gnunet-dev 0.9.3-7build1 / usr / include / gnunet / gnunet_container_lib.h

/*
     This file is part of GNUnet.
     (C) 2001, 2002, 2003, 2004, 2005, 2006, 2008, 2009, 2010 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 include/gnunet_container_lib.h
 * @brief container classes for GNUnet
 *
 * @author Christian Grothoff
 * @author Nils Durner
 */

#ifndef GNUNET_CONTAINER_LIB_H
#define GNUNET_CONTAINER_LIB_H

/* add error and config prototypes */
#include "gnunet_crypto_lib.h"
#include <extractor.h>

#ifndef EXTRACTOR_METATYPE_GNUNET_ORIGINAL_FILENAME
/* hack for LE < 0.6.3 */
#define EXTRACTOR_METATYPE_GNUNET_ORIGINAL_FILENAME 180
#endif

#ifdef __cplusplus
extern "C"
{
#if 0                           /* keep Emacsens' auto-indent happy */
}
#endif
#endif


/* ******************* bloomfilter ***************** */

/**
 * @brief bloomfilter representation (opaque)
 */
struct GNUNET_CONTAINER_BloomFilter;

/**
 * Iterator over HashCodes.
 *
 * @param cls closure
 * @param next set to the next hash code
 * @return GNUNET_YES if next was updated
 *         GNUNET_NO if there are no more entries
 */
typedef int (*GNUNET_HashCodeIterator) (void *cls, GNUNET_HashCode * next);


/**
 * Load a bloom-filter from a file.
 *
 * @param filename the name of the file (or the prefix)
 * @param size the size of the bloom-filter (number of
 *        bytes of storage space to use); will be rounded up
 *        to next power of 2
 * @param k the number of GNUNET_CRYPTO_hash-functions to apply per
 *        element (number of bits set per element in the set)
 * @return the bloomfilter
 */
struct GNUNET_CONTAINER_BloomFilter *
GNUNET_CONTAINER_bloomfilter_load (const char *filename, size_t size,
                                   unsigned int k);


/**
 * Create a bloom filter from raw bits.
 *
 * @param data the raw bits in memory (maybe NULL,
 *        in which case all bits should be considered
 *        to be zero).
 * @param size the size of the bloom-filter (number of
 *        bytes of storage space to use); also size of data
 *        -- unless data is NULL.  Must be a power of 2.
 * @param k the number of GNUNET_CRYPTO_hash-functions to apply per
 *        element (number of bits set per element in the set)
 * @return the bloomfilter
 */
struct GNUNET_CONTAINER_BloomFilter *
GNUNET_CONTAINER_bloomfilter_init (const char *data, size_t size,
                                   unsigned int k);


/**
 * Copy the raw data of this bloomfilter into
 * the given data array.
 *
 * @param data where to write the data
 * @param size the size of the given data array
 * @return GNUNET_SYSERR if the data array of the wrong size
 */
int
GNUNET_CONTAINER_bloomfilter_get_raw_data (const struct
                                           GNUNET_CONTAINER_BloomFilter *bf,
                                           char *data, size_t size);


/**
 * Test if an element is in the filter.
 * @param e the element
 * @param bf the filter
 * @return GNUNET_YES if the element is in the filter, GNUNET_NO if not
 */
int
GNUNET_CONTAINER_bloomfilter_test (const struct GNUNET_CONTAINER_BloomFilter
                                   *bf, const GNUNET_HashCode * e);


/**
 * Add an element to the filter
 * @param bf the filter
 * @param e the element
 */
void
GNUNET_CONTAINER_bloomfilter_add (struct GNUNET_CONTAINER_BloomFilter *bf,
                                  const GNUNET_HashCode * e);


/**
 * Remove an element from the filter.
 * @param bf the filter
 * @param e the element to remove
 */
void
GNUNET_CONTAINER_bloomfilter_remove (struct GNUNET_CONTAINER_BloomFilter *bf,
                                     const GNUNET_HashCode * e);


