[redis.git] / deps / jemalloc / src / ckh.c

/*
 *******************************************************************************
 * Implementation of (2^1+,2) cuckoo hashing, where 2^1+ indicates that each
 * hash bucket contains 2^n cells, for n >= 1, and 2 indicates that two hash
 * functions are employed.  The original cuckoo hashing algorithm was described
 * in:
 *
 *   Pagh, R., F.F. Rodler (2004) Cuckoo Hashing.  Journal of Algorithms
 *     51(2):122-144.
 *
 * Generalization of cuckoo hashing was discussed in:
 *
 *   Erlingsson, U., M. Manasse, F. McSherry (2006) A cool and practical
 *     alternative to traditional hash tables.  In Proceedings of the 7th
 *     Workshop on Distributed Data and Structures (WDAS'06), Santa Clara, CA,
 *     January 2006.
 *
 * This implementation uses precisely two hash functions because that is the
 * fewest that can work, and supporting multiple hashes is an implementation
 * burden.  Here is a reproduction of Figure 1 from Erlingsson et al. (2006)
 * that shows approximate expected maximum load factors for various
 * configurations:
 *
 *           |         #cells/bucket         |
 *   #hashes |   1   |   2   |   4   |   8   |
 *   --------+-------+-------+-------+-------+
 *         1 | 0.006 | 0.006 | 0.03  | 0.12  |
 *         2 | 0.49  | 0.86  |>0.93< |>0.96< |
 *         3 | 0.91  | 0.97  | 0.98  | 0.999 |
 *         4 | 0.97  | 0.99  | 0.999 |       |
 *
 * The number of cells per bucket is chosen such that a bucket fits in one cache
 * line.  So, on 32- and 64-bit systems, we use (8,2) and (4,2) cuckoo hashing,
 * respectively.
 *
 ******************************************************************************/
#define	JEMALLOC_CKH_C_
#include "jemalloc/internal/jemalloc_internal.h"

/******************************************************************************/
/* Function prototypes for non-inline static functions. */

static bool	ckh_grow(ckh_t *ckh);
static void	ckh_shrink(ckh_t *ckh);

/******************************************************************************/

/*
 * Search bucket for key and return the cell number if found; SIZE_T_MAX
 * otherwise.
 */
JEMALLOC_INLINE size_t
ckh_bucket_search(ckh_t *ckh, size_t bucket, const void *key)
{
	ckhc_t *cell;
	unsigned i;

	for (i = 0; i < (ZU(1) << LG_CKH_BUCKET_CELLS); i++) {
		cell = &ckh->tab[(bucket << LG_CKH_BUCKET_CELLS) + i];
		if (cell->key != NULL && ckh->keycomp(key, cell->key))
			return ((bucket << LG_CKH_BUCKET_CELLS) + i);
	}

	return (SIZE_T_MAX);
}

/*
 * Search table for key and return cell number if found; SIZE_T_MAX otherwise.
 */
JEMALLOC_INLINE size_t
ckh_isearch(ckh_t *ckh, const void *key)
{
	size_t hash1, hash2, bucket, cell;

	assert(ckh != NULL);

	ckh->hash(key, ckh->lg_curbuckets, &hash1, &hash2);

	/* Search primary bucket. */
	bucket = hash1 & ((ZU(1) << ckh->lg_curbuckets) - 1);
	cell = ckh_bucket_search(ckh, bucket, key);
	if (cell != SIZE_T_MAX)
		return (cell);

	/* Search secondary bucket. */
	bucket = hash2 & ((ZU(1) << ckh->lg_curbuckets) - 1);
	cell = ckh_bucket_search(ckh, bucket, key);
	return (cell);
}

JEMALLOC_INLINE bool
ckh_try_bucket_insert(ckh_t *ckh, size_t bucket, const void *key,
    const void *data)
{
	ckhc_t *cell;
	unsigned offset, i;

	/*
	 * Cycle through the cells in the bucket, starting at a random position.
	 * The randomness avoids worst-case search overhead as buckets fill up.
	 */
	prng32(offset, LG_CKH_BUCKET_CELLS, ckh->prng_state, CKH_A, CKH_C);
	for (i = 0; i < (ZU(1) << LG_CKH_BUCKET_CELLS); i++) {
		cell = &ckh->tab[(bucket << LG_CKH_BUCKET_CELLS) +
		    ((i + offset) & ((ZU(1) << LG_CKH_BUCKET_CELLS) - 1))];
		if (cell->key == NULL) {
			cell->key = key;
			cell->data = data;
			ckh->count++;
			return (false);
		}
	}

	return (true);
}

/*
 * No space is available in bucket.  Randomly evict an item, then try to find an
 * alternate location for that item.  Iteratively repeat this
 * eviction/relocation procedure until either success or detection of an
 * eviction/relocation bucket cycle.
 */
JEMALLOC_INLINE bool
ckh_evict_reloc_insert(ckh_t *ckh, size_t argbucket, void const **argkey,
    void const **argdata)
{
	const void *key, *data, *tkey, *tdata;
	ckhc_t *cell;
	size_t hash1, hash2, bucket, tbucket;
	unsigned i;

	bucket = argbucket;
	key = *argkey;
	data = *argdata;
	while (true) {
		/*
		 * Choose a random item within the bucket to evict.  This is
		 * critical to correct function, because without (eventually)
		 * evicting all items within a bucket during iteration, it
		 * would be possible to get stuck in an infinite loop if there
		 * were an item for which both hashes indicated the same
		 * bucket.
		 */
		prng32(i, LG_CKH_BUCKET_CELLS, ckh->prng_state, CKH_A, CKH_C);
		cell = &ckh->tab[(bucket << LG_CKH_BUCKET_CELLS) + i];
		assert(cell->key != NULL);

