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8dba58e45b
Add const qualifier to the value returned by ha_storage_put(). It must not be changed as this will invalidate the hash.
84 lines
2.7 KiB
C
84 lines
2.7 KiB
C
/******************************************************
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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 22, 2007 Vasil Dimov
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*******************************************************/
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#ifndef ha0storage_h
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#define ha0storage_h
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#include "univ.i"
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/* This value is used by default by ha_storage_create(). More memory
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is allocated later when/if it is needed. */
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#define HA_STORAGE_DEFAULT_HEAP_BYTES 1024
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/* This value is used by default by ha_storage_create(). It is a
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constant per ha_storage's lifetime. */
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#define HA_STORAGE_DEFAULT_HASH_CELLS 4096
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typedef struct ha_storage_struct ha_storage_t;
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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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Copies string into the storage and returns a pointer to the copy. If the
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same string is already present, then pointer to it is returned.
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Strings are considered to be equal if strcmp(str1, str2) == 0. */
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#define ha_storage_put_str(storage, str) \
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((const char*) ha_storage_put((storage), (str), strlen(str) + 1))
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/***********************************************************************
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Copies data into the storage and returns a pointer to the copy. If the
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same data chunk is already present, then pointer to it is returned.
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Data chunks are considered to be equal if len1 == len2 and
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memcmp(data1, data2, len1) == 0. */
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const void*
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ha_storage_put(
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/*===========*/
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ha_storage_t* storage, /* in/out: hash storage */
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const void* data, /* in: data to store */
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ulint data_len); /* in: data length */
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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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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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#ifndef UNIV_NONINL
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#include "ha0storage.ic"
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#endif
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#endif /* ha0storage_h */
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