slabhash.c File Reference

Implementation of hash table that consists of smaller hash tables. More...

#include "config.h"
#include "util/storage/slabhash.h"

Functions
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)
	Create new slabbed hash table. More...
void	slabhash_delete (struct slabhash *sl)
	Delete hash table. More...
void	slabhash_clear (struct slabhash *sl)
	Clear hash table. More...
static unsigned int	slab_idx (struct slabhash *sl, hashvalue_type hash)
	helper routine to calculate the slabhash index
void	slabhash_insert (struct slabhash *sl, hashvalue_type hash, struct lruhash_entry *entry, void *data, void *arg)
	Insert a new element into the hashtable, uses lruhash_insert. More...
struct lruhash_entry *	slabhash_lookup (struct slabhash *sl, hashvalue_type hash, void *key, int wr)
	Lookup an entry in the hashtable. More...
void	slabhash_remove (struct slabhash *sl, hashvalue_type hash, void *key)
	Remove entry from hashtable. More...
void	slabhash_status (struct slabhash *sl, const char *id, int extended)
	Output debug info to the log as to state of the hash table. More...
size_t	slabhash_get_size (struct slabhash *sl)
	Retrieve slab hash total size. More...
int	slabhash_is_size (struct slabhash *sl, size_t size, size_t slabs)
	See if slabhash is of given (size, slabs) configuration. More...
size_t	slabhash_get_mem (struct slabhash *sl)
	Retrieve slab hash current memory use. More...
struct lruhash *	slabhash_gettable (struct slabhash *sl, hashvalue_type hash)
	Get lruhash table for a given hash value. More...
static void	delkey (struct slabhash_testkey *k)
	delete key
static void	deldata (struct slabhash_testdata *d)
	delete data
size_t	test_slabhash_sizefunc (void *ATTR_UNUSED(key), void *ATTR_UNUSED(data))
int	test_slabhash_compfunc (void *key1, void *key2)
	test comparefunc for lruhash
void	test_slabhash_delkey (void *key, void *ATTR_UNUSED(arg))
void	test_slabhash_deldata (void *data, void *ATTR_UNUSED(arg))
void	slabhash_setmarkdel (struct slabhash *sl, lruhash_markdelfunc_type md)
	Set markdel function. More...
void	slabhash_traverse (struct slabhash *sh, int wr, void(*func)(struct lruhash_entry *, void *), void *arg)
	Traverse a slabhash. More...
size_t	count_slabhash_entries (struct slabhash *sh)
void	get_slabhash_stats (struct slabhash *sh, long long *num, long long *collisions)
	Retrieves number of items in slabhash and the current max collision level. More...

Detailed Description

Implementation of hash table that consists of smaller hash tables.

This results in a partitioned lruhash table. It cannot grow, but that gives it the ability to have multiple locks. Also this means there are multiple LRU lists.

Function Documentation

slabhash_create()

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
	)

Create new slabbed hash table.

Parameters

numtables	number of hash tables to use, other parameters used to initialize these smaller hashtables.
start_size	size of hashtable array at start, must be power of 2.
maxmem	maximum amount of memory this table is allowed to use. so every table gets maxmem/numtables to use for itself.
sizefunc	calculates memory usage of entries.
compfunc	compares entries, 0 on equality.
delkeyfunc	deletes key.
deldatafunc	deletes data.
arg	user argument that is passed to user function calls.

Returns

: new hash table or NULL on malloc failure.

References slabhash::array, lruhash::compfunc, lruhash::deldatafunc, lruhash::delkeyfunc, log_assert, lruhash_create(), slabhash::mask, slabhash::shift, slabhash::size, lruhash::sizefunc, and slabhash_delete().

Referenced by context_finalize(), daemon_apply_cfg(), infra_create(), key_cache_create(), rrset_cache_create(), and slabhash_test().

slabhash_delete()

void slabhash_delete

(

struct slabhash *

table

)

Delete hash table.

Entries are all deleted.

Parameters

table

to delete.

References slabhash::array, lruhash_delete(), and slabhash::size.

Referenced by context_finalize(), daemon_apply_cfg(), daemon_delete(), infra_delete(), key_cache_delete(), rrset_cache_delete(), slabhash_create(), and slabhash_test().

slabhash_clear()

void slabhash_clear

(

struct slabhash *

table

)

Clear hash table.

Entries are all deleted.

Parameters

table

to make empty.

References slabhash::array, lruhash_clear(), and slabhash::size.

Referenced by daemon_apply_cfg(), daemon_cleanup(), do_flush_infra(), libworker_alloc_cleanup(), test_long_table(), and worker_alloc_cleanup().

slabhash_insert()

void slabhash_insert	(	struct slabhash *	table,
		hashvalue_type	hash,
		struct lruhash_entry *	entry,
		void *	data,
		void *	cb_override
	)

Insert a new element into the hashtable, uses lruhash_insert.

If key is already present data pointer in that entry is updated.

Parameters

table	hash table.
hash	hash value. User calculates the hash.
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.
data	the data.
cb_override	if not NULL overrides the cb_arg for deletefunc.

References slabhash::array, lruhash_insert(), and slab_idx().

