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hsearch.h
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/*------------------------------------------------------------------------- * * hsearch.h * exported definitions for utils/hash/dynahash.c; see notes therein * * * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * src/include/utils/hsearch.h * *------------------------------------------------------------------------- */ #ifndef HSEARCH_H #define HSEARCH_H /* * Hash functions must have this signature. */ typedef uint32 (*HashValueFunc) (const void *key, Size keysize); /* * Key comparison functions must have this signature. Comparison functions * return zero for match, nonzero for no match. (The comparison function * definition is designed to allow memcmp() and strncmp() to be used directly * as key comparison functions.) */ typedef int (*HashCompareFunc) (const void *key1, const void *key2, Size keysize); /* * Key copying functions must have this signature. The return value is not * used. (The definition is set up to allow memcpy() and strncpy() to be * used directly.) */ typedef void *(*HashCopyFunc) (void *dest, const void *src, Size keysize); /* * Space allocation function for a hashtable --- designed to match malloc(). * Note: there is no free function API; can't destroy a hashtable unless you * use the default allocator. */ typedef void *(*HashAllocFunc) (Size request); /* * HASHELEMENT is the private part of a hashtable entry. The caller's data * follows the HASHELEMENT structure (on a MAXALIGN'd boundary). The hash key * is expected to be at the start of the caller's hash entry data structure. */ typedef struct HASHELEMENT { struct HASHELEMENT *link; /* link to next entry in same bucket */ uint32 hashvalue; /* hash function result for this entry */ } HASHELEMENT; /* Hash table header struct is an opaque type known only within dynahash.c */ typedef struct HASHHDR HASHHDR; /* Hash table control struct is an opaque type known only within dynahash.c */ typedef struct HTAB HTAB; /* Parameter data structure for hash_create */ /* Only those fields indicated by hash_flags need be set */ typedef struct HASHCTL { long num_partitions; /* # partitions (must be power of 2) */ long ssize; /* segment size */ long dsize; /* (initial) directory size */ long max_dsize; /* limit to dsize if dir size is limited */ long ffactor; /* fill factor */ Size keysize; /* hash key length in bytes */ Size entrysize; /* total user element size in bytes */ HashValueFunc hash; /* hash function */ HashCompareFunc match; /* key comparison function */ HashCopyFunc keycopy; /* key copying function */ HashAllocFunc alloc; /* memory allocator */ MemoryContext hcxt; /* memory context to use for allocations */ HASHHDR *hctl; /* location of header in shared mem */ } HASHCTL; /* Flags to indicate which parameters are supplied */ #define HASH_PARTITION 0x001 /* Hashtable is used w/partitioned locking */ #define HASH_SEGMENT 0x002 /* Set segment size */ #define HASH_DIRSIZE 0x004 /* Set directory size (initial and max) */ #define HASH_FFACTOR 0x008 /* Set fill factor */ #define HASH_FUNCTION 0x010 /* Set user defined hash function */ #define HASH_ELEM 0x020 /* Set keysize and entrysize */ #define HASH_SHARED_MEM 0x040 /* Hashtable is in shared memory */ #define HASH_ATTACH 0x080 /* Do not initialize hctl */ #define HASH_ALLOC 0x100 /* Set memory allocator */ #define HASH_CONTEXT 0x200 /* Set memory allocation context */ #define HASH_COMPARE 0x400 /* Set user defined comparison function */ #define HASH_KEYCOPY 0x800 /* Set user defined key-copying function */ #define HASH_FIXED_SIZE 0x1000 /* Initial size is a hard limit */ /* max_dsize value to indicate expansible directory */ #define NO_MAX_DSIZE (-1) /* hash_search operations */ typedef enum { HASH_FIND, HASH_ENTER, HASH_REMOVE, HASH_ENTER_NULL } HASHACTION; /* hash_seq status (should be considered an opaque type by callers) */ typedef struct { HTAB *hashp; uint32 curBucket; /* index of current bucket */ HASHELEMENT *curEntry; /* current entry in bucket */ } HASH_SEQ_STATUS; /* * prototypes for functions in dynahash.c */ extern HTAB *hash_create(const char *tabname, long nelem, HASHCTL *info, int flags); extern void hash_destroy(HTAB *hashp); extern void hash_stats(const char *where, HTAB *hashp); extern void *hash_search(HTAB *hashp, const void *keyPtr, HASHACTION action, bool *foundPtr); extern uint32 get_hash_value(HTAB *hashp, const void *keyPtr); extern void *hash_search_with_hash_value(HTAB *hashp, const void *keyPtr, uint32 hashvalue, HASHACTION action, bool *foundPtr); extern long hash_get_num_entries(HTAB *hashp); extern void hash_seq_init(HASH_SEQ_STATUS *status, HTAB *hashp); extern void *hash_seq_search(HASH_SEQ_STATUS *status); extern void hash_seq_term(HASH_SEQ_STATUS *status); extern void hash_freeze(HTAB *hashp); extern Size hash_estimate_size(long num_entries, Size entrysize); extern long hash_select_dirsize(long num_entries); extern Size hash_get_shared_size(HASHCTL *info, int flags); extern void AtEOXact_HashTables(bool isCommit); extern void AtEOSubXact_HashTables(bool isCommit, int nestDepth); /* * prototypes for functions in hashfn.c */ extern uint32 string_hash(const void *key, Size keysize); extern uint32 tag_hash(const void *key, Size keysize); extern uint32 oid_hash(const void *key, Size keysize); extern uint32 bitmap_hash(const void *key, Size keysize); extern int bitmap_match(const void *key1, const void *key2, Size keysize); #endif /* HSEARCH_H */