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107 lines
3.9 KiB
C
107 lines
3.9 KiB
C
/*-
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* See the file LICENSE for redistribution information.
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*
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* Copyright (c) 1996, 1997, 1998
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* Sleepycat Software. All rights reserved.
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*
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* @(#)db_shash.h 10.3 (Sleepycat) 4/10/98
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*/
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/* Hash Headers */
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typedef SH_TAILQ_HEAD(hash_head) DB_HASHTAB;
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/*
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* HASHLOOKUP --
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*
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* Look up something in a shared memory hash table. The "elt" argument
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* should be a key, and cmp_func must know how to compare a key to whatever
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* structure it is that appears in the hash table. The comparison function
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* cmp_func is called as: cmp_func(lookup_elt, table_elt);
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* begin: address of the beginning of the hash table.
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* type: the structure type of the elements that are linked in each bucket.
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* field: the name of the field by which the "type" structures are linked.
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* elt: the item for which we are searching in the hash table.
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* result: the variable into which we'll store the element if we find it.
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* nelems: the number of buckets in the hash table.
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* hash_func: the hash function that operates on elements of the type of elt
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* cmp_func: compare elements of the type of elt with those in the table (of
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* type "type").
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*
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* If the element is not in the hash table, this macro exits with result
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* set to NULL.
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*/
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#define HASHLOOKUP(begin, type, field, elt, r, n, hash, cmp) do { \
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DB_HASHTAB *__bucket; \
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u_int32_t __ndx; \
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\
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__ndx = hash(elt) % (n); \
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__bucket = &begin[__ndx]; \
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for (r = SH_TAILQ_FIRST(__bucket, type); \
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r != NULL; r = SH_TAILQ_NEXT(r, field, type)) \
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if (cmp(elt, r)) \
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break; \
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} while(0)
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/*
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* HASHINSERT --
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*
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* Insert a new entry into the hash table. This assumes that lookup has
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* failed; don't call it if you haven't already called HASHLOOKUP.
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* begin: the beginning address of the hash table.
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* type: the structure type of the elements that are linked in each bucket.
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* field: the name of the field by which the "type" structures are linked.
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* elt: the item to be inserted.
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* nelems: the number of buckets in the hash table.
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* hash_func: the hash function that operates on elements of the type of elt
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*/
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#define HASHINSERT(begin, type, field, elt, n, hash) do { \
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u_int32_t __ndx; \
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DB_HASHTAB *__bucket; \
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\
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__ndx = hash(elt) % (n); \
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__bucket = &begin[__ndx]; \
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SH_TAILQ_INSERT_HEAD(__bucket, elt, field, type); \
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} while(0)
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/*
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* HASHREMOVE --
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* Remove the entry with a key == elt.
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* begin: address of the beginning of the hash table.
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* type: the structure type of the elements that are linked in each bucket.
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* field: the name of the field by which the "type" structures are linked.
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* elt: the item to be deleted.
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* nelems: the number of buckets in the hash table.
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* hash_func: the hash function that operates on elements of the type of elt
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* cmp_func: compare elements of the type of elt with those in the table (of
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* type "type").
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*/
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#define HASHREMOVE(begin, type, field, elt, n, hash, cmp) { \
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u_int32_t __ndx; \
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DB_HASHTAB *__bucket; \
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SH_TAILQ_ENTRY *__entp; \
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\
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__ndx = hash(elt) % (n); \
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__bucket = &begin[__ndx]; \
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HASHLOOKUP(begin, type, field, elt, __entp, n, hash, cmp); \
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SH_TAILQ_REMOVE(__bucket, __entp, field, type); \
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}
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/*
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* HASHREMOVE_EL --
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* Given the object "obj" in the table, remove it.
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* begin: address of the beginning of the hash table.
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* type: the structure type of the elements that are linked in each bucket.
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* field: the name of the field by which the "type" structures are linked.
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* obj: the object in the table that we with to delete.
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* nelems: the number of buckets in the hash table.
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* hash_func: the hash function that operates on elements of the type of elt
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*/
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#define HASHREMOVE_EL(begin, type, field, obj, n, hash) { \
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u_int32_t __ndx; \
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DB_HASHTAB *__bucket; \
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\
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__ndx = hash(obj) % (n); \
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__bucket = &begin[__ndx]; \
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SH_TAILQ_REMOVE(__bucket, obj, field, type); \
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}
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