gStore/Signature/Signature.cpp

/*=============================================================================
# Filename: Signature.cpp
# Author: Bookug Lobert
# Mail: zengli-bookug@pku.edu.cn
# Last Modified: 2016-04-11 13:18
# Description:
=============================================================================*/

#include "Signature.h"

using namespace std;

std::string
Signature::BitSet2str(const EntityBitSet& _bitset)
{
	std::stringstream _ss;
	bool any = false;
	for (unsigned i = 0; i < _bitset.size(); i++)
	{
		if (_bitset.test(i))
		{
			_ss << "[" << i << "] ";
			any = true;
		}
	}
	if (!any)
	{
		_ss << "empty" << endl;
	}
	_ss << endl;
	return _ss.str();
}

void
Signature::encodePredicate2Entity(int _pre_id, EntityBitSet& _entity_bs, const char _type)
{
	if (Signature::PREDICATE_ENCODE_METHOD == 0)
	{
		//WARN:change if need to use again, because the encoding method has changed now!
		int pos = ((_pre_id + 10) % Signature::EDGE_SIG_LENGTH) + Signature::STR_SIG_LENGTH;
		_entity_bs.set(pos);
	}
	else
	{
		int seed_num = _pre_id % Signature::EDGE_SIG_INTERVAL_NUM_HALF;

		if (_type == Util::EDGE_OUT)
		{
			seed_num += Signature::EDGE_SIG_INTERVAL_NUM_HALF;
		}

		//int primeSize = 5;
		//int prime1[]={5003,5009,5011,5021,5023};
		//int prime2[]={49943,49957,49991,49993,49999};

		//NOTICE: more ones in the bitset(use more primes) means less conflicts, but also weakens the filtration of VSTree.
		// when the data set is big enough, cutting down the size of candidate list should come up to our primary consideration.
		// in this case we should not encode too many ones in entities' signature.
		// also, when the data set is small, hash conflicts can hardly happen.
		// therefore, I think using 2 primes(set up two ones in bitset) is enough.
		// --by hanshuo.
		//int primeSize = 2;
		//int prime1[] = {5003, 5011};
		//int prime2[] = {49957, 49993};

		//for(int i = 0; i < primeSize; i++)
		//{
		//int seed = _pre_id * prime1[i] % prime2[i];
		//int pos = (seed % Signature::EDGE_SIG_INTERVAL_BASE) + Signature::STR_SIG_LENGTH + Signature::EDGE_SIG_INTERVAL_BASE * seed_num;
		//_entity_bs.set(pos);
		//}
		int seed = _pre_id * 5003 % 49957;
		int pos = (seed % Signature::EDGE_SIG_INTERVAL_BASE) + Signature::STR_SIG_LENGTH + Signature::EDGE_SIG_INTERVAL_BASE * seed_num;
		_entity_bs.set(pos);
	}
}

void
Signature::encodePredicate2Edge(int _pre_id, EdgeBitSet& _edge_bs)
{
	if (Signature::PREDICATE_ENCODE_METHOD == 0)
	{
		int pos = (_pre_id + 10) % Signature::EDGE_SIG_LENGTH;
		_edge_bs.set(pos);
	}
	else
	{
		int seed_num = _pre_id % Signature::EDGE_SIG_INTERVAL_NUM_HALF;
		//int primeSize = 5;
		//int prime1[]={5003,5009,5011,5021,5023};
		//int prime2[]={49943,49957,49991,49993,49999};

		//int primeSize = 2;
		//int prime1[] = {5003,5011};
		//int prime2[] = {49957,49993};

		//for (int i = 0; i < primeSize; i++)
		//{
		//int seed = _pre_id * prime1[i] % prime2[i];
		//int pos = (seed % Signature::EDGE_SIG_INTERVAL_BASE) + Signature::EDGE_SIG_INTERVAL_BASE * seed_num;
		//_edge_bs.set(pos);
		//}
		int seed = _pre_id * 5003 % 49957;
		int pos = (seed % Signature::EDGE_SIG_INTERVAL_BASE) + Signature::EDGE_SIG_INTERVAL_BASE * seed_num;
		_edge_bs.set(pos);
	}
}

