dshash.c File Reference

#include "postgres.h"
#include "common/hashfn.h"
#include "lib/dshash.h"
#include "storage/ipc.h"
#include "storage/lwlock.h"
#include "utils/dsa.h"
#include "utils/memutils.h"

Include dependency graph for dshash.c:

Go to the source code of this file.

Data Structures
struct	dshash_table_item
struct	dshash_partition
struct	dshash_table_control
struct	dshash_table

Macros
#define	DSHASH_NUM_PARTITIONS_LOG2   7
#define	DSHASH_NUM_PARTITIONS   (1 << DSHASH_NUM_PARTITIONS_LOG2)
#define	DSHASH_MAGIC   0x75ff6a20
#define	ENTRY_FROM_ITEM(item)   ((char *)(item) + MAXALIGN(sizeof(dshash_table_item)))
#define	ITEM_FROM_ENTRY(entry)
#define	NUM_SPLITS(size_log2)   (size_log2 - DSHASH_NUM_PARTITIONS_LOG2)
#define	BUCKETS_PER_PARTITION(size_log2)   (((size_t) 1) << NUM_SPLITS(size_log2))
#define	MAX_COUNT_PER_PARTITION(hash_table)
#define	PARTITION_FOR_HASH(hash)   (hash >> ((sizeof(dshash_hash) * CHAR_BIT) - DSHASH_NUM_PARTITIONS_LOG2))
#define	BUCKET_INDEX_FOR_HASH_AND_SIZE(hash, size_log2)   (hash >> ((sizeof(dshash_hash) * CHAR_BIT) - (size_log2)))
#define	BUCKET_INDEX_FOR_PARTITION(partition, size_log2)   ((partition) << NUM_SPLITS(size_log2))
#define	BUCKET_FOR_HASH(hash_table, hash)
#define	PARTITION_LOCK(hash_table, i)   (&(hash_table)->control->partitions[(i)].lock)

Typedefs
typedef struct dshash_partition	dshash_partition
typedef struct dshash_table_control	dshash_table_control

Functions
static void	delete_item (dshash_table *hash_table, dshash_table_item *item)
static void	resize (dshash_table *hash_table, size_t new_size)
static void	ensure_valid_bucket_pointers (dshash_table *hash_table)
static dshash_table_item *	find_in_bucket (dshash_table *hash_table, const void *key, dsa_pointer item_pointer)
static void	insert_item_into_bucket (dshash_table *hash_table, dsa_pointer item_pointer, dshash_table_item *item, dsa_pointer *bucket)
static dshash_table_item *	insert_into_bucket (dshash_table *hash_table, const void *key, dsa_pointer *bucket)
static bool	delete_key_from_bucket (dshash_table *hash_table, const void *key, dsa_pointer *bucket_head)
static bool	delete_item_from_bucket (dshash_table *hash_table, dshash_table_item *item, dsa_pointer *bucket_head)
static dshash_hash	hash_key (dshash_table *hash_table, const void *key)
static bool	equal_keys (dshash_table *hash_table, const void *a, const void *b)
dshash_table *	dshash_create (dsa_area *area, const dshash_parameters *params, void *arg)
dshash_table *	dshash_attach (dsa_area *area, const dshash_parameters *params, dshash_table_handle handle, void *arg)
void	dshash_detach (dshash_table *hash_table)
void	dshash_destroy (dshash_table *hash_table)
dshash_table_handle	dshash_get_hash_table_handle (dshash_table *hash_table)
void *	dshash_find (dshash_table *hash_table, const void *key, bool exclusive)
void *	dshash_find_or_insert (dshash_table *hash_table, const void *key, bool *found)
bool	dshash_delete_key (dshash_table *hash_table, const void *key)
void	dshash_delete_entry (dshash_table *hash_table, void *entry)
void	dshash_release_lock (dshash_table *hash_table, void *entry)
int	dshash_memcmp (const void *a, const void *b, size_t size, void *arg)
dshash_hash	dshash_memhash (const void *v, size_t size, void *arg)
void	dshash_dump (dshash_table *hash_table)

Macro Definition Documentation

BUCKET_FOR_HASH

#define BUCKET_FOR_HASH	(		hash_table,
			hash
	)

Value:

(hash_table->buckets[                                               \
        BUCKET_INDEX_FOR_HASH_AND_SIZE(hash,                            \
                                       hash_table->size_log2)])

Definition at line 157 of file dshash.c.

Referenced by delete_item(), dshash_delete_key(), dshash_find(), and dshash_find_or_insert().

