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spot/src/taalgos/emptinessta.cc
Ala Eddine 81e80e6069 Add Testing Automata Product & Emptiness Check 
* src/taalgos/stats.hh, src/taalgos/stats.cc: Compute statistics for a
automaton.
* src/ta/ta.hh, src/ta/ta.cc: Abstract representation of a Testing
Automata(TA)
* src/ta/taexplicit.hh, src/ta/taexplicit.cc: Explicit representation of
a Testing Automata (TA)
* src/taalgos/dotty.cc: Print a TA in dot format.
* src/taalgos/reachiter.hh, src/taalgos/reachiter.cc: Iterate over all
reachable states of a TA
* src/taalgos/sba2ta.cc: implements the construction of a TA from a BA
(Buchi Automata)
* src/tgbatest/ltl2tgba.cc: add commands to test the TA implementation
* src/taalgos/emptinessta.hh, src/taalgos/emptinessta.cc: implementation
 of the TA emptiness-check algorithm
* src/ta/taproduct.hh, src/ta/taproduct.cc: representation of the
product (automaton) between a TA and a Kripke structure.
* src/ta/Makefile.am, src/taalgos/Makefile.am: add them
2012-07-15 18:10:00 +02:00

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// Copyright (C) 2008 Laboratoire de Recherche et Développement
// de l'Epita (LRDE).
// Copyright (C) 2003, 2004, 2005, 2006 Laboratoire d'Informatique de
// Paris 6 (LIP6), département Systèmes Répartis Coopératifs (SRC),
// Université Pierre et Marie Curie.
//
// This file is part of Spot, a model checking library.
//
// Spot is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// Spot is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
// or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
// License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Spot; see the file COPYING. If not, write to the Free
// Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
// 02111-1307, USA.
// #define TRACE
#include <iostream>
#ifdef TRACE
#define trace std::clog
#else
#define trace while (0) std::clog
#endif
#include "emptinessta.hh"
#include "misc/memusage.hh"
#include <math.h>
namespace spot
{
ta_check::ta_check(const ta* a, option_map o) :
a_(a), o_(o)
{
is_full_2_pass_ = o.get("is_full_2_pass", 0);
}
ta_check::~ta_check()
{
}
bool
ta_check::check()
{
// We use five main data in this algorithm:
// * h: a hash of all visited nodes, with their order,
// (it is called "Hash" in Couvreur's paper)
numbered_state_heap* h =
numbered_state_heap_hash_map_factory::instance()->build(); ///< Heap of visited states.
// * num: the number of visited nodes. Used to set the order of each
// visited node,
int num = 1;
// * todo: the depth-first search stack. This holds pairs of the
// form (STATE, ITERATOR) where ITERATOR is a ta_succ_iterator
// over the successors of STATE. In our use, ITERATOR should
// always be freed when TODO is popped, but STATE should not because
// it is also used as a key in H.
std::stack<pair_state_iter> todo;
// * init: the set of the depth-first search initial states
std::stack<spot::state*> init_set;
Sgi::hash_map<const state*, std::string, state_ptr_hash, state_ptr_equal>
colour;
trace
<< "PASS 1" << std::endl;
//const std::string WHITE = "W";
//const std::string GREY = "G";
//const std::string BLUE = "B";
//const std::string BLACK = "BK";
Sgi::hash_map<const state*, std::set<const state*, state_ptr_less_than>,
state_ptr_hash, state_ptr_equal> liveset;
std::stack<spot::state*> livelock_roots;
const ta::states_set_t init_states_set = a_->get_initial_states_set();
ta::states_set_t::const_iterator it;
for (it = init_states_set.begin(); it != init_states_set.end(); it++)
{
state* init_state = (*it);
init_set.push(init_state);
//colour[init_state] = WHITE;
}
while (!init_set.empty())
{
// Setup depth-first search from initial states.
