BitMagic-C++: sample4.cpp

BitMagic-C++

sample4.cpp

Exmaple demonstrates bitvector serialization/deserialization.For more information please visit: http://bmagic.sourceforge.net

See also
  bm::serializer
  bm::deserialize

/*
Copyright(c) 2002-2017 Anatoliy Kuznetsov(anatoliy_kuznetsov at yahoo.com)
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
For more information please visit: http://bitmagic.io
*/
/** \example sample4.cpp
Exmaple demonstrates bitvector serialization/deserialization.
For more information please visit: http://bmagic.sourceforge.net
\sa bm::serializer
\sa bm::deserialize
*/
/*! \file sample4.cpp
\brief Example: bvector<> serialization/deserialization.
*/
#include <stdlib.h>
#include <iostream>
#include "bm.h"
#include "bmserial.h"
using namespace std;
// This exmaple demonstrates bitvector serialization/deserialization.
const unsigned MAX_VALUE = 1000000;
// This procedure creates very dense bitvector.
// The resulting set will consists mostly from ON (1) bits
// interrupted with small gaps of 0 bits.
static
void fill_bvector(bm::bvector<>* bv)
{
for (unsigned i = 0; i < MAX_VALUE; ++i)
{
if (rand() % 2500)
{
bv->set_bit(i);
}
}
}
static
void print_statistics(const bm::bvector<>& bv)
{
bm::bvector<>::statistics st;
bv. calc_stat(&st);
cout << "Bits count:" << bv. count() << endl;
cout << "Bit blocks:" << st. bit_blocks << endl;
cout << "GAP blocks:" << st. gap_blocks << endl;
cout << "Memory used:"<< st. memory_used << endl;
cout << "Max.serialize mem.:" << st. max_serialize_mem << endl << endl;;
}
// This is fairly low level serialization method, saves into a buffer
//
static
unsigned char* serialize_bvector(bm::serializer<bm::bvector<> >& bvs,
bm::bvector<>& bv)
{
// It is reccomended to optimize vector before serialization.
BM_DECLARE_TEMP_BLOCK(tb)
bm::bvector<>::statistics st;
bv. optimize(tb, bm::bvector<>::opt_compress, &st);
cout << "Bits count:" << bv.count() << endl;
cout << "Bit blocks:" << st.bit_blocks << endl;
cout << "GAP blocks:" << st.gap_blocks << endl;
cout << "Memory used:"<< st.memory_used << endl;
cout << "Max.serialize mem.:" << st.max_serialize_mem << endl;
// Allocate serialization buffer.
unsigned char* buf = new unsigned char[st.max_serialize_mem];
// Serialization to memory.
size_t len = bvs.serialize(bv, buf, st.max_serialize_mem);
cout << "Serialized size:" << len << endl << endl;
return buf;
}
int main(void)
{
unsigned char* buf1 = 0;
unsigned char* buf2 = 0;
try
{
bm::bvector<> bv1;
bm::bvector<> bv2;
bv2. set_new_blocks_strat(bm::BM_GAP); // set DGAP compression mode ON
fill_bvector(&bv1);
fill_bvector(&bv2);
// Prepare a serializer class
// for best performance it is best to create serilizer once and reuse it
// (saves a memory allocations). Do NOT use it concurrently.
//
bm::serializer<bm::bvector<> > bvs;
// next settings provide lowest size
bvs. byte_order_serialization(false);
bvs. gap_length_serialization(false);
// 1: serializes into a new allocated buffer (needs to be deallocated)
buf1 = serialize_bvector(bvs, bv1);
// 2: use serialization buffer class (automatic RAI, freed on destruction)
bm::serializer<bm::bvector<> >::buffer sbuf;
{
bvs. serialize(bv2, sbuf);
buf2 = sbuf.data();
auto sz = sbuf.size();
cout << "BV2 Serialized size:" << sz << endl;
}
// Serialized bvectors (buf1 and buf2) now ready to be
// saved to a database, file or send over a network.
// ...
// Deserialization.
bm::bvector<> bv3;
// As a result of desrialization bv3 will contain all bits from
// bv1 and bv3:
// bv3 = bv1 OR bv2
bm::deserialize(bv3, buf1);
bm::deserialize(bv3, buf2);
print_statistics(bv3);
// After a complex operation we can try to optimize bv3.
bv3.optimize();
print_statistics(bv3);
// control check using OR on the original vectors
{
bm::bvector<> bv_c;
bv_c. bit_or(bv1, bv2, bm::bvector<>::opt_compress);
int cmp = bv_c. compare(bv3);
if (cmp != 0)