BUCKET_INDEX_FOR_HASH_AND_SIZE

#define BUCKET_INDEX_FOR_HASH_AND_SIZE	(		hash,
			size_log2
	)		(hash >> ((sizeof(dshash_hash) * CHAR_BIT) - (size_log2)))

Definition at line 149 of file dshash.c.

Referenced by resize().

BUCKET_INDEX_FOR_PARTITION

#define BUCKET_INDEX_FOR_PARTITION	(		partition,
			size_log2
	)		((partition) << NUM_SPLITS(size_log2))

Definition at line 153 of file dshash.c.

Referenced by dshash_dump().

BUCKETS_PER_PARTITION

#define BUCKETS_PER_PARTITION

(

size_log2

)

(((size_t) 1) << NUM_SPLITS(size_log2))

Definition at line 131 of file dshash.c.

DSHASH_MAGIC

#define DSHASH_MAGIC   0x75ff6a20

Definition at line 65 of file dshash.c.

Referenced by dshash_attach(), dshash_create(), dshash_delete_entry(), dshash_delete_key(), dshash_destroy(), dshash_dump(), dshash_find(), dshash_find_or_insert(), dshash_get_hash_table_handle(), and dshash_release_lock().

DSHASH_NUM_PARTITIONS

#define DSHASH_NUM_PARTITIONS   (1 << DSHASH_NUM_PARTITIONS_LOG2)

Definition at line 62 of file dshash.c.

Referenced by dshash_create(), dshash_dump(), and resize().

DSHASH_NUM_PARTITIONS_LOG2

#define DSHASH_NUM_PARTITIONS_LOG2   7

Definition at line 61 of file dshash.c.

Referenced by dshash_create().

ENTRY_FROM_ITEM

#define ENTRY_FROM_ITEM

(

item

)

((char *)(item) + MAXALIGN(sizeof(dshash_table_item)))

Definition at line 118 of file dshash.c.

Referenced by delete_key_from_bucket(), dshash_find(), dshash_find_or_insert(), find_in_bucket(), and insert_into_bucket().

ITEM_FROM_ENTRY

#define ITEM_FROM_ENTRY

(

entry

)

Value:

((dshash_table_item *)((char *)(entry) -                            \
                             MAXALIGN(sizeof(dshash_table_item))))

Definition at line 122 of file dshash.c.

Referenced by dshash_delete_entry(), and dshash_release_lock().

MAX_COUNT_PER_PARTITION

#define MAX_COUNT_PER_PARTITION

(

hash_table

)

Value:

(BUCKETS_PER_PARTITION(hash_table->size_log2) / 2 + \
     BUCKETS_PER_PARTITION(hash_table->size_log2) / 4)

Definition at line 135 of file dshash.c.

Referenced by dshash_find_or_insert().

NUM_SPLITS

#define NUM_SPLITS

(

size_log2

)

(size_log2 - DSHASH_NUM_PARTITIONS_LOG2)

Definition at line 127 of file dshash.c.

PARTITION_FOR_HASH

#define PARTITION_FOR_HASH

(

hash

)

(hash >> ((sizeof(dshash_hash) * CHAR_BIT) - DSHASH_NUM_PARTITIONS_LOG2))

Definition at line 140 of file dshash.c.

Referenced by delete_item(), dshash_delete_entry(), dshash_delete_key(), dshash_find(), dshash_find_or_insert(), and dshash_release_lock().

PARTITION_LOCK

#define PARTITION_LOCK	(		hash_table,
			i
	)		(&(hash_table)->control->partitions[(i)].lock)

Definition at line 186 of file dshash.c.

Referenced by delete_item(), dshash_delete_entry(), dshash_delete_key(), dshash_dump(), dshash_find(), dshash_find_or_insert(), dshash_release_lock(), and resize().

Typedef Documentation

dshash_partition

typedef struct dshash_partition dshash_partition

dshash_table_control

typedef struct dshash_table_control dshash_table_control

Function Documentation

delete_item()

static void delete_item ( dshash_table *  hash_table, dshash_table_item *  item  )

static

Definition at line 654 of file dshash.c.

References Assert, BUCKET_FOR_HASH, dshash_table::control, dshash_partition::count, delete_item_from_bucket(), dshash_table_item::hash, LWLockHeldByMe(), PARTITION_FOR_HASH, PARTITION_LOCK, and dshash_table_control::partitions.

Referenced by dshash_delete_entry().

