--- BDB/BDB.xs	2008/07/08 08:25:31	1.40
+++ BDB/BDB.xs	2008/07/09 12:15:36	1.41
@@ -342,7 +342,7 @@
 {
   dSP;
 
-  if (SvOK (req->callback))
+  if (req->callback)
     {
       ENTER;
       SAVETMPS;
@@ -519,7 +519,7 @@
     }
 
   // synthesize callback if none given
-  if (!SvOK (req->callback))
+  if (!req->callback)
     {
       int count;
 
@@ -969,14 +969,14 @@
   int req_pri = next_pri;					\
   next_pri = DEFAULT_PRI + PRI_BIAS;				\
 								\
-  if (SvOK (callback) && !SvROK (callback))			\
-    croak ("callback must be undef or of reference type");	\
+  if (callback && SvOK (callback))				\
+    croak ("callback has illegal type or extra arguments");	\
 								\
   Newz (0, req, 1, bdb_cb);	        			\
   if (!req)							\
     croak ("out of memory during bdb_req allocation");		\
 								\
-  req->callback = newSVsv (callback);				\
+  req->callback = cb ? SvREFCNT_inc (cb) : 0;			\
   req->type = (reqtype); 					\
   req->pri = req_pri
 
@@ -1048,6 +1048,27 @@
   mg->mg_virtual = &vtbl_errno;
 }
 
+static SV *
+pop_callback (I32 *ritems, SV *sv)
+{
+  if (SvROK (sv))
+    {
+      HV *st;
+      GV *gvp;
+      CV *cv = sv_2cv (sv, &st, &gvp, 0);
+
+      if (cv)
+        {
+          --*ritems;
+          return (SV *)cv;
+        }
+    }
+
+  return 0;
+}
+
+#define CALLBACK SV *cb = pop_callback (&items, ST (items - 1));
+
 MODULE = BDB                PACKAGE = BDB
 
 PROTOTYPES: ENABLE
@@ -1433,11 +1454,12 @@
 	RETVAL
 
 void
-db_env_open (DB_ENV *env, bdb_filename db_home, U32 open_flags, int mode, SV *callback = &PL_sv_undef)
+db_env_open (DB_ENV *env, bdb_filename db_home, U32 open_flags, int mode, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_ENV_OPEN);
-
         req->env   = env;
         req->uint1 = open_flags | DB_THREAD;
         req->int1  = mode;
@@ -1446,7 +1468,9 @@
 }
 
 void
-db_env_close (DB_ENV *env, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_env_close (DB_ENV *env, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
 	dREQ (REQ_ENV_CLOSE);
@@ -1457,7 +1481,9 @@
 }
 
 void
-db_env_txn_checkpoint (DB_ENV *env, U32 kbyte = 0, U32 min = 0, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_env_txn_checkpoint (DB_ENV *env, U32 kbyte = 0, U32 min = 0, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_ENV_TXN_CHECKPOINT);
@@ -1469,18 +1495,23 @@
 }
 
 void
-db_env_lock_detect (DB_ENV *env, U32 flags = 0, U32 atype = DB_LOCK_DEFAULT, SV *dummy = 0, SV *callback = &PL_sv_undef)
+db_env_lock_detect (DB_ENV *env, U32 flags = 0, U32 atype = DB_LOCK_DEFAULT, SV *dummy = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_ENV_LOCK_DETECT);
         req->env   = env;
         req->uint1 = flags;
         req->uint2 = atype;
+        /* req->int2  = 0; dummy */
         REQ_SEND;
 }
 
 void
-db_env_memp_sync (DB_ENV *env, SV *dummy = 0, SV *callback = &PL_sv_undef)
+db_env_memp_sync (DB_ENV *env, SV *dummy = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_ENV_MEMP_SYNC);
@@ -1489,7 +1520,9 @@
 }
 
 void
-db_env_memp_trickle (DB_ENV *env, int percent, SV *dummy = 0, SV *callback = &PL_sv_undef)
+db_env_memp_trickle (DB_ENV *env, int percent, SV *dummy = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_ENV_MEMP_TRICKLE);
@@ -1499,7 +1532,9 @@
 }
 
 void
-db_env_dbremove (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_env_dbremove (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
 	dREQ (REQ_ENV_DBREMOVE);
@@ -1511,7 +1546,9 @@
 }
 
 void
-db_env_dbrename (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, bdb_filename newname, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_env_dbrename (DB_ENV *env, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, bdb_filename newname, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
 	dREQ (REQ_ENV_DBRENAME);
@@ -1538,7 +1575,9 @@
 	RETVAL
 
 void
-db_open (DB *db, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, int type, U32 flags, int mode, SV *callback = &PL_sv_undef)
+db_open (DB *db, DB_TXN_ornull *txnid, bdb_filename file, bdb_filename database, int type, U32 flags, int mode, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_DB_OPEN);
@@ -1553,7 +1592,9 @@
 }
 
