquire synchronization */ - curr->read_from(reads_from); - r_modification_order(curr,reads_from); - } else { - /* Read from future value */ - value = curr->get_node()->get_future_value(); - curr->read_from(NULL); - Promise *valuepromise = new Promise(curr, value); - promises->push_back(valuepromise); + /* Add the action to lists before any other model-checking tasks */ + if (!second_part_of_rmw) + add_action_to_lists(newcurr); + + /* Build may_read_from set for newly-created actions */ + if (curr == newcurr && curr->is_read()) + build_reads_from_past(curr); + curr = newcurr; + + /* Initialize work_queue with the "current action" work */ + work_queue_t work_queue(1, CheckCurrWorkEntry(curr)); + + while (!work_queue.empty()) { + WorkQueueEntry work = work_queue.front(); + work_queue.pop_front(); + + switch (work.type) { + case WORK_CHECK_CURR_ACTION: { + ModelAction *act = work.action; + bool update = false; /* update this location's release seq's */ + bool update_all = false; /* update all release seq's */ + + if (process_thread_action(curr)) + update_all = true; + + if (act->is_read() && process_read(act, second_part_of_rmw)) + update = true; + + if (act->is_write() && process_write(act)) + update = true; + + if (act->is_mutex_op() && process_mutex(act)) + update_all = true; + + if (update_all) + work_queue.push_back(CheckRelSeqWorkEntry(NULL)); + else if (update) + work_queue.push_back(CheckRelSeqWorkEntry(act->get_location())); + break; + } + case WORK_CHECK_RELEASE_SEQ: + resolve_release_sequences(work.location, &work_queue); + break; + case WORK_CHECK_MO_EDGES: { + /** @todo Complete verification of work_queue */ + ModelAction *act = work.action; + bool updated = false; + + if (act->is_read()) { + const ModelAction *rf = act->get_reads_from(); + if (rf != NULL && r_modification_order(act, rf)) + updated = true; + } + if (act->is_write()) { + if (w_modification_order(act)) + updated = true; + } + mo_graph->commitChanges(); + + if (updated) + work_queue.push_back(CheckRelSeqWorkEntry(act->get_location())); + break; + } + default: + ASSERT(false); + break; } - } else if (curr->is_write()) { - w_modification_order(curr); - resolve_promises(curr); } - th->set_return_value(value); + check_curr_backtracking(curr); - /* Add action to list. */ - if (!already_added) - add_action_to_lists(curr); + set_backtracking(curr); - /** @todo Is there a better interface for setting the next thread rather - than this field/convoluted approach? Perhaps like just returning - it or something? */ + return get_next_thread(curr); +} - /* Do not split atomic actions. */ - if (curr->is_rmwr()) - nextThread = thread_current()->get_id(); - else - nextThread = get_next_replay_thread(); +/** + * Complete a THREAD_JOIN operation, by synchronizing with the THREAD_FINISH + * operation from the Thread it is joining with. Must be called after the + * completion of the Thread in question. + * @param join The THREAD_JOIN action + */ +void ModelChecker::do_complete_join(ModelAction *join) +{ + Thread *blocking = (Thread *)join->get_location(); + ModelAction *act = get_last_action(blocking->get_id()); + join->synchronize_with(act); +} +void ModelChecker::check_curr_backtracking(ModelAction * curr) { Node *currnode = curr->get_node(); Node *parnode = currnode->get_parent(); - if (!parnode->backtrack_empty() || !currnode->read_from_empty() || - !currnode->future_value_empty() || !currnode->promise_empty()) - if (!next_backtrack || *curr > *next_backtrack) - next_backtrack = curr; + if ((!parnode->backtrack_empty() || + !currnode->read_from_empty() || + !currnode->future_value_empty() || + !currnode->promise_empty()) + && (!priv->next_backtrack || + *curr > *priv->next_backtrack)) { + priv->next_backtrack = curr; + } +} - set_backtracking(curr); +bool ModelChecker::promises_expired() { + for (unsigned int promise_index = 0; promise_index < promises->size(); promise_index++) { + Promise *promise = (*promises)[promise_index]; + if (promise->get_expiration()used_sequence_numbers) { + return