{
    size_t      hash = item->hash;
    size_t      partition = PARTITION_FOR_HASH(hash);

    Assert(LWLockHeldByMe(PARTITION_LOCK(hash_table, partition)));

    if (delete_item_from_bucket(hash_table, item,
                                &BUCKET_FOR_HASH(hash_table, hash)))
    {
        Assert(hash_table->control->partitions[partition].count > 0);
        --hash_table->control->partitions[partition].count;
    }
    else
    {
        Assert(false);
    }
}

delete_item_from_bucket()

static bool delete_item_from_bucket ( dshash_table *  hash_table, dshash_table_item *  item, dsa_pointer *  bucket_head  )

static

Definition at line 855 of file dshash.c.

References dshash_table::area, dsa_free(), dsa_get_address(), DsaPointerIsValid, and dshash_table_item::next.

Referenced by delete_item().

{
    while (DsaPointerIsValid(*bucket_head))
    {
        dshash_table_item *bucket_item;

        bucket_item = dsa_get_address(hash_table->area, *bucket_head);

        if (bucket_item == item)
        {
            dsa_pointer next;

            next = item->next;
            dsa_free(hash_table->area, *bucket_head);
            *bucket_head = next;
            return true;
        }
        bucket_head = &bucket_item->next;
    }
    return false;
}

delete_key_from_bucket()

static bool delete_key_from_bucket ( dshash_table *  hash_table, const void *  key, dsa_pointer *  bucket_head  )

static

Definition at line 826 of file dshash.c.

References dshash_table::area, dsa_free(), dsa_get_address(), DsaPointerIsValid, ENTRY_FROM_ITEM, equal_keys(), and dshash_table_item::next.

Referenced by dshash_delete_key().

{
    while (DsaPointerIsValid(*bucket_head))
    {
        dshash_table_item *item;

        item = dsa_get_address(hash_table->area, *bucket_head);

        if (equal_keys(hash_table, key, ENTRY_FROM_ITEM(item)))
        {
            dsa_pointer next;

            next = item->next;
            dsa_free(hash_table->area, *bucket_head);
            *bucket_head = next;

            return true;
        }
        bucket_head = &item->next;
    }
    return false;
}

dshash_attach()

dshash_table* dshash_attach	(	dsa_area *	area,
		const dshash_parameters *	params,
		dshash_table_handle	handle,
		void *	arg
	)

Definition at line 263 of file dshash.c.

References dshash_table::area, arg, dshash_table::arg, Assert, dshash_table::buckets, dshash_table::control, dsa_get_address(), DSHASH_MAGIC, dshash_table::find_exclusively_locked, dshash_table::find_locked, dshash_table_control::magic, palloc(), dshash_table::params, and dshash_table::size_log2.

Referenced by SharedRecordTypmodRegistryAttach().

{
    dshash_table *hash_table;
    dsa_pointer control;

    /* Allocate the backend-local object representing the hash table. */
    hash_table = palloc(sizeof(dshash_table));

    /* Find the control object in shared memory. */
    control = handle;

    /* Set up the local hash table struct. */
    hash_table->area = area;
    hash_table->params = *params;
    hash_table->arg = arg;
    hash_table->control = dsa_get_address(area, control);
    hash_table->find_locked = false;
    hash_table->find_exclusively_locked = false;
    Assert(hash_table->control->magic == DSHASH_MAGIC);

    /*
     * These will later be set to the correct values by
     * ensure_valid_bucket_pointers(), at which time we'll be holding a
     * partition lock for interlocking against concurrent resizing.
     */
    hash_table->buckets = NULL;
    hash_table->size_log2 = 0;

    return hash_table;
}

dshash_create()

dshash_table* dshash_create	(	dsa_area *	area,
		const dshash_parameters *	params,
		void *	arg
	)

Definition at line 196 of file dshash.c.

References dshash_table::area, arg, dshash_table::arg, dshash_table_control::buckets, dshash_table::buckets, dshash_table::control, dshash_partition::count, DSA_ALLOC_NO_OOM, DSA_ALLOC_ZERO, dsa_allocate, dsa_allocate_extended(), dsa_free(), dsa_get_address(), DsaPointerIsValid, DSHASH_MAGIC, DSHASH_NUM_PARTITIONS, DSHASH_NUM_PARTITIONS_LOG2, ereport, errcode(), errdetail(), errmsg(), ERROR, dshash_table::find_exclusively_locked, dshash_table::find_locked, dshash_table_control::handle, i, dshash_table_control::lwlock_tranche_id, LWLockInitialize(), dshash_table_control::magic, palloc(), dshash_table::params, dshash_table_control::partitions, partitions, dshash_table_control::size_log2, dshash_table::size_log2, and dshash_parameters::tranche_id.

Referenced by SharedRecordTypmodRegistryInit().

