2014-11-18 23:08:34 +08:00
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/*-
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* See the file LICENSE for redistribution information.
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*
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* Copyright (c) 1996-2004
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* Sleepycat Software. All rights reserved.
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*
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* $Id: db_shash.h,v 11.13 2004/01/28 03:36:02 bostic Exp $
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*/
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#ifndef _DB_SHASH_H_
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#define _DB_SHASH_H_
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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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*
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* begin: address of the beginning of the hash table.
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* ndx: index into table for this item.
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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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* res: the variable into which we'll store the element if we find it.
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* cmp: called as: cmp(lookup_elt, table_elt).
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*
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* If the element is not in the hash table, this macro exits with res set
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* to NULL.
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*/
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#define HASHLOOKUP(begin, ndx, type, field, elt, res, cmp) do { \
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DB_HASHTAB *__bucket; \
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\
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__bucket = &begin[ndx]; \
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for (res = SH_TAILQ_FIRST(__bucket, type); \
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res != NULL; res = SH_TAILQ_NEXT(res, field, type)) \
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if (cmp(elt, res)) \
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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 you already
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* have the bucket locked and that lookup has failed; don't call it if you
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* haven't already called HASHLOOKUP. If you do, you could get duplicate
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* entries.
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*
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* begin: the beginning address of the hash table.
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* ndx: the index for this element.
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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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*/
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#define HASHINSERT(begin, ndx, type, field, elt) do { \
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DB_HASHTAB *__bucket; \
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\
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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_EL --
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* Given the object "obj" in the table, remove it.
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*
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* begin: address of the beginning of the hash table.
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* ndx: index into hash table of where this element belongs.
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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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*/
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#define HASHREMOVE_EL(begin, ndx, type, field, obj) { \
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DB_HASHTAB *__bucket; \
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\
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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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#endif /* !_DB_SHASH_H_ */
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