#include "model.h"
#include "action.h"
-#include "tree.h"
+#include "nodestack.h"
#include "schedule.h"
+#include "snapshot-interface.h"
#include "common.h"
+#include "clockvector.h"
#define INITIAL_THREAD_ID 0
ModelChecker *model;
+/** @brief Constructor */
ModelChecker::ModelChecker()
-{
- /* First thread created will have id (INITIAL_THREAD_ID + 1) */
- this->used_thread_id = INITIAL_THREAD_ID;
- used_sequence_numbers = 0;
+ :
/* Initialize default scheduler */
- this->scheduler = new Scheduler();
-
- num_executions = 0;
- this->current_action = NULL;
- this->exploring = NULL;
- this->nextThread = THREAD_ID_T_NONE;
-
- rootNode = new TreeNode(NULL);
- currentNode = rootNode;
- action_trace = new action_list_t();
+ 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),
+ current_action(NULL),
+ diverge(NULL),
+ nextThread(THREAD_ID_T_NONE),
+ action_trace(new action_list_t()),
+ thread_map(new std::map<int, Thread *>),
+ obj_thrd_map(new std::map<void *, std::vector<action_list_t> >()),
+ thrd_last_action(new std::vector<ModelAction *>(1)),
+ node_stack(new NodeStack()),
+ next_backtrack(NULL)
+{
}
+/** @brief Destructor */
ModelChecker::~ModelChecker()
{
+ std::map<int, Thread *>::iterator it;
+ for (it = thread_map->begin(); it != thread_map->end(); it++)
+ delete (*it).second;
+ delete thread_map;
+
+ delete obj_thrd_map;
delete action_trace;
- delete this->scheduler;
- delete rootNode;
+ delete thrd_last_action;
+ delete node_stack;
+ delete scheduler;
}
+/**
+ * Restores user program to initial state and resets all model-checker data
+ * structures.
+ */
void ModelChecker::reset_to_initial_state()
{
DEBUG("+++ Resetting to initial state +++\n");
- std::map<int, class Thread *>::iterator it;
- for (it = thread_map.begin(); it != thread_map.end(); it++)
- delete (*it).second;
- thread_map.clear();
- action_trace = new action_list_t();
- currentNode = rootNode;
+ node_stack->reset_execution();
current_action = NULL;
- used_thread_id = INITIAL_THREAD_ID;
+ next_thread_id = INITIAL_THREAD_ID;
used_sequence_numbers = 0;
- /* scheduler reset ? */
+ nextThread = 0;
+ next_backtrack = NULL;
+ snapshotObject->backTrackBeforeStep(0);
}
+/** @returns a thread ID for a new Thread */
thread_id_t ModelChecker::get_next_id()
{
- return ++used_thread_id;
+ return next_thread_id++;
+}
+
+/** @returns the number of user threads created during this execution */
+int ModelChecker::get_num_threads()
+{
+ return next_thread_id;
}
-int ModelChecker::get_next_seq_num()
+/** @returns a sequence number for a new ModelAction */
+modelclock_t ModelChecker::get_next_seq_num()
{
return ++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.
+ *
+ * @return The next thread chosen by the model-checker. If the model-checker
+ * makes no selection, retuns NULL.
+ */
Thread * ModelChecker::schedule_next_thread()
{
Thread *t;
if (nextThread == THREAD_ID_T_NONE)
return NULL;
- t = thread_map[id_to_int(nextThread)];
- if (t == NULL)
- DEBUG("*** error: thread not in thread_map: id = %d\n", nextThread);
+ t = (*thread_map)[id_to_int(nextThread)];
+
+ ASSERT(t != NULL);
+
return t;
}
-/*
- * get_next_replay_thread() - Choose the next thread in the replay sequence
+/**
+ * Choose the next thread in the replay sequence.
*
- * If we've reached the 'diverge' point, then we pick a thread from the
- * backtracking set.