/**
 * Create a copy of a bloomfilter.
 *
 * @param bf the filter
 * @return copy of bf
 */
struct GNUNET_CONTAINER_BloomFilter *
GNUNET_CONTAINER_bloomfilter_copy (const struct GNUNET_CONTAINER_BloomFilter
                                   *bf);



/**
 * Free the space associcated with a filter
 * in memory, flush to drive if needed (do not
 * free the space on the drive)
 * @param bf the filter
 */
void
GNUNET_CONTAINER_bloomfilter_free (struct GNUNET_CONTAINER_BloomFilter *bf);


/**
 * Get size of the bloom filter.
 *
 * @param bf the filter
 * @return number of bytes used for the data of the bloom filter
 */
size_t
GNUNET_CONTAINER_bloomfilter_get_size (const struct GNUNET_CONTAINER_BloomFilter
                                       *bf);


/**
 * Reset a bloom filter to empty.
 * @param bf the filter
 */
void
GNUNET_CONTAINER_bloomfilter_clear (struct GNUNET_CONTAINER_BloomFilter *bf);

/**
 * Or the entries of the given raw data array with the
 * data of the given bloom filter.  Assumes that
 * the size of the data array and the current filter
 * match.
 *
 * @param bf the filter
 * @param data data to OR-in
 * @param size size of data
 * @return GNUNET_OK on success
 */
int
GNUNET_CONTAINER_bloomfilter_or (struct GNUNET_CONTAINER_BloomFilter *bf,
                                 const char *data, size_t size);

/**
 * Or the entries of the given raw data array with the
 * data of the given bloom filter.  Assumes that
 * the size of the data array and the current filter
 * match.
 *
 * @param bf the filter
 * @param to_or the bloomfilter to or-in
 * @param size number of bytes in data
 */
int
GNUNET_CONTAINER_bloomfilter_or2 (struct GNUNET_CONTAINER_BloomFilter *bf,
                                  const struct GNUNET_CONTAINER_BloomFilter
                                  *to_or, size_t size);

/**
 * Resize a bloom filter.  Note that this operation
 * is pretty costly.  Essentially, the bloom filter
 * needs to be completely re-build.
 *
 * @param bf the filter
 * @param iterator an iterator over all elements stored in the BF
 * @param iterator_cls closure for iterator
 * @param size the new size for the filter
 * @param k the new number of GNUNET_CRYPTO_hash-function to apply per element
 */
void
GNUNET_CONTAINER_bloomfilter_resize (struct GNUNET_CONTAINER_BloomFilter *bf,
                                     GNUNET_HashCodeIterator iterator,
                                     void *iterator_cls, size_t size,
                                     unsigned int k);

/* ****************** metadata ******************* */

/**
 * Meta data to associate with a file, directory or namespace.
 */
struct GNUNET_CONTAINER_MetaData;

/**
 * Create a fresh MetaData token.
 *
 * @return empty meta-data container
 */
struct GNUNET_CONTAINER_MetaData *
GNUNET_CONTAINER_meta_data_create (void);

/**
 * Duplicate a MetaData token.
 *
 * @param md what to duplicate
 * @return duplicate meta-data container
 */
struct GNUNET_CONTAINER_MetaData *
GNUNET_CONTAINER_meta_data_duplicate (const struct GNUNET_CONTAINER_MetaData
                                      *md);

/**
 * Free meta data.
 *
 * @param md what to free
 */
void
GNUNET_CONTAINER_meta_data_destroy (struct GNUNET_CONTAINER_MetaData *md);

/**
 * Test if two MDs are equal. We consider them equal if
 * the meta types, formats and content match (we do not
 * include the mime types and plugins names in this
 * consideration).
 *
 * @param md1 first value to check
 * @param md2 other value to check
 * @return GNUNET_YES if they are equal
 */
int
GNUNET_CONTAINER_meta_data_test_equal (const struct GNUNET_CONTAINER_MetaData
                                       *md1,
                                       const struct GNUNET_CONTAINER_MetaData
                                       *md2);