true; + } + } + return false; } -/** @returns whether the current partial trace is feasible. */ +/** @return whether the current partial trace must be a prefix of a + * feasible trace. */ +bool ModelChecker::isfeasibleprefix() { + return promises->size() == 0 && pending_acq_rel_seq->size() == 0; +} + +/** @return whether the current partial trace is feasible. */ bool ModelChecker::isfeasible() { - return !mo_graph->checkForCycles() && !failed_promise; + if (DBG_ENABLED() && mo_graph->checkForRMWViolation()) + DEBUG("Infeasible: RMW violation\n"); + + return !mo_graph->checkForRMWViolation() && isfeasibleotherthanRMW(); +} + +/** @return whether the current partial trace is feasible other than + * multiple RMW reading from the same store. */ +bool ModelChecker::isfeasibleotherthanRMW() { + if (DBG_ENABLED()) { + if (mo_graph->checkForCycles()) + DEBUG("Infeasible: modification order cycles\n"); + if (failed_promise) + DEBUG("Infeasible: failed promise\n"); + if (too_many_reads) + DEBUG("Infeasible: too many reads\n"); + if (bad_synchronization) + DEBUG("Infeasible: bad synchronization ordering\n"); + if (promises_expired()) + DEBUG("Infeasible: promises expired\n"); + } + return !mo_graph->checkForCycles() && !failed_promise && !too_many_reads && !bad_synchronization && !promises_expired(); } /** Returns whether the current completed trace is feasible. */ bool ModelChecker::isfinalfeasible() { + if (DBG_ENABLED() && promises->size() != 0) + DEBUG("Infeasible: unrevolved promises\n"); + return isfeasible() && promises->size() == 0; } @@ -378,19 +790,128 @@ ModelAction * ModelChecker::process_rmw(ModelAction *act) { int tid = id_to_int(act->get_tid()); ModelAction *lastread = get_last_action(tid); lastread->process_rmw(act); - if (act->is_rmw()) + if (act->is_rmw() && lastread->get_reads_from()!=NULL) { mo_graph->addRMWEdge(lastread->get_reads_from(), lastread); + mo_graph->commitChanges(); + } return lastread; } /** - * Updates the mo_graph with the constraints imposed from the current read. + * Checks whether a thread has read from the same write for too many times + * without seeing the effects of a later write. + * + * Basic idea: + * 1) there must a different write that we could read from that would satisfy the modification order, + * 2) we must have read from the same value in excess of maxreads times, and + * 3) that other write must have been in the reads_from set for maxreads times. + * + * If so, we decide that the execution is no longer feasible. + */ +void ModelChecker::check_recency(ModelAction *curr, const ModelAction *rf) { + if (params.maxreads != 0) { + + if (curr->get_node()->get_read_from_size() <= 1) + return; + //Must make sure that execution is currently feasible... We could + //accidentally clear by rolling back + if (!isfeasible()) + return; + std::vector *thrd_lists = obj_thrd_map->get_safe_ptr(curr->get_location()); + int tid = id_to_int(curr->get_tid()); + + /* Skip checks */ + if ((int)thrd_lists->size() <= tid) + return; + action_list_t *list = &(*thrd_lists)[tid]; + + action_list_t::reverse_iterator rit = list->rbegin(); + /* Skip past curr */ + for (; (*rit) != curr; rit++) + ; + /* go past curr now */ + rit++; + + action_list_t::reverse_iterator ritcopy = rit; + //See if we have enough reads from the same value + int count = 0; + for (; count < params.maxreads; rit++,count++) { + if (rit==list->rend()) + return; + ModelAction *act = *rit; + if (!act->is_read()) + return; + + if (act->get_reads_from() != rf) + return; + if (act->get_node()->get_read_from_size() <= 1) + return; + } + for (int i = 0; iget_node()->get_read_from_size(); i++) { + //Get write + const ModelAction * write = curr->get_node()->get_read_from_at(i); + + //Need a different write + if (write==rf) + continue; + + /* Test to see whether this is a feasible write to read from*/ + mo_graph->startChanges(); + r_modification_order(curr, write); + bool feasiblereadfrom = isfeasible(); + mo_graph->rollbackChanges(); + + if (!feasiblereadfrom) + continue; + rit = ritcopy; + + bool feasiblewrite = true; + //new we need to see if this write works for everyone + + for (int loop = count; loop>0; loop--,rit++) { + ModelAction *act=*rit; + bool foundvalue = false; + for (int j = 0; jget_node()->get_read_from_size(); j++) { + if (act->get_node()->get_read_from_at(i)==write) { + foundvalue = true; + break; + } + } + if (!foundvalue) { + feasiblewrite = false; + break; + } + } + if (feasiblewrite) { + too_many_reads = true; + return; + } + } + } +} + +/** + * Updates the mo_graph with the constraints imposed from the current + * read. + * + * Basic idea is the following: Go through each other thread and find + * the lastest action that happened before our read. Two cases: + * + * (1) The action is a write => that write must either occur before + * the write we read from or be the write we read from. + * + * (2) The action is a read => the write that that action read from + * must occur before the write we read from or be the same write. + * * @param curr The current action. Must be a read. * @param rf The action that curr reads from. Must be a write. + * @return True if modification order edges were added; false otherwise */ -void ModelChecker::r_modification_order(ModelAction * curr, const ModelAction *rf) { +bool ModelChecker::r_modification_order(ModelAction *curr, const ModelAction *rf) +{ std::vector *thrd_lists = obj_thrd_map->get_safe_ptr(curr->get_location()); unsigned int i; + bool added = false; ASSERT(curr->is_read()); /* Iterate over all threads */ @@ -401,22 +922,46 @@ void ModelChecker::r_modification_order(ModelAction * curr, const ModelAction *r for (rit = list->rbegin(); rit != list->rend(); rit++) { ModelAction *act = *rit; - /* Include at most one act per-thread that "happens before" curr */ - if (act->happens_before(curr)) { - if (act->is_read()) { + /* + * Include at most one act per-thread that "happens + * before" curr. Don't consider reflexively. + */ + if (act->happens_before(curr) && act != curr) { + if (act->is_write()) { + if (rf != act) { + mo_graph->addEdge(act, rf); + added = true; + } + } else { const ModelAction *prevreadfrom = act->get_reads_from(); - if (prevreadfrom != NULL && rf != prevreadfrom) + if (prevreadfrom != NULL && rf != prevreadfrom) { mo_graph->addEdge(prevreadfrom, rf); - } else if (rf != act) { - mo_graph->addEdge(act, rf); + added = true; + } } break; } } } + + return added; } -/** Updates the mo_graph with the constraints imposed from the current read. */ +/** This method fixes up the modification order when we resolve a + * 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 + * the Action rf and that action. If the action is a read, we add a + * MO edge between the Action rf, and whatever the read accessed. + * + * @param curr is the read ModelAction that we are fixing up MO edges for. + * @param rf is the write ModelAction that curr reads from. + * + */ void ModelChecker::post_r_modification_order(ModelAction *curr, const ModelAction *rf) { std::vector *thrd_lists = obj_thrd_map->get_safe_ptr(curr->get_location()); @@ -430,10 +975,10 @@ void ModelChecker::post_r_modification_order(ModelAction *curr, const ModelActio action_list_t::reverse_iterator rit; ModelAction *lastact = NULL; - /* Find last action that happens after curr */ + /* Find last action that happens after curr that is either not curr or a rmw */ for (rit = list->rbegin(); rit != list->rend(); rit++) { ModelAction *act = *rit; - if (curr->happens_before(act)) { + if (curr->happens_before(act) && (curr != act || curr->is_rmw())) { lastact = act; } else break; @@ -441,12 +986,25 @@ void ModelChecker::post_r_modification_order(ModelAction *curr, const ModelActio /* Include at most one act per-thread that "happens before" curr */ if (lastact != NULL) { - if (lastact->is_read()) { + if (lastact==curr) { + //Case 1: The resolved read is a RMW, and we need to make sure + //that the write portion of the RMW mod order after rf + + mo_graph->addEdge(rf, lastact); + } else if (lastact->is_read()) { + //Case 2: The resolved read is a normal read and the next + //operation is a read, and we need to make sure the value read + //is mod ordered after rf + const ModelAction *postreadfrom = lastact->get_reads_from(); if (postreadfrom != NULL&&rf != postreadfrom) mo_graph->addEdge(rf, postreadfrom); - } else if (rf != lastact) { - mo_graph->addEdge(rf, lastact); + } else { + //Case 3: The resolved read is a normal read and the next + //operation is a write, and we need to make sure that the + //write is mod ordered after rf + if (lastact!