[GNUnet-SVN] r9212 - gnunet/src/util

[gnunet]

Author: grothoff
Date: 2009-10-20 01:21:23 -0600 (Tue, 20 Oct 2009)
New Revision: 9212

Modified:
   gnunet/src/util/container_multihashmap.c
Log:
fix bugs and add comments

Modified: gnunet/src/util/container_multihashmap.c
===================================================================
--- gnunet/src/util/container_multihashmap.c    2009-10-20 07:21:07 UTC (rev 
9211)
+++ gnunet/src/util/container_multihashmap.c    2009-10-20 07:21:23 UTC (rev 
9212)
@@ -29,43 +29,75 @@
 #include "gnunet_crypto_lib.h"
 
 /**
- *
+ * An entry in the hash map.
  */
 struct MapEntry
 {
+
+  /**
+   * Key for the entry.
+   */
   GNUNET_HashCode key;
+
+  /**
+   * Value of the entry.
+   */
   void *value;
+
+  /**
+   * If there is a hash collision, we create a linked list.
+   */
   struct MapEntry *next;
+
 };
 
 /**
- *
+ * Internal representation of the hash map.
  */
 struct GNUNET_CONTAINER_MultiHashMap
 {
 
+  /**
+   * All of our buckets.
+   */
   struct MapEntry **map;
 
+  /**
+   * Number of entries in the map.
+   */
   unsigned int size;
 
+  /**
+   * Length of the "map" array.
+   */
   unsigned int map_length;
 };
 
 
+/**
+ * Create a multi hash map.
+ *
+ * @param len initial size (map will grow as needed)
+ * @return NULL on error
+ */
 struct GNUNET_CONTAINER_MultiHashMap *
 GNUNET_CONTAINER_multihashmap_create (unsigned int len)
 {
   struct GNUNET_CONTAINER_MultiHashMap *ret;
 
   ret = GNUNET_malloc (sizeof (struct GNUNET_CONTAINER_MultiHashMap));
-  ret->size = 0;
   ret->map = GNUNET_malloc (len * sizeof (struct MapEntry *));
-  memset (ret->map, 0, len * sizeof (struct MapEntry *));
   ret->map_length = len;
   return ret;
 }
 
 
+/**
+ * Destroy a hash map.  Will not free any values
+ * stored in the hash map!
+ *
+ * @param map the map
+ */
 void
 GNUNET_CONTAINER_multihashmap_destroy (struct GNUNET_CONTAINER_MultiHashMap
                                        *map)
@@ -85,6 +117,14 @@
   GNUNET_free (map);
 }
 
+
+/**
+ * Compute the index of the bucket for the given key.
+ *
+ * @param m hash map for which to compute the index
+ * @param key what key should the index be computed for
+ * @return offset into the "map" array of "m"
+ */
 static unsigned int
 idx_of (const struct GNUNET_CONTAINER_MultiHashMap *m,
         const GNUNET_HashCode * key)
@@ -93,6 +133,12 @@
 }
 
 
+/**
+ * Get the number of key-value pairs in the map.
+ *
+ * @param map the map
+ * @return the number of key value pairs
+ */
 unsigned int
 GNUNET_CONTAINER_multihashmap_size (const struct GNUNET_CONTAINER_MultiHashMap
                                     *map)
@@ -101,6 +147,16 @@
 }
 
 
+/**
+ * Given a key find a value in the map matching the key.
+ *
+ * @param map the map
+ * @param key what to look for
+ * @return NULL if no value was found; note that
+ *   this is indistinguishable from values that just
+ *   happen to be NULL; use "contains" to test for
+ *   key-value pairs with value NULL
+ */
 void *
 GNUNET_CONTAINER_multihashmap_get (const struct GNUNET_CONTAINER_MultiHashMap
                                    *map, const GNUNET_HashCode * key)
@@ -118,11 +174,20 @@
 }
 