 void
-db_close (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_close (DB *db, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_DB_CLOSE);
@@ -1565,7 +1606,9 @@
 }
 
 void
-db_compact (DB *db, DB_TXN_ornull *txn = 0, SV *start = 0, SV *stop = 0, SV *unused1 = 0, U32 flags = DB_FREE_SPACE, SV *unused2 = 0, SV *callback = &PL_sv_undef)
+db_compact (DB *db, DB_TXN_ornull *txn = 0, SV *start = 0, SV *stop = 0, SV *unused1 = 0, U32 flags = DB_FREE_SPACE, SV *unused2 = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_DB_COMPACT);
@@ -1578,7 +1621,9 @@
 }
 
 void
-db_sync (DB *db, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_sync (DB *db, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_DB_SYNC);
@@ -1588,7 +1633,9 @@
 }
 
 void
-db_upgrade (DB *db, bdb_filename file, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_upgrade (DB *db, bdb_filename file, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_DB_SYNC);
@@ -1599,7 +1646,9 @@
 }
 
 void
-db_key_range (DB *db, DB_TXN_ornull *txn, SV *key, SV *key_range, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_key_range (DB *db, DB_TXN_ornull *txn, SV *key, SV *key_range, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_DB_KEY_RANGE);
@@ -1612,7 +1661,9 @@
 }
 
 void
-db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_put (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_DB_PUT);
@@ -1625,7 +1676,9 @@
 }
 
 void
-db_get (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_get (DB *db, DB_TXN_ornull *txn, SV *key, SV *data, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
         if (SvREADONLY (data))
           croak ("can't modify read-only data scalar in db_get");
@@ -1641,7 +1694,9 @@
 }
 
 void
-db_pget (DB *db, DB_TXN_ornull *txn, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_pget (DB *db, DB_TXN_ornull *txn, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
         if (SvREADONLY (data))
           croak ("can't modify read-only data scalar in db_pget");
@@ -1658,7 +1713,9 @@
 }
 
 void
-db_del (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_del (DB *db, DB_TXN_ornull *txn, SV *key, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_DB_DEL);
@@ -1670,7 +1727,9 @@
 }
 
 void
-db_txn_commit (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_txn_commit (DB_TXN *txn, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_TXN_COMMIT);
@@ -1681,7 +1740,9 @@
 }
 
 void
-db_txn_abort (DB_TXN *txn, SV *callback = &PL_sv_undef)
+db_txn_abort (DB_TXN *txn, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_TXN_ABORT);
@@ -1691,7 +1752,9 @@
 }
 
 void
-db_txn_finish (DB_TXN *txn, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_txn_finish (DB_TXN *txn, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_TXN_FINISH);
@@ -1702,7 +1765,9 @@
 }
 
 void
-db_c_close (DBC *dbc, SV *callback = &PL_sv_undef)
+db_c_close (DBC *dbc, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_C_CLOSE);
@@ -1712,7 +1777,9 @@
 }
 
 void
-db_c_count (DBC *dbc, SV *count, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_c_count (DBC *dbc, SV *count, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_C_COUNT);
@@ -1722,7 +1789,9 @@
 }
 
 void
-db_c_put (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_c_put (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_C_PUT);
@@ -1734,7 +1803,9 @@
 }
 
 void
-db_c_get (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_c_get (DBC *dbc, SV *key, SV *data, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_C_GET);
@@ -1759,7 +1830,9 @@
 }
 
 void
-db_c_pget (DBC *dbc, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_c_pget (DBC *dbc, SV *key, SV *pkey, SV *data, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_C_PGET);
@@ -1787,7 +1860,9 @@
 }
 
 void
-db_c_del (DBC *dbc, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_c_del (DBC *dbc, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_C_DEL);
@@ -1798,7 +1873,9 @@
 
 
 void
-db_sequence_open (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, SV *key, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_sequence_open (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, SV *key, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_SEQ_OPEN);
@@ -1810,7 +1887,9 @@
 }
 
 void
-db_sequence_close (DB_SEQUENCE *seq, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_sequence_close (DB_SEQUENCE *seq, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_SEQ_CLOSE);
@@ -1821,7 +1900,9 @@
 }
 
 void
-db_sequence_get (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, int delta, SV *seq_value, U32 flags = DB_TXN_NOSYNC, SV *callback = &PL_sv_undef)
+db_sequence_get (DB_SEQUENCE *seq, DB_TXN_ornull *txnid, int delta, SV *seq_value, U32 flags = DB_TXN_NOSYNC, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_SEQ_GET);
@@ -1834,7 +1915,9 @@
 }
 
 void
-db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = &PL_sv_undef)
+db_sequence_remove (DB_SEQUENCE *seq, DB_TXN_ornull *txnid = 0, U32 flags = 0, SV *callback = 0)
+	PREINIT:
+        CALLBACK
 	CODE:
 {
         dREQ (REQ_SEQ_REMOVE);