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/*
This file is part of GNUnet
Copyright (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 3, 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 set/gnunet-service-set_union_strata_estimator.c
* @brief invertible bloom filter
* @author Florian Dold
*/
#include "platform.h"
#include "gnunet_util_lib.h"
#include "ibf.h"
#include "gnunet-service-set_union_strata_estimator.h"
/**
* Write the given strata estimator to the buffer.
*
* @param se strata estimator to serialize
* @param buf buffer to write to, must be of appropriate size
*/
void
strata_estimator_write (const struct StrataEstimator *se,
void *buf)
{
unsigned int i;
GNUNET_assert (NULL != se);
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;
}
}
/**
* Read strata from the buffer into the given strata
* estimator. The strata estimator must already be allocated.
*
* @param buf buffer to read from
* @param se strata estimator to write to
*/
void
strata_estimator_read (const void *buf,
struct StrataEstimator *se)
{
unsigned 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;
}
}
/**
* Add a key to the strata estimator.
*
* @param se strata estimator to add the key to
* @param key key to add
*/
void
strata_estimator_insert (struct StrataEstimator *se,
struct IBF_Key key)
{
uint64_t v;
unsigned int i;
v = key.key_val;
/* count trailing '1'-bits of v */
for (i = 0; v & 1; v>>=1, i++)
/* empty */;
ibf_insert (se->strata[i], key);
}
/**
* Remove a key from the strata estimator.
*
* @param se strata estimator to remove the key from
* @param key key to remove
*/
void
strata_estimator_remove (struct StrataEstimator *se,
struct IBF_Key key)
{
uint64_t v;
unsigned int i;
v = key.key_val;
/* count trailing '1'-bits of v */
for (i = 0; v & 1; v>>=1, i++)
/* empty */;
ibf_remove (se->strata[i], key);
}
/**
* Create a new strata estimator with the given parameters.
*
* @param strata_count number of stratas, that is, number of ibfs in the estimator
* @param ibf_size size of each ibf stratum
* @param ibf_hashnum hashnum parameter of each ibf
* @return a freshly allocated, empty strata estimator
*/
struct StrataEstimator *
strata_estimator_create (unsigned int strata_count,
uint32_t ibf_size,
uint8_t ibf_hashnum)
{
struct StrataEstimator *se;
unsigned int i;
/* fixme: allocate everything in one chunk */
se = GNUNET_new (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;
unsigned 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;
/* FIXME: implement this without always allocating new IBFs */
diff = ibf_dup (se1->strata[i]);
ibf_subtract (diff, se2->strata[i]);
for (ibf_count = 0; GNUNET_YES; ibf_count++)
{
int more;
more = ibf_decode (diff, NULL, NULL);
if (GNUNET_NO == more)
{
count += ibf_count;
break;
}
/* Estimate if decoding fails or would not terminate */
if ((GNUNET_SYSERR == more) || (ibf_count > diff->size))
{
ibf_destroy (diff);
return count * (1 << (i + 1));
}
}
ibf_destroy (diff);
}
return count;
}
/**
* Make a copy of a strata estimator.
*
* @param se the strata estimator to copy
* @return the copy
*/
struct StrataEstimator *
strata_estimator_dup (struct StrataEstimator *se)
{
struct StrataEstimator *c;
unsigned int i;
c = GNUNET_new (struct StrataEstimator);
c->strata_count = se->strata_count;
c->ibf_size = se->ibf_size;
c->strata = GNUNET_malloc (sizeof (struct InvertibleBloomFilter *) * se->strata_count);
for (i = 0; i < se->strata_count; i++)
c->strata[i] = ibf_dup (se->strata[i]);
return c;
}
/**
* Destroy a strata estimator, free all of its resources.
*
* @param se strata estimator to destroy.
*/
void
strata_estimator_destroy (struct StrataEstimator *se)
{
unsigned 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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