		/* Swap cell->{key,data} and {key,data} (evict). */
		tkey = cell->key; tdata = cell->data;
		cell->key = key; cell->data = data;
		key = tkey; data = tdata;

#ifdef CKH_COUNT
		ckh->nrelocs++;
#endif

		/* Find the alternate bucket for the evicted item. */
		ckh->hash(key, ckh->lg_curbuckets, &hash1, &hash2);
		tbucket = hash2 & ((ZU(1) << ckh->lg_curbuckets) - 1);
		if (tbucket == bucket) {
			tbucket = hash1 & ((ZU(1) << ckh->lg_curbuckets) - 1);
			/*
			 * It may be that (tbucket == bucket) still, if the
			 * item's hashes both indicate this bucket.  However,
			 * we are guaranteed to eventually escape this bucket
			 * during iteration, assuming pseudo-random item
			 * selection (true randomness would make infinite
			 * looping a remote possibility).  The reason we can
			 * never get trapped forever is that there are two
			 * cases:
			 *
			 * 1) This bucket == argbucket, so we will quickly
			 *    detect an eviction cycle and terminate.
			 * 2) An item was evicted to this bucket from another,
			 *    which means that at least one item in this bucket
			 *    has hashes that indicate distinct buckets.
			 */
		}
		/* Check for a cycle. */
		if (tbucket == argbucket) {
			*argkey = key;
			*argdata = data;
			return (true);
		}

		bucket = tbucket;
		if (ckh_try_bucket_insert(ckh, bucket, key, data) == false)
			return (false);
	}
}

JEMALLOC_INLINE bool
ckh_try_insert(ckh_t *ckh, void const**argkey, void const**argdata)
{
	size_t hash1, hash2, bucket;
	const void *key = *argkey;
	const void *data = *argdata;

	ckh->hash(key, ckh->lg_curbuckets, &hash1, &hash2);

	/* Try to insert in primary bucket. */
	bucket = hash1 & ((ZU(1) << ckh->lg_curbuckets) - 1);
	if (ckh_try_bucket_insert(ckh, bucket, key, data) == false)
		return (false);

	/* Try to insert in secondary bucket. */
	bucket = hash2 & ((ZU(1) << ckh->lg_curbuckets) - 1);
	if (ckh_try_bucket_insert(ckh, bucket, key, data) == false)
		return (false);

	/*
	 * Try to find a place for this item via iterative eviction/relocation.
	 */
	return (ckh_evict_reloc_insert(ckh, bucket, argkey, argdata));
}

/*
 * Try to rebuild the hash table from scratch by inserting all items from the
 * old table into the new.
 */
JEMALLOC_INLINE bool
ckh_rebuild(ckh_t *ckh, ckhc_t *aTab)
{
	size_t count, i, nins;
	const void *key, *data;

	count = ckh->count;
	ckh->count = 0;
	for (i = nins = 0; nins < count; i++) {
		if (aTab[i].key != NULL) {
			key = aTab[i].key;
			data = aTab[i].data;
			if (ckh_try_insert(ckh, &key, &data)) {
				ckh->count = count;
				return (true);
			}
			nins++;
		}
	}

	return (false);
}

static bool
ckh_grow(ckh_t *ckh)
{
	bool ret;
	ckhc_t *tab, *ttab;
	size_t lg_curcells;
	unsigned lg_prevbuckets;

#ifdef CKH_COUNT
	ckh->ngrows++;
#endif

	/*
	 * It is possible (though unlikely, given well behaved hashes) that the
	 * table will have to be doubled more than once in order to create a
	 * usable table.
	 */
	lg_prevbuckets = ckh->lg_curbuckets;
	lg_curcells = ckh->lg_curbuckets + LG_CKH_BUCKET_CELLS;
	while (true) {
		size_t usize;

		lg_curcells++;
		usize = sa2u(sizeof(ckhc_t) << lg_curcells, CACHELINE);
		if (usize == 0) {
			ret = true;
			goto label_return;
		}
		tab = (ckhc_t *)ipalloc(usize, CACHELINE, true);
		if (tab == NULL) {
			ret = true;
			goto label_return;
		}
		/* Swap in new table. */
		ttab = ckh->tab;
		ckh->tab = tab;
		tab = ttab;
		ckh->lg_curbuckets = lg_curcells - LG_CKH_BUCKET_CELLS;

		if (ckh_rebuild(ckh, tab) == false) {
			idalloc(tab);
			break;
		}

		/* Rebuilding failed, so back out partially rebuilt table. */
		idalloc(ckh->tab);
		ckh->tab = tab;
		ckh->lg_curbuckets = lg_prevbuckets;
	}

	ret = false;
label_return:
	return (ret);
}

static void
ckh_shrink(ckh_t *ckh)
{
	ckhc_t *tab, *ttab;
	size_t lg_curcells, usize;
	unsigned lg_prevbuckets;