{
    dshash_table *hash_table;
    dsa_pointer control;

    /* Allocate the backend-local object representing the hash table. */
    hash_table = palloc(sizeof(dshash_table));

    /* Allocate the control object in shared memory. */
    control = dsa_allocate(area, sizeof(dshash_table_control));

    /* Set up the local and shared hash table structs. */
    hash_table->area = area;
    hash_table->params = *params;
    hash_table->arg = arg;
    hash_table->control = dsa_get_address(area, control);
    hash_table->control->handle = control;
    hash_table->control->magic = DSHASH_MAGIC;
    hash_table->control->lwlock_tranche_id = params->tranche_id;

    /* Set up the array of lock partitions. */
    {
        dshash_partition *partitions = hash_table->control->partitions;
        int         tranche_id = hash_table->control->lwlock_tranche_id;
        int         i;

        for (i = 0; i < DSHASH_NUM_PARTITIONS; ++i)
        {
            LWLockInitialize(&partitions[i].lock, tranche_id);
            partitions[i].count = 0;
        }
    }

    hash_table->find_locked = false;
    hash_table->find_exclusively_locked = false;

    /*
     * Set up the initial array of buckets.  Our initial size is the same as
     * the number of partitions.
     */
    hash_table->control->size_log2 = DSHASH_NUM_PARTITIONS_LOG2;
    hash_table->control->buckets =
        dsa_allocate_extended(area,
                              sizeof(dsa_pointer) * DSHASH_NUM_PARTITIONS,
                              DSA_ALLOC_NO_OOM | DSA_ALLOC_ZERO);
    if (!DsaPointerIsValid(hash_table->control->buckets))
    {
        dsa_free(area, control);
        ereport(ERROR,
                (errcode(ERRCODE_OUT_OF_MEMORY),
                 errmsg("out of memory"),
                 errdetail("Failed on DSA request of size %zu.",
                           sizeof(dsa_pointer) * DSHASH_NUM_PARTITIONS)));
    }
    hash_table->buckets = dsa_get_address(area,
                                          hash_table->control->buckets);
    hash_table->size_log2 = hash_table->control->size_log2;

    return hash_table;
}

dshash_delete_entry()

void dshash_delete_entry	(	dshash_table *	hash_table,
		void *	entry
	)

Definition at line 540 of file dshash.c.

References Assert, dshash_table::control, delete_item(), DSHASH_MAGIC, dshash_table::find_exclusively_locked, dshash_table::find_locked, dshash_table_item::hash, ITEM_FROM_ENTRY, LW_EXCLUSIVE, LWLockHeldByMeInMode(), LWLockRelease(), dshash_table_control::magic, PARTITION_FOR_HASH, and PARTITION_LOCK.

{
    dshash_table_item *item = ITEM_FROM_ENTRY(entry);
    size_t      partition = PARTITION_FOR_HASH(item->hash);

    Assert(hash_table->control->magic == DSHASH_MAGIC);
    Assert(hash_table->find_locked);
    Assert(hash_table->find_exclusively_locked);
    Assert(LWLockHeldByMeInMode(PARTITION_LOCK(hash_table, partition),
                                LW_EXCLUSIVE));

    delete_item(hash_table, item);
    hash_table->find_locked = false;
    hash_table->find_exclusively_locked = false;
    LWLockRelease(PARTITION_LOCK(hash_table, partition));
}

dshash_delete_key()

bool dshash_delete_key	(	dshash_table *	hash_table,
		const void *	key
	)

Definition at line 502 of file dshash.c.

References Assert, BUCKET_FOR_HASH, dshash_table::control, dshash_partition::count, delete_key_from_bucket(), DSHASH_MAGIC, ensure_valid_bucket_pointers(), dshash_table::find_locked, dshash_table_item::hash, hash_key(), LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), dshash_table_control::magic, PARTITION_FOR_HASH, PARTITION_LOCK, and dshash_table_control::partitions.

Referenced by find_or_make_matching_shared_tupledesc().

{
    dshash_hash hash;
    size_t      partition;
    bool        found;

    Assert(hash_table->control->magic == DSHASH_MAGIC);
    Assert(!hash_table->find_locked);

    hash = hash_key(hash_table, key);
    partition = PARTITION_FOR_HASH(hash);

    LWLockAcquire(PARTITION_LOCK(hash_table, partition), LW_EXCLUSIVE);
    ensure_valid_bucket_pointers(hash_table);

    if (delete_key_from_bucket(hash_table, key,
                               &BUCKET_FOR_HASH(hash_table, hash)))
    {
        Assert(hash_table->control->partitions[partition].count > 0);
        found = true;
        --hash_table->control->partitions[partition].count;
    }
    else
        found = false;

    LWLockRelease(PARTITION_LOCK(hash_table, partition));

    return found;
}

dshash_destroy()

void dshash_destroy

(

dshash_table *

hash_table

)

Definition at line 318 of file dshash.c.