- * Otherwise, we simply return the next thread in the 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()
{
ModelAction *next;
thread_id_t tid;
- next = exploring->get_state();
+ /* Have we completed exploring the preselected path? */
+ if (diverge == NULL)
+ return THREAD_ID_T_NONE;
- if (next == exploring->get_diverge()) {
- TreeNode *node = next->get_node();
+ /* Else, we are trying to replay an execution */
+ next = node_stack->get_next()->get_action();
- /* Reached divergence point; discard our current 'exploring' */
- DEBUG("*** Discard 'Backtrack' object ***\n");
- tid = node->getNextBacktrack();
- delete exploring;
- exploring = NULL;
+ if (next == diverge) {
+ Node *node = next->get_node()->get_parent();
+
+ /* Reached divergence point */
+ DEBUG("*** Divergence point ***\n");
+ tid = node->get_next_backtrack();
+ diverge = NULL;
} else {
tid = next->get_tid();
}
return tid;
}
-thread_id_t ModelChecker::advance_backtracking_state()
-{
- /* Have we completed exploring the preselected path? */
- if (exploring == NULL)
- return THREAD_ID_T_NONE;
-
- /* Else, we are trying to replay an execution */
- exploring->advance_state();
- if (exploring->get_state() == NULL)
- DEBUG("*** error: reached end of backtrack trace\n");
-
- return get_next_replay_thread();
-}
-
+/**
+ * Queries the model-checker for more executions to explore and, if one
+ * exists, resets the model-checker state to execute a new execution.
+ *
+ * @return If there are more executions to explore, return true. Otherwise,
+ * return false.
+ */
bool ModelChecker::next_execution()
{
+ DBG();
+
num_executions++;
print_summary();
- if ((exploring = model->get_next_backtrack()) == NULL)
+ if ((diverge = model->get_next_backtrack()) == NULL)
return false;
+
+ if (DBG_ENABLED()) {
+ printf("Next execution will diverge at:\n");
+ diverge->print();
+ }
+
model->reset_to_initial_state();
- nextThread = get_next_replay_thread();
return true;
}
action_list_t::reverse_iterator rit;
for (rit = action_trace->rbegin(); rit != action_trace->rend(); rit++) {
ModelAction *prev = *rit;
- if (act->is_dependent(prev))
+ if (act->is_synchronizing(prev))
return prev;
}
return NULL;
void ModelChecker::set_backtracking(ModelAction *act)
{
ModelAction *prev;
- TreeNode *node;
+ Node *node;
+ Thread *t = get_thread(act->get_tid());
prev = get_last_conflict(act);
if (prev == NULL)
return;
- node = prev->get_node();
+ node = prev->get_node()->get_parent();
+
+ while (!node->is_enabled(t))
+ t = t->get_parent();
/* Check if this has been explored already */
- if (node->hasBeenExplored(act->get_tid()))
+ if (node->has_been_explored(t->get_id()))
return;
+
+ /* Cache the latest backtracking point */
+ if (!next_backtrack || *prev > *next_backtrack)
+ next_backtrack = prev;
+
/* If this is a new backtracking point, mark the tree */
- if (node->setBacktrack(act->get_tid()) != 0)
+ if (!node->set_backtrack(t->get_id()))
return;
-
DEBUG("Setting backtrack: conflict = %d, instead tid = %d\n",
- prev->get_tid(), act->get_tid());
+ prev->get_tid(), t->get_id());
if (DBG_ENABLED()) {
prev->print();
act->print();
}
-
- Backtrack *back = new Backtrack(prev, action_trace);
- backtrack_list.push_back(back);
}
-Backtrack * ModelChecker::get_next_backtrack()
+ModelAction * ModelChecker::get_next_backtrack()
{
- Backtrack *next;
- if (backtrack_list.empty())
- return NULL;
- next = backtrack_list.back();
- backtrack_list.pop_back();
+ ModelAction *next = next_backtrack;
+ next_backtrack = NULL;
return next;
}
void ModelChecker::check_current_action(void)
{
- ModelAction *next = this->current_action;
+ Node *currnode;
- if (!next) {
+ ModelAction *curr = this->current_action;
