2 This file is part of GNUnet
3 (C) 2012 Christian Grothoff (and other contributing authors)
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6 it under the terms of the GNU General Public License as published
7 by the Free Software Foundation; either version 2, or (at your
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
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22 * @file consensus/ibf.h
23 * @brief invertible bloom filter
24 * @author Florian Dold
28 #include "gnunet_common.h"
30 #include "strata_estimator.h"
33 strata_estimator_write (const struct StrataEstimator *se, void *buf)
36 for (i = 0; i < se->strata_count; i++)
38 ibf_write_slice (se->strata[i], 0, se->ibf_size, buf);
39 buf += se->ibf_size * IBF_BUCKET_SIZE;
44 strata_estimator_read (const void *buf, struct StrataEstimator *se)
47 for (i = 0; i < se->strata_count; i++)
49 ibf_read_slice (buf, 0, se->ibf_size, se->strata[i]);
50 buf += se->ibf_size * IBF_BUCKET_SIZE;
56 strata_estimator_insert (struct StrataEstimator *se, struct GNUNET_HashCode *key)
61 /* count trailing '1'-bits of v */
62 for (i = 0; v & 1; v>>=1, i++)
64 ibf_insert (se->strata[i], ibf_key_from_hashcode (key));
69 struct StrataEstimator *
70 strata_estimator_create (unsigned int strata_count, uint32_t ibf_size, uint8_t ibf_hashnum)
72 struct StrataEstimator *se;
75 /* fixme: allocate everything in one chunk */
77 se = GNUNET_malloc (sizeof (struct StrataEstimator));
78 se->strata_count = strata_count;
79 se->ibf_size = ibf_size;
80 se->strata = GNUNET_malloc (sizeof (struct InvertibleBloomFilter *) * strata_count);
81 for (i = 0; i < strata_count; i++)
82 se->strata[i] = ibf_create (ibf_size, ibf_hashnum);
88 * Estimate set difference with two strata estimators,
89 * i.e. arrays of IBFs.
90 * Does not not modify its arguments.
92 * @param se1 first strata estimator
93 * @param se2 second strata estimator
94 * @return the estimated difference
97 strata_estimator_difference (const struct StrataEstimator *se1,
98 const struct StrataEstimator *se2)
103 GNUNET_assert (se1->strata_count == se2->strata_count);
105 for (i = se1->strata_count - 1; i >= 0; i--)
107 struct InvertibleBloomFilter *diff;
108 /* number of keys decoded from the ibf */
112 /* FIXME: implement this without always allocating new IBFs */
113 diff = ibf_dup (se1->strata[i]);
114 ibf_subtract (diff, se2->strata[i]);
117 more = ibf_decode (diff, NULL, NULL);
118 if (GNUNET_NO == more)
123 if (GNUNET_SYSERR == more)
126 return count * (1 << (i + 1));
137 strata_estimator_destroy (struct StrataEstimator *se)
140 for (i = 0; i < se->strata_count; i++)
141 ibf_destroy (se->strata[i]);
142 GNUNET_free (se->strata);