155 lines
6.6 KiB
C
155 lines
6.6 KiB
C
/* -------------------------------------------------------------------------
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*
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* hsearch.h
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* exported definitions for utils/hash/dynahash.c; see notes therein
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*
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*
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* Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/utils/hsearch.h
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*
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* -------------------------------------------------------------------------
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*/
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#ifndef HSEARCH_H
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#define HSEARCH_H
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/*
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* Hash functions must have this signature.
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*/
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typedef uint32 (*HashValueFunc)(const void* key, Size keysize);
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/*
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* Key comparison functions must have this signature. Comparison functions
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* return zero for match, nonzero for no match. (The comparison function
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* definition is designed to allow memcmp() and strncmp() to be used directly
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* as key comparison functions.)
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*/
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typedef int (*HashCompareFunc)(const void* key1, const void* key2, Size keysize);
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/*
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* Key copying functions must have this signature. The return value is not
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* used. (The definition is set up to allow memcpy() and strncpy() to be
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* used directly.)
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*/
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typedef void* (*HashCopyFunc)(void* dest, const void* src, Size keysize);
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/*
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* Space allocation function for a hashtable --- designed to match malloc().
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* Note: there is no free function API; can't destroy a hashtable unless you
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* use the default allocator.
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*/
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typedef void* (*HashAllocFunc)(Size request);
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/*
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* Space deallocation function for a hashtable --- designed to match allocator().
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* Note: it's a free function API; you must use it with allocator you defined.
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*/
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typedef void (*HashDeallocFunc)(void* pointer);
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/*
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* HASHELEMENT is the private part of a hashtable entry. The caller's data
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* follows the HASHELEMENT structure (on a MAXALIGN'd boundary). The hash key
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* is expected to be at the start of the caller's hash entry data structure.
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*/
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typedef struct HASHELEMENT {
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struct HASHELEMENT* link; /* link to next entry in same bucket */
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uint32 hashvalue; /* hash function result for this entry */
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} HASHELEMENT;
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/* Hash table header struct is an opaque type known only within dynahash.c */
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typedef struct HASHHDR HASHHDR;
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/* Hash table control struct is an opaque type known only within dynahash.c */
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typedef struct HTAB HTAB;
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/* Parameter data structure for hash_create */
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/* Only those fields indicated by hash_flags need be set */
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typedef struct HASHCTL {
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long num_partitions; /* # partitions (must be power of 2) */
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long ssize; /* segment size */
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long dsize; /* (initial) directory size */
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long max_dsize; /* limit to dsize if dir size is limited */
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long ffactor; /* fill factor */
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Size keysize; /* hash key length in bytes */
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Size entrysize; /* total user element size in bytes */
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HashValueFunc hash; /* hash function */
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HashCompareFunc match; /* key comparison function */
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HashCopyFunc keycopy; /* key copying function */
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HashAllocFunc alloc; /* memory allocator */
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HashDeallocFunc dealloc; /* memory deallocator */
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MemoryContext hcxt; /* memory context to use for allocations */
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HASHHDR* hctl; /* location of header in shared mem */
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} HASHCTL;
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/* Flags to indicate which parameters are supplied */
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#define HASH_PARTITION 0x001 /* Hashtable is used w/partitioned locking */
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#define HASH_SEGMENT 0x002 /* Set segment size */
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#define HASH_DIRSIZE 0x004 /* Set directory size (initial and max) */
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#define HASH_FFACTOR 0x008 /* Set fill factor */
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#define HASH_FUNCTION 0x010 /* Set user defined hash function */
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#define HASH_ELEM 0x020 /* Set keysize and entrysize */
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#define HASH_SHARED_MEM 0x040 /* Hashtable is in shared memory */
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#define HASH_ATTACH 0x080 /* Do not initialize hctl */
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#define HASH_ALLOC 0x100 /* Set memory allocator */
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#define HASH_CONTEXT 0x200 /* Set memory allocation context */
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#define HASH_COMPARE 0x400 /* Set user defined comparison function */
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#define HASH_KEYCOPY 0x800 /* Set user defined key-copying function */
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#define HASH_FIXED_SIZE 0x1000 /* Initial size is a hard limit */
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#define HASH_HEAP_MEM 0x2000 /* Hashtable is in heap memory */
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#define HASH_EXTERN_CONTEXT 0x4000 /* use extern context directly */
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#define HASH_SHRCTX 0x8000 /* Set shared memory allocation context */
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#define HASH_DEALLOC 0x10000 /* Set memory deallocator */
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#define HASH_BLOBS 0x20000 /* Select support functions for binary keys */
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#define HASH_NOEXCEPT 0x40000 /* Do not throw exception when malloc memory */
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/* max_dsize value to indicate expansible directory */
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#define NO_MAX_DSIZE (-1)
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/* hash_search operations */
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typedef enum { HASH_FIND, HASH_ENTER, HASH_REMOVE, HASH_ENTER_NULL } HASHACTION;
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/* hash_seq status (should be considered an opaque type by callers) */
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typedef struct {
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HTAB* hashp;
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uint32 curBucket; /* index of current bucket */
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HASHELEMENT* curEntry; /* current entry in bucket */
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} HASH_SEQ_STATUS;
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/*
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* prototypes for functions in dynahash.c
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*/
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extern HTAB* hash_create(const char* tabname, long nelem, HASHCTL* info, int flags);
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extern void hash_destroy(HTAB* hashp);
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extern void hash_remove(HTAB* hashp);
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extern void hash_stats(const char* where, HTAB* hashp);
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extern void* hash_search(HTAB* hashp, const void* keyPtr, HASHACTION action, bool* foundPtr);
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extern uint32 get_hash_value(HTAB* hashp, const void* keyPtr);
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extern void* hash_search_with_hash_value(
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HTAB* hashp, const void* keyPtr, uint32 hashvalue, HASHACTION action, bool* foundPtr);
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extern long hash_get_num_entries(HTAB* hashp);
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extern void hash_seq_init(HASH_SEQ_STATUS* status, HTAB* hashp);
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extern void* hash_seq_search(HASH_SEQ_STATUS* status);
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extern void hash_seq_term(HASH_SEQ_STATUS* status);
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extern void hash_freeze(HTAB* hashp);
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extern Size hash_estimate_size(long num_entries, Size entrysize);
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extern long hash_select_dirsize(long num_entries);
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extern Size hash_get_shared_size(HASHCTL* info, int flags);
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extern void AtEOXact_HashTables(bool isCommit);
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extern void AtEOSubXact_HashTables(bool isCommit, int nestDepth);
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extern int hash_get_seq_num();
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extern void release_all_seq_scan();
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extern MemoryContext hash_get_current_dynacxt(void);
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/*
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* prototypes for functions in hashfn.c
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*/
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extern uint32 string_hash(const void* key, Size keysize);
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extern uint32 tag_hash(const void* key, Size keysize);
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extern uint32 uint32_hash(const void *key, Size keysize);
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extern uint32 oid_hash(const void* key, Size keysize);
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extern uint32 bitmap_hash(const void* key, Size keysize);
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extern int bitmap_match(const void* key1, const void* key2, Size keysize);
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#endif /* HSEARCH_H */
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