 
+/**
+ * Iterate over all entries in the map.
+ *
+ * @param map the map
+ * @param it function to call on each entry
+ * @param it_cls extra argument to it
+ * @return the number of key value pairs processed,
+ *         GNUNET_SYSERR if it aborted iteration
+ */
 int
 GNUNET_CONTAINER_multihashmap_iterate (const struct
                                        GNUNET_CONTAINER_MultiHashMap *map,
                                        GNUNET_CONTAINER_HashMapIterator it,
-                                       void *cls)
+                                       void *it_cls)
 {
   int count;
   unsigned int i;
@@ -134,7 +199,8 @@
       e = map->map[i];
       while (e != NULL)
         {
-          if ((NULL != it) && (GNUNET_OK != it (cls, &e->key, e->value)))
+          if ( (NULL != it) && 
+              (GNUNET_OK != it (it_cls, &e->key, e->value)) )
             return GNUNET_SYSERR;
           count++;
           e = e->next;
@@ -144,6 +210,17 @@
 }
 
 
+/**
+ * Remove the given key-value pair from the map.  Note that if the
+ * key-value pair is in the map multiple times, only one of the pairs
+ * will be removed.
+ *
+ * @param map the map
+ * @param key key of the key-value pair
+ * @param value value of the key-value pair
+ * @return GNUNET_YES on success, GNUNET_NO if the key-value pair
+ *  is not in the map
+ */
 int
 GNUNET_CONTAINER_multihashmap_remove (struct GNUNET_CONTAINER_MultiHashMap
                                       *map, const GNUNET_HashCode * key,
@@ -158,8 +235,8 @@
   e = map->map[i];
   while (e != NULL)
     {
-      if ((0 == memcmp (key, &e->key, sizeof (GNUNET_HashCode))) &&
-          (value == e->value))
+      if ( (0 == memcmp (key, &e->key, sizeof (GNUNET_HashCode))) &&
+          (value == e->value))
         {
           if (p == NULL)
             map->map[i] = e->next;
@@ -176,6 +253,14 @@
 }
 
 
+/**
+ * Remove all entries for the given key from the map.
+ * Note that the values would not be "freed".
+ *
+ * @param map the map
+ * @param key identifies values to be removed
+ * @return number of values removed
+ */
 int
 GNUNET_CONTAINER_multihashmap_remove_all (struct GNUNET_CONTAINER_MultiHashMap
                                           *map, const GNUNET_HashCode * key)
@@ -215,16 +300,23 @@
 }
 
 
+/**
+ * Check if the map contains any value under the given
+ * key (including values that are NULL).
+ *
+ * @param map the map
+ * @param key the key to test if a value exists for it
+ * @return GNUNET_YES if such a value exists,
+ *         GNUNET_NO if not
+ */
 int
 GNUNET_CONTAINER_multihashmap_contains (const struct
                                         GNUNET_CONTAINER_MultiHashMap *map,
                                         const GNUNET_HashCode * key)
 {
   struct MapEntry *e;
-  unsigned int i;
 
-  i = idx_of (map, key);
-  e = map->map[i];
+  e = map->map[idx_of (map, key)];
   while (e != NULL)
     {
       if (0 == memcmp (key, &e->key, sizeof (GNUNET_HashCode)))
@@ -235,32 +327,54 @@
 }
 
 
+/**
+ * Grow the given map to a more appropriate size.
+ *
+ * @param map the hash map to grow
+ */
 static void
 grow (struct GNUNET_CONTAINER_MultiHashMap *map)
 {
-  struct MapEntry **old;
+  struct MapEntry **old_map;
+  struct MapEntry **new_map;
   struct MapEntry *e;
+  unsigned int old_len;
+  unsigned int new_len;
+  unsigned int idx;
   unsigned int i;
-  unsigned int l;
 
-  old = map->map;
-  l = map->map_length;
-  map->map_length *= 2;
-  map->map = GNUNET_malloc (sizeof (struct MapEntry *) * map->map_length);
-  memset (map->map, 0, sizeof (struct MapEntry *) * map->map_length);
-  for (i = 0; i < l; i++)
+  old_map = map->map;
+  old_len = map->map_length;
+  new_len = old_len * 2;
+  new_map = GNUNET_malloc (sizeof (struct MapEntry *) * new_len);
+  map->map_length = new_len;
+  map->map = new_map;
+  for (i = 0; i < old_len; i++)
     {
-      while (NULL != (e = old[i]))
+      while (NULL != (e = old_map[i]))
         {
-          old[i] = e->next;
-          e->next = map->map[idx_of (map, &e->key)];
-          map->map[idx_of (map, &e->key)] = e;
+          old_map[i] = e->next;
+         idx = idx_of (map, &e->key);
+          e->next = new_map[idx];
+          new_map[idx] = e;
         }
     }
-  GNUNET_free (old);
+  GNUNET_free (old_map);
 }
 