=rf) + mo_graph->addEdge(rf, lastact); } break; } @@ -455,19 +1013,41 @@ void ModelChecker::post_r_modification_order(ModelAction *curr, const ModelActio /** * Updates the mo_graph with the constraints imposed from the current write. + * + * Basic idea is the following: Go through each other thread and find + * the lastest action that happened before our write. Two cases: + * + * (1) The action is a write => that write must occur before + * the current write + * + * (2) The action is a read => the write that that action read from + * must occur before the current write. + * + * This method also handles two other issues: + * + * (I) Sequential Consistency: Making sure that if the current write is + * seq_cst, that it occurs after the previous seq_cst write. + * + * (II) Sending the write back to non-synchronizing reads. + * * @param curr The current action. Must be a write. + * @return True if modification order edges were added; false otherwise */ -void ModelChecker::w_modification_order(ModelAction * curr) { +bool ModelChecker::w_modification_order(ModelAction *curr) +{ std::vector *thrd_lists = obj_thrd_map->get_safe_ptr(curr->get_location()); unsigned int i; + bool added = false; ASSERT(curr->is_write()); if (curr->is_seqcst()) { /* We have to at least see the last sequentially consistent write, so we are initialized. */ - ModelAction *last_seq_cst = get_last_seq_cst(curr->get_location()); - if (last_seq_cst != NULL) + ModelAction *last_seq_cst = get_last_seq_cst(curr); + if (last_seq_cst != NULL) { mo_graph->addEdge(last_seq_cst, curr); + added = true; + } } /* Iterate over all threads */ @@ -477,13 +1057,35 @@ void ModelChecker::w_modification_order(ModelAction * curr) { action_list_t::reverse_iterator rit; for (rit = list->rbegin(); rit != list->rend(); rit++) { ModelAction *act = *rit; + if (act == curr) { + /* + * If RMW, we already have all relevant edges, + * so just skip to next thread. + * If normal write, we need to look at earlier + * actions, so continue processing list. + */ + if (curr->is_rmw()) + break; + else + continue; + } - /* Include at most one act per-thread that "happens before" curr */ + /* + * Include at most one act per-thread that "happens + * before" curr + */ if (act->happens_before(curr)) { - if (act->is_read()) - mo_graph->addEdge(act->get_reads_from(), curr); - else + /* + * Note: if act is RMW, just add edge: + * act --mo--> curr + * The following edge should be handled elsewhere: + * readfrom(act) --mo--> act + */ + if (act->is_write()) mo_graph->addEdge(act, curr); + else if (act->is_read() && act->get_reads_from() != NULL) + mo_graph->addEdge(act->get_reads_from(), curr); + added = true; break; } else if (act->is_read() && !act->is_synchronizing(curr) && !act->same_thread(curr)) { @@ -495,12 +1097,265 @@ void ModelChecker::w_modification_order(ModelAction * curr) { => that read could potentially read from our write. */ - if (act->get_node()->add_future_value(curr->get_value()) && - (!next_backtrack || *act > *next_backtrack)) - next_backtrack = act; + 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())) { + struct PendingFutureValue pfv = {curr->get_value(),curr->get_seq_number()+params.maxfuturedelay,act}; + futurevalues->push_back(pfv); + } + } + } + } + } + + return added; +} + +/** Arbitrary reads from the future are not allowed. Section 29.3 + * part 9 places some constraints. This method checks one result of constraint + * constraint. Others require