	/*
	 * It is possible (though unlikely, given well behaved hashes) that the
	 * table rebuild will fail.
	 */
	lg_prevbuckets = ckh->lg_curbuckets;
	lg_curcells = ckh->lg_curbuckets + LG_CKH_BUCKET_CELLS - 1;
	usize = sa2u(sizeof(ckhc_t) << lg_curcells, CACHELINE);
	if (usize == 0)
		return;
	tab = (ckhc_t *)ipalloc(usize, CACHELINE, true);
	if (tab == NULL) {
		/*
		 * An OOM error isn't worth propagating, since it doesn't
		 * prevent this or future operations from proceeding.
		 */
		return;
	}
	/* Swap in new table. */
	ttab = ckh->tab;
	ckh->tab = tab;
	tab = ttab;
	ckh->lg_curbuckets = lg_curcells - LG_CKH_BUCKET_CELLS;

	if (ckh_rebuild(ckh, tab) == false) {
		idalloc(tab);
#ifdef CKH_COUNT
		ckh->nshrinks++;
#endif
		return;
	}

	/* Rebuilding failed, so back out partially rebuilt table. */
	idalloc(ckh->tab);
	ckh->tab = tab;
	ckh->lg_curbuckets = lg_prevbuckets;
#ifdef CKH_COUNT
	ckh->nshrinkfails++;
#endif
}

bool
ckh_new(ckh_t *ckh, size_t minitems, ckh_hash_t *hash, ckh_keycomp_t *keycomp)
{
	bool ret;
	size_t mincells, usize;
	unsigned lg_mincells;

	assert(minitems > 0);
	assert(hash != NULL);
	assert(keycomp != NULL);

#ifdef CKH_COUNT
	ckh->ngrows = 0;
	ckh->nshrinks = 0;
	ckh->nshrinkfails = 0;
	ckh->ninserts = 0;
	ckh->nrelocs = 0;
#endif
	ckh->prng_state = 42; /* Value doesn't really matter. */
	ckh->count = 0;

	/*
	 * Find the minimum power of 2 that is large enough to fit aBaseCount
	 * entries.  We are using (2+,2) cuckoo hashing, which has an expected
	 * maximum load factor of at least ~0.86, so 0.75 is a conservative load
	 * factor that will typically allow 2^aLgMinItems to fit without ever
	 * growing the table.
	 */
	assert(LG_CKH_BUCKET_CELLS > 0);
	mincells = ((minitems + (3 - (minitems % 3))) / 3) << 2;
	for (lg_mincells = LG_CKH_BUCKET_CELLS;
	    (ZU(1) << lg_mincells) < mincells;
	    lg_mincells++)
		; /* Do nothing. */
	ckh->lg_minbuckets = lg_mincells - LG_CKH_BUCKET_CELLS;
	ckh->lg_curbuckets = lg_mincells - LG_CKH_BUCKET_CELLS;
	ckh->hash = hash;
	ckh->keycomp = keycomp;

	usize = sa2u(sizeof(ckhc_t) << lg_mincells, CACHELINE);
	if (usize == 0) {
		ret = true;
		goto label_return;
	}
	ckh->tab = (ckhc_t *)ipalloc(usize, CACHELINE, true);
	if (ckh->tab == NULL) {
		ret = true;
		goto label_return;
	}

	ret = false;
label_return:
	return (ret);
}

void
ckh_delete(ckh_t *ckh)
{

	assert(ckh != NULL);

#ifdef CKH_VERBOSE
	malloc_printf(
	    "%s(%p): ngrows: %"PRIu64", nshrinks: %"PRIu64","
	    " nshrinkfails: %"PRIu64", ninserts: %"PRIu64","
	    " nrelocs: %"PRIu64"\n", __func__, ckh,
	    (unsigned long long)ckh->ngrows,
	    (unsigned long long)ckh->nshrinks,
	    (unsigned long long)ckh->nshrinkfails,
	    (unsigned long long)ckh->ninserts,
	    (unsigned long long)ckh->nrelocs);
#endif

	idalloc(ckh->tab);
#ifdef JEMALLOC_DEBUG
	memset(ckh, 0x5a, sizeof(ckh_t));
#endif
}

size_t
ckh_count(ckh_t *ckh)
{

	assert(ckh != NULL);

	return (ckh->count);
}

bool
ckh_iter(ckh_t *ckh, size_t *tabind, void **key, void **data)
{
	size_t i, ncells;

	for (i = *tabind, ncells = (ZU(1) << (ckh->lg_curbuckets +
	    LG_CKH_BUCKET_CELLS)); i < ncells; i++) {
		if (ckh->tab[i].key != NULL) {
			if (key != NULL)
				*key = (void *)ckh->tab[i].key;
			if (data != NULL)
				*data = (void *)ckh->tab[i].data;
			*tabind = i + 1;
			return (false);
		}
	}

	return (true);
}

bool
ckh_insert(ckh_t *ckh, const void *key, const void *data)
{
	bool ret;

	assert(ckh != NULL);
	assert(ckh_search(ckh, key, NULL, NULL));