References dshash_table::area, Assert, dshash_table_control::buckets, dshash_table::buckets, dshash_table::control, dsa_free(), dsa_get_address(), DsaPointerIsValid, DSHASH_MAGIC, ensure_valid_bucket_pointers(), dshash_table_control::handle, i, dshash_table_control::magic, dshash_table_item::next, pfree(), and dshash_table::size_log2.

{
    size_t      size;
    size_t      i;

    Assert(hash_table->control->magic == DSHASH_MAGIC);
    ensure_valid_bucket_pointers(hash_table);

    /* Free all the entries. */
    size = ((size_t) 1) << hash_table->size_log2;
    for (i = 0; i < size; ++i)
    {
        dsa_pointer item_pointer = hash_table->buckets[i];

        while (DsaPointerIsValid(item_pointer))
        {
            dshash_table_item *item;
            dsa_pointer next_item_pointer;

            item = dsa_get_address(hash_table->area, item_pointer);
            next_item_pointer = item->next;
            dsa_free(hash_table->area, item_pointer);
            item_pointer = next_item_pointer;
        }
    }

    /*
     * Vandalize the control block to help catch programming errors where
     * other backends access the memory formerly occupied by this hash table.
     */
    hash_table->control->magic = 0;

    /* Free the active table and control object. */
    dsa_free(hash_table->area, hash_table->control->buckets);
    dsa_free(hash_table->area, hash_table->control->handle);

    pfree(hash_table);
}

dshash_detach()

void dshash_detach

(

dshash_table *

hash_table

)

Definition at line 302 of file dshash.c.

References Assert, dshash_table::find_locked, and pfree().

Referenced by shared_record_typmod_registry_detach().

{
    Assert(!hash_table->find_locked);

    /* The hash table may have been destroyed.  Just free local memory. */
    pfree(hash_table);
}

dshash_dump()

void dshash_dump

(

dshash_table *

hash_table

)

Definition at line 600 of file dshash.c.

References dshash_table::area, Assert, BUCKET_INDEX_FOR_PARTITION, dshash_table::buckets, dshash_table::control, dshash_partition::count, dsa_get_address(), DsaPointerIsValid, DSHASH_MAGIC, DSHASH_NUM_PARTITIONS, ensure_valid_bucket_pointers(), dshash_table::find_locked, fprintf, i, LW_SHARED, LWLockAcquire(), LWLockHeldByMe(), LWLockRelease(), dshash_table_control::magic, dshash_table_item::next, PARTITION_LOCK, dshash_table_control::partitions, and dshash_table::size_log2.

{
    size_t      i;
    size_t      j;

    Assert(hash_table->control->magic == DSHASH_MAGIC);
    Assert(!hash_table->find_locked);

    for (i = 0; i < DSHASH_NUM_PARTITIONS; ++i)
    {
        Assert(!LWLockHeldByMe(PARTITION_LOCK(hash_table, i)));
        LWLockAcquire(PARTITION_LOCK(hash_table, i), LW_SHARED);
    }

    ensure_valid_bucket_pointers(hash_table);

    fprintf(stderr,
            "hash table size = %zu\n", (size_t) 1 << hash_table->size_log2);
    for (i = 0; i < DSHASH_NUM_PARTITIONS; ++i)
    {
        dshash_partition *partition = &hash_table->control->partitions[i];
        size_t      begin = BUCKET_INDEX_FOR_PARTITION(i, hash_table->size_log2);
        size_t      end = BUCKET_INDEX_FOR_PARTITION(i + 1, hash_table->size_log2);

        fprintf(stderr, "  partition %zu\n", i);
        fprintf(stderr,
                "    active buckets (key count = %zu)\n", partition->count);

        for (j = begin; j < end; ++j)
        {
            size_t      count = 0;
            dsa_pointer bucket = hash_table->buckets[j];

            while (DsaPointerIsValid(bucket))
            {
                dshash_table_item *item;

                item = dsa_get_address(hash_table->area, bucket);

                bucket = item->next;
                ++count;
            }
            fprintf(stderr, "      bucket %zu (key count = %zu)\n", j, count);
        }
    }

    for (i = 0; i < DSHASH_NUM_PARTITIONS; ++i)
        LWLockRelease(PARTITION_LOCK(hash_table, i));
}

dshash_find()

void* dshash_find	(	dshash_table *	hash_table,
		const void *	key,
		bool	exclusive
	)

Definition at line 385 of file dshash.c.

