/*- * See the file LICENSE for redistribution information. * * Copyright (c) 1996-2003 * Sleepycat Software. All rights reserved. * * $Id: db_shash.h,v 1.2 2004/03/30 01:21:28 jtownsen Exp $ */ #ifndef _DB_SHASH_H_ #define _DB_SHASH_H_ /* Hash Headers */ typedef SH_TAILQ_HEAD(__hash_head) DB_HASHTAB; /* * HASHLOOKUP -- * * Look up something in a shared memory hash table. The "elt" argument * should be a key, and cmp_func must know how to compare a key to whatever * structure it is that appears in the hash table. The comparison function * * begin: address of the beginning of the hash table. * ndx: index into table for this item. * type: the structure type of the elements that are linked in each bucket. * field: the name of the field by which the "type" structures are linked. * elt: the item for which we are searching in the hash table. * res: the variable into which we'll store the element if we find it. * cmp: called as: cmp(lookup_elt, table_elt). * * If the element is not in the hash table, this macro exits with res set * to NULL. */ #define HASHLOOKUP(begin, ndx, type, field, elt, res, cmp) do { \ DB_HASHTAB *__bucket; \ \ __bucket = &begin[ndx]; \ for (res = SH_TAILQ_FIRST(__bucket, type); \ res != NULL; res = SH_TAILQ_NEXT(res, field, type)) \ if (cmp(elt, res)) \ break; \ } while (0) /* * HASHINSERT -- * * Insert a new entry into the hash table. This assumes that you already * have the bucket locked and that lookup has failed; don't call it if you * haven't already called HASHLOOKUP. If you do, you could get duplicate * entries. * * begin: the beginning address of the hash table. * ndx: the index for this element. * type: the structure type of the elements that are linked in each bucket. * field: the name of the field by which the "type" structures are linked. * elt: the item to be inserted. */ #define HASHINSERT(begin, ndx, type, field, elt) do { \ DB_HASHTAB *__bucket; \ \ __bucket = &begin[ndx]; \ SH_TAILQ_INSERT_HEAD(__bucket, elt, field, type); \ } while (0) /* * HASHREMOVE_EL -- * Given the object "obj" in the table, remove it. * * begin: address of the beginning of the hash table. * ndx: index into hash table of where this element belongs. * type: the structure type of the elements that are linked in each bucket. * field: the name of the field by which the "type" structures are linked. * obj: the object in the table that we with to delete. */ #define HASHREMOVE_EL(begin, ndx, type, field, obj) { \ DB_HASHTAB *__bucket; \ \ __bucket = &begin[ndx]; \ SH_TAILQ_REMOVE(__bucket, obj, field, type); \ } #endif /* !_DB_SHASH_H_ */