/**
 * Extend metadata.
 *
 * @param md metadata to extend
 * @param plugin_name name of the plugin that produced this value;
 *        special values can be used (i.e. '&lt;zlib&gt;' for zlib being
 *        used in the main libextractor library and yielding
 *        meta data).
 * @param type libextractor-type describing the meta data
 * @param format basic format information about data
 * @param data_mime_type mime-type of data (not of the original file);
 *        can be NULL (if mime-type is not known)
 * @param data actual meta-data found
 * @param data_len number of bytes in data
 * @return GNUNET_OK on success, GNUNET_SYSERR if this entry already exists
 *         data_mime_type and plugin_name are not considered for "exists" checks
 */
int
GNUNET_CONTAINER_meta_data_insert (struct GNUNET_CONTAINER_MetaData *md,
                                   const char *plugin_name,
                                   enum EXTRACTOR_MetaType type,
                                   enum EXTRACTOR_MetaFormat format,
                                   const char *data_mime_type, const char *data,
                                   size_t data_len);


/**
 * Extend metadata.  Merges the meta data from the second argument
 * into the first, discarding duplicate key-value pairs.
 *
 * @param md metadata to extend
 * @param in metadata to merge
 */
void
GNUNET_CONTAINER_meta_data_merge (struct GNUNET_CONTAINER_MetaData *md,
                                  const struct GNUNET_CONTAINER_MetaData *in);


/**
 * Remove an item.
 *
 * @param md metadata to manipulate
 * @param type type of the item to remove
 * @param data specific value to remove, NULL to remove all
 *        entries of the given type
 * @param data_len number of bytes in data
 * @return GNUNET_OK on success, GNUNET_SYSERR if the item does not exist in md
 */
int
GNUNET_CONTAINER_meta_data_delete (struct GNUNET_CONTAINER_MetaData *md,
                                   enum EXTRACTOR_MetaType type,
                                   const char *data, size_t data_len);


/**
 * Remove all items in the container.
 *
 * @param md metadata to manipulate
 */
void
GNUNET_CONTAINER_meta_data_clear (struct GNUNET_CONTAINER_MetaData *md);


/**
 * Add the current time as the publication date
 * to the meta-data.
 *
 * @param md metadata to modify
 */
void
GNUNET_CONTAINER_meta_data_add_publication_date (struct
                                                 GNUNET_CONTAINER_MetaData *md);


/**
 * Iterate over MD entries.
 *
 * @param md metadata to inspect
 * @param iter function to call on each entry
 * @param iter_cls closure for iterator
 * @return number of entries
 */
int
GNUNET_CONTAINER_meta_data_iterate (const struct GNUNET_CONTAINER_MetaData *md,
                                    EXTRACTOR_MetaDataProcessor iter,
                                    void *iter_cls);

/**
 * Get the first MD entry of the given type.  Caller
 * is responsible for freeing the return value.
 * Also, only meta data items that are strings (0-terminated)
 * are returned by this function.
 *
 * @param md metadata to inspect
 * @param type type to look for
 * @return NULL if no entry was found
 */
char *
GNUNET_CONTAINER_meta_data_get_by_type (const struct GNUNET_CONTAINER_MetaData
                                        *md, enum EXTRACTOR_MetaType type);


/**
 * Get the first matching MD entry of the given types. Caller is
 * responsible for freeing the return value.  Also, only meta data
 * items that are strings (0-terminated) are returned by this
 * function.
 *
 * @param md metadata to inspect
 * @param ... -1-terminated list of types
 * @return NULL if we do not have any such entry,
 *  otherwise client is responsible for freeing the value!
 */
char *
GNUNET_CONTAINER_meta_data_get_first_by_types (const struct
                                               GNUNET_CONTAINER_MetaData *md,
                                               ...);

/**
 * Get a thumbnail from the meta-data (if present).  Only matches meta
 * data with mime type "image" and binary format.
 *
 * @param md metadata to inspect
 * @param thumb will be set to the thumbnail data.  Must be
 *        freed by the caller!
 * @return number of bytes in thumbnail, 0 if not available
 */
size_t
GNUNET_CONTAINER_meta_data_get_thumbnail (const struct GNUNET_CONTAINER_MetaData
                                          *md, unsigned char **thumb);