#ifdef CKH_COUNT
	ckh->ninserts++;
#endif

	while (ckh_try_insert(ckh, &key, &data)) {
		if (ckh_grow(ckh)) {
			ret = true;
			goto label_return;
		}
	}

	ret = false;
label_return:
	return (ret);
}

bool
ckh_remove(ckh_t *ckh, const void *searchkey, void **key, void **data)
{
	size_t cell;

	assert(ckh != NULL);

	cell = ckh_isearch(ckh, searchkey);
	if (cell != SIZE_T_MAX) {
		if (key != NULL)
			*key = (void *)ckh->tab[cell].key;
		if (data != NULL)
			*data = (void *)ckh->tab[cell].data;
		ckh->tab[cell].key = NULL;
		ckh->tab[cell].data = NULL; /* Not necessary. */

		ckh->count--;
		/* Try to halve the table if it is less than 1/4 full. */
		if (ckh->count < (ZU(1) << (ckh->lg_curbuckets
		    + LG_CKH_BUCKET_CELLS - 2)) && ckh->lg_curbuckets
		    > ckh->lg_minbuckets) {
			/* Ignore error due to OOM. */
			ckh_shrink(ckh);
		}

		return (false);
	}

	return (true);
}

bool
ckh_search(ckh_t *ckh, const void *searchkey, void **key, void **data)
{
	size_t cell;

	assert(ckh != NULL);

	cell = ckh_isearch(ckh, searchkey);
	if (cell != SIZE_T_MAX) {
		if (key != NULL)
			*key = (void *)ckh->tab[cell].key;
		if (data != NULL)
			*data = (void *)ckh->tab[cell].data;
		return (false);
	}

	return (true);
}

void
ckh_string_hash(const void *key, unsigned minbits, size_t *hash1, size_t *hash2)
{
	size_t ret1, ret2;
	uint64_t h;

	assert(minbits <= 32 || (SIZEOF_PTR == 8 && minbits <= 64));
	assert(hash1 != NULL);
	assert(hash2 != NULL);

	h = hash(key, strlen((const char *)key), UINT64_C(0x94122f335b332aea));
	if (minbits <= 32) {
		/*
		 * Avoid doing multiple hashes, since a single hash provides
		 * enough bits.
		 */
		ret1 = h & ZU(0xffffffffU);
		ret2 = h >> 32;
	} else {
		ret1 = h;
		ret2 = hash(key, strlen((const char *)key),
		    UINT64_C(0x8432a476666bbc13));
	}

	*hash1 = ret1;
	*hash2 = ret2;
}

bool
ckh_string_keycomp(const void *k1, const void *k2)
{

    assert(k1 != NULL);
    assert(k2 != NULL);

    return (strcmp((char *)k1, (char *)k2) ? false : true);
}

void
ckh_pointer_hash(const void *key, unsigned minbits, size_t *hash1,
    size_t *hash2)
{
	size_t ret1, ret2;
	uint64_t h;
	union {
		const void	*v;
		uint64_t	i;
	} u;

	assert(minbits <= 32 || (SIZEOF_PTR == 8 && minbits <= 64));
	assert(hash1 != NULL);
	assert(hash2 != NULL);

	assert(sizeof(u.v) == sizeof(u.i));
#if (LG_SIZEOF_PTR != LG_SIZEOF_INT)
	u.i = 0;
#endif
	u.v = key;
	h = hash(&u.i, sizeof(u.i), UINT64_C(0xd983396e68886082));
	if (minbits <= 32) {
		/*
		 * Avoid doing multiple hashes, since a single hash provides
		 * enough bits.
		 */
		ret1 = h & ZU(0xffffffffU);
		ret2 = h >> 32;
	} else {
		assert(SIZEOF_PTR == 8);
		ret1 = h;
		ret2 = hash(&u.i, sizeof(u.i), UINT64_C(0x5e2be9aff8709a5d));
	}

