1 files changed, 98 insertions, 0 deletions
diff --git a/src/lock/lock_util.c b/src/lock/lock_util.c
new file mode 100644
index 00000000..f7029cd7
--- /dev/null
+++ b/src/lock/lock_util.c
@@ -0,0 +1,98 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 1996, 2012 Oracle and/or its affiliates.  All rights reserved.
+ *
+ * $Id$
+ */
+
+#include "db_config.h"
+
+#include "db_int.h"
+#include "dbinc/db_page.h"
+#include "dbinc/hash.h"
+#include "dbinc/lock.h"
+
+/*
+ * The next two functions are the hash functions used to store objects in the
+ * lock hash tables.  They are hashing the same items, but one (__lock_ohash)
+ * takes a DBT (used for hashing a parameter passed from the user) and the
+ * other (__lock_lhash) takes a DB_LOCKOBJ (used for hashing something that is
+ * already in the lock manager).  In both cases, we have a special check to
+ * fast path the case where we think we are doing a hash on a DB page/fileid
+ * pair.  If the size is right, then we do the fast hash.
+ *
+ * We know that DB uses DB_LOCK_ILOCK types for its lock objects.  The first
+ * four bytes are the 4-byte page number and the next DB_FILE_ID_LEN bytes
+ * are a unique file id, where the first 4 bytes on UNIX systems are the file
+ * inode number, and the first 4 bytes on Windows systems are the FileIndexLow
+ * bytes.  This is followed by a random number.  The inode values tend
+ * to increment fairly slowly and are not good for hashing.  So, we use
+ * the XOR of the page number and the four bytes of the file id random
+ * number to produce a 32-bit hash value.
+ *
+ * We have no particular reason to believe that this algorithm will produce
+ * a good hash, but we want a fast hash more than we want a good one, when
+ * we're coming through this code path.
+ */
+#define	FAST_HASH(P) {			\
+	u_int32_t __h;			\
+	u_int8_t *__cp, *__hp;		\
+	__hp = (u_int8_t *)&__h;	\
+	__cp = (u_int8_t *)(P);		\
+	__hp[0] = __cp[0] ^ __cp[12];	\
+	__hp[1] = __cp[1] ^ __cp[13];	\
+	__hp[2] = __cp[2] ^ __cp[14];	\
+	__hp[3] = __cp[3] ^ __cp[15];	\
+	return (__h);			\
+}
+
+/*
+ * __lock_ohash --
+ *
+ * PUBLIC: u_int32_t __lock_ohash __P((const DBT *));
+ */
+u_int32_t
+__lock_ohash(dbt)
+	const DBT *dbt;
+{
+	if (dbt->size == sizeof(DB_LOCK_ILOCK))
+		FAST_HASH(dbt->data);
+
+	return (__ham_func5(NULL, dbt->data, dbt->size));
+}
+
+/*
+ * __lock_lhash --
+ *
+ * PUBLIC: u_int32_t __lock_lhash __P((DB_LOCKOBJ *));
+ */
+u_int32_t
+__lock_lhash(lock_obj)
+	DB_LOCKOBJ *lock_obj;
+{
+	void *obj_data;
+
+	obj_data = SH_DBT_PTR(&lock_obj->lockobj);
+
+	if (lock_obj->lockobj.size == sizeof(DB_LOCK_ILOCK))
+		FAST_HASH(obj_data);
+
+	return (__ham_func5(NULL, obj_data, lock_obj->lockobj.size));
+}
+
+/*
+ * __lock_nomem --
+ *	Report a lack of some resource.
+ *
+ * PUBLIC: int __lock_nomem __P((ENV *, const char *));
+ */
+int
+__lock_nomem(env, res)
+	ENV *env;
+	const char *res;
+{
+	__db_errx(env, DB_STR_A("2055", "Lock table is out of available %s",
+	    "%s"), res);
+	return (ENOMEM);
+}