r2026: Simplify statcache to use an in-memory tdb. Modify tdb to use

a customer hash function for this tdb (yes it does make a difference
on benchmarks). Remove the no longer used hash.c code.
Jeremy.
(This used to be commit 3fbadac85b8cad89b93d295968e99c38c8677575)

2 files changed, 34 insertions, 26 deletions

diff --git a/source3/tdb/tdb.c b/source3/tdb/tdb.c
index cda9fc2475..0ebbc8b21e 100644
--- a/source3/tdb/tdb.c
+++ b/source3/tdb/tdb.c
@@ -329,19 +329,6 @@ static int tdb_unlock(TDB_CONTEXT *tdb, int list, int ltype)
 	return ret;
 }
 
-/* This is based on the hash algorithm from gdbm */
-static u32 tdb_hash(TDB_DATA *key)
-{
-	u32 value;	/* Used to compute the hash value.  */
-	u32   i;	/* Used to cycle through random values. */
-
-	/* Set the initial value from the key size. */
-	for (value = 0x238F13AF * key->dsize, i=0; i < key->dsize; i++)
-		value = (value + (key->dptr[i] << (i*5 % 24)));
-
-	return (1103515243 * value + 12345);  
-}
-
 /* check for an out of bounds access - if it is out of bounds then
    see if the database has been expanded by someone else and expand
    if necessary 
@@ -1121,7 +1108,7 @@ TDB_DATA tdb_fetch(TDB_CONTEXT *tdb, TDB_DATA key)
 	u32 hash;
 
 	/* find which hash bucket it is in */
-	hash = tdb_hash(&key);
+	hash = tdb->hash_fn(&key);
 	if (!(rec_ptr = tdb_find_lock_hash(tdb,key,hash,F_RDLCK,&rec)))
 		return tdb_null;
 
@@ -1153,7 +1140,7 @@ static int tdb_exists_hash(TDB_CONTEXT *tdb, TDB_DATA key, u32 hash)
 
 int tdb_exists(TDB_CONTEXT *tdb, TDB_DATA key)
 {
-	u32 hash = tdb_hash(&key);
+	u32 hash = tdb->hash_fn(&key);
 	return tdb_exists_hash(tdb, key, hash);
 }
 
@@ -1413,7 +1400,7 @@ TDB_DATA tdb_nextkey(TDB_CONTEXT *tdb, TDB_DATA oldkey)
 
 	if (!tdb->travlocks.off) {
 		/* No previous element: do normal find, and lock record */
-		tdb->travlocks.off = tdb_find_lock_hash(tdb, oldkey, tdb_hash(&oldkey), F_WRLCK, &rec);
+		tdb->travlocks.off = tdb_find_lock_hash(tdb, oldkey, tdb->hash_fn(&oldkey), F_WRLCK, &rec);
 		if (!tdb->travlocks.off)
 			return tdb_null;
 		tdb->travlocks.hash = BUCKET(rec.full_hash);
@@ -1457,7 +1444,7 @@ static int tdb_delete_hash(TDB_CONTEXT *tdb, TDB_DATA key, u32 hash)
 
 int tdb_delete(TDB_CONTEXT *tdb, TDB_DATA key)
 {
-	u32 hash = tdb_hash(&key);
+	u32 hash = tdb->hash_fn(&key);
 	return tdb_delete_hash(tdb, key, hash);
 }
 
@@ -1475,7 +1462,7 @@ int tdb_store(TDB_CONTEXT *tdb, TDB_DATA key, TDB_DATA dbuf, int flag)
 	int ret = 0;
 
 	/* find which hash bucket it is in */
-	hash = tdb_hash(&key);
+	hash = tdb->hash_fn(&key);
 	if (!tdb_keylocked(tdb, hash))
 		return -1;
 	if (tdb_lock(tdb, BUCKET(hash), F_WRLCK) == -1)
@@ -1593,7 +1580,7 @@ int tdb_append(TDB_CONTEXT *tdb, TDB_DATA key, TDB_DATA new_dbuf)
 	size_t new_data_size = 0;
 
 	/* find which hash bucket it is in */
-	hash = tdb_hash(&key);
+	hash = tdb->hash_fn(&key);
 	if (!tdb_keylocked(tdb, hash))
 		return -1;
 	if (tdb_lock(tdb, BUCKET(hash), F_WRLCK) == -1)
@@ -1689,6 +1676,24 @@ static int tdb_already_open(dev_t device,
 	return 0;
 }
 
+/* This is based on the hash algorithm from gdbm */
+static u32 default_tdb_hash(TDB_DATA *key)
+{
+	u32 value;	/* Used to compute the hash value.  */
+	u32   i;	/* Used to cycle through random values. */
+
+	/* Set the initial value from the key size. */
+	for (value = 0x238F13AF * key->dsize, i=0; i < key->dsize; i++)
+		value = (value + (key->dptr[i] << (i*5 % 24)));
+
+	return (1103515243 * value + 12345);  
+}
+
+void tdb_set_hash_function(TDB_CONTEXT *tdb, tdb_hash_func fn)
+{
+	tdb->hash_fn = fn;
+}
+
 /* open the database, creating it if necessary 
 
