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/*
This file is part of GNUnet
(C) 2012 Christian Grothoff (and other contributing authors)
GNUnet 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, or (at your
option) any later version.
GNUnet 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 GNUnet; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
*/
/**
* @file consensus/ibf.h
* @brief invertible bloom filter
* @author Florian Dold
*/
#include "platform.h"
#include "gnunet_common.h"
#include "ibf.h"
#include "strata_estimator.h"
void
strata_estimator_write (const struct StrataEstimator *se, void *buf)
{
int i;
for (i = 0; i < se->strata_count; i++)
{
ibf_write_slice (se->strata[i], 0, se->ibf_size, buf);
buf += se->ibf_size * IBF_BUCKET_SIZE;
}
}
void
strata_estimator_read (const void *buf, struct StrataEstimator *se)
{
int i;
for (i = 0; i < se->strata_count; i++)
{
ibf_read_slice (buf, 0, se->ibf_size, se->strata[i]);
buf += se->ibf_size * IBF_BUCKET_SIZE;
}
}
void
strata_estimator_insert (struct StrataEstimator *se, struct GNUNET_HashCode *key)
{
uint32_t v;
int i;
v = key->bits[0];
/* count trailing '1'-bits of v */
for (i = 0; v & 1; v>>=1, i++)
/* empty */;
ibf_insert (se->strata[i], ibf_key_from_hashcode (key));
}
struct StrataEstimator *
strata_estimator_create (unsigned int strata_count, uint32_t ibf_size, uint8_t ibf_hashnum)
{
struct StrataEstimator *se;
int i;
/* fixme: allocate everything in one chunk */
se = GNUNET_malloc (sizeof (struct StrataEstimator));
se->strata_count = strata_count;
se->ibf_size = ibf_size;
se->strata = GNUNET_malloc (sizeof (struct InvertibleBloomFilter *) * strata_count);
for (i = 0; i < strata_count; i++)
se->strata[i] = ibf_create (ibf_size, ibf_hashnum);
return se;
}
/**
* Estimate set difference with two strata estimators,
* i.e. arrays of IBFs.
* Does not not modify its arguments.
*
* @param se1 first strata estimator
* @param se2 second strata estimator
* @return the estimated difference
*/
unsigned int
strata_estimator_difference (const struct StrataEstimator *se1,
const struct StrataEstimator *se2)
{
int i;
int count;
GNUNET_assert (se1->strata_count == se2->strata_count);
count = 0;
for (i = se1->strata_count - 1; i >= 0; i--)
{
struct InvertibleBloomFilter *diff;
/* number of keys decoded from the ibf */
int ibf_count;
int more;
ibf_count = 0;
/* FIXME: implement this without always allocating new IBFs */
diff = ibf_dup (se1->strata[i]);
ibf_subtract (diff, se2->strata[i]);
for (;;)
{
more = ibf_decode (diff, NULL, NULL);
if (GNUNET_NO == more)
{
count += ibf_count;
break;
}
if (GNUNET_SYSERR == more)
{
ibf_destroy (diff);
return count * (1 << (i + 1));
}
ibf_count++;
}
ibf_destroy (diff);
}
return count;
}
void
strata_estimator_destroy (struct StrataEstimator *se)
{
int i;
for (i = 0; i < se->strata_count; i++)
ibf_destroy (se->strata[i]);
GNUNET_free (se->strata);
GNUNET_free (se);
}
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