References Assert, BUCKET_FOR_HASH, dshash_table::control, DSHASH_MAGIC, ensure_valid_bucket_pointers(), ENTRY_FROM_ITEM, dshash_table::find_exclusively_locked, find_in_bucket(), dshash_table::find_locked, dshash_table_item::hash, hash_key(), LW_EXCLUSIVE, LW_SHARED, LWLockAcquire(), LWLockRelease(), dshash_table_control::magic, PARTITION_FOR_HASH, and PARTITION_LOCK.

Referenced by find_or_make_matching_shared_tupledesc(), and lookup_rowtype_tupdesc_internal().

{
    dshash_hash hash;
    size_t      partition;
    dshash_table_item *item;

    hash = hash_key(hash_table, key);
    partition = PARTITION_FOR_HASH(hash);

    Assert(hash_table->control->magic == DSHASH_MAGIC);
    Assert(!hash_table->find_locked);

    LWLockAcquire(PARTITION_LOCK(hash_table, partition),
                  exclusive ? LW_EXCLUSIVE : LW_SHARED);
    ensure_valid_bucket_pointers(hash_table);

    /* Search the active bucket. */
    item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));

    if (!item)
    {
        /* Not found. */
        LWLockRelease(PARTITION_LOCK(hash_table, partition));
        return NULL;
    }
    else
    {
        /* The caller will free the lock by calling dshash_release_lock. */
        hash_table->find_locked = true;
        hash_table->find_exclusively_locked = exclusive;
        return ENTRY_FROM_ITEM(item);
    }
}

dshash_find_or_insert()

void* dshash_find_or_insert	(	dshash_table *	hash_table,
		const void *	key,
		bool *	found
	)

Definition at line 430 of file dshash.c.

References Assert, BUCKET_FOR_HASH, dshash_table::control, dshash_partition::count, DSHASH_MAGIC, ensure_valid_bucket_pointers(), ENTRY_FROM_ITEM, dshash_table::find_exclusively_locked, find_in_bucket(), dshash_table::find_locked, dshash_table_item::hash, hash_key(), insert_into_bucket(), LW_EXCLUSIVE, LWLockAcquire(), LWLockRelease(), dshash_table_control::magic, MAX_COUNT_PER_PARTITION, PARTITION_FOR_HASH, PARTITION_LOCK, dshash_table_control::partitions, resize(), and dshash_table::size_log2.

Referenced by find_or_make_matching_shared_tupledesc(), and SharedRecordTypmodRegistryInit().

{
    dshash_hash hash;
    size_t      partition_index;
    dshash_partition *partition;
    dshash_table_item *item;

    hash = hash_key(hash_table, key);
    partition_index = PARTITION_FOR_HASH(hash);
    partition = &hash_table->control->partitions[partition_index];

    Assert(hash_table->control->magic == DSHASH_MAGIC);
    Assert(!hash_table->find_locked);

restart:
    LWLockAcquire(PARTITION_LOCK(hash_table, partition_index),
                  LW_EXCLUSIVE);
    ensure_valid_bucket_pointers(hash_table);

    /* Search the active bucket. */
    item = find_in_bucket(hash_table, key, BUCKET_FOR_HASH(hash_table, hash));

    if (item)
        *found = true;
    else
    {
        *found = false;

        /* Check if we are getting too full. */
        if (partition->count > MAX_COUNT_PER_PARTITION(hash_table))
        {
            /*
             * The load factor (= keys / buckets) for all buckets protected by
             * this partition is > 0.75.  Presumably the same applies
             * generally across the whole hash table (though we don't attempt
             * to track that directly to avoid contention on some kind of
             * central counter; we just assume that this partition is
             * representative).  This is a good time to resize.
             *
             * Give up our existing lock first, because resizing needs to
             * reacquire all the locks in the right order to avoid deadlocks.
             */
            LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
            resize(hash_table, hash_table->size_log2 + 1);

            goto restart;
        }

        /* Finally we can try to insert the new item. */
        item = insert_into_bucket(hash_table, key,
                                  &BUCKET_FOR_HASH(hash_table, hash));
        item->hash = hash;
        /* Adjust per-lock-partition counter for load factor knowledge. */
        ++partition->count;
    }

    /* The caller must release the lock with dshash_release_lock. */
    hash_table->find_locked = true;
    hash_table->find_exclusively_locked = true;
    return ENTRY_FROM_ITEM(item);
}

dshash_get_hash_table_handle()

dshash_table_handle dshash_get_hash_table_handle

(

dshash_table *

hash_table

)

Definition at line 362 of file dshash.c.

References Assert, dshash_table::control, DSHASH_MAGIC, dshash_table_control::handle, and dshash_table_control::magic.

