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Diffstat (limited to 'bdb/dbinc/db_shash.h')
| -rw-r--r-- | bdb/dbinc/db_shash.h | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/bdb/dbinc/db_shash.h b/bdb/dbinc/db_shash.h new file mode 100644 index 00000000000..2c54d6145c5 --- /dev/null +++ b/bdb/dbinc/db_shash.h @@ -0,0 +1,81 @@ +/*- + * See the file LICENSE for redistribution information. + * + * Copyright (c) 1996-2002 + * Sleepycat Software. All rights reserved. + * + * $Id: db_shash.h,v 11.11 2002/01/11 15:52:26 bostic 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_ */ |