/**
 * Options for metadata serialization.
 */
enum GNUNET_CONTAINER_MetaDataSerializationOptions
{
  /**
   * Serialize all of the data.
   */
  GNUNET_CONTAINER_META_DATA_SERIALIZE_FULL = 0,

  /**
   * If not enough space is available, it is acceptable
   * to only serialize some of the metadata.
   */
  GNUNET_CONTAINER_META_DATA_SERIALIZE_PART = 1,

  /**
   * Speed is of the essence, do not allow compression.
   */
  GNUNET_CONTAINER_META_DATA_SERIALIZE_NO_COMPRESS = 2
};


/**
 * Serialize meta-data to target.
 *
 * @param md metadata to serialize
 * @param target where to write the serialized metadata;
 *         *target can be NULL, in which case memory is allocated
 * @param max maximum number of bytes available
 * @param opt is it ok to just write SOME of the
 *        meta-data to match the size constraint,
 *        possibly discarding some data?
 * @return number of bytes written on success,
 *         -1 on error (typically: not enough
 *         space)
 */
ssize_t
GNUNET_CONTAINER_meta_data_serialize (const struct GNUNET_CONTAINER_MetaData
                                      *md, char **target, size_t max,
                                      enum
                                      GNUNET_CONTAINER_MetaDataSerializationOptions
                                      opt);


/**
 * Get the size of the full meta-data in serialized form.
 *
 * @param md metadata to inspect
 * @return number of bytes needed for serialization, -1 on error
 */
ssize_t
GNUNET_CONTAINER_meta_data_get_serialized_size (const struct
                                                GNUNET_CONTAINER_MetaData *md);


/**
 * Deserialize meta-data.  Initializes md.
 *
 * @param input serialized meta-data.
 * @param size number of bytes available
 * @return MD on success, NULL on error (i.e.
 *         bad format)
 */
struct GNUNET_CONTAINER_MetaData *
GNUNET_CONTAINER_meta_data_deserialize (const char *input, size_t size);


/* ******************************* HashMap **************************** */

/**
 * Opaque handle for a HashMap.
 */
struct GNUNET_CONTAINER_MultiHashMap;

/**
 * Options for storing values in the HashMap.
 */
enum GNUNET_CONTAINER_MultiHashMapOption
{

  /**
   * If a value with the given key exists, replace it.  Note that the
   * old value would NOT be freed by replace (the application has to
   * make sure that this happens if required).
   */
  GNUNET_CONTAINER_MULTIHASHMAPOPTION_REPLACE,

  /**
   * Allow multiple values with the same key.
   */
  GNUNET_CONTAINER_MULTIHASHMAPOPTION_MULTIPLE,

  /**
   * There must only be one value per key; storing a value should fail
   * if a value under the same key already exists.
   */
  GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_ONLY,

  /**
   * There must only be one value per key, but don't bother checking
   * if a value already exists (faster than UNIQUE_ONLY; implemented
   * just like MULTIPLE but this option documents better what is
   * intended if UNIQUE is what is desired).
   */
  GNUNET_CONTAINER_MULTIHASHMAPOPTION_UNIQUE_FAST
};


/**
 * Iterator over hash map entries.
 *
 * @param cls closure
 * @param key current key code
 * @param value value in the hash map
 * @return GNUNET_YES if we should continue to
 *         iterate,
 *         GNUNET_NO if not.
 */
typedef int (*GNUNET_CONTAINER_HashMapIterator) (void *cls,
                                                 const GNUNET_HashCode * key,
                                                 void *value);


/**
 * 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);


/**
 * 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);


/**
 * 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);


/**
 * 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);

/**
 * 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);


/**
 * 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);