{
state* init = dynamic_cast<state*> (init_set.top());
init_set.pop();
numbered_state_heap::state_index_p h_init = h->find(init);
if (h_init.first)
continue;
h->insert(init, ++num);
scc.push(num);
ta_succ_iterator* iter = a_->succ_iter(init);
iter->first();
todo.push(pair_state_iter(init, iter));
//colour[init] = GREY;
inc_depth();
//push potential root of live-lock accepting cycle
if (a_->is_livelock_accepting_state(init))
livelock_roots.push(init);
}
while (!todo.empty())
{
state* curr = todo.top().first;
// We are looking at the next successor in SUCC.
ta_succ_iterator* succ = todo.top().second;
// If there is no more successor, backtrack.
if (succ->done())
{
// We have explored all successors of state CURR.
// Backtrack TODO.
todo.pop();
dec_depth();
trace
<< "PASS 1 : backtrack" << std::endl;
// fill rem with any component removed,
numbered_state_heap::state_index_p spi =
h->index(curr->clone());
assert(spi.first);
scc.rem().push_front(curr);
inc_depth();
// set the h value of the Backtracked state to negative value.
// colour[curr] = BLUE;
*spi.second = -std::abs(*spi.second);
// Backtrack livelock_roots.
if (!livelock_roots.empty() && !livelock_roots.top()->compare(
curr))
livelock_roots.pop();
// When backtracking the root of an SSCC, we must also
// remove that SSCC from the ROOT stacks. We must
// discard from H all reachable states from this SSCC.
assert(!scc.empty());
if (scc.top().index == std::abs(*spi.second))
{
// removing states
std::list<state*>::iterator i;
for (i = scc.rem().begin(); i != scc.rem().end(); ++i)
{
numbered_state_heap::state_index_p spi = h->index(
(*i)->clone());
assert(spi.first->compare(*i) == 0);
assert(*spi.second != -1);
*spi.second = -1;
//colour[*i] = BLACK;
}
dec_depth(scc.rem().size());
scc.pop();
}
delete succ;
// Do not delete CURR: it is a key in H.
continue;
}
// We have a successor to look at.
inc_transitions();
trace
<< "PASS 1: transition" << std::endl;
// Fetch the values destination state we are interested in...
state* dest = succ->current_state();
//may be Buchi accepting scc
scc.top().is_accepting = a_->is_accepting_state(curr)
&& !succ->is_stuttering_transition();
bool is_stuttering_transition = succ->is_stuttering_transition();
// ... and point the iterator to the next successor, for
// the next iteration.
succ->next();
// We do not need SUCC from now on.
// Are we going to a new state?
numbered_state_heap::state_index_p spi = h->find(dest);
// Is this a new state?
if (!spi.first)
{
// Number it, stack it, and register its successors
// for later processing.
h->insert(dest, ++num);
scc.push(num);
ta_succ_iterator* iter = a_->succ_iter(dest);
iter->first();
todo.push(pair_state_iter(dest, iter));
//colour[dest] = GREY;
inc_depth();
//push potential root of live-lock accepting cycle
if (a_->is_livelock_accepting_state(dest)
&& !is_stuttering_transition)
livelock_roots.push(dest);
continue;
}
// If we have reached a dead component, ignore it.
if (*spi.second == -1)
continue;
// Now this is the most interesting case. We have reached a
// state S1 which is already part of a non-dead SSCC. Any such
// non-dead SSCC has necessarily been crossed by our path to
// this state: there is a state S2 in our path which belongs
// to this SSCC too. We are going to merge all states between
// this S1 and S2 into this SSCC.
//
// This merge is easy to do because the order of the SSCC in
// ROOT is ascending: we just have to merge all SSCCs from the
// top of ROOT that have an index greater to the one of
// the SSCC of S2 (called the "threshold").
int threshold = std::abs(*spi.second);
std::list<state*> rem;
bool acc = false;
while (threshold < scc.top().index)
{
assert(!scc.empty());
acc |= scc.top().is_accepting;
rem.splice(rem.end(), scc.rem());
scc.pop();
}
// Note that we do not always have
// threshold == scc.top().index
// after this loop, the SSCC whose index is threshold might have
// been merged with a lower SSCC.