Referenced by SharedRecordTypmodRegistryInit().

{
    Assert(hash_table->control->magic == DSHASH_MAGIC);

    return hash_table->control->handle;
}

dshash_memcmp()

int dshash_memcmp	(	const void *	a,
		const void *	b,
		size_t	size,
		void *	arg
	)

Definition at line 581 of file dshash.c.

{
    return memcmp(a, b, size);
}

dshash_memhash()

dshash_hash dshash_memhash	(	const void *	v,
		size_t	size,
		void *	arg
	)

Definition at line 590 of file dshash.c.

References tag_hash().

{
    return tag_hash(v, size);
}

dshash_release_lock()

void dshash_release_lock	(	dshash_table *	hash_table,
		void *	entry
	)

Definition at line 561 of file dshash.c.

References Assert, dshash_table::control, DSHASH_MAGIC, dshash_table::find_exclusively_locked, dshash_table::find_locked, dshash_table_item::hash, ITEM_FROM_ENTRY, LW_EXCLUSIVE, LW_SHARED, LWLockHeldByMeInMode(), LWLockRelease(), dshash_table_control::magic, PARTITION_FOR_HASH, and PARTITION_LOCK.

Referenced by find_or_make_matching_shared_tupledesc(), lookup_rowtype_tupdesc_internal(), and SharedRecordTypmodRegistryInit().

{
    dshash_table_item *item = ITEM_FROM_ENTRY(entry);
    size_t      partition_index = PARTITION_FOR_HASH(item->hash);

    Assert(hash_table->control->magic == DSHASH_MAGIC);
    Assert(hash_table->find_locked);
    Assert(LWLockHeldByMeInMode(PARTITION_LOCK(hash_table, partition_index),
                                hash_table->find_exclusively_locked
                                ? LW_EXCLUSIVE : LW_SHARED));

    hash_table->find_locked = false;
    hash_table->find_exclusively_locked = false;
    LWLockRelease(PARTITION_LOCK(hash_table, partition_index));
}

ensure_valid_bucket_pointers()

static void ensure_valid_bucket_pointers ( dshash_table *  hash_table )

inlinestatic

Definition at line 757 of file dshash.c.

References dshash_table::area, dshash_table_control::buckets, dshash_table::buckets, dshash_table::control, dsa_get_address(), dshash_table_control::size_log2, and dshash_table::size_log2.

Referenced by dshash_delete_key(), dshash_destroy(), dshash_dump(), dshash_find(), and dshash_find_or_insert().

{
    if (hash_table->size_log2 != hash_table->control->size_log2)
    {
        hash_table->buckets = dsa_get_address(hash_table->area,
                                              hash_table->control->buckets);
        hash_table->size_log2 = hash_table->control->size_log2;
    }
}

equal_keys()

static bool equal_keys ( dshash_table *  hash_table, const void *  a, const void *  b  )

inlinestatic

Definition at line 894 of file dshash.c.

References dshash_table::arg, dshash_parameters::compare_function, dshash_parameters::key_size, and dshash_table::params.

Referenced by delete_key_from_bucket(), and find_in_bucket().

{
    return hash_table->params.compare_function(a, b,
                                               hash_table->params.key_size,
                                               hash_table->arg) == 0;
}

find_in_bucket()

static dshash_table_item * find_in_bucket ( dshash_table *  hash_table, const void *  key, dsa_pointer  item_pointer  )

inlinestatic

Definition at line 771 of file dshash.c.

References dshash_table::area, dsa_get_address(), DsaPointerIsValid, ENTRY_FROM_ITEM, equal_keys(), and dshash_table_item::next.

Referenced by dshash_find(), and dshash_find_or_insert().

{
    while (DsaPointerIsValid(item_pointer))
    {
        dshash_table_item *item;

        item = dsa_get_address(hash_table->area, item_pointer);
        if (equal_keys(hash_table, key, ENTRY_FROM_ITEM(item)))
            return item;
        item_pointer = item->next;
    }
    return NULL;
}

hash_key()

static dshash_hash hash_key ( dshash_table *  hash_table, const void *  key  )

inlinestatic

Definition at line 883 of file dshash.c.

References dshash_table::arg, dshash_parameters::hash_function, dshash_parameters::key_size, and dshash_table::params.

Referenced by compute_tsvector_stats(), dshash_delete_key(), dshash_find(), and dshash_find_or_insert().

{
    return hash_table->params.hash_function(key,
                                            hash_table->params.key_size,
                                            hash_table->arg);
}

insert_into_bucket()

static dshash_table_item * insert_into_bucket ( dshash_table *  hash_table, const void *  key, dsa_pointer *  bucket  )

static

Definition at line 806 of file dshash.c.