//NOTICE: no need to encode itself because only variable in query need to be filtered!
//So only consider all neighbors!
void
Signature::encodeStr2Entity(const char* _str, EntityBitSet& _entity_bs)
{
	//_str is subject or object or literal
	if (strlen(_str) >0 && _str[0] == '?')
		return;

	int length = (int)strlen(_str);
	unsigned int hashKey = 0;
	unsigned int pos = 0;
	char *str2 = (char*)calloc(length + 1, sizeof(char));
	strcpy(str2, _str);
	char *str = str2;

	unsigned base = Signature::STR_SIG_BASE * (Signature::HASH_NUM - 1);
	for (int i = Signature::HASH_NUM - 1; i >= 0; --i)
	{
		HashFunction hf = Util::hash[i];
		if (hf == NULL)
			break;
		hashKey = hf(str);
		str = str2;
		pos = base + hashKey % Signature::STR_SIG_BASE;
		base -= Signature::STR_SIG_BASE;
		if (_str[0] == '"')
		{
			pos += Signature::STR_SIG_LENGTH2;
		}
		else if (_str[0] != '<')
		{
#ifdef DEBUG_VSTREE
			cerr << "error in encodeStr2Entity(): neighbor is neither a literal or entity!" << endl;
#endif
		}
		_entity_bs.set(pos);
	}
	//BETTER: use multiple threads for different hash functions

#ifdef DEBUG_VSTREE
	//std::stringstream _ss;
	//_ss << "encodeStr2Entity:" << str2 << endl;
	//Util::logging(_ss.str());
#endif
	free(str2);
}

void
Signature::encodeStrID2Entity(int _str_id, EntityBitSet& _entity_bs)
{
	//TODO
}

EntitySig::EntitySig()
{
	this->entityBitSet.reset();
}

EntitySig::EntitySig(const EntitySig* _p_sig)
{
	this->entityBitSet.reset();
	this->entityBitSet |= _p_sig->entityBitSet;
}

EntitySig::EntitySig(const EntitySig& _sig)
{
	this->entityBitSet.reset();
	this->entityBitSet |= _sig.entityBitSet;
}

EntitySig::EntitySig(const EntityBitSet& _bitset)
{
	this->entityBitSet.reset();
	this->entityBitSet |= _bitset;
}

EntitySig&
EntitySig::operator|=(const EntitySig& _sig)
{
	this->entityBitSet |= _sig.entityBitSet;
	return *this;
}

bool
EntitySig::operator==(const EntitySig& _sig)const
{
	return (this->entityBitSet == _sig.entityBitSet);
}

bool
EntitySig::operator!=(const EntitySig& _sig)const
{
	return (this->entityBitSet != _sig.entityBitSet);
}

EntitySig&
EntitySig::operator=(const EntitySig& _sig)
{
	this->entityBitSet.reset();
	this->entityBitSet |= _sig.getBitset();
	return *this;
}

const EntityBitSet&
EntitySig::getBitset()const
{
	return this->entityBitSet;
}

EdgeSig::EdgeSig()
{
	this->edgeBitSet.reset();
}

EdgeSig::EdgeSig(const EdgeSig* _p_sig)
{
	this->edgeBitSet.reset();
	this->edgeBitSet |= _p_sig->edgeBitSet;
}

EdgeSig::EdgeSig(const EdgeSig& _sig)
{
	this->edgeBitSet.reset();
	this->edgeBitSet |= _sig.edgeBitSet;
}

EdgeSig::EdgeSig(const EdgeBitSet& _bitset)
{
	this->edgeBitSet.reset();
	this->edgeBitSet |= _bitset;
}

EdgeSig&
EdgeSig::operator|=(const EdgeSig& _sig)
{
	this->edgeBitSet |= _sig.edgeBitSet;
	return *this;
}

string
EntitySig::to_str() const
{
	std::stringstream _ss;

	_ss << Signature::BitSet2str(this->entityBitSet);

	return _ss.str();
}