	*hash1 = ret1;
	*hash2 = ret2;
}

bool
ckh_pointer_keycomp(const void *k1, const void *k2)
{

	return ((k1 == k2) ? true : false);
}
Commit	Line	Data
a78e148b	1	/*
	2	*******************************************************************************
	3	* Implementation of (2^1+,2) cuckoo hashing, where 2^1+ indicates that each
	4	* hash bucket contains 2^n cells, for n >= 1, and 2 indicates that two hash
	5	* functions are employed. The original cuckoo hashing algorithm was described
	6	* in:
	7	*
	8	* Pagh, R., F.F. Rodler (2004) Cuckoo Hashing. Journal of Algorithms
	9	* 51(2):122-144.
	10	*
	11	* Generalization of cuckoo hashing was discussed in:
	12	*
	13	* Erlingsson, U., M. Manasse, F. McSherry (2006) A cool and practical
	14	* alternative to traditional hash tables. In Proceedings of the 7th
	15	* Workshop on Distributed Data and Structures (WDAS'06), Santa Clara, CA,
	16	* January 2006.
	17	*
	18	* This implementation uses precisely two hash functions because that is the
	19	* fewest that can work, and supporting multiple hashes is an implementation
	20	* burden. Here is a reproduction of Figure 1 from Erlingsson et al. (2006)
	21	* that shows approximate expected maximum load factors for various
	22	* configurations:
	23	*
	24	* \| #cells/bucket \|
	25	* #hashes \| 1 \| 2 \| 4 \| 8 \|
	26	* --------+-------+-------+-------+-------+
	27	* 1 \| 0.006 \| 0.006 \| 0.03 \| 0.12 \|
	28	* 2 \| 0.49 \| 0.86 \|>0.93< \|>0.96< \|
	29	* 3 \| 0.91 \| 0.97 \| 0.98 \| 0.999 \|
	30	* 4 \| 0.97 \| 0.99 \| 0.999 \| \|
	31	*
	32	* The number of cells per bucket is chosen such that a bucket fits in one cache
	33	* line. So, on 32- and 64-bit systems, we use (8,2) and (4,2) cuckoo hashing,
	34	* respectively.
	35	*
	36	******************************************************************************/
	37	#define JEMALLOC_CKH_C_
	38	#include "jemalloc/internal/jemalloc_internal.h"
	39
	40	/******************************************************************************/
	41	/* Function prototypes for non-inline static functions. */
	42
	43	static bool ckh_grow(ckh_t *ckh);
	44	static void ckh_shrink(ckh_t *ckh);
	45
	46	/******************************************************************************/
	47
	48	/*
	49	* Search bucket for key and return the cell number if found; SIZE_T_MAX
	50	* otherwise.
	51	*/
	52	JEMALLOC_INLINE size_t
	53	ckh_bucket_search(ckh_t ckh, size_t bucket, const void key)
	54	{
	55	ckhc_t *cell;
	56	unsigned i;
	57
	58	for (i = 0; i < (ZU(1) << LG_CKH_BUCKET_CELLS); i++) {
	59	cell = &ckh->tab[(bucket << LG_CKH_BUCKET_CELLS) + i];
	60	if (cell->key != NULL && ckh->keycomp(key, cell->key))
	61	return ((bucket << LG_CKH_BUCKET_CELLS) + i);
	62	}
	63
	64	return (SIZE_T_MAX);
65	}
66
67	/*
68	* Search table for key and return cell number if found; SIZE_T_MAX otherwise.
69	*/
70	JEMALLOC_INLINE size_t
71	ckh_isearch(ckh_t ckh, const void key)
72	{
73	size_t hash1, hash2, bucket, cell;
74
75	assert(ckh != NULL);
a78e148b	76
	77	ckh->hash(key, ckh->lg_curbuckets, &hash1, &hash2);
	78
	79	/* Search primary bucket. */
	80	bucket = hash1 & ((ZU(1) << ckh->lg_curbuckets) - 1);
	81	cell = ckh_bucket_search(ckh, bucket, key);
	82	if (cell != SIZE_T_MAX)
	83	return (cell);
	84
	85	/* Search secondary bucket. */
	86	bucket = hash2 & ((ZU(1) << ckh->lg_curbuckets) - 1);
	87	cell = ckh_bucket_search(ckh, bucket, key);
	88	return (cell);
	89	}
	90
	91	JEMALLOC_INLINE bool
	92	ckh_try_bucket_insert(ckh_t ckh, size_t bucket, const void key,
	93	const void *data)
	94	{
	95	ckhc_t *cell;
	96	unsigned offset, i;
	97
	98	/*
	99	* Cycle through the cells in the bucket, starting at a random position.
	100	* The randomness avoids worst-case search overhead as buckets fill up.
	101	*/
4934f93d	102	prng32(offset, LG_CKH_BUCKET_CELLS, ckh->prng_state, CKH_A, CKH_C);
a78e148b	103	for (i = 0; i < (ZU(1) << LG_CKH_BUCKET_CELLS); i++) {
	104	cell = &ckh->tab[(bucket << LG_CKH_BUCKET_CELLS) +
	105	((i + offset) & ((ZU(1) << LG_CKH_BUCKET_CELLS) - 1))];
	106	if (cell->key == NULL) {
	107	cell->key = key;
	108	cell->data = data;
	109	ckh->count++;
	110	return (false);
	111	}
	112	}
	113
	114	return (true);
	115	}
	116
	117	/*
	118	* No space is available in bucket. Randomly evict an item, then try to find an
	119	* alternate location for that item. Iteratively repeat this
