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/** @file include/ha0storage.ic
 Hash storage.
 Provides a data structure that stores chunks of data in
 its own storage, avoiding duplicates.

 Created September 24, 2007 Vasil Dimov
 *******************************************************/

#include "ha0storage.h"
#include "hash0hash.h"
#include "mem0mem.h"
#include "univ.i"

/** Hash storage for strings */
struct ha_storage_t {
  mem_heap_t *heap;   /*!< memory heap from which memory is
                      allocated */
  hash_table_t *hash; /*!< hash table used to avoid
                      duplicates */
};

/** Objects of this type are stored in ha_storage_t */
struct ha_storage_node_t {
  ulint data_len;          /*!< length of the data */
  const void *data;        /*!< pointer to data */
  ha_storage_node_t *next; /*!< next node in hash chain */
};

/** Creates a hash storage. If any of the parameters is 0, then a default
 value is used.
 @return own: hash storage */
UNIV_INLINE
ha_storage_t *ha_storage_create(
    ulint initial_heap_bytes, /*!< in: initial heap's size */
    ulint initial_hash_cells) /*!< in: initial number of cells
                              in the hash table */
{
  ha_storage_t *storage;
  mem_heap_t *heap;

  if (initial_heap_bytes == 0) {
    initial_heap_bytes = HA_STORAGE_DEFAULT_HEAP_BYTES;
  }

  if (initial_hash_cells == 0) {
    initial_hash_cells = HA_STORAGE_DEFAULT_HASH_CELLS;
  }

  /* we put "storage" within "storage->heap" */

  heap = mem_heap_create(sizeof(ha_storage_t) + initial_heap_bytes);

  storage = (ha_storage_t *)mem_heap_alloc(heap, sizeof(ha_storage_t));

  storage->heap = heap;
  storage->hash = hash_create(initial_hash_cells);

  return (storage);
}

/** Empties a hash storage, freeing memory occupied by data chunks.
 This invalidates any pointers previously returned by ha_storage_put().
 The hash storage is not invalidated itself and can be used again. */
UNIV_INLINE
void ha_storage_empty(ha_storage_t **storage) /*!< in/out: hash storage */
{
  ha_storage_t temp_storage;

  temp_storage.heap = (*storage)->heap;
  temp_storage.hash = (*storage)->hash;

  hash_table_clear(temp_storage.hash);
  mem_heap_empty(temp_storage.heap);

  *storage =
      (ha_storage_t *)mem_heap_alloc(temp_storage.heap, sizeof(ha_storage_t));

  (*storage)->heap = temp_storage.heap;
  (*storage)->hash = temp_storage.hash;
}

/** Frees a hash storage and everything it contains, it cannot be used after
 this call.
 This invalidates any pointers previously returned by ha_storage_put(). */
UNIV_INLINE
void ha_storage_free(ha_storage_t *storage) /*!< in, own: hash storage */
{
  /* order is important because the pointer storage->hash is
  within the heap */
  hash_table_free(storage->hash);
  mem_heap_free(storage->heap);
}

/** Gets the size of the memory used by a storage.
 @return bytes used */
UNIV_INLINE
ulint ha_storage_get_size(const ha_storage_t *storage) /*!< in: hash storage */
{
  ulint ret;

  ret = mem_heap_get_size(storage->heap);

  /* this assumes hash->heap and hash->heaps are NULL */
  ret += sizeof(hash_table_t);
  ret += sizeof(hash_cell_t) * hash_get_n_cells(storage->hash);

  return (ret);
}