// Accumulate all acceptance conditions into the merged SSCC.
scc.top().is_accepting |= acc;
scc.rem().splice(scc.rem().end(), rem);
if (scc.top().is_accepting)
{
clear(h, todo, init_set);
trace
<< "PASS 1: SUCCESS" << std::endl;
return true;
}
//ADDLINKS
if (!is_full_2_pass_ && a_->is_livelock_accepting_state(curr)
&& is_stuttering_transition)
{
trace
<< "PASS 1: heuristic livelock detection " << std::endl;
const state* dest = spi.first;
std::set<const state*, state_ptr_less_than> liveset_dest =
liveset[dest];
std::set<const state*, state_ptr_less_than> liveset_curr =
liveset[curr];
int h_livelock_root = 0;
if (!livelock_roots.empty())
h_livelock_root = *(h->find((livelock_roots.top()))).second;
if (heuristic_livelock_detection(dest, h, h_livelock_root,
liveset_curr))
{
clear(h, todo, init_set);
return true;
}
std::set<const state*, state_ptr_less_than>::const_iterator it;
for (it = liveset_dest.begin(); it != liveset_dest.end(); it++)
{
const state* succ = (*it);
if (heuristic_livelock_detection(succ, h, h_livelock_root,
liveset_curr))
{
clear(h, todo, init_set);
return true;
}
}
}
}
}
clear(h, todo, init_set);
return livelock_detection(a_);
}
bool
ta_check::heuristic_livelock_detection(const state * u,
numbered_state_heap* h, int h_livelock_root, std::set<const state*,
state_ptr_less_than> liveset_curr)
{
numbered_state_heap::state_index_p hu = h->find(u);
if (*hu.second > 0) // colour[u] == GREY
{
if (*hu.second >= h_livelock_root)
{
trace
<< "PASS 1: heuristic livelock detection SUCCESS" << std::endl;
return true;
}
liveset_curr.insert(u);
}
return false;
}
bool
ta_check::livelock_detection(const ta* t)
{
// We use five main data in this algorithm:
// * sscc: a stack of strongly stuttering-connected components (SSCC)
// * h: a hash of all visited nodes, with their order,
// (it is called "Hash" in Couvreur's paper)
numbered_state_heap* h =
numbered_state_heap_hash_map_factory::instance()->build(); ///< Heap of visited states.
// * num: the number of visited nodes. Used to set the order of each
// visited node,
trace
<< "PASS 2" << std::endl;
int num = 0;
// * todo: the depth-first search stack. This holds pairs of the
// form (STATE, ITERATOR) where ITERATOR is a tgba_succ_iterator
// over the successors of STATE. In our use, ITERATOR should
// always be freed when TODO is popped, but STATE should not because
// it is also used as a key in H.
std::stack<pair_state_iter> todo;
// * init: the set of the depth-first search initial states
std::stack<spot::state*> init_set;
const ta::states_set_t init_states_set = a_->get_initial_states_set();
ta::states_set_t::const_iterator it;
for (it = init_states_set.begin(); it != init_states_set.end(); it++)
{
state* init_state = (*it);
init_set.push(init_state);
}
while (!init_set.empty())
{
// Setup depth-first search from initial states.
{
state* init = init_set.top();
init_set.pop();
numbered_state_heap::state_index_p h_init = h->find(init);
if (h_init.first)
continue;
h->insert(init, ++num);
sscc.push(num);
sscc.top().is_accepting = t->is_livelock_accepting_state(init);
ta_succ_iterator* iter = t->succ_iter(init);
iter->first();
todo.push(pair_state_iter(init, iter));
inc_depth();
}
while (!todo.empty())
{
state* curr = todo.top().first;
// We are looking at the next successor in SUCC.
ta_succ_iterator* succ = todo.top().second;
// If there is no more successor, backtrack.
if (succ->done())
{
// We have explored all successors of state CURR.
