From a23393a8fa54e0318f3958838acbdec6d5d3d82a Mon Sep 17 00:00:00 2001
From: Brian Norris <banorris@uci.edu>
Date: Mon, 14 May 2012 13:26:03 -0700
Subject: [PATCH] model: replace TreeNode with NodeStack
Big structural change to the model-checker internal data structure. It's now
tested to work, and hopefully it's still easy enough to understand.
Note that also, we remove the backtrack_list, since this type of structure
depended on keeping around "action lists" of each trace. Instead, I can free up
those lists at the end of each execution, preventing leaks and limiting memory
usage.
---
action.h | 4 ---
model.cc | 84 ++++++++++++++++++++++++++++----------------------------
model.h | 13 ++++-----
3 files changed, 48 insertions(+), 53 deletions(-)
diff --git a/action.h b/action.h
index cfe1f34e..b30b6500 100644
--- a/action.h
+++ b/action.h
@@ -17,7 +17,6 @@ typedef enum action_type {
} action_type_t;
/* Forward declaration */
-class TreeNode;
class Node;
class ModelAction {
@@ -31,8 +30,6 @@ public:
void * get_location() { return location; }
int get_seq_number() const { return seq_number; }
- TreeNode * get_treenode() { return treenode; }
- void set_node(TreeNode *n) { treenode = n; }
Node * get_node() { return node; }
void set_node(Node *n) { node = n; }
@@ -56,7 +53,6 @@ private:
void *location;
thread_id_t tid;
int value;
- TreeNode *treenode;
Node *node;
int seq_number;
};
diff --git a/model.cc b/model.cc
index c19c37f0..e5af1a6f 100644
--- a/model.cc
+++ b/model.cc
@@ -2,7 +2,7 @@
#include "model.h"
#include "action.h"
-#include "tree.h"
+#include "nodestack.h"
#include "schedule.h"
#include "common.h"
@@ -48,11 +48,11 @@ ModelChecker::ModelChecker()
num_executions(0),
current_action(NULL),
- exploring(NULL),
+ diverge(NULL),
nextThread(THREAD_ID_T_NONE),
action_trace(new action_list_t()),
- rootNode(new TreeNode()),
- currentNode(rootNode)
+ node_stack(new NodeStack()),
+ next_backtrack(NULL)
{
}
@@ -63,10 +63,10 @@ ModelChecker::~ModelChecker()
delete (*it).second;
thread_map.clear();
- free_action_list(action_trace);
+ delete action_trace;
+ delete node_stack;
delete scheduler;
- delete rootNode;
}
void ModelChecker::reset_to_initial_state()
@@ -76,12 +76,14 @@ void ModelChecker::reset_to_initial_state()
for (it = thread_map.begin(); it != thread_map.end(); it++)
delete (*it).second;
thread_map.clear();
+ delete action_trace;
action_trace = new action_list_t();
- currentNode = rootNode;
+ node_stack->reset_execution();
current_action = NULL;
next_thread_id = INITIAL_THREAD_ID;
used_sequence_numbers = 0;
nextThread = 0;
+ next_backtrack = NULL;
/* scheduler reset ? */
}
@@ -120,24 +122,19 @@ thread_id_t ModelChecker::get_next_replay_thread()
thread_id_t tid;
/* Have we completed exploring the preselected path? */
- if (exploring == NULL)
+ if (diverge == NULL)
return THREAD_ID_T_NONE;
/* Else, we are trying to replay an execution */
- exploring->advance_state();
+ next = node_stack->get_next()->get_action();
- ASSERT(exploring->get_state() != NULL);
+ if (next == diverge) {
+ Node *node = next->get_node();
- next = exploring->get_state();
-
- if (next == exploring->get_diverge()) {
- TreeNode *node = next->get_treenode();
-
- /* Reached divergence point; discard our current 'exploring' */
- DEBUG("*** Discard 'Backtrack' object ***\n");
- tid = node->getNextBacktrack();
- delete exploring;
- exploring = NULL;
+ /* Reached divergence point */
+ DEBUG("*** Divergence point ***\n");
+ tid = node->get_next_backtrack();
+ diverge = NULL;
} else {
tid = next->get_tid();
}
@@ -151,13 +148,12 @@ bool ModelChecker::next_execution()
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");
- exploring->get_diverge()->print();
- print_list(exploring->get_trace());
+ diverge->print();
}
model->reset_to_initial_state();
@@ -191,48 +187,47 @@ ModelAction * ModelChecker::get_last_conflict(ModelAction *act)
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_treenode();
+ node = prev->get_node();
- while (t && !node->is_enabled(t))
+ while (!node->is_enabled(t))
t = t->get_parent();
/* Check if this has been explored already */
- if (node->hasBeenExplored(t->get_id()))
+ if (node->has_been_explored(t->get_id()))
return;
+
+ if (!next_backtrack || *prev > *next_backtrack)
+ next_backtrack = prev;
+
/* If this is a new backtracking point, mark the tree */
- if (node->setBacktrack(t->get_id()) != 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();
}
-
- 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)
{
+ Node *currnode;
+
ModelAction *curr = this->current_action;
current_action = NULL;
if (!curr) {
@@ -240,10 +235,16 @@ void ModelChecker::check_current_action(void)
return;
}
+ curr = node_stack->explore_action(curr);
nextThread = get_next_replay_thread();
- curr->set_node(currentNode);
+
+ currnode = curr->get_node();
+
+ if (!currnode->backtrack_empty())
+ if (!next_backtrack || *curr > *next_backtrack)
+ next_backtrack = curr;
+
set_backtracking(curr);
- currentNode = currentNode->explore_child(curr);
this->action_trace->push_back(curr);
}
@@ -251,13 +252,12 @@ void ModelChecker::print_summary(void)
{
printf("\n");
printf("Number of executions: %d\n", num_executions);
- printf("Total nodes created: %d\n", TreeNode::getTotalNodes());
+ printf("Total nodes created: %d\n", Node::get_total_nodes());
scheduler->print();
print_list(action_trace);
printf("\n");
-
}
void ModelChecker::print_list(action_list_t *list)
diff --git a/model.h b/model.h
index 8651a4f9..e8a8c5eb 100644
--- a/model.h
+++ b/model.h
@@ -13,8 +13,7 @@
#include "action.h"
/* Forward declaration */
-class TreeNode;
-class Backtrack;
+class NodeStack;
class ModelChecker {
public:
@@ -48,20 +47,20 @@ private:
ModelAction * get_last_conflict(ModelAction *act);
void set_backtracking(ModelAction *act);
thread_id_t get_next_replay_thread();
- Backtrack * get_next_backtrack();
+ ModelAction * get_next_backtrack();
void reset_to_initial_state();
void print_list(action_list_t *list);
- class ModelAction *current_action;
- Backtrack *exploring;
+ ModelAction *current_action;
+ ModelAction *diverge;
thread_id_t nextThread;
ucontext_t *system_context;
action_list_t *action_trace;
std::map<int, class Thread *> thread_map;
- class TreeNode *rootNode, *currentNode;
- std::list<class Backtrack *> backtrack_list;
+ class NodeStack *node_stack;
+ ModelAction *next_backtrack;
};
extern ModelChecker *model;
--
2.34.1