/**
 * Check if the map contains the given value under the given
 * key.
 *
 * @param map the map
 * @param key the key to test if a value exists for it
 * @param value value to test for
 * @return GNUNET_YES if such a value exists,
 *         GNUNET_NO if not
 */
int
GNUNET_CONTAINER_multihashmap_contains_value (const struct
                                              GNUNET_CONTAINER_MultiHashMap
                                              *map, const GNUNET_HashCode * key,
                                              const void *value);


/**
 * 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);

/**
 * 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);


/**
 * 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);


/**
 * 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);


/* ******************** doubly-linked list *************** */
/* To avoid mistakes: head->prev == tail->next == NULL     */

/**
 * Insert an element at the head of a DLL. Assumes that head, tail and
 * element are structs with prev and next fields.
 *
 * @param head pointer to the head of the DLL
 * @param tail pointer to the tail of the DLL
 * @param element element to insert
 */
#define GNUNET_CONTAINER_DLL_insert(head,tail,element) do { \
  GNUNET_assert ( ( (element)->prev == NULL) && ((head) != (element))); \
  GNUNET_assert ( ( (element)->next == NULL) && ((tail) != (element))); \
  (element)->next = (head); \
  (element)->prev = NULL; \
  if ((tail) == NULL) \
    (tail) = element; \
  else \
    (head)->prev = element; \
  (head) = (element); } while (0)


/**
 * Insert an element at the tail of a DLL. Assumes that head, tail and
 * element are structs with prev and next fields.
 *
 * @param head pointer to the head of the DLL
 * @param tail pointer to the tail of the DLL
 * @param element element to insert
 */
#define GNUNET_CONTAINER_DLL_insert_tail(head,tail,element) do { \
  GNUNET_assert ( ( (element)->prev == NULL) && ((head) != (element))); \
  GNUNET_assert ( ( (element)->next == NULL) && ((tail) != (element))); \
  (element)->prev = (tail); \
  (element)->next = NULL; \
  if ((head) == NULL) \
    (head) = element; \
  else \
    (tail)->next = element; \
  (tail) = (element); } while (0)


/**
 * Insert an element into a DLL after the given other element.  Insert
 * at the head if the other element is NULL.
 *
 * @param head pointer to the head of the DLL
 * @param tail pointer to the tail of the DLL
 * @param other prior element, NULL for insertion at head of DLL
 * @param element element to insert
 */
#define GNUNET_CONTAINER_DLL_insert_after(head,tail,other,element) do { \
  GNUNET_assert ( ( (element)->prev == NULL) && ((head) != (element))); \
  GNUNET_assert ( ( (element)->next == NULL) && ((tail) != (element))); \
  (element)->prev = (other); \
  if (NULL == other) \
    { \
      (element)->next = (head); \
      (head) = (element); \
    } \
  else \
    { \
      (element)->next = (other)->next; \
      (other)->next = (element); \
    } \
  if (NULL == (element)->next) \
    (tail) = (element); \
  else \
    (element)->next->prev = (element); } while (0)


/**
 * Insert an element into a DLL before the given other element.  Insert
 * at the tail if the other element is NULL.
 *
 * @param head pointer to the head of the DLL
 * @param tail pointer to the tail of the DLL
 * @param other prior element, NULL for insertion at head of DLL
 * @param element element to insert
 */
#define GNUNET_CONTAINER_DLL_insert_before(head,tail,other,element) do { \
  GNUNET_assert ( ( (element)->prev == NULL) && ((head) != (element))); \
  GNUNET_assert ( ( (element)->next == NULL) && ((tail) != (element))); \
  (element)->next = (other); \
  if (NULL == other) \
    { \
      (element)->prev = (tail); \
      (tail) = (element); \
    } \
  else \
    { \
      (element)->prev = (other)->prev; \
      (other)->prev = (element); \
    } \
  if (NULL == (element)->prev) \
    (head) = (element); \
  else \
    (element)->prev->next = (element); } while (0)


