#include <stdio.h>
#include "model.h"
+#include "action.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 (system_thread) will have id 1 */
- this->used_thread_id = 0;
+ :
/* Initialize default scheduler */
- this->scheduler = new Scheduler();
-
- this->current_action = NULL;
- this->exploring = NULL;
- this->nextThread = THREAD_ID_T_NONE;
+ scheduler(new Scheduler()),
+ /* First thread created will have id INITIAL_THREAD_ID */
+ next_thread_id(INITIAL_THREAD_ID),
+ used_sequence_numbers(0),
- rootNode = new TreeNode(NULL);
- currentNode = rootNode;
- action_trace = new action_list_t();
+ 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");
+ node_stack->reset_execution();
+ current_action = NULL;
+ next_thread_id = INITIAL_THREAD_ID;
+ used_sequence_numbers = 0;
+ nextThread = 0;
+ next_backtrack = NULL;
+ snapshotObject->backTrackBeforeStep(0);
+}
+
+/** @returns a thread ID for a new Thread */
+thread_id_t ModelChecker::get_next_id()
+{
+ return next_thread_id++;
}
-void ModelChecker::assign_id(Thread *t)
+/** @returns the number of user threads created during this execution */
+int ModelChecker::get_num_threads()
{
- t->set_id(++used_thread_id);
+ return next_thread_id;
}
-void ModelChecker::add_system_thread(Thread *t)
+/** @returns a sequence number for a new ModelAction */
+modelclock_t ModelChecker::get_next_seq_num()
{
- this->system_thread = t;
+ return ++used_sequence_numbers;
}
-Thread *ModelChecker::schedule_next_thread()
+/**
+ * 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[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;
}
-ModelAction *ModelChecker::get_last_conflict(ModelAction *act)
+/**
+ * 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()
+{
+ ModelAction *next;
+ thread_id_t tid;
+
+ /* Have we completed exploring the preselected path? */
+ if (diverge == NULL)
+ return THREAD_ID_T_NONE;
+
+ /* Else, we are trying to replay an execution */
+ next = node_stack->get_next()->get_action();
+
+ 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();
+ }
+ DEBUG("*** ModelChecker chose next thread = %d ***\n", tid);
+ return tid;
+}
+
+/**
+ * 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 ((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();
+ return true;
+}
+
+ModelAction * ModelChecker::get_last_conflict(ModelAction *act)
{
- void *loc = act->get_location();
action_type type = act->get_type();
- thread_id_t id = act->get_tid();
switch (type) {
case THREAD_CREATE:
default:
break;
}
+ /* linear search: from most recent to oldest */
action_list_t::reverse_iterator rit;
for (rit = action_trace->rbegin(); rit != action_trace->rend(); rit++) {
ModelAction *prev = *rit;
- if (prev->get_location() != loc)
- continue;
- if (type == ATOMIC_READ && prev->get_type() != ATOMIC_WRITE)
- continue;
- /* Conflict from the same thread is not really a conflict */
- if (id == prev->get_tid())
- return NULL;
- return 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(), t->get_id());
+ if (DBG_ENABLED()) {
+ prev->print();
+ act->print();
+ }
+}
- printf("Setting backtrack: conflict = %d, instead tid = %d\n",
- prev->get_tid(), act->get_tid());
- prev->print();
- act->print();
-
- Backtrack *back = new Backtrack(prev, action_trace);
- backtrack_list.push_back(back);
+ModelAction * ModelChecker::get_next_backtrack()
+{
+ 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;
}
- next->set_node(currentNode);
- set_backtracking(next);
- currentNode = currentNode->exploreChild(next->get_tid());
- this->action_trace->push_back(next);
+
+ 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);
+ }
+
+ /* Assign 'creation' parent */
+ if (curr->get_type() == THREAD_CREATE) {
+ Thread *th = (Thread *)curr->get_location();
+ th->set_creation(curr);
+ }
+
+ nextThread = get_next_replay_thread();
+
+ currnode = curr->get_node()->get_parent();
+
+ if (!currnode->backtrack_empty())
+ if (!next_backtrack || *curr > *next_backtrack)
+ next_backtrack = curr;
+
+ set_backtracking(curr);
+
+ add_action_to_lists(curr);
+}
+
+/**
+ * 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)
+{
+ action_trace->push_back(act);
+
+ 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 * ModelChecker::get_last_action(thread_id_t tid)
+{
+ 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)];
+}
+
+ModelAction * ModelChecker::get_parent_action(thread_id_t tid)
+{
+ ModelAction *parent = get_last_action(tid);
+ if (!parent)
+ parent = get_thread(tid)->get_creation();
+ return parent;
+}
+
+ClockVector * ModelChecker::get_cv(thread_id_t tid) {
+ return get_parent_action(tid)->get_cv();
}
-void ModelChecker::print_trace(void)
+/**
+ * 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)
+{
+ 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);
+}
+
+static void print_list(action_list_t *list)
{
action_list_t::iterator it;
- printf("\n");
printf("---------------------------------------------------------------------\n");
- printf("Total nodes created: %d\n\n", TreeNode::getTotalNodes());
+ printf("Trace:\n");
- for (it = action_trace->begin(); it != action_trace->end(); it++) {
- DBG();
+ for (it = list->begin(); it != list->end(); it++) {
(*it)->print();
}
printf("---------------------------------------------------------------------\n");
}
+void ModelChecker::print_summary(void)
+{
+ 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");
+}
+
int ModelChecker::add_thread(Thread *t)
{
- thread_map[t->get_id()] = t;
+ (*thread_map)[id_to_int(t->get_id())] = t;
+ scheduler->add_thread(t);
return 0;
}
+void ModelChecker::remove_thread(Thread *t)
+{
+ scheduler->remove_thread(t);
+}
+
int ModelChecker::switch_to_master(ModelAction *act)
{
- Thread *old, *next;
+ Thread *old;
DBG();
old = thread_current();
set_current_action(act);
old->set_state(THREAD_READY);
- next = system_thread;
- return old->swap(next);
-}
-
-ModelAction::ModelAction(action_type_t type, memory_order order, void *loc, int value)
-{
- Thread *t = thread_current();
- ModelAction *act = this;
-
- act->type = type;
- act->order = order;
- act->location = loc;
- act->tid = t->get_id();
- act->value = value;
-}
-
-void ModelAction::print(void)
-{
- 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";
- }
-
- printf("Thread: %d\tAction: %s\tMO: %d\tLoc: %#014zx\tValue: %d\n", tid, type_str, order, (size_t)location, value);
+ return Thread::swap(old, get_system_context());
}
projects / model-checker.git / blobdiff