1 files changed, 56 insertions, 0 deletions
diff --git a/mysys/my_safehash.h b/mysys/my_safehash.h
new file mode 100644
index 00000000..71aaf5d0
--- /dev/null
+++ b/mysys/my_safehash.h
@@ -0,0 +1,56 @@
+/* Copyright (C) 2003 MySQL AB
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA */
+
+/*
+  Handling of multiple key caches
+
+  The idea is to have a thread safe hash on the table name,
+  with a default key cache value that is returned if the table name is not in
+  the cache.
+*/
+
+#include <hash.h>
+
+/*
+  Struct to store a key and pointer to object
+*/
+
+typedef struct st_safe_hash_entry
+{
+  uchar *key;
+  uint length;
+  uchar *data;
+  struct st_safe_hash_entry *next, **prev;
+} SAFE_HASH_ENTRY;
+
+
+typedef struct st_safe_hash_with_default
+{
+  mysql_rwlock_t mutex;
+  HASH hash;
+  uchar *default_value;
+  SAFE_HASH_ENTRY *root;
+} SAFE_HASH;
+
+
+my_bool safe_hash_init(SAFE_HASH *hash, uint elements,
+                       uchar *default_value);
+void safe_hash_free(SAFE_HASH *hash);
+uchar *safe_hash_search(SAFE_HASH *hash, const uchar *key, uint length,
+                       uchar *def);
+my_bool safe_hash_set(SAFE_HASH *hash, const uchar *key, uint length,
+                      uchar *data);
+void safe_hash_change(SAFE_HASH *hash, uchar *old_data, uchar *new_data);