- fix 2699

[oweals/gnunet.git] / src / consensus / ibf.h

diff --git a/src/consensus/ibf.h b/src/consensus/ibf.h
index 2c9931e69532f4d7ff402e7bb8c595258d637ffd..72345d3e1c115cdc70777a91e5b7e34ca66a369e 100644 (file)
--- a/src/consensus/ibf.h
+++ b/src/consensus/ibf.h
@@ -16,8 +16,7 @@
       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
@@ -25,26 +24,102 @@
  * @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.
@@ -53,24 +128,33 @@ ibf_create(int size, int salt, int hash_num);
  * @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);
 
 
 /**
@@ -81,12 +165,6 @@ ibf_decode (struct InvertibleBloomFilter *ibf, struct GNUNET_HashCode *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.
@@ -96,3 +174,13 @@ ibf_ntoh();
 void
 ibf_destroy (struct InvertibleBloomFilter *ibf);
 
+
+#if 0                           /* keep Emacsens' auto-indent happy */
+{
+#endif
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+