compiler support. */ +bool ModelChecker::thin_air_constraint_may_allow(const ModelAction * writer, const ModelAction *reader) { + if (!writer->is_rmw()) + return true; + + if (!reader->is_rmw()) + return true; + + for (const ModelAction *search = writer->get_reads_from(); search != NULL; search = search->get_reads_from()) { + if (search == reader) + return false; + if (search->get_tid() == reader->get_tid() && + search->happens_before(reader)) + break; + } + + return true; +} + +/** + * Finds the head(s) of the release sequence(s) containing a given ModelAction. + * The ModelAction under consideration is expected to be taking part in + * release/acquire synchronization as an object of the "reads from" relation. + * Note that this can only provide release sequence support for RMW chains + * which do not read from the future, as those actions cannot be traced until + * their "promise" is fulfilled. Similarly, we may not even establish the + * presence of a release sequence with certainty, as some modification order + * constraints may be decided further in the future. Thus, this function + * "returns" two pieces of data: a pass-by-reference vector of @a release_heads + * and a boolean representing certainty. + * + * @todo Finish lazy updating, when promises are fulfilled in the future + * @param rf The action that might be part of a release sequence. Must be a + * write. + * @param release_heads A pass-by-reference style return parameter. After + * execution of this function, release_heads will contain the heads of all the + * relevant release sequences, if any exists + * @return true, if the ModelChecker is certain that release_heads is complete; + * false otherwise + */ +bool ModelChecker::release_seq_head(const ModelAction *rf, rel_heads_list_t *release_heads) const +{ + /* Only check for release sequences if there are no cycles */ + if (mo_graph->checkForCycles()) + return false; + + while (rf) { + ASSERT(rf->is_write()); + + if (rf->is_release()) + release_heads->push_back(rf); + if (!rf->is_rmw()) + break; /* End of RMW chain */ + + /** @todo Need to be smarter here... In the linux lock + * example, this will run to the beginning of the program for + * every acquire. */ + /** @todo The way to be smarter here is to keep going until 1 + * thread has a release preceded by an acquire and you've seen + * both. */ + + /* acq_rel RMW is a sufficient stopping condition */ + if (rf->is_acquire() && rf->is_release()) + return true; /* complete */ + + rf = rf->get_reads_from(); + }; + if (!rf) { + /* read from future: need to settle this later */ + return false; /* incomplete */ + } + + if (rf->is_release()) + return true; /* complete */ + + /* else relaxed write; check modification order for contiguous subsequence + * -> rf must be same thread as release */ + int tid = id_to_int(rf->get_tid()); + std::vector *thrd_lists = obj_thrd_map->get_safe_ptr(rf->get_location()); + action_list_t *list = &(*thrd_lists)[tid]; + action_list_t::const_reverse_iterator rit; + + /* Find rf in the thread list */ + rit = std::find(list->rbegin(), list->rend(), rf); + ASSERT(rit != list->rend()); + + /* Find the last write/release */ + for (; rit != list->rend(); rit++) + if ((*rit)->is_release()) + break; + if (rit == list->rend()) { + /* No write-release in this thread */ + return true; /* complete */ + } + ModelAction *release = *rit; + + ASSERT(rf->same_thread(release)); + + bool certain = true; + for (unsigned int i = 0; i < thrd_lists->size(); i++) { + if (id_to_int(rf->get_tid()) == (int)i) + continue; + list = &(*thrd_lists)[i]; + + /* Can we ensure no future writes from this thread may break + * the release seq? */ + bool future_ordered = false; + + ModelAction *last = get_last_action(int_to_id(i)); + if (last && (rf->happens_before(last) || + last->get_type() == THREAD_FINISH)) + future_ordered = true; + + for (rit = list->rbegin(); rit != list->rend(); rit++) { + const ModelAction *act = *rit; + /* Reach synchronization -> this thread is complete */ + if (act->happens_before(release)) + break; + if (rf->happens_before(act)) { + future_ordered = true; + continue; + } + + /* Only writes can break release sequences */ + if (!act->is_write()) + continue; + + /* Check modification order */ + if (mo_graph->checkReachable(rf, act)) { + /* rf --mo--> act */ + future_ordered = true; + continue; + } + if (mo_graph->checkReachable(act, release)) + /* act --mo--> release */ + break; + if (mo_graph->checkReachable(release, act) && + mo_graph->checkReachable(act, rf)) { + /* release --mo-> act --mo--> rf */ + return true; /* complete */ } + certain = false; } + if (!future_ordered) + return false; /* This thread is uncertain */ } + + if (certain) + release_heads->push_back(release); + return certain; +} + +/** + * A public interface for getting the release sequence head(s) with which a + * given ModelAction must synchronize. This function only returns a non-empty + * result when it can locate a release sequence head with certainty. Otherwise, + * it may mark the internal state of the ModelChecker so that it will handle + * the release sequence at a later time, causing @a act to update its + * synchronization at some later point in execution. + * @param act The 'acquire' action that may read from a release sequence + * @param release_heads A pass-by-reference return parameter. Will be filled + * with the head(s) of the release sequence(s), if they exists with certainty. + * @see ModelChecker::release_seq_head + */ +void ModelChecker::get_release_seq_heads(ModelAction *act, rel_heads_list_t *release_heads) +{ + const ModelAction *rf = act->get_reads_from(); + bool complete; + complete = release_seq_head(rf, release_heads); + if (!complete) { + /* add act to 'lazy checking' list */ + pending_acq_rel_seq->push_back(act); + } +} + +/** + * Attempt to resolve all stashed operations that might synchronize with a + * release sequence for a given location. This implements the "lazy" portion of + * determining whether or not a release sequence was contiguous, since not all + * modification order information is present at the time an action occurs. + * + * @param location The location/object that should be checked for release + * sequence resolutions. A NULL value means to check all locations. + * @param work_queue The work queue to which to add work items as they are + * generated + * @return True if any updates occurred (new synchronization, new mo_graph + * edges) + */ +bool ModelChecker::resolve_release_sequences(void *location, work_queue_t *work_queue) +{ + bool updated = false; + std::vector::iterator it = pending_acq_rel_seq->begin(); + while (it != pending_acq_rel_seq->end()) { + ModelAction *act = *it; + + /* Only resolve sequences on the given location, if provided */ + if (location && act->get_location() != location) { + it++; + continue; + } + + const ModelAction *rf = act->get_reads_from(); + rel_heads_list_t release_heads; + bool complete; + complete = release_seq_head(rf, &release_heads); + for (unsigned int i = 0; i < release_heads.size(); i++) { + if (!act->has_synchronized_with(release_heads[i])) { + if (act->synchronize_with(release_heads[i])) + updated = true; + else + set_bad_synchronization(); + } + } + + if (updated) { + /* Re-check all pending release sequences */ + work_queue->push_back(CheckRelSeqWorkEntry(NULL)); + /* Re-check act for mo_graph edges */ + work_queue->push_back(MOEdgeWorkEntry(act)); + + /* propagate synchronization to later actions */ + action_list_t::reverse_iterator rit = action_trace->rbegin(); + for (; (*rit) != act; rit++) { + ModelAction *propagate = *rit; + if (act->happens_before(propagate)) { + propagate->synchronize_with(act); + /* Re-check 'propagate' for mo_graph edges */ + work_queue->push_back(MOEdgeWorkEntry(propagate)); + } + } + } + if (complete) + it = pending_acq_rel_seq->erase(it); + else + it++; + } + + // If we resolved promises or data races, see if we have realized a data race. + if (checkDataRaces()) { + set_assert(); + } + + return updated; } /** @@ -519,7 +1374,7 @@ void ModelChecker::add_action_to_lists(ModelAction *act) std::vector *vec = obj_thrd_map->get_safe_ptr(act->get_location()); if (tid >= (int)vec->size()) - vec->resize(next_thread_id); + vec->resize(priv->next_thread_id); (*vec)[tid].push_back(act); if ((int)thrd_last_action->size() <= tid) @@ -527,27 +1382,56 @@ 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 nthreads = get_num_threads(); - if ((int)thrd_last_action->size() < nthreads) - thrd_last_action->resize(nthreads); - return (*thrd_last_action)[id_to_int(tid)]; + int threadid = id_to_int(tid); + if (threadid < (int)thrd_last_action->size()) + return (*thrd_last_action)[id_to_int(tid)]; + else + return NULL; } /** - * Gets the last memory_order_seq_cst action (in the total global sequence) - * performed on a particular object (i.e., memory location). - * @param location The object location to check - * @return The last seq_cst action performed + * Gets the last memory_order_seq_cst write (in the total global sequence) + * performed on a particular object (i.e., memory location), not including the + * current action. + * @param curr The current ModelAction; also denotes the object location to + * check + * @return The last seq_cst write */ -ModelAction * ModelChecker::get_last_seq_cst(const void *location) +ModelAction * ModelChecker::get_last_seq_cst(ModelAction *curr) const { + void *location = curr->get_location(); action_list_t *list = obj_map->get_safe_ptr(location); /* Find: max({i in dom(S) | seq_cst(t_i) && isWrite(t_i) && samevar(t_i, t)}) */ action_list_t::reverse_iterator rit; for (rit = list->rbegin(); rit != list->rend(); rit++) - if ((*rit)->is_write() && (*rit)->is_seqcst()) + if ((*rit)->is_write() && (*rit)->is_seqcst() && (*rit) != curr) + return *rit; + 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; } @@ -574,20 +1458,36 @@ ClockVector * ModelChecker::get_cv(thread_id_t tid) * Resolve a set of Promises with a current write. The set is provided in the * Node corresponding to @a write. * @param write The ModelAction that is fulfilling Promises + * @return True if promises were resolved; false otherwise */ -void ModelChecker::resolve_promises(ModelAction *write) +bool ModelChecker::resolve_promises(ModelAction *write) { + bool resolved = false; + for (unsigned int i = 0, promise_index = 0; promise_index < promises->size(); i++) { Promise *promise = (*promises)[promise_index]; if (write->get_node()->get_promise(i)) { ModelAction *read = promise->get_action(); + if (read->is_rmw()) { + mo_graph->addRMWEdge(write, read); + } read->read_from(write); + //First fix up the modification order for actions that happened + //before the read r_modification_order(read, write); + //Next fix up the modification order for actions that happened + //after the read. post_r_modification_order(read, write); + //Make sure the promise's value matches the write's value + ASSERT(promise->get_value() == write->get_value()); + + delete(promise); promises->erase(promises->begin() + promise_index); + resolved = true; } else promise_index++; } + return resolved; } /** @@ -621,7 +1521,7 @@ void ModelChecker::check_promises(ClockVector *old_cv, ClockVector *merge_cv) merge_cv->synchronized_since(act)) { //This thread is no longer able to send values back to satisfy the promise int num_synchronized_threads = promise->increment_threads(); - if (num_synchronized_threads == model->get_num_threads()) { + if (num_synchronized_threads == get_num_threads()) { //Promise has failed failed_promise = true; return; @@ -649,7 +1549,7 @@ void ModelChecker::build_reads_from_past(ModelAction *curr) bool initialized = false; if (curr->is_seqcst()) { - last_seq_cst = get_last_seq_cst(curr->get_location()); + last_seq_cst = get_last_seq_cst(curr); /* We have to at least see the last sequentially consistent write, so we are initialized. */ if (last_seq_cst != NULL) @@ -665,11 +1565,11 @@ void ModelChecker::build_reads_from_past(ModelAction *curr) ModelAction *act = *rit; /* Only consider 