dfc224c292
With the routines for key/value copy and free it is possible to duplicate or free different data types in the hash tables. The user_alloc() routine is the first example.
117 lines
4.0 KiB
C
117 lines
4.0 KiB
C
#ifndef _HASTABLE_H
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#define _HASTABLE_H
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/*
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* This file is distributed as part of the SkySQL Gateway. It is free
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* software: you can redistribute it and/or modify it under the terms of the
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* GNU General Public License as published by the Free Software Foundation,
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* version 2.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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* details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc., 51
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* Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Copyright SkySQL Ab 2013
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*/
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/**
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* @file hashtable.h A general purpose hashtable mechanism for use within the
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* gateway
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*
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* @verbatim
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* Revision History
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*
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* Date Who Description
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* 23/06/2013 Mark Riddoch Initial implementation
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* 23/07/2013 Mark Riddoch Addition of iterator mechanism
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* 08/01/2014 Massimiliano Pinto Added function pointers for key/value copy and free
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* the routine hashtable_memory_fns() changed accordingly
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*
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* @endverbatim
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*/
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#include <skygw_debug.h>
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#include <spinlock.h>
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#include <atomic.h>
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#include <dcb.h>
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/**
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* The entries within a hashtable.
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*
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* A NULL value for key indicates an empty entry.
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* The next pointer is the overflow chain for this hashentry.
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*/
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typedef struct hashentry {
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void *key; /**< The value of the key or NULL if empty entry */
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void *value; /**< The value associated with key */
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struct hashentry *next; /**< The overflow chain */
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} HASHENTRIES;
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/**
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* HASHTABLE iterator - used to walk the hashtable in a thread safe
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* way
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*/
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typedef struct hashiterator {
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struct hashtable
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*table; /**< The hashtable the iterator refers to */
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int chain; /**< The current chain we are walking */
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int depth; /**< The current depth down the chain */
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} HASHITERATOR;
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/**
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* The type definition for the memory allocation functions
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*/
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typedef void *(*HASHMEMORYFN)(void *);
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/**
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* The general purpose hashtable struct.
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*/
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typedef struct hashtable {
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#if defined(SS_DEBUG)
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skygw_chk_t ht_chk_top;
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#endif
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int hashsize; /**< The number of HASHENTRIES */
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HASHENTRIES **entries; /**< The entries themselves */
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int (*hashfn)(void *); /**< The hash function */
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int (*cmpfn)(void *, void *); /**< The key comparison function */
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HASHMEMORYFN kcopyfn; /**< Optional key copy function */
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HASHMEMORYFN vcopyfn; /**< Optional value copy function */
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HASHMEMORYFN kfreefn; /**< Optional key free function */
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HASHMEMORYFN vfreefn; /**< Optional value free function */
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SPINLOCK spin; /**< Internal spinlock for the hashtable */
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int n_readers; /**< Number of clients reading the table */
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int writelock; /**< The table is locked by a writer */
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#if defined(SS_DEBUG)
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skygw_chk_t ht_chk_tail;
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#endif
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} HASHTABLE;
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extern HASHTABLE *hashtable_alloc(int, int (*hashfn)(), int (*cmpfn)());
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/**< Allocate a hashtable */
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extern void hashtable_memory_fns(HASHTABLE *, HASHMEMORYFN, HASHMEMORYFN, HASHMEMORYFN, HASHMEMORYFN);
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/**< Provide an interface to control key/value memory
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* manipulation
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*/
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extern void hashtable_free(HASHTABLE *); /**< Free a hashtable */
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extern int hashtable_add(HASHTABLE *, void *, void *); /**< Add an entry */
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extern int hashtable_delete(HASHTABLE *, void *);
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/**< Delete an entry table */
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extern void *hashtable_fetch(HASHTABLE *, void *);
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/**< Fetch the data for a given key */
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extern void hashtable_stats(HASHTABLE *); /**< Print statisitics */
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void hashtable_get_stats(
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void* hashtable,
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int* hashsize,
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int* nelems,
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int* longest);
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extern HASHITERATOR *hashtable_iterator(HASHTABLE *);
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/**< Allocate an iterator on the hashtable */
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extern void *hashtable_next(HASHITERATOR *);
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/**< Return the key of the hash table iterator */
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extern void hashtable_iterator_free(HASHITERATOR *);
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#endif
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