 
+/**
+ * Store a key-value pair in the map.
+ *
+ * @param map the map
+ * @param key key to use
+ * @param value value to use
+ * @param opt options for put
+ * @return GNUNET_OK on success,
+ *         GNUNET_NO if a value was replaced (with REPLACE)
+ *         GNUNET_SYSERR if UNIQUE_ONLY was the option and the
+ *                       value already exists
+ */
 int
 GNUNET_CONTAINER_multihashmap_put (struct GNUNET_CONTAINER_MultiHashMap *map,
                                    const GNUNET_HashCode * key,
@@ -272,14 +386,13 @@
   unsigned int i;
 
   i = idx_of (map, key);
-  if ((opt != GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE) &&
-      (opt != GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST))
+  if ( (opt != GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE) &&
+       (opt != GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST) )
     {
       e = map->map[i];
       while (e != NULL)
         {
-          if ((0 == memcmp (key, &e->key, sizeof (GNUNET_HashCode))) &&
-              (value == e->value))
+          if (0 == memcmp (key, &e->key, sizeof (GNUNET_HashCode)))
             {
               if (opt == GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY)
                 return GNUNET_SYSERR;
@@ -289,7 +402,7 @@
           e = e->next;
         }
     }
-  if (map->size / 3 > map->map_length / 4)
+  if (map->size / 3 >= map->map_length / 4)
     grow (map);
   e = GNUNET_malloc (sizeof (struct MapEntry));
   e->key = *key;
@@ -301,12 +414,22 @@
 }
 
 
+/**
+ * Iterate over all entries in the map that match a particular key.
+ *
+ * @param map the map
+ * @param key key that the entries must correspond to
+ * @param it function to call on each entry
+ * @param it_cls extra argument to it
+ * @return the number of key value pairs processed,
+ *         GNUNET_SYSERR if it aborted iteration
+ */
 int
 GNUNET_CONTAINER_multihashmap_get_multiple (const struct
                                             GNUNET_CONTAINER_MultiHashMap
                                             *map, const GNUNET_HashCode * key,
                                             GNUNET_CONTAINER_HashMapIterator
-                                            it, void *cls)
+                                            it, void *it_cls)
 {
   int count;
   struct MapEntry *e;
@@ -317,7 +440,8 @@
     {
       if (0 == memcmp (key, &e->key, sizeof (GNUNET_HashCode)))
         {
-          if ((it != NULL) && (GNUNET_OK != it (&e->key, e->value, cls)))
+          if ( (it != NULL) && 
+              (GNUNET_OK != it (it_cls, &e->key, e->value)) )
             return GNUNET_SYSERR;
           count++;
         }
@@ -327,26 +451,34 @@
 }
 
 
+/**
+ * Returns the stored value of a random non-null entry in the hash
+ * table.  Returns only the first value, does not go inside bucket
+ * linked list (yet).  Runs with a worst case time of N, so it's not
+ * efficient in any way shape or form!!!!.
+ *
+ * @param map the map
+ * @return value associated with a random key
+ */
 void *
 GNUNET_CONTAINER_multihashmap_get_random (const struct
                                           GNUNET_CONTAINER_MultiHashMap *map)
 {
   unsigned int rand;
   struct MapEntry *e;
-  e = NULL;
 
   if (map->size == 0)
     return NULL;
-
-  while (e == NULL)
+  while (1)
     {
       rand =
         GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK,
                                   map->map_length);
-      e = map->map[rand];
+      if (NULL != (e = map->map[rand]))
+       return e->value;
     }
-
   return e->value;
 }
 
+
 /* end of container_multihashmap.c */