	120	* eviction/relocation procedure until either success or detection of an
	121	* eviction/relocation bucket cycle.
	122	*/
	123	JEMALLOC_INLINE bool
	124	ckh_evict_reloc_insert(ckh_t ckh, size_t argbucket, void const *argkey,
	125	void const **argdata)
	126	{
	127	const void key, data, tkey, tdata;
	128	ckhc_t *cell;
	129	size_t hash1, hash2, bucket, tbucket;
	130	unsigned i;
	131
	132	bucket = argbucket;
	133	key = *argkey;
	134	data = *argdata;
	135	while (true) {
	136	/*
	137	* Choose a random item within the bucket to evict. This is
	138	* critical to correct function, because without (eventually)
	139	* evicting all items within a bucket during iteration, it
	140	* would be possible to get stuck in an infinite loop if there
	141	* were an item for which both hashes indicated the same
	142	* bucket.
	143	*/
4934f93d	144	prng32(i, LG_CKH_BUCKET_CELLS, ckh->prng_state, CKH_A, CKH_C);
a78e148b	145	cell = &ckh->tab[(bucket << LG_CKH_BUCKET_CELLS) + i];
	146	assert(cell->key != NULL);
	147
	148	/* Swap cell->{key,data} and {key,data} (evict). */
	149	tkey = cell->key; tdata = cell->data;
	150	cell->key = key; cell->data = data;
	151	key = tkey; data = tdata;
	152
	153	#ifdef CKH_COUNT
	154	ckh->nrelocs++;
	155	#endif
	156
	157	/* Find the alternate bucket for the evicted item. */
	158	ckh->hash(key, ckh->lg_curbuckets, &hash1, &hash2);
	159	tbucket = hash2 & ((ZU(1) << ckh->lg_curbuckets) - 1);
	160	if (tbucket == bucket) {
	161	tbucket = hash1 & ((ZU(1) << ckh->lg_curbuckets) - 1);
	162	/*
	163	* It may be that (tbucket == bucket) still, if the
	164	* item's hashes both indicate this bucket. However,
	165	* we are guaranteed to eventually escape this bucket
	166	* during iteration, assuming pseudo-random item
	167	* selection (true randomness would make infinite
	168	* looping a remote possibility). The reason we can
	169	* never get trapped forever is that there are two
	170	* cases:
	171	*
	172	* 1) This bucket == argbucket, so we will quickly
	173	* detect an eviction cycle and terminate.
	174	* 2) An item was evicted to this bucket from another,
	175	* which means that at least one item in this bucket
	176	* has hashes that indicate distinct buckets.
	177	*/
	178	}
	179	/* Check for a cycle. */
	180	if (tbucket == argbucket) {
	181	*argkey = key;
	182	*argdata = data;
	183	return (true);
	184	}
	185
	186	bucket = tbucket;
	187	if (ckh_try_bucket_insert(ckh, bucket, key, data) == false)
	188	return (false);
	189	}
	190	}
	191
	192	JEMALLOC_INLINE bool
	193	ckh_try_insert(ckh_t ckh, void constargkey, void const*argdata)
	194	{
	195	size_t hash1, hash2, bucket;
	196	const void key = argkey;
	197	const void data = argdata;
	198
	199	ckh->hash(key, ckh->lg_curbuckets, &hash1, &hash2);
	200
	201	/* Try to insert in primary bucket. */
	202	bucket = hash1 & ((ZU(1) << ckh->lg_curbuckets) - 1);
	203	if (ckh_try_bucket_insert(ckh, bucket, key, data) == false)
	204	return (false);
	205
	206	/* Try to insert in secondary bucket. */
	207	bucket = hash2 & ((ZU(1) << ckh->lg_curbuckets) - 1);
	208	if (ckh_try_bucket_insert(ckh, bucket, key, data) == false)
209	return (false);
210
211	/*
212	* Try to find a place for this item via iterative eviction/relocation.
213	*/
214	return (ckh_evict_reloc_insert(ckh, bucket, argkey, argdata));
215	}
216
217	/*
218	* Try to rebuild the hash table from scratch by inserting all items from the
219	* old table into the new.
220	*/
221	JEMALLOC_INLINE bool
222	ckh_rebuild(ckh_t ckh, ckhc_t aTab)
223	{
224	size_t count, i, nins;
225	const void key, data;
226
227	count = ckh->count;
228	ckh->count = 0;
229	for (i = nins = 0; nins < count; i++) {
230	if (aTab[i].key != NULL) {
231	key = aTab[i].key;
232	data = aTab[i].data;
233	if (ckh_try_insert(ckh, &key, &data)) {
234	ckh->count = count;
235	return (true);
236	}
237	nins++;
238	}
239	}
240
241	return (false);
242	}
243
244	static bool
245	ckh_grow(ckh_t *ckh)
246	{
247	bool ret;
248	ckhc_t tab, ttab;
249	size_t lg_curcells;
250	unsigned lg_prevbuckets;
251
252	#ifdef CKH_COUNT
253	ckh->ngrows++;
254	#endif
255
256	/*
257	* It is possible (though unlikely, given well behaved hashes) that the
258	* table will have to be doubled more than once in order to create a
259	* usable table.
260	*/
261	lg_prevbuckets = ckh->lg_curbuckets;
262	lg_curcells = ckh->lg_curbuckets + LG_CKH_BUCKET_CELLS;
263	while (true) {