Referenced by dns_cache_store_msg(), dnsc_nonce_cache_insert(), dnsc_shared_secret_cache_insert(), infra_create_ratedata(), infra_edns_update(), infra_host(), infra_rtt_update(), infra_set_lame(), key_cache_insert(), rrset_cache_update(), test_short_table(), testadd(), and testadd_unlim().

slabhash_lookup()

struct lruhash_entry* slabhash_lookup	(	struct slabhash *	table,
		hashvalue_type	hash,
		void *	key,
		int	wr
	)

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).

Parameters

table	hash table.
hash	hash of key.
key	what to look for, compared against entries in overflow chain. the hash value must be set, and must work with compare function.
wr	set to true if you desire a writelock on the entry. with a writelock you can update the data part.

Returns

: pointer to the entry or NULL. The entry is locked. The user must unlock the entry when done.

References slabhash::array, lruhash_entry::hash, lruhash_entry::key, lruhash_lookup(), and slab_idx().

Referenced by dns_cache_lookup(), dnsc_nonces_lookup(), dnsc_shared_secrets_lookup(), infra_find_ip_ratedata(), infra_find_ratedata(), infra_lookup_nottl(), invalidateQueryInCache(), key_cache_search(), mesh_serve_expired_lookup(), msg_cache_lookup(), rrset_cache_lookup(), rrset_cache_update(), rrset_check_sec_status(), rrset_update_sec_status(), test_short_table(), testlookup(), and testlookup_unlim().

slabhash_remove()

void slabhash_remove	(	struct slabhash *	table,
		hashvalue_type	hash,
		void *	key
	)

Remove entry from hashtable.

Does nothing if not found in hashtable. Delfunc is called for the entry. Uses lruhash_remove.

Parameters

table	hash table.
hash	hash of key.
key	what to look for.

References slabhash::array, lruhash_entry::hash, lruhash_entry::key, lruhash_remove(), and slab_idx().

Referenced by do_cache_remove(), key_cache_remove(), msg_cache_remove(), rrset_cache_remove(), test_short_table(), testremove(), and testremove_unlim().

slabhash_status()

void slabhash_status	(	struct slabhash *	table,
		const char *	id,
		int	extended
	)

Output debug info to the log as to state of the hash table.

Parameters

table	hash table.
id	string printed with table to identify the hash table.
extended	set to true to print statistics on overflow bin lengths.

References slabhash::array, log_info(), lruhash_status(), slabhash::mask, slabhash::shift, and slabhash::size.

Referenced by test_long_table(), test_thr_main(), and test_threaded_table().

slabhash_get_size()

size_t slabhash_get_size

(

struct slabhash *

table

)

Retrieve slab hash total size.

Parameters

table

hash table.

Returns

size configured as max.

References slabhash::array, lruhash::lock, slabhash::size, and lruhash::space_max.

Referenced by slabhash_is_size().

slabhash_is_size()

int slabhash_is_size	(	struct slabhash *	table,
		size_t	size,
		size_t	slabs
	)

See if slabhash is of given (size, slabs) configuration.

Parameters

table	hash table
size	max size to test for
slabs	slab count to test for.

Returns

true if equal

References slabhash::size, and slabhash_get_size().

Referenced by context_finalize(), daemon_apply_cfg(), infra_adjust(), and rrset_cache_adjust().

slabhash_get_mem()

size_t slabhash_get_mem

(

struct slabhash *

table

)

Retrieve slab hash current memory use.

Parameters

table

hash table.

Returns

memory in use.

References slabhash::array, lruhash_get_mem(), lruhash::size, and slabhash::size.

Referenced by infra_get_mem(), key_cache_get_mem(), and print_mem().

slabhash_gettable()

struct lruhash* slabhash_gettable	(	struct slabhash *	table,
		hashvalue_type	hash
	)

Get lruhash table for a given hash value.

Parameters

table	slabbed hash table.
hash	hash value.

Returns

the lru hash table.

References slabhash::array, and slab_idx().

Referenced by rrset_cache_touch().

slabhash_setmarkdel()

void slabhash_setmarkdel	(	struct slabhash *	table,
		lruhash_markdelfunc_type	md
	)

Set markdel function.

Parameters

table	slabbed hash table.
md	markdel function ptr.

References slabhash::array, lruhash_setmarkdel(), and slabhash::size.

Referenced by rrset_cache_create().

slabhash_traverse()

void slabhash_traverse	(	struct slabhash *	table,
		int	wr,
		void(*)(struct lruhash_entry *, void *)	func,
		void *	arg
	)

Traverse a slabhash.

Parameters

table	slabbed hash table.
wr	if true, writelock is obtained, otherwise readlock.
func	function to call for every element.
arg	user argument to function.

References slabhash::array, lruhash_traverse(), and slabhash::size.

Referenced by do_dump_infra(), do_flush_bogus(), do_flush_infra(), do_flush_negative(), do_flush_zone(), and do_ratelimit_list().

get_slabhash_stats()

void get_slabhash_stats	(	struct slabhash *	table,
		long long *	entries_count,
		long long *	max_collisions
	)

Retrieves number of items in slabhash and the current max collision level.

Parameters

table	slabbed hash table.
entries_count	where to save the current number of elements.
max_collisions	where to save the current max collisions level.

References slabhash::array, lruhash::lock, lruhash::max_collisions, lruhash::num, and slabhash::size.

Referenced by server_stats_compile().