    The open_flags and mode are passed straight to the open call on the
@@ -1728,7 +1733,8 @@ TDB_CONTEXT *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
 	tdb->flags = tdb_flags;
 	tdb->open_flags = open_flags;
 	tdb->log_fn = log_fn;
-	
+	tdb->hash_fn = default_tdb_hash;
+
 	if ((open_flags & O_ACCMODE) == O_WRONLY) {
 		TDB_LOG((tdb, 0, "tdb_open_ex: can't open tdb %s write-only\n",
 			 name));
@@ -1973,7 +1979,7 @@ int tdb_lockkeys(TDB_CONTEXT *tdb, u32 number, TDB_DATA keys[])
 
 	/* Insertion sort by bucket */
 	for (i = 0; i < number; i++) {
-		hash = tdb_hash(&keys[i]);
+		hash = tdb->hash_fn(&keys[i]);
 		for (j = 0; j < i && BUCKET(tdb->lockedkeys[j+1]) < BUCKET(hash); j++);
 			memmove(&tdb->lockedkeys[j+2], &tdb->lockedkeys[j+1], sizeof(u32) * (i-j));
 		tdb->lockedkeys[j+1] = hash;
@@ -2008,22 +2014,22 @@ void tdb_unlockkeys(TDB_CONTEXT *tdb)
    contention - it cannot guarantee how many records will be locked */
 int tdb_chainlock(TDB_CONTEXT *tdb, TDB_DATA key)
 {
-	return tdb_lock(tdb, BUCKET(tdb_hash(&key)), F_WRLCK);
+	return tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
 }
 
 int tdb_chainunlock(TDB_CONTEXT *tdb, TDB_DATA key)
 {
-	return tdb_unlock(tdb, BUCKET(tdb_hash(&key)), F_WRLCK);
+	return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_WRLCK);
 }
 
 int tdb_chainlock_read(TDB_CONTEXT *tdb, TDB_DATA key)
 {
-	return tdb_lock(tdb, BUCKET(tdb_hash(&key)), F_RDLCK);
+	return tdb_lock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK);
 }
 
 int tdb_chainunlock_read(TDB_CONTEXT *tdb, TDB_DATA key)
 {
-	return tdb_unlock(tdb, BUCKET(tdb_hash(&key)), F_RDLCK);
+	return tdb_unlock(tdb, BUCKET(tdb->hash_fn(&key)), F_RDLCK);
 }
 
 
@@ -2033,7 +2039,6 @@ void tdb_logging_function(TDB_CONTEXT *tdb, void (*fn)(TDB_CONTEXT *, int , cons
 	tdb->log_fn = fn;
 }
 
-
 /* reopen a tdb - this can be used after a fork to ensure that we have an independent
    seek pointer from our parent and to re-establish locks */
 int tdb_reopen(TDB_CONTEXT *tdb)
diff --git a/source3/tdb/tdb.h b/source3/tdb/tdb.h
index eb120a8cec..8f4421d8fa 100644
--- a/source3/tdb/tdb.h
+++ b/source3/tdb/tdb.h
@@ -102,11 +102,13 @@ typedef struct tdb_context {
 	dev_t device;	/* uniquely identifies this tdb */
 	ino_t inode;	/* uniquely identifies this tdb */
 	void (*log_fn)(struct tdb_context *tdb, int level, const char *, ...); /* logging function */
+	u32 (*hash_fn)(TDB_DATA *key);
 	int open_flags; /* flags used in the open - needed by reopen */
 } TDB_CONTEXT;
 
 typedef int (*tdb_traverse_func)(TDB_CONTEXT *, TDB_DATA, TDB_DATA, void *);
 typedef void (*tdb_log_func)(TDB_CONTEXT *, int , const char *, ...);
+typedef u32 (*tdb_hash_func)(TDB_DATA *key);
 
 TDB_CONTEXT *tdb_open(const char *name, int hash_size, int tdb_flags,
 		      int open_flags, mode_t mode);
@@ -117,6 +119,7 @@ TDB_CONTEXT *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
 int tdb_reopen(TDB_CONTEXT *tdb);
 int tdb_reopen_all(void);
 void tdb_logging_function(TDB_CONTEXT *tdb, tdb_log_func);
+void tdb_set_hash_function(TDB_CONTEXT *tdb, tdb_hash_func);
 enum TDB_ERROR tdb_error(TDB_CONTEXT *tdb);
 const char *tdb_errorstr(TDB_CONTEXT *tdb);
 TDB_DATA tdb_fetch(TDB_CONTEXT *tdb, TDB_DATA key);