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Add a type that stores chunks of data in its own storage and avoids duplicates. Supported methods: ha_storage_create() Allocates new storage object. ha_storage_put() Copies a given data chunk into the storage and returns pointer to the copy. If the data chunk is already present, a pointer to the existing object is returned and the given data chunk is not copied. ha_storage_empty() Clears (empties) the storage from all data chunks that are stored in it. ha_storage_free() Destroys a storage object. Opposite to ha_storage_create(). Approved by: Marko
112 lines
3 KiB
Text
112 lines
3 KiB
Text
/******************************************************
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Hash storage.
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Provides a data structure that stores chunks of data in
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its own storage, avoiding duplicates.
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(c) 2007 Innobase Oy
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Created September 24, 2007 Vasil Dimov
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*******************************************************/
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#include "univ.i"
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#include "ha0storage.h"
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#include "hash0hash.h"
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#include "mem0mem.h"
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struct ha_storage_struct {
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mem_heap_t* heap; /* storage from which memory is
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allocated */
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hash_table_t* hash; /* hash table used to avoid
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duplicates */
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};
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/* Objects of this type are put in the hash */
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typedef struct ha_storage_node_struct ha_storage_node_t;
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struct ha_storage_node_struct {
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ulint data_len;/* length of the data */
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void* data; /* pointer to data */
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ha_storage_node_t* next; /* next node in hash chain */
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};
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/***********************************************************************
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Creates a hash storage. If any of the parameters is 0, then a default
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value is used. */
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UNIV_INLINE
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ha_storage_t*
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ha_storage_create(
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/*==============*/
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/* out, own: hash storage */
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ulint initial_heap_bytes, /* in: initial heap's size */
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ulint initial_hash_cells) /* in: initial number of cells
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in the hash table */
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{
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ha_storage_t* storage;
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mem_heap_t* heap;
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if (initial_heap_bytes == 0) {
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initial_heap_bytes = HA_STORAGE_DEFAULT_HEAP_BYTES;
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}
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if (initial_hash_cells == 0) {
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initial_hash_cells = HA_STORAGE_DEFAULT_HASH_CELLS;
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}
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/* we put "storage" within "storage->heap" */
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heap = mem_heap_create(sizeof(ha_storage_t)
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+ initial_heap_bytes);
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storage = (ha_storage_t*) mem_heap_alloc(heap,
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sizeof(ha_storage_t));
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storage->heap = heap;
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storage->hash = hash_create(initial_hash_cells);
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return(storage);
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}
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/***********************************************************************
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Empties a hash storage, freeing memory occupied by data chunks.
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This invalidates any pointers previously returned by ha_storage_put().
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The hash storage is not invalidated itself and can be used again. */
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UNIV_INLINE
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void
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ha_storage_empty(
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/*=============*/
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ha_storage_t** storage) /* in/out: hash storage */
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{
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ha_storage_t temp_storage;
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temp_storage.heap = (*storage)->heap;
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temp_storage.hash = (*storage)->hash;
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/* order is important because the pointer temp_storage.hash is
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within the heap */
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hash_table_clear(temp_storage.hash);
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mem_heap_empty(temp_storage.heap);
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*storage = (ha_storage_t*) mem_heap_alloc(temp_storage.heap,
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sizeof(ha_storage_t));
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(*storage)->heap = temp_storage.heap;
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(*storage)->hash = temp_storage.hash;
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}
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/***********************************************************************
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Frees a hash storage and everything it contains, it cannot be used after
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this call.
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This invalidates any pointers previously returned by ha_storage_put().
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*/
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UNIV_INLINE
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void
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ha_storage_free(
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/*============*/
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ha_storage_t* storage) /* in/out: hash storage */
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{
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/* order is important because the pointer storage->hash is
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within the heap */
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hash_table_free(storage->hash);
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mem_heap_free(storage->heap);
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}
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