path: root/src/util/container_multihashmap.c

/*
     This file is part of GNUnet.
     (C) 2008 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 util/container_multihashmap.c
 * @brief hash map where the same key may be present multiple times
 * @author Christian Grothoff
 */

#include "platform.h"
#include "gnunet_common.h"
#include "gnunet_container_lib.h"
#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->map = GNUNET_malloc (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)
{
  unsigned int i;
  struct MapEntry *e;

  for (i = 0; i < map->map_length; i++)
    {
      while (NULL != (e = map->map[i]))
        {
          map->map[i] = e->next;
          GNUNET_free (e);
        }
    }
  GNUNET_free (map->map);
  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)
{
  return (*(unsigned int *) key) % m->map_length;
}


/**
 * 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)
{
  return map->size;
}


/**
 * 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)
{
  struct MapEntry *e;

  e = map->map[idx_of (map, key)];
  while (e != NULL)
    {
      if (0 == memcmp (key, &e->key, sizeof (GNUNET_HashCode)))
        return e->value;
      e = e->next;
    }
  return NULL;
}


/**
 * 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 *it_cls)
{
  int count;
  unsigned int i;
  struct MapEntry *e;

  count = 0;
  for (i = 0; i < map->map_length; i++)
    {
      e = map->map[i];
      while (e != NULL)
        {
          if ( (NULL != it) && 
	       (GNUNET_OK != it (it_cls, &e->key, e->value)) )
            return GNUNET_SYSERR;
          count++;
          e = e->next;
        }
    }
  return count;
}


/**
 * 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,
                                      void *value)
{
  struct MapEntry *e;
  struct MapEntry *p;
  unsigned int i;

  i = idx_of (map, key);
  p = NULL;
  e = map->map[i];
  while (e != NULL)
    {
      if ( (0 == memcmp (key, &e->key, sizeof (GNUNET_HashCode))) &&
	   (value == e->value))
        {
          if (p == NULL)
            map->map[i] = e->next;
          else
            p->next = e->next;
          GNUNET_free (e);
          map->size--;
          return GNUNET_YES;
        }
      p = e;
      e = e->next;
    }
  return GNUNET_NO;
}


/**
 * 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)
{
  struct MapEntry *e;
  struct MapEntry *p;
  unsigned int i;
  int ret;

  ret = 0;
  i = idx_of (map, key);
  p = NULL;
  e = map->map[i];
  while (e != NULL)
    {
      if (0 == memcmp (key, &e->key, sizeof (GNUNET_HashCode)))
        {
          if (p == NULL)
            map->map[i] = e->next;
          else
            p->next = e->next;
          GNUNET_free (e);
          map->size--;
          if (p == NULL)
            e = map->map[i];
          else
            e = p->next;
          ret++;
        }
      else
        {
          p = e;
          e = e->next;
        }
    }
  return ret;
}


/**
 * 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;

  e = map->map[idx_of (map, key)];
  while (e != NULL)
    {
      if (0 == memcmp (key, &e->key, sizeof (GNUNET_HashCode)))
        return GNUNET_YES;
      e = e->next;
    }
  return GNUNET_NO;
}


/**
 * 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_map;
  struct MapEntry **new_map;
  struct MapEntry *e;
  unsigned int old_len;
  unsigned int new_len;
  unsigned int idx;
  unsigned int 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_map[i]))
        {
          old_map[i] = e->next;
	  idx = idx_of (map, &e->key);
          e->next = new_map[idx];
          new_map[idx] = e;
        }
    }
  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,
                                   void *value,
                                   enum GNUNET_CONTAINER_MultiHashMapOption
                                   opt)
{
  struct MapEntry *e;
  unsigned int i;

  i = idx_of (map, key);
  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)))
            {
              if (opt == GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY)
                return GNUNET_SYSERR;
              e->value = value;
              return GNUNET_NO;
            }
          e = e->next;
        }
    }
  if (map->size / 3 >= map->map_length / 4)
    {
      grow (map);
      i = idx_of (map, key);  
    }
  e = GNUNET_malloc (sizeof (struct MapEntry));
  e->key = *key;
  e->value = value;
  e->next = map->map[i];
  map->map[i] = e;
  map->size++;
  return GNUNET_OK;
}


/**
 * 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 *it_cls)
{
  int count;
  struct MapEntry *e;

  count = 0;
  e = map->map[idx_of (map, key)];
  while (e != NULL)
    {
      if (0 == memcmp (key, &e->key, sizeof (GNUNET_HashCode)))
        {
          if ( (it != NULL) && 
	       (GNUNET_OK != it (it_cls, &e->key, e->value)) )
            return GNUNET_SYSERR;
          count++;
        }
      e = e->next;
    }
  return count;
}


/* end of container_multihashmap.c */