// Backtrack TODO.
todo.pop();
dec_depth();
trace
<< "PASS 2 : backtrack" << std::endl;
// fill rem with any component removed,
numbered_state_heap::state_index_p spi =
h->index(curr->clone());
assert(spi.first);
sscc.rem().push_front(curr);
inc_depth();
// When backtracking the root of an SSCC, we must also
// remove that SSCC from the ROOT stacks. We must
// discard from H all reachable states from this SSCC.
assert(!sscc.empty());
if (sscc.top().index == *spi.second)
{
// removing states
std::list<state*>::iterator i;
for (i = sscc.rem().begin(); i != sscc.rem().end(); ++i)
{
numbered_state_heap::state_index_p spi = h->index(
(*i)->clone());
assert(spi.first->compare(*i) == 0);
assert(*spi.second != -1);
*spi.second = -1;
}
dec_depth(sscc.rem().size());
sscc.pop();
}
delete succ;
// Do not delete CURR: it is a key in H.
continue;
}
// We have a successor to look at.
inc_transitions();
trace
<< "PASS 2 : transition" << std::endl;
// Fetch the values destination state we are interested in...
state* dest = succ->current_state();
bool is_stuttering_transition = succ->is_stuttering_transition();
// ... and point the iterator to the next successor, for
// the next iteration.
succ->next();
// We do not need SUCC from now on.
numbered_state_heap::state_index_p spi = h->find(dest);
// Is this a new state?
if (!spi.first)
{
// Are we going to a new state through a stuttering transition?
if (!is_stuttering_transition)
{
init_set.push(dest);
continue;
}
// Number it, stack it, and register its successors
// for later processing.
h->insert(dest, ++num);
sscc.push(num);
sscc.top().is_accepting = t->is_livelock_accepting_state(dest);
ta_succ_iterator* iter = t->succ_iter(dest);
iter->first();
todo.push(pair_state_iter(dest, iter));
inc_depth();
continue;
}
// If we have reached a dead component, ignore it.
if (*spi.second == -1)
continue;
//self loop state
if (!curr->compare(spi.first))
{
state * self_loop_state = (curr);
if (t->is_livelock_accepting_state(self_loop_state))
{
clear(h, todo, init_set);
trace
<< "PASS 2: SUCCESS" << std::endl;
return true;
}
}
// Now this is the most interesting case. We have reached a
// state S1 which is already part of a non-dead SSCC. Any such
// non-dead SSCC has necessarily been crossed by our path to
// this state: there is a state S2 in our path which belongs
// to this SSCC too. We are going to merge all states between
// this S1 and S2 into this SSCC.
//
// This merge is easy to do because the order of the SSCC in
// ROOT is ascending: we just have to merge all SSCCs from the
// top of ROOT that have an index greater to the one of
// the SSCC of S2 (called the "threshold").
int threshold = *spi.second;
std::list<state*> rem;
bool acc = false;
while (threshold < sscc.top().index)
{
assert(!sscc.empty());
acc |= sscc.top().is_accepting;
rem.splice(rem.end(), sscc.rem());
sscc.pop();
}
// Note that we do not always have
// threshold == sscc.top().index
// after this loop, the SSCC whose index is threshold might have
// been merged with a lower SSCC.
// Accumulate all acceptance conditions into the merged SSCC.
sscc.top().is_accepting |= acc;
sscc.rem().splice(sscc.rem().end(), rem);
if (sscc.top().is_accepting)
{
clear(h, todo, init_set);
trace
<< "PASS 2: SUCCESS" << std::endl;
return true;
}
}
}
clear(h, todo, init_set);
return false;
}
void
ta_check::clear(numbered_state_heap* h, std::stack<pair_state_iter> todo,
std::stack<spot::state*> init_states)
{
set_states(states() + h->size());
while (!init_states.empty())
{
a_->free_state(init_states.top());
init_states.pop();
}
// Release all iterators in TODO.
while (!todo.empty())
{
delete todo.top().second;
todo.pop();
dec_depth();
}
delete h;
}
std::ostream&
ta_check::print_stats(std::ostream& os) const
{
// ecs_->print_stats(os);
os << states() << " unique states visited" << std::endl;
//TODO sscc;
os << scc.size() << " strongly connected components in search stack"
<< std::endl;
os << transitions() << " transitions explored" << std::endl;
os << max_depth() << " items max in DFS search stack" << std::endl;
return os;
}
//////////////////////////////////////////////////////////////////////
}
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