added skeleton for gnunet set

1 files changed, 224 insertions, 0 deletions

diff --git a/src/set/ibf.h b/src/set/ibf.h
new file mode 100644
index 0000000000..2bf3ef7c78
--- /dev/null
+++ b/src/set/ibf.h
@@ -0,0 +1,224 @@
+/*
+      This file is part of GNUnet
+      (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 2, 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 consensus/ibf.h
+ * @brief invertible bloom filter
+ * @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
+
+
+struct IBF_Key
+{
+  uint64_t key_val;
+};
+
+struct IBF_KeyHash
+{
+  uint32_t key_hash_val;
+};
+
+struct IBF_Count
+{
+  int8_t count_val;
+};
+
+/**
+ * Size of one ibf bucket in bytes
+ */
+#define IBF_BUCKET_SIZE (sizeof (struct IBF_Count) + sizeof (struct IBF_Key) + \
+    sizeof (struct IBF_KeyHash))
+
+/**
+ * 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.
+   */
+  uint8_t hash_num;
+
+  /**
+   * Xor sums of the elements' keys, used to identify the elements.
+   * Array of 'size' elements.
+   */
+  struct IBF_Key *key_sum;
+
+  /**
+   * Xor sums of the hashes of the keys of inserted elements.
+   * Array of 'size' elements.
+   */
+  struct IBF_KeyHash *key_hash_sum;
+
+  /**
+   * How many times has a bucket been hit?
+   * Can be negative, as a result of IBF subtraction.
+   * Array of 'size' elements.
+   */
+  struct IBF_Count *count;
+};
+
+
+/**
+ * Write buckets from an ibf to a buffer.
+ * Exactly (IBF_BUCKET_SIZE*ibf->size) bytes are written to buf.
+ * 
+ * @param ibf the ibf to write
+ * @param start with which bucket to start
+ * @param count how many buckets to write
+ * @param buf buffer to write the data to
+ */
+void
+ibf_write_slice (const struct InvertibleBloomFilter *ibf, uint32_t start, uint32_t count, void *buf);
+
+
+/**
+ * Read buckets from a buffer into an ibf.
+ *
+ * @param buf pointer to the buffer to read from
+ * @param start which bucket to start at
+ * @param count how many buckets to read
+ * @param ibf the ibf to read from
+ */
+void
+ibf_read_slice (const void *buf, uint32_t start, uint32_t count, struct InvertibleBloomFilter *ibf);
+
+
+/**
+ * Create a key from a hashcode.
+ *
+ * @param hash the hashcode
+ * @return a key
+ */
+struct IBF_Key
+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 (struct IBF_Key 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
+ * @return the newly created invertible bloom filter
+ */
+struct InvertibleBloomFilter *
+ibf_create (uint32_t size, uint8_t hash_num);
+
+
+/**
+ * Insert an element into an IBF.
+ *
+ * @param ibf the IBF
+ * @param key the element's hash code
+ */
+void
+ibf_insert (struct InvertibleBloomFilter *ibf, struct IBF_Key key);
+
+
+/**
+ * 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, const struct InvertibleBloomFilter *ibf2);
+
+
+/**
+ * Decode and remove an element from the IBF, if possible.
+ *
+ * @param ibf the invertible bloom filter to decode
+ * @param ret_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 receives 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 failed
+ */
+int
+ibf_decode (struct InvertibleBloomFilter *ibf, int *ret_side, struct IBF_Key *ret_id);
+
+
+/**
+ * Create a copy of an IBF, the copy has to be destroyed properly.
+ *
+ * @param ibf the IBF to copy
+ */
+struct InvertibleBloomFilter *
+ibf_dup (const struct InvertibleBloomFilter *ibf);
+
+/**
+ * Destroy all resources associated with the invertible bloom filter.
+ * No more ibf_*-functions may be called on ibf after calling destroy.
+ *
+ * @param ibf the intertible bloom filter to destroy
+ */
+void
+ibf_destroy (struct InvertibleBloomFilter *ibf);
+
+
+#if 0                           /* keep Emacsens' auto-indent happy */
+{
+#endif
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+