/**
 * Remove an element from a DLL. Assumes
 * that head, tail and element are structs
 * with prev and next fields.
 *
 * @param head pointer to the head of the DLL
 * @param tail pointer to the tail of the DLL
 * @param element element to remove
 */
#define GNUNET_CONTAINER_DLL_remove(head,tail,element) do { \
  GNUNET_assert ( ( (element)->prev != NULL) || ((head) == (element))); \
  GNUNET_assert ( ( (element)->next != NULL) || ((tail) == (element))); \
  if ((element)->prev == NULL) \
    (head) = (element)->next;  \
  else \
    (element)->prev->next = (element)->next; \
  if ((element)->next == NULL) \
    (tail) = (element)->prev;  \
  else \
    (element)->next->prev = (element)->prev; \
  (element)->next = NULL; \
  (element)->prev = NULL; } while (0)



/* ******************** Heap *************** */


/**
 * Cost by which elements in a heap can be ordered.
 */
typedef uint64_t GNUNET_CONTAINER_HeapCostType;


/*
 * Heap type, either max or min.  Hopefully makes the
 * implementation more useful.
 */
enum GNUNET_CONTAINER_HeapOrder
{
  /**
   * Heap with the maximum cost at the root.
   */
  GNUNET_CONTAINER_HEAP_ORDER_MAX,

  /**
   * Heap with the minimum cost at the root.
   */
  GNUNET_CONTAINER_HEAP_ORDER_MIN
};


/**
 * Handle to a Heap.
 */
struct GNUNET_CONTAINER_Heap;



/**
 * Handle to a node in a heap.
 */
struct GNUNET_CONTAINER_HeapNode;


/**
 * Create a new heap.
 *
 * @param order how should the heap be sorted?
 * @return handle to the heap
 */
struct GNUNET_CONTAINER_Heap *
GNUNET_CONTAINER_heap_create (enum GNUNET_CONTAINER_HeapOrder order);


/**
 * Destroys the heap.  Only call on a heap that
 * is already empty.
 *
 * @param heap heap to destroy
 */
void
GNUNET_CONTAINER_heap_destroy (struct GNUNET_CONTAINER_Heap *heap);


/**
 * Get element stored at root of heap.
 *
 * @param heap heap to inspect
 * @return NULL if heap is empty
 */
void *
GNUNET_CONTAINER_heap_peek (const struct GNUNET_CONTAINER_Heap *heap);


/**
 * Get the current size of the heap
 *
 * @param heap the heap to get the size of
 * @return number of elements stored
 */
unsigned int
GNUNET_CONTAINER_heap_get_size (const struct GNUNET_CONTAINER_Heap *heap);


/**
 * Get the current cost of the node
 *
 * @param node the node to get the cost of
 * @return cost of the node
 */
GNUNET_CONTAINER_HeapCostType
GNUNET_CONTAINER_heap_node_get_cost (const struct GNUNET_CONTAINER_HeapNode
                                     *node);

/**
 * Iterator for heap
 *
 * @param cls closure
 * @param node internal node of the heap
 * @param element value stored at the node
 * @param cost cost associated with the node
 * @return GNUNET_YES if we should continue to iterate,
 *         GNUNET_NO if not.
 */
typedef int (*GNUNET_CONTAINER_HeapIterator) (void *cls,
                                              struct GNUNET_CONTAINER_HeapNode *
                                              node, void *element,
                                              GNUNET_CONTAINER_HeapCostType
                                              cost);


/**
 * Iterate over all entries in the heap.
 *
 * @param heap the heap
 * @param iterator function to call on each entry
 * @param iterator_cls closure for iterator
 */
void
GNUNET_CONTAINER_heap_iterate (const struct GNUNET_CONTAINER_Heap *heap,
                               GNUNET_CONTAINER_HeapIterator iterator,
                               void *iterator_cls);


/**
 * Return a *uniform* random element from the heap.  Choose a random
 * number between 0 and heap size and then walk directly to it.
 * This cost can be between 0 and n, amortized cost of logN.
 *
 * @param heap heap to choose random element from
 * @param max how many nodes from the heap to choose from
 *
 * @return data stored at the chosen random node,
 *         NULL if the heap is empty.
 *
 */
void *
GNUNET_CONTAINER_heap_get_random (struct GNUNET_CONTAINER_Heap *heap,
                                  uint32_t max);