'write' actions */ - if (!act->is_write()) + if (!act->is_write() || act == curr) continue; /* Don't consider more than one seq_cst write if we are a seq_cst read. */ - if (!act->is_seqcst() || !curr->is_seqcst() || 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(); @@ -715,13 +1615,48 @@ static void print_list(action_list_t *list) printf("---------------------------------------------------------------------\n"); } +#if SUPPORT_MOD_ORDER_DUMP +void ModelChecker::dumpGraph(char *filename) { + char buffer[200]; + sprintf(buffer, "%s.dot",filename); + FILE *file=fopen(buffer, "w"); + fprintf(file, "digraph %s {\n",filename); + mo_graph->dumpNodes(file); + ModelAction ** thread_array=(ModelAction **)model_calloc(1, sizeof(ModelAction *)*get_num_threads()); + + for (action_list_t::iterator it = action_trace->begin(); it != action_trace->end(); it++) { + ModelAction *action=*it; + if (action->is_read()) { + fprintf(file, "N%u [label=\"%u, T%u\"];\n", action->get_seq_number(),action->get_seq_number(), action->get_tid()); + fprintf(file, "N%u -> N%u[label=\"rf\", color=red];\n", action->get_seq_number(), action->get_reads_from()->get_seq_number()); + } + if (thread_array[action->get_tid()] != NULL) { + fprintf(file, "N%u -> N%u[label=\"sb\", color=blue];\n", thread_array[action->get_tid()]->get_seq_number(), action->get_seq_number()); + } + + thread_array[action->get_tid()]=action; + } + fprintf(file,"}\n"); + model_free(thread_array); + fclose(file); +} +#endif + void ModelChecker::print_summary() { printf("\n"); printf("Number of executions: %d\n", num_executions); + printf("Number of feasible executions: %d\n", num_feasible_executions); printf("Total nodes created: %d\n", node_stack->get_total_nodes()); +#if SUPPORT_MOD_ORDER_DUMP scheduler->print(); + char buffername[100]; + sprintf(buffername, "exec%04u", num_executions); + mo_graph->dumpGraphToFile(buffername); + sprintf(buffername, "graph%04u", num_executions); + dumpGraph(buffername); +#endif if (!isfinalfeasible()) printf("INFEASIBLE EXECUTION!\n"); @@ -740,6 +1675,10 @@ 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); @@ -750,10 +1689,10 @@ void ModelChecker::remove_thread(Thread *t) * context). This switch is made with the intention of exploring a particular * model-checking action (described by a ModelAction object). Must be called * from a user-thread context. - * @param act The current action that will be explored. May be NULL, although - * there is little reason to switch to the model-checker without an action to - * explore (note: act == NULL is sometimes used as a hack to allow a thread to - * yield control without performing any progress; see thrd_join()). + * + * @param act The current action that will be explored. May be NULL only if + * trace is exiting via an assertion (see ModelChecker::set_assert and + * ModelChecker::has_asserted). * @return Return status from the 'swap' call (i.e., success/fail, 0/-1) */ int ModelChecker::switch_to_master(ModelAction *act) @@ -770,21 +1709,24 @@ int ModelChecker::switch_to_master(ModelAction *act) * @return Returns true (success) if a step was taken and false otherwise. */ bool ModelChecker::take_step() { - Thread *curr, *next; + if (has_asserted()) + return false; - curr = thread_current(); + Thread * curr = thread_current(); if (curr) { if (curr->get_state() == THREAD_READY) { - check_current_action(); - scheduler->add_thread(curr); - } else if (curr->get_state() == THREAD_RUNNING) { - /* Stopped while running; i.e., completed */ - curr->complete(); + ASSERT(priv->current_action); + + priv->nextThread = check_current_action(priv->current_action); + priv->current_action = NULL; + + if (curr->is_blocked() || curr->is_complete()) + scheduler->remove_thread(curr); } else { ASSERT(false); } } - next = scheduler->next_thread(); + Thread * next = scheduler->next_thread(priv->nextThread); /* Infeasible -> don't take any more steps */ if (!isfeasible()) @@ -797,6 +1739,15 @@ 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); }