+ ModelAction *tmp;
+ current_action = NULL;
+ if (!curr) {
DEBUG("trying to push NULL action...\n");
return;
}
- current_action = NULL;
- nextThread = advance_backtracking_state();
- next->set_node(currentNode);
- set_backtracking(next);
- currentNode = currentNode->exploreChild(next->get_tid());
- this->action_trace->push_back(next);
-}
-void ModelChecker::print_summary(void)
-{
- action_list_t::iterator it;
+ tmp = node_stack->explore_action(curr);
+ if (tmp) {
+ /* Discard duplicate ModelAction; use action from NodeStack */
+ 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);
+ }
- printf("\n");
- printf("---------------------------------------------------------------------\n");
- printf("Number of executions: %d\n", num_executions);
- printf("Total nodes created: %d\n\n", TreeNode::getTotalNodes());
+ /* Assign 'creation' parent */
+ if (curr->get_type() == THREAD_CREATE) {
+ Thread *th = (Thread *)curr->get_location();
+ th->set_creation(curr);
+ }
- scheduler->print();
+ nextThread = get_next_replay_thread();
- printf("Trace:\n\n");
+ currnode = curr->get_node()->get_parent();
- for (it = action_trace->begin(); it != action_trace->end(); it++) {
- DBG();
- (*it)->print();
- }
- printf("---------------------------------------------------------------------\n");
-}
+ if (!currnode->backtrack_empty())
+ if (!next_backtrack || *curr > *next_backtrack)
+ next_backtrack = curr;
-int ModelChecker::add_thread(Thread *t)
-{
- thread_map[id_to_int(t->get_id())] = t;
- scheduler->add_thread(t);
- return 0;
-}
+ set_backtracking(curr);
-void ModelChecker::remove_thread(Thread *t)
-{
- scheduler->remove_thread(t);
+ add_action_to_lists(curr);
}
-int ModelChecker::switch_to_master(ModelAction *act)
+/**
+ * Performs various bookkeeping operations for the current ModelAction. For
+ * instance, adds action to the per-object, per-thread action vector and to the
+ * action trace list of all thread actions.
+ *
+ * @param act is the ModelAction to add.
+ */
+void ModelChecker::add_action_to_lists(ModelAction *act)
{
- Thread *old;
+ action_trace->push_back(act);
- DBG();
- old = thread_current();
- set_current_action(act);
- old->set_state(THREAD_READY);
- return Thread::swap(old, get_system_context());
+ std::vector<action_list_t> *vec = &(*obj_thrd_map)[act->get_location()];
+ if (id_to_int(act->get_tid()) >= (int)vec->size())
+ vec->resize(next_thread_id);
+ (*vec)[id_to_int(act->get_tid())].push_back(act);
+
+ (*thrd_last_action)[id_to_int(act->get_tid())] = act;
}
-ModelAction::ModelAction(action_type_t type, memory_order order, void *loc, int value)
+ModelAction * ModelChecker::get_last_action(thread_id_t tid)
{
- Thread *t = thread_current();
- ModelAction *act = this;
-
- act->type = type;
- act->order = order;
- act->location = loc;
- act->tid = t->get_id();
- act->value = value;
- act->seq_number = model->get_next_seq_num();
+ 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)];
}
-bool ModelAction::is_read()
+ModelAction * ModelChecker::get_parent_action(thread_id_t tid)
{
- return type == ATOMIC_READ;
+ ModelAction *parent = get_last_action(tid);
+ if (!parent)
+ parent = get_thread(tid)->get_creation();
+ return parent;
}
-bool ModelAction::is_write()
-{
- return type == ATOMIC_WRITE;
+ClockVector * ModelChecker::get_cv(thread_id_t tid) {
+ return get_parent_action(tid)->get_cv();
}
-bool ModelAction::is_acquire()
+/**
+ * Build up an initial set of all past writes that this 'read' action may read
+ * from. This set is determined by the clock vector's "happens before"
+ * relationship.
+ * @param curr is the current ModelAction that we are exploring; it must be a
+ * 'read' operation.
