Author: timbo
Date: Fri Jan 27 04:40:55 2012
New Revision: 15102
Modified:
dbi/trunk/DBI.xs
Log:
enable xsbypass for threaded perls, provide escape hatch env var
Modified: dbi/trunk/DBI.xs
==============================================================================
--- dbi/trunk/DBI.xs (original)
+++ dbi/trunk/DBI.xs Fri Jan 27 04:40:55 2012
@@ -19,9 +19,16 @@
#define MY_VERSION "DBI(" XS_VERSION ")"
#if (defined USE_THREADS || defined PERL_CAPI || defined PERL_OBJECT)
-static int xsbypass = 0; /* disable XSUB->XSUB shortcut */
+/* The XS dispatcher code can optimize calls to XS driver methods,
+ * bypassing the usual call_sv() and argument handling overheads.
+ * For many years this bypass was disabled for threaded (etc) perls.
+ * However, the reasons have been lost in the mists of time, and it
+ * seems to work fine. So it's now enabled by default. Just-in-case
+ * there's an (undocumented) way to disable it by setting an env var.
+ */
+static int use_xsbypass = (getenv("PERL_DBI_NO_XSBYPASS") ? 0 : 1);
#else
-static int xsbypass = 1; /* enable XSUB->XSUB shortcut */
+static int use_xsbypass = 1;
#endif
#ifndef CvISXSUB
#define CvISXSUB(sv) CvXSUB(sv)
@@ -3477,7 +3484,7 @@
*/
/* SHORT-CUT ALERT! */
- if (xsbypass && isGV(imp_msv) && CvISXSUB(GvCV(imp_msv))
+ if (use_xsbypass && isGV(imp_msv) && CvISXSUB(GvCV(imp_msv))
&& CvXSUB(GvCV(imp_msv))) {
/* If we are calling an XSUB we jump directly to its C code and