/**
 * Perform a random walk of the tree.  The walk is biased
 * towards elements closer to the root of the tree (since
 * each walk starts at the root and ends at a random leaf).
 * The heap internally tracks the current position of the
 * walk.
 *
 * @param heap heap to walk
 * @return data stored at the next random node in the walk;
 *         NULL if the tree is empty.
 */
void *
GNUNET_CONTAINER_heap_walk_get_next (struct GNUNET_CONTAINER_Heap *heap);


/**
 * Inserts a new element into the heap.
 *
 * @param heap heap to modify
 * @param element element to insert
 * @param cost cost for the element
 * @return node for the new element
 */
struct GNUNET_CONTAINER_HeapNode *
GNUNET_CONTAINER_heap_insert (struct GNUNET_CONTAINER_Heap *heap, void *element,
                              GNUNET_CONTAINER_HeapCostType cost);


/**
 * Remove root of the heap.
 *
 * @param heap heap to modify
 * @return element data stored at the root node
 */
void *
GNUNET_CONTAINER_heap_remove_root (struct GNUNET_CONTAINER_Heap *heap);


/**
 * Removes a node from the heap.
 *
 * @param node node to remove
 * @return element data stored at the node, NULL if heap is empty
 */
void *
GNUNET_CONTAINER_heap_remove_node (struct GNUNET_CONTAINER_HeapNode *node);


/**
 * Updates the cost of any node in the tree
 *
 * @param heap heap to modify
 * @param node node for which the cost is to be changed
 * @param new_cost new cost for the node
 */
void
GNUNET_CONTAINER_heap_update_cost (struct GNUNET_CONTAINER_Heap *heap,
                                   struct GNUNET_CONTAINER_HeapNode *node,
                                   GNUNET_CONTAINER_HeapCostType new_cost);


/* ******************** Singly linked list *************** */

/**
 * Possible ways for how data stored in the linked list
 * might be allocated.
 */
enum GNUNET_CONTAINER_SListDisposition
{
    /**
     * Single-linked list must copy the buffer.
     */
  GNUNET_CONTAINER_SLIST_DISPOSITION_TRANSIENT = 0,

    /**
     * Data is static, no need to copy or free.
     */
  GNUNET_CONTAINER_SLIST_DISPOSITION_STATIC = 2,

    /**
     * Data is dynamic, do not copy but free when done.
     */
  GNUNET_CONTAINER_SLIST_DISPOSITION_DYNAMIC = 4
};



/**
 * Handle to a singly linked list
 */
struct GNUNET_CONTAINER_SList;

/**
 * Handle to a singly linked list iterator
 */
struct GNUNET_CONTAINER_SList_Iterator
{
  /**
   * Linked list that we are iterating over.
   */
  struct GNUNET_CONTAINER_SList *list;

  /**
   * Last element accessed.
   */
  struct GNUNET_CONTAINER_SList_Elem *last;

  /**
   * Current list element.
   */
  struct GNUNET_CONTAINER_SList_Elem *elem;
};



/**
 * Add a new element to the list
 * @param l list
 * @param disp memory disposition
 * @param buf payload buffer
 * @param len length of the buffer
 */
void
GNUNET_CONTAINER_slist_add (struct GNUNET_CONTAINER_SList *l,
                            enum GNUNET_CONTAINER_SListDisposition disp,
                            const void *buf, size_t len);


/**
 * Add a new element to the end of the list
 * @param l list
 * @param disp memory disposition
 * @param buf payload buffer
 * @param len length of the buffer
 */
void
GNUNET_CONTAINER_slist_add_end (struct GNUNET_CONTAINER_SList *l,
                                enum GNUNET_CONTAINER_SListDisposition disp,
                                const void *buf, size_t len);


/**
 * Append a singly linked list to another
 * @param dst list to append to
 * @param src source
 */
void
GNUNET_CONTAINER_slist_append (struct GNUNET_CONTAINER_SList *dst,
                               struct GNUNET_CONTAINER_SList *src);


