- fix 2699

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

diff --git a/src/consensus/ibf.h b/src/consensus/ibf.h
index 12aef5d2f1029347180f7e063373b6b0961c1922..72345d3e1c115cdc70777a91e5b7e34ca66a369e 100644 (file)
--- a/src/consensus/ibf.h
+++ b/src/consensus/ibf.h
@@ -39,27 +39,86 @@ extern "C"
 #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;
+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
+ * @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
  * @return the newly created invertible bloom filter
  */
 struct InvertibleBloomFilter *
-ibf_create(unsigned int size, unsigned int hash_num, uint32_t salt);
+ibf_create(uint32_t size, unsigned int hash_num, uint32_t salt);
 
 
 /**
@@ -69,30 +128,33 @@ ibf_create(unsigned int size, unsigned int hash_num, uint32_t salt);
  * @param id the element's hash code
  */
 void
-ibf_insert (struct InvertibleBloomFilter *ibf, const struct 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 to decode
- * @param ret_id the hash code of the decoded element, if successful
  * @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, int *side, struct GNUNET_HashCode *ret_id);
+ibf_decode (struct InvertibleBloomFilter *ibf, int *side, uint64_t *ret_id);
 
 
 /**
@@ -103,15 +165,6 @@ ibf_decode (struct InvertibleBloomFilter *ibf, int *side, struct GNUNET_HashCode
 struct InvertibleBloomFilter *
 ibf_dup (struct InvertibleBloomFilter *ibf);
 
-
-/*
-ibf_hton ();
-
-ibf_ntoh ();
-
-ibf_get_nbo_size ();
-*/
-
 /**
  * Destroy all resources associated with the invertible bloom filter.
  * No more ibf_*-functions may be called on ibf after calling destroy.