{
std::cerr << "Error: bug in serialization" << std::endl;
}
bm::serializer<bm::bvector<> >::buffer sbuf2;
// destructive serialization, "bv_c" should not be used after
bvs. optimize_serialize_destroy(bv_c, sbuf2);
cout << "BV_C Serialized size:" << sbuf2.size() << endl;
}
}
catch(std::exception& ex)
{
std::cerr << ex.what() << std::endl;
delete [] buf1;
return 1;
}
delete [] buf1;
return 0;
}
bm::deserialize
size_t deserialize(BV &bv, const unsigned char *buf, bm::word_t *temp_block=0, const bm::bv_ref_vector< BV > *ref_vect=0)
Bitvector deserialization from a memory BLOB.
Definition: bmserial.h:2688
bm::bvector::calc_stat
void calc_stat(struct bm::bvector< Alloc >::statistics *st) const BMNOEXCEPT
Calculates bitvector statistics.
Definition: bm.h:3393
bm::bv_statistics::max_serialize_mem
size_t max_serialize_mem
estimated maximum memory for serialization
Definition: bmfunc.h:60
MAX_VALUE
const unsigned MAX_VALUE
Definition: sample4.cpp:42
bm::bvector::set_new_blocks_strat
void set_new_blocks_strat(strategy strat)
Sets new blocks allocation strategy.
Definition: bm.h:1810
fill_bvector
static void fill_bvector(bm::bvector<> *bv)
Definition: sample4.cpp:49
bm::bv_statistics::bit_blocks
size_t bit_blocks
Number of bit blocks.
Definition: bmfunc.h:56
bm::bvector::bit_or
bm::bvector< Alloc > & bit_or(const bm::bvector< Alloc > &bv1, const bm::bvector< Alloc > &bv2, typename bm::bvector< Alloc >::optmode opt_mode)
3-operand OR : this := bv1 OR bv2
Definition: bm.h:4809
BM_DECLARE_TEMP_BLOCK
#define BM_DECLARE_TEMP_BLOCK(x)
Definition: bm.h:47
bm::serializer::serialize
size_type serialize(const BV &bv, unsigned char *buf, size_t buf_size)
Bitvector serialization into memory block.
Definition: bmserial.h:2264
bm::bvector::compare
int compare(const bvector< Alloc > &bvect) const BMNOEXCEPT
Lexicographical comparison with a bitvector.
Definition: bm.h:3159
serialize_bvector
static unsigned char * serialize_bvector(bm::serializer< bm::bvector<> > &bvs, bm::bvector<> &bv)
Definition: sample4.cpp:76
bm::bv_statistics::gap_blocks
size_t gap_blocks
Number of GAP blocks.
Definition: bmfunc.h:57
bm::bvector<>
bm::serializer::optimize_serialize_destroy
void optimize_serialize_destroy(BV &bv, typename serializer< BV >::buffer &buf)
Bitvector serialization into buffer object (resized automatically) Input bit-vector gets optimized an...
Definition: bmserial.h:1925
bm::bvector::count
size_type count() const BMNOEXCEPT
population cout (count of ON bits)
Definition: bm.h:2194
bm::serializer::gap_length_serialization
void gap_length_serialization(bool value) BMNOEXCEPT
Set GAP length serialization (serializes GAP levels of the original vector)
Definition: bmserial.h:1126
print_statistics
static void print_statistics(const bm::bvector<> &bv)
Definition: sample4.cpp:61
bm::BM_GAP
@ BM_GAP
GAP compression is ON.
Definition: bmconst.h:144
bm::serializer
Bit-vector serialization class.
Definition: bmserial.h:75
bmserial.h
Serialization / compression of bvector<>. Set theoretical operations on compressed BLOBs.
bm::serializer::byte_order_serialization
void byte_order_serialization(bool value) BMNOEXCEPT
Set byte-order serialization (for cross platform compatibility)
Definition: bmserial.h:1132
main
int main(void)
Definition: sample4.cpp:102
bm::bv_statistics::memory_used
size_t memory_used
memory usage for all blocks and service tables
Definition: bmfunc.h:61
bm.h
Compressed bit-vector bvector<> container, set algebraic methods, traversal iterators.
bm::bvector::set_bit
bool set_bit(size_type n, bool val=true)
Sets bit n.
Definition: bm.h:3617
bm::bvector::optimize
void optimize(bm::word_t *temp_block=0, optmode opt_mode=opt_compress, statistics *stat=0)
Optimize memory bitvector's memory allocation.
Definition: bm.h:3071
bm::bvector::statistics
Statistical information about bitset's memory allocation details.
Definition: bm.h:121