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/********************* */
/** node_manager.cpp
** Original author: mdeters
** Major contributors: dejan
** Minor contributors (to current version): none
** This file is part of the CVC4 prototype.
** Copyright (c) 2009, 2010 The Analysis of Computer Systems Group (ACSys)
** Courant Institute of Mathematical Sciences
** New York University
** See the file COPYING in the top-level source directory for licensing
** information.
**
** Expression manager implementation.
**/
#include "node_manager.h"
#include <ext/hash_set>
using namespace std;
using namespace CVC4::expr;
using __gnu_cxx::hash_set;
namespace CVC4 {
__thread NodeManager* NodeManager::s_current = 0;
NodeValue* NodeManager::poolLookup(NodeValue* nv) const {
NodeValueSet::const_iterator find = d_nodeValueSet.find(nv);
if(find == d_nodeValueSet.end()) {
return NULL;
} else {
return *find;
}
}
/**
* This class ensure that NodeManager::d_reclaiming gets set to false
* even on exceptional exit from NodeManager::reclaimZombies().
*/
struct Reclaim {
bool& d_reclaimField;
Reclaim(bool& reclaim) :
d_reclaimField(reclaim) {
Debug("gc") << ">> setting RECLAIM field\n";
d_reclaimField = true;
}
~Reclaim() {
Debug("gc") << "<< clearing RECLAIM field\n";
d_reclaimField = false;
}
};
/**
* Reclaim a particular zombie.
*/
void NodeManager::reclaimZombie(expr::NodeValue* nv) {
Debug("gc") << "deleting node value " << nv
<< " [" << nv->d_id << "]: " << nv->toString() << "\n";
if(nv->getKind() != kind::VARIABLE) {
poolRemove(nv);
}
d_attrManager.deleteAllAttributes(nv);
// dtor decr's ref counts of children
// FIXME: NOT ACTUALLY GARBAGE COLLECTING YET (DUE TO ISSUES WITH
// CDMAPs (?) ) delete nv;
}
void NodeManager::reclaimZombies() {
// FIXME multithreading
Debug("gc") << "reclaiming " << d_zombies.size() << " zombie(s)!\n";
// during reclamation, reclaimZombies() is never supposed to be called
Assert(! d_reclaiming, "NodeManager::reclaimZombies() not re-entrant!");
Reclaim r(d_reclaiming);
// We copy the set away and clear the NodeManager's set of zombies.
// This is because reclaimZombie() decrements the RC of the
// NodeValue's children, which may (recursively) reclaim them.
//
// Let's say we're reclaiming zombie NodeValue "A" and its child "B"
// then becomes a zombie (NodeManager::gc(B) is called).
//
// One way to handle B's zombification is simply to put it into
// d_zombies. This is what we do. However, if we're currently
// processing d_zombies in the loop below, such addition may be
// invisible to us (B is leaked) or even invalidate our iterator,
// causing a crash.
vector<NodeValue*> zombies;
zombies.reserve(d_zombies.size());
std::copy(d_zombies.begin(),
d_zombies.end(),
std::back_inserter(zombies));
d_zombies.clear();
for(vector<NodeValue*>::iterator i = zombies.begin();
i != zombies.end();
++i) {
// collect ONLY IF still zero
if((*i)->d_rc == 0) {
reclaimZombie(*i);
}
}
}
}/* CVC4 namespace */
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