References dshash_table::area, dsa_allocate, dsa_get_address(), ENTRY_FROM_ITEM, dshash_parameters::entry_size, insert_item_into_bucket(), dshash_parameters::key_size, MAXALIGN, and dshash_table::params.

Referenced by dshash_find_or_insert().

{
    dsa_pointer item_pointer;
    dshash_table_item *item;

    item_pointer = dsa_allocate(hash_table->area,
                                hash_table->params.entry_size +
                                MAXALIGN(sizeof(dshash_table_item)));
    item = dsa_get_address(hash_table->area, item_pointer);
    memcpy(ENTRY_FROM_ITEM(item), key, hash_table->params.key_size);
    insert_item_into_bucket(hash_table, item_pointer, item, bucket);
    return item;
}

insert_item_into_bucket()

static void insert_item_into_bucket ( dshash_table *  hash_table, dsa_pointer  item_pointer, dshash_table_item *  item, dsa_pointer *  bucket  )

static

Definition at line 790 of file dshash.c.

References dshash_table::area, Assert, dsa_get_address(), and dshash_table_item::next.

Referenced by insert_into_bucket(), and resize().

{
    Assert(item == dsa_get_address(hash_table->area, item_pointer));

    item->next = *bucket;
    *bucket = item_pointer;
}

resize()

static void resize ( dshash_table *  hash_table, size_t  new_size  )

static

Definition at line 680 of file dshash.c.

References dshash_table::area, Assert, BUCKET_INDEX_FOR_HASH_AND_SIZE, dshash_table_control::buckets, dshash_table::buckets, dshash_table::control, dsa_allocate0, dsa_free(), dsa_get_address(), DsaPointerIsValid, DSHASH_NUM_PARTITIONS, dshash_table_item::hash, i, insert_item_into_bucket(), LW_EXCLUSIVE, LWLockAcquire(), LWLockHeldByMe(), LWLockRelease(), dshash_table_item::next, PARTITION_LOCK, and dshash_table_control::size_log2.

Referenced by dshash_find_or_insert().

{
    dsa_pointer old_buckets;
    dsa_pointer new_buckets_shared;
    dsa_pointer *new_buckets;
    size_t      size;
    size_t      new_size = ((size_t) 1) << new_size_log2;
    size_t      i;

    /*
     * Acquire the locks for all lock partitions.  This is expensive, but we
     * shouldn't have to do it many times.
     */
    for (i = 0; i < DSHASH_NUM_PARTITIONS; ++i)
    {
        Assert(!LWLockHeldByMe(PARTITION_LOCK(hash_table, i)));

        LWLockAcquire(PARTITION_LOCK(hash_table, i), LW_EXCLUSIVE);
        if (i == 0 && hash_table->control->size_log2 >= new_size_log2)
        {
            /*
             * Another backend has already increased the size; we can avoid
             * obtaining all the locks and return early.
             */
            LWLockRelease(PARTITION_LOCK(hash_table, 0));
            return;
        }
    }

    Assert(new_size_log2 == hash_table->control->size_log2 + 1);

    /* Allocate the space for the new table. */
    new_buckets_shared = dsa_allocate0(hash_table->area,
                                       sizeof(dsa_pointer) * new_size);
    new_buckets = dsa_get_address(hash_table->area, new_buckets_shared);

    /*
     * We've allocated the new bucket array; all that remains to do now is to
     * reinsert all items, which amounts to adjusting all the pointers.
     */
    size = ((size_t) 1) << hash_table->control->size_log2;
    for (i = 0; i < size; ++i)
    {
        dsa_pointer item_pointer = hash_table->buckets[i];

        while (DsaPointerIsValid(item_pointer))
        {
            dshash_table_item *item;
            dsa_pointer next_item_pointer;

            item = dsa_get_address(hash_table->area, item_pointer);
            next_item_pointer = item->next;
            insert_item_into_bucket(hash_table, item_pointer, item,
                                    &new_buckets[BUCKET_INDEX_FOR_HASH_AND_SIZE(item->hash,
                                                                                new_size_log2)]);
            item_pointer = next_item_pointer;
        }
    }

    /* Swap the hash table into place and free the old one. */
    old_buckets = hash_table->control->buckets;
    hash_table->control->buckets = new_buckets_shared;
    hash_table->control->size_log2 = new_size_log2;
    hash_table->buckets = new_buckets;
    dsa_free(hash_table->area, old_buckets);

    /* Release all the locks. */
    for (i = 0; i < DSHASH_NUM_PARTITIONS; ++i)
        LWLockRelease(PARTITION_LOCK(hash_table, i));
}