+ */
+void ModelChecker::build_reads_from_past(ModelAction *curr)
{
- switch (order) {
- case memory_order_acquire:
- case memory_order_acq_rel:
- case memory_order_seq_cst:
- return true;
- default:
- return false;
+ std::vector<action_list_t> *thrd_lists = &(*obj_thrd_map)[curr->get_location()];
+ unsigned int i;
+
+ ASSERT(curr->is_read());
+
+ /* Track whether this object has been initialized */
+ bool initialized = false;
+
+ for (i = 0; i < thrd_lists->size(); i++) {
+ action_list_t *list = &(*thrd_lists)[i];
+ action_list_t::reverse_iterator rit;
+ for (rit = list->rbegin(); rit != list->rend(); rit++) {
+ ModelAction *act = *rit;
+
+ /* Only consider 'write' actions */
+ if (!act->is_write())
+ continue;
+
+ DEBUG("Adding action to may_read_from:\n");
+ if (DBG_ENABLED()) {
+ act->print();
+ curr->print();
+ }
+ curr->get_node()->add_read_from(act);
+
+ /* Include at most one act per-thread that "happens before" curr */
+ if (act->happens_before(curr)) {
+ initialized = true;
+ break;
+ }
+ }
+ }
+
+ if (!initialized) {
+ /* TODO: need a more informative way of reporting errors */
+ printf("ERROR: may read from uninitialized atomic\n");
}
+
+ if (DBG_ENABLED() || !initialized) {
+ printf("Reached read action:\n");
+ curr->print();
+ printf("Printing may_read_from\n");
+ curr->get_node()->print_may_read_from();
+ printf("End printing may_read_from\n");
+ }
+
+ ASSERT(initialized);
}
-bool ModelAction::is_release()
+static void print_list(action_list_t *list)
{
- switch (order) {
- case memory_order_release:
- case memory_order_acq_rel:
- case memory_order_seq_cst:
- return true;
- default:
- return false;
+ action_list_t::iterator it;
+
+ printf("---------------------------------------------------------------------\n");
+ printf("Trace:\n");
+
+ for (it = list->begin(); it != list->end(); it++) {
+ (*it)->print();
}
+ printf("---------------------------------------------------------------------\n");
}
-bool ModelAction::same_var(ModelAction *act)
+void ModelChecker::print_summary(void)
{
- return location == act->location;
+ printf("\n");
+ printf("Number of executions: %d\n", num_executions);
+ printf("Total nodes created: %d\n", node_stack->get_total_nodes());
+
+ scheduler->print();
+
+ print_list(action_trace);
+ printf("\n");
}
-bool ModelAction::same_thread(ModelAction *act)
+int ModelChecker::add_thread(Thread *t)
{
- return tid == act->tid;
+ (*thread_map)[id_to_int(t->get_id())] = t;
+ scheduler->add_thread(t);
+ return 0;
}
-bool ModelAction::is_dependent(ModelAction *act)
+void ModelChecker::remove_thread(Thread *t)
{
- if (!is_read() && !is_write())
- return false;
- if (!act->is_read() && !act->is_write())
- return false;
- if (same_var(act) && !same_thread(act) &&
- (is_write() || act->is_write()))
- return true;
- return false;
+ scheduler->remove_thread(t);
}
-void ModelAction::print(void)
+int ModelChecker::switch_to_master(ModelAction *act)
{
- const char *type_str;
- switch (this->type) {
- case THREAD_CREATE:
- type_str = "thread create";
- break;
- case THREAD_YIELD:
- type_str = "thread yield";
- break;
- case THREAD_JOIN:
- type_str = "thread join";
- break;
- case ATOMIC_READ:
- type_str = "atomic read";
- break;
- case ATOMIC_WRITE:
- type_str = "atomic write";
- break;
- default:
- type_str = "unknown type";
- }
+ Thread *old;
- printf("(%4d) Thread: %d\tAction: %s\tMO: %d\tLoc: %14p\tValue: %d\n",
- seq_number, id_to_int(tid), type_str, order, location, value);
+ DBG();
+ old = thread_current();
+ set_current_action(act);
+ old->set_state(THREAD_READY);
+ return Thread::swap(old, get_system_context());
}
projects / model-checker.git / blobdiff