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/*
* util/storage/slabhash.h - hashtable consisting of several smaller tables.
*
* Copyright (c) 2007, NLnet Labs. All rights reserved.
*
* This software is open source.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* Neither the name of the NLNET LABS nor the names of its contributors may
* be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
* \file
*
* Hash table that consists of smaller hash tables.
* It cannot grow, but that gives it the ability to have multiple
* locks. Also this means there are multiple LRU lists.
*/
#ifndef UTIL_STORAGE_SLABHASH_H
#define UTIL_STORAGE_SLABHASH_H
#include "util/storage/lruhash.h"
/** default number of slabs */
#define HASH_DEFAULT_SLABS 4
/**
* Hash table formed from several smaller ones.
* This results in a partitioned lruhash table, a 'slashtable'.
* None of the data inside the slabhash may be altered.
* Therefore, no locks are needed to access the structure.
*/
struct slabhash {
/** the size of the array - must be power of 2 */
size_t size;
/** size bitmask - uses high bits. */
uint32_t mask;
/** shift right this many bits to get index into array. */
unsigned int shift;
/** lookup array of hash tables */
struct lruhash** array;
};
/**
* Create new slabbed hash table.
* @param numtables: number of hash tables to use, other parameters used to
* initialize these smaller hashtables.
* @param start_size: size of hashtable array at start, must be power of 2.
* @param maxmem: maximum amount of memory this table is allowed to use.
* so every table gets maxmem/numtables to use for itself.
* @param sizefunc: calculates memory usage of entries.
* @param compfunc: compares entries, 0 on equality.
* @param delkeyfunc: deletes key.
* @param deldatafunc: deletes data.
* @param arg: user argument that is passed to user function calls.
* @return: new hash table or NULL on malloc failure.
*/
struct slabhash* slabhash_create(size_t numtables, size_t start_size,
size_t maxmem, lruhash_sizefunc_type sizefunc,
lruhash_compfunc_type compfunc, lruhash_delkeyfunc_type delkeyfunc,
lruhash_deldatafunc_type deldatafunc, void* arg);
/**
* Delete hash table. Entries are all deleted.
* @param table: to delete.
*/
void slabhash_delete(struct slabhash* table);
/**
* Clear hash table. Entries are all deleted.
* @param table: to make empty.
*/
void slabhash_clear(struct slabhash* table);
/**
* Insert a new element into the hashtable, uses lruhash_insert.
* If key is already present data pointer in that entry is updated.
*
* @param table: hash table.
* @param hash: hash value. User calculates the hash.
* @param entry: identifies the entry.
* If key already present, this entry->key is deleted immediately.
* But entry->data is set to NULL before deletion, and put into
* the existing entry. The data is then freed.
* @param data: the data.
* @param cb_override: if not NULL overrides the cb_arg for deletefunc.
*/
void slabhash_insert(struct slabhash* table, hashvalue_type hash,
struct lruhash_entry* entry, void* data, void* cb_override);
/**
* Lookup an entry in the hashtable. Uses lruhash_lookup.
* At the end of the function you hold a (read/write)lock on the entry.
* The LRU is updated for the entry (if found).
* @param table: hash table.
* @param hash: hash of key.
* @param key: what to look for, compared against entries in overflow chain.
* the hash value must be set, and must work with compare function.
* @param wr: set to true if you desire a writelock on the entry.
* with a writelock you can update the data part.
* @return: pointer to the entry or NULL. The entry is locked.
* The user must unlock the entry when done.
*/
struct lruhash_entry* slabhash_lookup(struct slabhash* table,
hashvalue_type hash, void* key, int wr);
/**
* Remove entry from hashtable. Does nothing if not found in hashtable.
* Delfunc is called for the entry. Uses lruhash_remove.
* @param table: hash table.
* @param hash: hash of key.
* @param key: what to look for.
*/
void slabhash_remove(struct slabhash* table, hashvalue_type hash, void* key);
/**
* Output debug info to the log as to state of the hash table.
* @param table: hash table.
* @param id: string printed with table to identify the hash table.
* @param extended: set to true to print statistics on overflow bin lengths.
*/
void slabhash_status(struct slabhash* table, const char* id, int extended);
/**
* Retrieve slab hash total size.
* @param table: hash table.
* @return size configured as max.
*/
size_t slabhash_get_size(struct slabhash* table);
/**
* See if slabhash is of given (size, slabs) configuration.
* @param table: hash table
* @param size: max size to test for
* @param slabs: slab count to test for.
* @return true if equal
*/
int slabhash_is_size(struct slabhash* table, size_t size, size_t slabs);
/**
* Retrieve slab hash current memory use.
* @param table: hash table.
* @return memory in use.
*/
size_t slabhash_get_mem(struct slabhash* table);
/**
* Get lruhash table for a given hash value
* @param table: slabbed hash table.
* @param hash: hash value.
* @return the lru hash table.
*/
struct lruhash* slabhash_gettable(struct slabhash* table, hashvalue_type hash);
/**
* Set markdel function
* @param table: slabbed hash table.
* @param md: markdel function ptr.
*/
void slabhash_setmarkdel(struct slabhash* table, lruhash_markdelfunc_type md);
/**
* Traverse a slabhash.
* @param table: slabbed hash table.
* @param wr: if true, writelock is obtained, otherwise readlock.
* @param func: function to call for every element.
* @param arg: user argument to function.
*/
void slabhash_traverse(struct slabhash* table, int wr,
void (*func)(struct lruhash_entry*, void*), void* arg);
/*
* Count entries in slabhash.
* @param table: slabbed hash table;
* @return the number of items
*/
size_t count_slabhash_entries(struct slabhash* table);
/**
* Retrieves number of items in slabhash and the current max collision level
* @param table: slabbed hash table.
* @param entries_count: where to save the current number of elements.
* @param max_collisions: where to save the current max collisions level.
*/
void get_slabhash_stats(struct slabhash* table,
long long* entries_count, long long* max_collisions);
/* --- test representation --- */
/** test structure contains test key */
struct slabhash_testkey {
/** the key id */
int id;
/** the entry */
struct lruhash_entry entry;
};
/** test structure contains test data */
struct slabhash_testdata {
/** data value */
int data;
};
/** test sizefunc for lruhash */
size_t test_slabhash_sizefunc(void*, void*);
/** test comparefunc for lruhash */
int test_slabhash_compfunc(void*, void*);
/** test delkey for lruhash */
void test_slabhash_delkey(void*, void*);
/** test deldata for lruhash */
void test_slabhash_deldata(void*, void*);
/* --- end test representation --- */
#endif /* UTIL_STORAGE_SLABHASH_H */
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