X-Git-Url: http://plrg.eecs.uci.edu/git/?p=model-checker.git;a=blobdiff_plain;f=nodestack.cc;h=409c4e1e52ba431b729ec4b1c6d95168cfbc675b;hp=1d2bc9648fc1365d059cceab96490866c3fd2cf5;hb=1dbc6ce8102e79ead8c3ae09214126abab1b5c51;hpb=17e0164944342a21d72d1de5e77d633cf3c2a307 diff --git a/nodestack.cc b/nodestack.cc index 1d2bc96..409c4e1 100644 --- a/nodestack.cc +++ b/nodestack.cc @@ -3,23 +3,42 @@ #include "common.h" #include "model.h" -int Node::total_nodes = 0; - -Node::Node(ModelAction *act, int nthreads) +/** + * @brief Node constructor + * + * Constructs a single Node for use in a NodeStack. Each Node is associated + * with exactly one ModelAction (exception: the first Node should be created + * as an empty stub, to represent the first thread "choice") and up to one + * parent. + * + * @param act The ModelAction to associate with this Node. May be NULL. + * @param par The parent Node in the NodeStack. May be NULL if there is no + * parent. + * @param nthreads The number of threads which exist at this point in the + * execution trace. + */ +Node::Node(ModelAction *act, Node *par, int nthreads) : action(act), + parent(par), num_threads(nthreads), explored_children(num_threads), - backtrack(num_threads) + backtrack(num_threads), + numBacktracks(0), + may_read_from(), + read_from_index(0) { - total_nodes++; + if (act) + act->set_node(this); } +/** @brief Node desctructor */ Node::~Node() { if (action) delete action; } +/** Prints debugging info for the ModelAction associated with this Node */ void Node::print() { if (action) @@ -28,46 +47,83 @@ void Node::print() printf("******** empty action ********\n"); } +/** @brief Prints info about may_read_from set */ +void Node::print_may_read_from() +{ + readfrom_set_t::iterator it; + for (it = may_read_from.begin(); it != may_read_from.end(); it++) + (*it)->print(); +} + +/** + * Checks if the Thread associated with this thread ID has been explored from + * this Node already. + * @param tid is the thread ID to check + * @return true if this thread choice has been explored already, false + * otherwise + */ bool Node::has_been_explored(thread_id_t tid) { int id = id_to_int(tid); return explored_children[id]; } +/** + * Checks if the backtracking set is empty. + * @return true if the backtracking set is empty + */ bool Node::backtrack_empty() { - unsigned int i; - for (i = 0; i < backtrack.size(); i++) - if (backtrack[i] == true) - return false; - return true; + return (numBacktracks == 0); } + +/** + * Checks whether the readsfrom set for this node is empty. + * @return true if the readsfrom set is empty. + */ +bool Node::readsfrom_empty() { + return ((read_from_index+1)>=may_read_from.size()); +} + +/** + * Mark the appropriate backtracking infromation for exploring a thread choice. + * @param act The ModelAction to explore + */ void Node::explore_child(ModelAction *act) { - act->set_node(this); explore(act->get_tid()); } +/** + * Records a backtracking reference for a thread choice within this Node. + * Provides feedback as to whether this thread choice is already set for + * backtracking. + * @return false if the thread was already set to be backtracked, true + * otherwise + */ bool Node::set_backtrack(thread_id_t id) { int i = id_to_int(id); if (backtrack[i]) return false; backtrack[i] = true; + numBacktracks++; return true; } thread_id_t Node::get_next_backtrack() { - /* TODO: find next backtrack */ + /** @todo Find next backtrack */ unsigned int i; for (i = 0; i < backtrack.size(); i++) if (backtrack[i] == true) break; - if (i >= backtrack.size()) - return THREAD_ID_T_NONE; + /* Backtrack set was empty? */ + ASSERT(i != backtrack.size()); + backtrack[i] = false; + numBacktracks--; return int_to_id(i); } @@ -76,10 +132,43 @@ bool Node::is_enabled(Thread *t) return id_to_int(t->get_id()) < num_threads; } +/** + * Add an action to the may_read_from set. + * @param act is the action to add + */ +void Node::add_read_from(const ModelAction *act) +{ + may_read_from.push_back(act); +} + +/** + * Gets the next 'may_read_from' action from this Node. Only valid for a node + * where this->action is a 'read'. + * @todo Perform reads_from backtracking/replay properly, so that this function + * may remove elements from may_read_from + * @return The first element in may_read_from + */ +const ModelAction * Node::get_read_from() { + ASSERT(read_from_indexhas_been_explored(act->get_tid())) { - /* Discard duplicate ModelAction */ - delete act; - iter++; - } else { /* Diverging from previous execution */ - /* Clear out remainder of list */ - node_list_t::iterator it = iter; - it++; - clear_node_list(&node_list, it, node_list.end()); - - /* Record action */ - get_head()->explore_child(act); - act->create_cv(get_head()->get_action()); - node_list.push_back(new Node(act, model->get_num_threads())); + if (it != node_list.end()) { iter++; + return (*iter)->get_action(); } - return (*iter)->get_action(); + + /* Record action */ + get_head()->explore_child(act); + node_list.push_back(new Node(act, get_head(), model->get_num_threads())); + total_nodes++; + iter++; + return NULL; +} + +/** + * Empties the stack of all trailing nodes after a given position and calls the + * destructor for each. This function is provided an offset which determines + * how many nodes (relative to the current replay state) to save before popping + * the stack. + * @param numAhead gives the number of Nodes (including this Node) to skip over + * before removing nodes. + */ +void NodeStack::pop_restofstack(int numAhead) +{ + /* Diverging from previous execution; clear out remainder of list */ + node_list_t::iterator it = iter; + while (numAhead--) + it++; + clear_node_list(&node_list, it, node_list.end()); } Node * NodeStack::get_head()