xchaff_dbase.cpp

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#include "xchaff_utils.h"
#include "xchaff_dbase.h"

CDatabase::CDatabase() : _variables(1)
{ 
    _stats.mem_used_up_counts = 0;
    _stats.mem_used_up = false;

    _stats.init_num_clauses = 0;
    _stats.init_num_literals = 0;
    _stats.num_added_clauses = 0;
    _stats.num_added_literals = 0;
    _stats.num_deleted_clauses = 0;
    _stats.num_deleted_literals = 0;

    _lit_pool_start = new CLitPoolElement[STARTUP_LIT_POOL_SIZE]; 
    _lit_pool_finish = _lit_pool_start;
    _lit_pool_end_storage = _lit_pool_start + STARTUP_LIT_POOL_SIZE;
    lit_pool_push_back(0); //set the first element as a spacing element

    _mem_limit = 1024*1024*512; //that's 0.5 G
}


void CDatabase::compact_lit_pool(void)
{
    CHECK(cout << "Begin Compaction " << endl;);
    int new_index = 1;
    for (int i=1; i< lit_pool_size(); ++i){ //begin with 1 because 0 position is always 0
        if (lit_pool(i).val()<=0 && lit_pool(i-1).val()<=0)
            continue;
        else {
            lit_pool(new_index) = lit_pool(i);
            ++new_index;
        }
    }
    _lit_pool_finish = lit_pool_begin() + new_index;
    //update all the pointers of the clauses;
    //1. clean up the pt pointers from variables
    for (unsigned i=1; i<variables().size(); ++i) {
        variable(i).ht_ptr(0).clear();
        variable(i).ht_ptr(1).clear();
    }
    //2. reinsert the ht_pointers
    for (int i=1; i< lit_pool_size(); ++i) {
        if (lit_pool(i).val() > 0 && lit_pool(i).is_ht()) {
            int var_idx = lit_pool(i).var_index();
            int sign = lit_pool(i).var_sign();
            variable(var_idx).ht_ptr(sign).push_back(& lit_pool(i));
        }
    }
    //3. update the clauses' first literal pointer
    for (int i=1; i< lit_pool_size(); ++i) {
        if (lit_pool(i).val() <= 0) {
            int cls_idx = -lit_pool(i).val();
            clause(cls_idx).first_lit() = &lit_pool(i) - clause(cls_idx).num_lits();
        }
    }
    CHECK(output_lit_pool_state(); 
          cout << endl << endl;);
}

bool CDatabase::enlarge_lit_pool(void) //will return true if successful, otherwise false.
{
    CHECK (output_lit_pool_state());
    if (lit_pool_size() - num_clauses() > num_literals() * 2) {
        //memory fragmented. ratio of efficiency < 0.5
        //minus num_clauses() is because of spacing for 
        //each clause in lit_pool
        compact_lit_pool();
        return true;
    }
    CHECK(cout << "Begin Enlarge Lit Pool" << endl;);

    //otherwise we have to enlarge it.
    //first, check if memory is running out
    int current_mem = estimate_mem_usage();
    float grow_ratio;
    if (current_mem < _mem_limit /2 ) {
        grow_ratio = 2;
    }
    else if (current_mem < _mem_limit * 0.8) {
        grow_ratio = 1.2;
    }
    else {
        _stats.mem_used_up = true;
        if (lit_pool_size() - num_clauses() > num_literals() * 1.1) {
            compact_lit_pool();
            return true;
        }
        else 
            return false;
    }
    //second, make room for new lit pool.
    CLitPoolElement * old_start = _lit_pool_start;
    CLitPoolElement * old_finish = _lit_pool_finish;
    int old_size = _lit_pool_end_storage - _lit_pool_start;
    int new_size = (int)(old_size * grow_ratio);
    _lit_pool_start = new CLitPoolElement[new_size];
    _lit_pool_finish = _lit_pool_start;
    _lit_pool_end_storage = _lit_pool_start + new_size;
    //copy the old content into new place
    for (CLitPoolElement * ptr = old_start; ptr != old_finish; ++ptr) {
        *_lit_pool_finish = *ptr;
        _lit_pool_finish ++;
    }
    //update all the pointers
    int displacement = _lit_pool_start - old_start;
    for (unsigned i=0; i< clauses().size(); ++i)
        if (clause(i).in_use()) 
            clause(i).first_lit() += displacement; 

    for (unsigned i=0; i< variables().size(); ++i) {
        CVariable & v = variable(i);
        for (int j=0; j< 2 ; ++j) {
            vector<CLitPoolElement *> & ht_ptr = v.ht_ptr(j);
            for (unsigned k=0; k< ht_ptr.size(); ++k) {
                ht_ptr[k] += displacement; 
            }
        }
    }
    //free old space
    delete [] old_start;
    CHECK(output_lit_pool_state());
    CHECK(cout << endl << endl);
    return true;
}


void CDatabase::output_lit_pool_state (void) 
{
    cout << "Lit_Pool Used " << lit_pool_size() << " Free " << lit_pool_free_space()
         << " Total " << lit_pool_size() + lit_pool_free_space()
         << " Num. Cl " << num_clauses() << " Num. Lit " << num_literals(); 
    cout << " Efficiency " << (float)((float)num_literals()) / (float)((lit_pool_size() - num_clauses())) << endl;
}


void CDatabase::detail_dump_cl(ClauseIdx cl_idx, ostream & os) {
    os << "Clause : " << cl_idx;
    CClause & cl = clause(cl_idx);
    if (!cl.in_use()) 
        os << "\t\t\t======removed=====";
    char * value;
    int i, sz;
    sz = cl.num_lits(); 
    if (cl.num_lits() < 0) {
        os << ">> " ;
        sz = -sz;
    }
    for (i=0; i<sz; ++i) {
        if (literal_value(cl.literals()[i])==0) value = "0";
        else if (literal_value(cl.literals()[i])==1) value = "1";
        else value = "X";
        os << cl.literals()[i] << "(" << value << "@" << variable(cl.literal(i).var_index()).dlevel()<< ")  ";
    }
    os << endl;
}

void CDatabase::dump(ostream & os) {
    os << "Dump Database: " << endl;
    for(unsigned i=0; i<_clauses.size(); ++i) 
        detail_dump_cl(i);
//          os << "Cl: " << i << " " << clause(i) << endl;
    for(unsigned i=1; i<_variables.size(); ++i)
        os << "VID: " << i << "\t" << variable(i);
}

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