1 /*-------------------------------------------------------------------------
4 * exported definitions for utils/hash/dynahash.c; see notes therein
7 * Portions Copyright (c) 1996-2014, PostgreSQL Global Development Group
8 * Portions Copyright (c) 1994, Regents of the University of California
10 * src/include/utils/hsearch.h
12 *-------------------------------------------------------------------------
19 * Hash functions must have this signature.
21 typedef uint32 (*HashValueFunc) (const void *key, Size keysize);
24 * Key comparison functions must have this signature. Comparison functions
25 * return zero for match, nonzero for no match. (The comparison function
26 * definition is designed to allow memcmp() and strncmp() to be used directly
27 * as key comparison functions.)
29 typedef int (*HashCompareFunc) (const void *key1, const void *key2,
33 * Key copying functions must have this signature. The return value is not
34 * used. (The definition is set up to allow memcpy() and strncpy() to be
37 typedef void *(*HashCopyFunc) (void *dest, const void *src, Size keysize);
40 * Space allocation function for a hashtable --- designed to match malloc().
41 * Note: there is no free function API; can't destroy a hashtable unless you
42 * use the default allocator.
44 typedef void *(*HashAllocFunc) (Size request);
47 * HASHELEMENT is the private part of a hashtable entry. The caller's data
48 * follows the HASHELEMENT structure (on a MAXALIGN'd boundary). The hash key
49 * is expected to be at the start of the caller's hash entry data structure.
51 typedef struct HASHELEMENT
53 struct HASHELEMENT *link; /* link to next entry in same bucket */
54 uint32 hashvalue; /* hash function result for this entry */
57 /* Hash table header struct is an opaque type known only within dynahash.c */
58 typedef struct HASHHDR HASHHDR;
60 /* Hash table control struct is an opaque type known only within dynahash.c */
61 typedef struct HTAB HTAB;
63 /* Parameter data structure for hash_create */
64 /* Only those fields indicated by hash_flags need be set */
65 typedef struct HASHCTL
67 long num_partitions; /* # partitions (must be power of 2) */
68 long ssize; /* segment size */
69 long dsize; /* (initial) directory size */
70 long max_dsize; /* limit to dsize if dir size is limited */
71 long ffactor; /* fill factor */
72 Size keysize; /* hash key length in bytes */
73 Size entrysize; /* total user element size in bytes */
74 HashValueFunc hash; /* hash function */
75 HashCompareFunc match; /* key comparison function */
76 HashCopyFunc keycopy; /* key copying function */
77 HashAllocFunc alloc; /* memory allocator */
78 MemoryContext hcxt; /* memory context to use for allocations */
79 HASHHDR *hctl; /* location of header in shared mem */
82 /* Flags to indicate which parameters are supplied */
83 #define HASH_PARTITION 0x001 /* Hashtable is used w/partitioned locking */
84 #define HASH_SEGMENT 0x002 /* Set segment size */
85 #define HASH_DIRSIZE 0x004 /* Set directory size (initial and max) */
86 #define HASH_FFACTOR 0x008 /* Set fill factor */
87 #define HASH_FUNCTION 0x010 /* Set user defined hash function */
88 #define HASH_ELEM 0x020 /* Set keysize and entrysize */
89 #define HASH_SHARED_MEM 0x040 /* Hashtable is in shared memory */
90 #define HASH_ATTACH 0x080 /* Do not initialize hctl */
91 #define HASH_ALLOC 0x100 /* Set memory allocator */
92 #define HASH_CONTEXT 0x200 /* Set memory allocation context */
93 #define HASH_COMPARE 0x400 /* Set user defined comparison function */
94 #define HASH_KEYCOPY 0x800 /* Set user defined key-copying function */
95 #define HASH_FIXED_SIZE 0x1000 /* Initial size is a hard limit */
98 /* max_dsize value to indicate expansible directory */
99 #define NO_MAX_DSIZE (-1)
101 /* hash_search operations */
110 /* hash_seq status (should be considered an opaque type by callers) */
114 uint32 curBucket; /* index of current bucket */
115 HASHELEMENT *curEntry; /* current entry in bucket */
119 * prototypes for functions in dynahash.c
121 extern HTAB *hash_create(const char *tabname, long nelem,
122 HASHCTL *info, int flags);
123 extern void hash_destroy(HTAB *hashp);
124 extern void hash_stats(const char *where, HTAB *hashp);
125 extern void *hash_search(HTAB *hashp, const void *keyPtr, HASHACTION action,
127 extern uint32 get_hash_value(HTAB *hashp, const void *keyPtr);
128 extern void *hash_search_with_hash_value(HTAB *hashp, const void *keyPtr,
129 uint32 hashvalue, HASHACTION action,
131 extern bool hash_update_hash_key(HTAB *hashp, void *existingEntry,
132 const void *newKeyPtr);
133 extern long hash_get_num_entries(HTAB *hashp);
134 extern void hash_seq_init(HASH_SEQ_STATUS *status, HTAB *hashp);
135 extern void *hash_seq_search(HASH_SEQ_STATUS *status);
136 extern void hash_seq_term(HASH_SEQ_STATUS *status);
137 extern void hash_freeze(HTAB *hashp);
138 extern Size hash_estimate_size(long num_entries, Size entrysize);
139 extern long hash_select_dirsize(long num_entries);
140 extern Size hash_get_shared_size(HASHCTL *info, int flags);
141 extern void AtEOXact_HashTables(bool isCommit);
142 extern void AtEOSubXact_HashTables(bool isCommit, int nestDepth);
145 * prototypes for functions in hashfn.c
147 extern uint32 string_hash(const void *key, Size keysize);
148 extern uint32 tag_hash(const void *key, Size keysize);
149 extern uint32 oid_hash(const void *key, Size keysize);
150 extern uint32 bitmap_hash(const void *key, Size keysize);
151 extern int bitmap_match(const void *key1, const void *key2, Size keysize);
153 #endif /* HSEARCH_H */