/**
 * Create a new singly linked list
 * @return the new list
 */
struct GNUNET_CONTAINER_SList *
GNUNET_CONTAINER_slist_create (void);


/**
 * Destroy a singly linked list
 * @param l the list to be destroyed
 */
void
GNUNET_CONTAINER_slist_destroy (struct GNUNET_CONTAINER_SList *l);


/**
 * Return the beginning of a list
 *
 * @param l list
 * @return iterator pointing to the beginning (by value! Either allocate the
 *   structure on the stack, or use GNUNET_malloc() yourself! All other
 *   functions do take pointer to this struct though)
 */
struct GNUNET_CONTAINER_SList_Iterator
GNUNET_CONTAINER_slist_begin (struct GNUNET_CONTAINER_SList *l);


/**
 * Clear a list
 *
 * @param l list
 */
void
GNUNET_CONTAINER_slist_clear (struct GNUNET_CONTAINER_SList *l);


/**
 * Check if a list contains a certain element
 * @param l list
 * @param buf payload buffer to find
 * @param len length of the payload (number of bytes in buf)
 *
 * @return GNUNET_YES if found, GNUNET_NO otherwise
 */
int
GNUNET_CONTAINER_slist_contains (const struct GNUNET_CONTAINER_SList *l,
                                 const void *buf, size_t len);

/**
 * Check if a list contains a certain element using 'compare' function
 *
 * @param l list
 * @param buf payload buffer to find
 * @param len length of the payload (number of bytes in buf)
 * @param compare comparison function
 *
 * @return NULL if the 'buf' could not be found, pointer to the
 *         list element, if found
 */
void *
GNUNET_CONTAINER_slist_contains2 (const struct GNUNET_CONTAINER_SList *l,
                                  const void *buf, size_t len,
                                  int (*compare)(const void *, const size_t, const void *, const size_t));
/**
 * Count the elements of a list
 * @param l list
 * @return number of elements in the list
 */
int
GNUNET_CONTAINER_slist_count (const struct GNUNET_CONTAINER_SList *l);


/**
 * Remove an element from the list
 * @param i iterator that points to the element to be removed
 */
void
GNUNET_CONTAINER_slist_erase (struct GNUNET_CONTAINER_SList_Iterator *i);


/**
 * Insert an element into a list at a specific position
 * @param before where to insert the new element
 * @param disp memory disposition
 * @param buf payload buffer
 * @param len length of the payload
 */
void
GNUNET_CONTAINER_slist_insert (struct GNUNET_CONTAINER_SList_Iterator *before,
                               enum GNUNET_CONTAINER_SListDisposition disp,
                               const void *buf, size_t len);


/**
 * Advance an iterator to the next element
 * @param i iterator
 * @return GNUNET_YES on success, GNUNET_NO if the end has been reached
 */
int
GNUNET_CONTAINER_slist_next (struct GNUNET_CONTAINER_SList_Iterator *i);


/**
 * Check if an iterator points beyond the end of a list
 * @param i iterator
 * @return GNUNET_YES if the end has been reached, GNUNET_NO if the iterator
 *         points to a valid element
 */
int
GNUNET_CONTAINER_slist_end (struct GNUNET_CONTAINER_SList_Iterator *i);


/**
 * Retrieve the element at a specific position in a list
 *
 * @param i iterator
 * @param len set to the payload length
 * @return payload
 */
void *
GNUNET_CONTAINER_slist_get (const struct GNUNET_CONTAINER_SList_Iterator *i,
                            size_t * len);


/**
 * Release an iterator
 * @param i iterator
 */
void
GNUNET_CONTAINER_slist_iter_destroy (struct GNUNET_CONTAINER_SList_Iterator *i);


#if 0                           /* keep Emacsens' auto-indent happy */
{
#endif
#ifdef __cplusplus
}
#endif


/* ifndef GNUNET_CONTAINER_LIB_H */
#endif
/* end of gnunet_container_lib.h */