264	size_t usize;
265
266	lg_curcells++;
4934f93d	267	usize = sa2u(sizeof(ckhc_t) << lg_curcells, CACHELINE);
a78e148b	268	if (usize == 0) {
a78e148b	269	ret = true;
4934f93d	270	goto label_return;
a78e148b	271	}
	272	tab = (ckhc_t *)ipalloc(usize, CACHELINE, true);
	273	if (tab == NULL) {
	274	ret = true;
4934f93d	275	goto label_return;
a78e148b	276	}
	277	/* Swap in new table. */
	278	ttab = ckh->tab;
	279	ckh->tab = tab;
	280	tab = ttab;
	281	ckh->lg_curbuckets = lg_curcells - LG_CKH_BUCKET_CELLS;
	282
	283	if (ckh_rebuild(ckh, tab) == false) {
	284	idalloc(tab);
	285	break;
	286	}
	287
	288	/* Rebuilding failed, so back out partially rebuilt table. */
	289	idalloc(ckh->tab);
	290	ckh->tab = tab;
	291	ckh->lg_curbuckets = lg_prevbuckets;
	292	}
	293
	294	ret = false;
4934f93d	295	label_return:
a78e148b	296	return (ret);
	297	}
	298
	299	static void
	300	ckh_shrink(ckh_t *ckh)
	301	{
	302	ckhc_t tab, ttab;
	303	size_t lg_curcells, usize;
	304	unsigned lg_prevbuckets;
	305
	306	/*
	307	* It is possible (though unlikely, given well behaved hashes) that the
	308	* table rebuild will fail.
	309	*/
	310	lg_prevbuckets = ckh->lg_curbuckets;
	311	lg_curcells = ckh->lg_curbuckets + LG_CKH_BUCKET_CELLS - 1;
4934f93d	312	usize = sa2u(sizeof(ckhc_t) << lg_curcells, CACHELINE);
a78e148b	313	if (usize == 0)
	314	return;
	315	tab = (ckhc_t *)ipalloc(usize, CACHELINE, true);
	316	if (tab == NULL) {
	317	/*
	318	* An OOM error isn't worth propagating, since it doesn't
	319	* prevent this or future operations from proceeding.
	320	*/
	321	return;
	322	}
	323	/* Swap in new table. */
	324	ttab = ckh->tab;
	325	ckh->tab = tab;
	326	tab = ttab;
	327	ckh->lg_curbuckets = lg_curcells - LG_CKH_BUCKET_CELLS;
	328
	329	if (ckh_rebuild(ckh, tab) == false) {
	330	idalloc(tab);
	331	#ifdef CKH_COUNT
	332	ckh->nshrinks++;
	333	#endif
	334	return;
	335	}
	336
	337	/* Rebuilding failed, so back out partially rebuilt table. */
	338	idalloc(ckh->tab);
	339	ckh->tab = tab;
	340	ckh->lg_curbuckets = lg_prevbuckets;
	341	#ifdef CKH_COUNT
	342	ckh->nshrinkfails++;
	343	#endif
	344	}
	345
	346	bool
	347	ckh_new(ckh_t ckh, size_t minitems, ckh_hash_t hash, ckh_keycomp_t *keycomp)
	348	{
	349	bool ret;
	350	size_t mincells, usize;
	351	unsigned lg_mincells;
	352
	353	assert(minitems > 0);
	354	assert(hash != NULL);
	355	assert(keycomp != NULL);
	356
	357	#ifdef CKH_COUNT
	358	ckh->ngrows = 0;
	359	ckh->nshrinks = 0;
	360	ckh->nshrinkfails = 0;
	361	ckh->ninserts = 0;
	362	ckh->nrelocs = 0;
	363	#endif
4934f93d	364	ckh->prng_state = 42; /* Value doesn't really matter. */
a78e148b	365	ckh->count = 0;
	366
	367	/*
	368	* Find the minimum power of 2 that is large enough to fit aBaseCount
	369	* entries. We are using (2+,2) cuckoo hashing, which has an expected
	370	* maximum load factor of at least ~0.86, so 0.75 is a conservative load
	371	* factor that will typically allow 2^aLgMinItems to fit without ever
	372	* growing the table.
	373	*/
	374	assert(LG_CKH_BUCKET_CELLS > 0);
	375	mincells = ((minitems + (3 - (minitems % 3))) / 3) << 2;
	376	for (lg_mincells = LG_CKH_BUCKET_CELLS;
	377	(ZU(1) << lg_mincells) < mincells;
	378	lg_mincells++)
	379	; /* Do nothing. */
	380	ckh->lg_minbuckets = lg_mincells - LG_CKH_BUCKET_CELLS;
	381	ckh->lg_curbuckets = lg_mincells - LG_CKH_BUCKET_CELLS;
	382	ckh->hash = hash;
	383	ckh->keycomp = keycomp;
	384
4934f93d	385	usize = sa2u(sizeof(ckhc_t) << lg_mincells, CACHELINE);
a78e148b	386	if (usize == 0) {
a78e148b	387	ret = true;
4934f93d	388	goto label_return;
a78e148b	389	}
	390	ckh->tab = (ckhc_t *)ipalloc(usize, CACHELINE, true);
	391	if (ckh->tab == NULL) {
	392	ret = true;
4934f93d	393	goto label_return;
a78e148b	394	}
a78e148b	395
a78e148b	396	ret = false;
4934f93d	397	label_return:
a78e148b	398	return (ret);
	399	}
	400
	401	void
	402	ckh_delete(ckh_t *ckh)
	403	{
	404
	405	assert(ckh != NULL);
a78e148b	406
	407	#ifdef CKH_VERBOSE
	408	malloc_printf(
	409	"%s(%p): ngrows: %"PRIu64", nshrinks: %"PRIu64","
	410	" nshrinkfails: %"PRIu64", ninserts: %"PRIu64","
	411	" nrelocs: %"PRIu64"\n", __func__, ckh,
	412	(unsigned long long)ckh->ngrows,
	413	(unsigned long long)ckh->nshrinks,
	414	(unsigned long long)ckh->nshrinkfails,
	415	(unsigned long long)ckh->ninserts,
	416	(unsigned long long)ckh->nrelocs);
	417	#endif
	418
	419	idalloc(ckh->tab);
	420	#ifdef JEMALLOC_DEBUG
