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
* @author Florian Dold
*/
+#ifndef GNUNET_CONSENSUS_IBF_H
+#define GNUNET_CONSENSUS_IBF_H
+
+#include "platform.h"
+#include "gnunet_common.h"
+#include "gnunet_util_lib.h"
+
+#ifdef __cplusplus
+extern "C"
+{
+#if 0 /* keep Emacsens' auto-indent happy */
+}
+#endif
+#endif
+
+/**
+ * Size of one ibf bucket in bytes
+ */
+#define IBF_BUCKET_SIZE (8+4+1)
+
/**
- * Opaque handle to an invertible bloom filter (IBF).
+ * Invertible bloom filter (IBF).
*
* An IBF is a counting bloom filter that has the ability to restore
* the hashes of its stored elements with high probability.
*/
struct InvertibleBloomFilter
+{
+ /**
+ * How many cells does this IBF have?
+ */
+ uint32_t size;
+
+ /**
+ * In how many cells do we hash one element?
+ * Usually 4 or 3.
+ */
+ unsigned int hash_num;
+
+ /**
+ * Salt for mingling hashes
+ */
+ uint32_t salt;
+
+ /**
+ * xor sums of the elements' hash codes, used to identify the elements.
+ */
+ uint64_t *id_sum;
+
+ /**
+ * xor sums of the "hash of the hash".
+ */
+ uint32_t *hash_sum;
+
+ /**
+ * How many times has a bucket been hit?
+ * Can be negative, as a result of IBF subtraction.
+ */
+ int8_t *count;
+};
+
+
+/**
+ * Create a key from a hashcode.
+ *
+ * @param hash the hashcode
+ * @return a key
+ */
+uint64_t
+ibf_key_from_hashcode (const struct GNUNET_HashCode *hash);
+
+
+/**
+ * Create a hashcode from a key, by replicating the key
+ * until the hascode is filled
+ *
+ * @param key the key
+ * @param dst hashcode to store the result in
+ */
+void
+ibf_hashcode_from_key (uint64_t key, struct GNUNET_HashCode *dst);
+
/**
* Create an invertible bloom filter.
*
* @param size number of IBF buckets
+ * @param hash_num number of buckets one element is hashed in, usually 3 or 4
* @param salt salt for mingling hashes, different salt may
* result in less (or more) collisions
- * @param hash_num number of buckets one element is hashed in
* @return the newly created invertible bloom filter
*/
struct InvertibleBloomFilter *
-ibf_create(int size, int salt, int hash_num);
+ibf_create(uint32_t size, unsigned int hash_num, uint32_t salt);
+
/**
* Insert an element into an IBF.
* @param id the element's hash code
*/
void
-ibf_insert (struct InvertibleBloomFilter *ibf, GNUNET_HashCode *id);
+ibf_insert (struct InvertibleBloomFilter *ibf, uint64_t id);
+
/**
* Subtract ibf2 from ibf1, storing the result in ibf1.
* The two IBF's must have the same parameters size and hash_num.
+ *
+ * @param ibf1 IBF that is subtracted from
+ * @param ibf2 IBF that will be subtracted from ibf1
*/
void
-ibf_subtract (struct InvertibleBloomFilter *ibf1, struct InvertibleBloomFilter *ibf2);
+ibf_subtract (struct InvertibleBloomFilter *ibf1, const struct InvertibleBloomFilter *ibf2);
+
/**
* Decode and remove an element from the IBF, if possible.
*
- * @param ibf the invertible bloom filter
- * @param the id of the element is written to this hash code
- * @return GNUNET_YES if decoding an element was successful, GNUNET_NO if it failed to decode
+ * @param ibf the invertible bloom filter to decode
+ * @param side sign of the cell's count where the decoded element came from.
+ * A negative sign indicates that the element was recovered resides in an IBF
+ * that was previously subtracted from.
+ * @param ret_id the hash code of the decoded element, if successful
+ * @return GNUNET_YES if decoding an element was successful, GNUNET_NO if the IBF is empty,
+ * GNUNET_SYSERR if the decoding has faile
*/
int
-ibf_decode (struct InvertibleBloomFilter *ibf, struct GNUNET_HashCode *ret_id);
+ibf_decode (struct InvertibleBloomFilter *ibf, int *side, uint64_t *ret_id);
/**
struct InvertibleBloomFilter *
ibf_dup (struct InvertibleBloomFilter *ibf);
-/*
-ibf_hton();
-
-ibf_ntoh();
-*/
-
/**
* Destroy all resources associated with the invertible bloom filter.
* No more ibf_*-functions may be called on ibf after calling destroy.
void
ibf_destroy (struct InvertibleBloomFilter *ibf);
+
+#if 0 /* keep Emacsens' auto-indent happy */
+{
+#endif
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+