	421	memset(ckh, 0x5a, sizeof(ckh_t));
	422	#endif
	423	}
	424
	425	size_t
	426	ckh_count(ckh_t *ckh)
	427	{
	428
	429	assert(ckh != NULL);
a78e148b	430
	431	return (ckh->count);
	432	}
	433
	434	bool
	435	ckh_iter(ckh_t ckh, size_t tabind, void key, void data)
	436	{
	437	size_t i, ncells;
	438
	439	for (i = *tabind, ncells = (ZU(1) << (ckh->lg_curbuckets +
	440	LG_CKH_BUCKET_CELLS)); i < ncells; i++) {
	441	if (ckh->tab[i].key != NULL) {
	442	if (key != NULL)
	443	key = (void )ckh->tab[i].key;
	444	if (data != NULL)
	445	data = (void )ckh->tab[i].data;
	446	*tabind = i + 1;
	447	return (false);
	448	}
	449	}
	450
	451	return (true);
	452	}
	453
	454	bool
	455	ckh_insert(ckh_t ckh, const void key, const void *data)
	456	{
	457	bool ret;
	458
	459	assert(ckh != NULL);
a78e148b	460	assert(ckh_search(ckh, key, NULL, NULL));
	461
	462	#ifdef CKH_COUNT
	463	ckh->ninserts++;
	464	#endif
	465
	466	while (ckh_try_insert(ckh, &key, &data)) {
	467	if (ckh_grow(ckh)) {
	468	ret = true;
4934f93d	469	goto label_return;
a78e148b	470	}
	471	}
	472
	473	ret = false;
4934f93d	474	label_return:
a78e148b	475	return (ret);
	476	}
	477
	478	bool
	479	ckh_remove(ckh_t ckh, const void searchkey, void key, void data)
	480	{
	481	size_t cell;
	482
	483	assert(ckh != NULL);
a78e148b	484
	485	cell = ckh_isearch(ckh, searchkey);
	486	if (cell != SIZE_T_MAX) {
	487	if (key != NULL)
	488	key = (void )ckh->tab[cell].key;
	489	if (data != NULL)
	490	data = (void )ckh->tab[cell].data;
	491	ckh->tab[cell].key = NULL;
	492	ckh->tab[cell].data = NULL; /* Not necessary. */
	493
	494	ckh->count--;
	495	/* Try to halve the table if it is less than 1/4 full. */
	496	if (ckh->count < (ZU(1) << (ckh->lg_curbuckets
	497	+ LG_CKH_BUCKET_CELLS - 2)) && ckh->lg_curbuckets
	498	> ckh->lg_minbuckets) {
	499	/* Ignore error due to OOM. */
	500	ckh_shrink(ckh);
	501	}
	502
	503	return (false);
	504	}
	505
	506	return (true);
	507	}
	508
	509	bool
	510	ckh_search(ckh_t ckh, const void searchkey, void key, void data)
	511	{
	512	size_t cell;
	513
	514	assert(ckh != NULL);
a78e148b	515
	516	cell = ckh_isearch(ckh, searchkey);
	517	if (cell != SIZE_T_MAX) {
	518	if (key != NULL)
	519	key = (void )ckh->tab[cell].key;
	520	if (data != NULL)
	521	data = (void )ckh->tab[cell].data;
	522	return (false);
	523	}
	524
	525	return (true);
	526	}
	527
	528	void
	529	ckh_string_hash(const void key, unsigned minbits, size_t hash1, size_t *hash2)
	530	{
	531	size_t ret1, ret2;
	532	uint64_t h;
	533
	534	assert(minbits <= 32 \|\| (SIZEOF_PTR == 8 && minbits <= 64));
	535	assert(hash1 != NULL);
	536	assert(hash2 != NULL);
	537
4934f93d	538	h = hash(key, strlen((const char *)key), UINT64_C(0x94122f335b332aea));
a78e148b	539	if (minbits <= 32) {
	540	/*
	541	* Avoid doing multiple hashes, since a single hash provides
	542	* enough bits.
	543	*/
	544	ret1 = h & ZU(0xffffffffU);
	545	ret2 = h >> 32;
	546	} else {
	547	ret1 = h;
	548	ret2 = hash(key, strlen((const char *)key),
4934f93d	549	UINT64_C(0x8432a476666bbc13));
a78e148b	550	}
	551
	552	*hash1 = ret1;
	553	*hash2 = ret2;
	554	}
	555
	556	bool
	557	ckh_string_keycomp(const void k1, const void k2)
	558	{
	559
	560	assert(k1 != NULL);
	561	assert(k2 != NULL);
	562
	563	return (strcmp((char )k1, (char )k2) ? false : true);
	564	}
	565
	566	void
	567	ckh_pointer_hash(const void key, unsigned minbits, size_t hash1,
	568	size_t *hash2)
	569	{
	570	size_t ret1, ret2;
	571	uint64_t h;
	572	union {
	573	const void *v;
	574	uint64_t i;
	575	} u;
	576
	577	assert(minbits <= 32 \|\| (SIZEOF_PTR == 8 && minbits <= 64));
	578	assert(hash1 != NULL);
	579	assert(hash2 != NULL);
	580
	581	assert(sizeof(u.v) == sizeof(u.i));
	582	#if (LG_SIZEOF_PTR != LG_SIZEOF_INT)
	583	u.i = 0;
	584	#endif
	585	u.v = key;
4934f93d	586	h = hash(&u.i, sizeof(u.i), UINT64_C(0xd983396e68886082));
a78e148b	587	if (minbits <= 32) {
	588	/*
	589	* Avoid doing multiple hashes, since a single hash provides
	590	* enough bits.
	591	*/
	592	ret1 = h & ZU(0xffffffffU);
	593	ret2 = h >> 32;
	594	} else {
	595	assert(SIZEOF_PTR == 8);
	596	ret1 = h;
4934f93d	597	ret2 = hash(&u.i, sizeof(u.i), UINT64_C(0x5e2be9aff8709a5d));
a78e148b	598	}
	599
	600	*hash1 = ret1;
	601	*hash2 = ret2;
	602	}
	603
	604	bool
	605	ckh_pointer_keycomp(const void k1, const void k2)
	606	{
	607
	608	return ((k1 == k2) ? true : false);
	609	}