* generic/tclVar.c (TclObjLookupVar, TclObjUnsetVar2): fix for new

	(in tcl8.4) exteriorisations of [Bug 736729] due to the use of
	tclNsVarNameType obj types. Reenabling the use of this objType
	("VAR ref absolute" benchmark down to 66 ms, from 230).
	Added comments in TclLookupSimpleVar explaining my current
	understanding of [Bug 736729].

1 files changed, 30 insertions, 12 deletions

diff --git a/generic/tclVar.c b/generic/tclVar.c
index a177cf8..9097fd1 100644
--- a/generic/tclVar.c
+++ b/generic/tclVar.c
@@ -15,7 +15,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclVar.c,v 1.80 2004/05/22 03:42:56 msofer Exp $
+ * RCS: @(#) $Id: tclVar.c,v 1.81 2004/05/22 16:21:17 msofer Exp $
  */
 
 #include "tclInt.h"
@@ -542,17 +542,10 @@ TclObjLookupVar(interp, part1Ptr, part2, flags, msg, createPart1, createPart2,
 	procPtr->refCount++;
 	part1Ptr->internalRep.twoPtrValue.ptr1 = (VOID *) procPtr;
 	part1Ptr->internalRep.twoPtrValue.ptr2 = (VOID *) index;
-#if 0
-    /*
-     * TEMPORARYLY DISABLED tclNsVarNameType
-     *
-     * This is a stop-gap fix for [Bug 736729]; it may not address the 
-     * real issue (which I haven't pinned down yet).
-     * This optimisation will hopefully be turned back on soon.
-     *      Miguel Sofer, 2004-05-22
-     */
-
     } else if (index > -3) {
+	/*
+	 * A cacheable namespace or global variable.
+	 */
 	Namespace *nsPtr;
     
 	nsPtr = ((index == -1)? iPtr->globalNsPtr : varFramePtr->nsPtr);
@@ -560,7 +553,6 @@ TclObjLookupVar(interp, part1Ptr, part2, flags, msg, createPart1, createPart2,
 	part1Ptr->typePtr = &tclNsVarNameType;
 	part1Ptr->internalRep.twoPtrValue.ptr1 = (VOID *) nsPtr;
 	part1Ptr->internalRep.twoPtrValue.ptr2 = (VOID *) varPtr;
-#endif
     } else {
 	/*
 	 * At least mark part1Ptr as already parsed.
@@ -767,6 +759,21 @@ TclLookupSimpleVar(interp, varName, flags, create, errMsgPtr, indexPtr)
 	} 
 
 	/*
+	 * FIXME: [Bug 736729]
+	 *
+	 * When a varName is looked from a namespace different from the
+	 * global one, there is no corresponding variable in the namespace and
+	 * there is a "zombie" variable in the global namespace (ie, the
+	 * varName is in the hash table, but the variable is unset), this code
+	 * returns a reference to the zombie. It should instead create a
+	 * variable in the namespace.
+	 *
+	 * Fix in progress - that it is not here yet may indicate that the
+	 * picture above is incomplete or wrong.
+	 *    - Miguel Sofer, 2004-05-22
+	 */
+
+        /*
 	 * Don't pass TCL_LEAVE_ERR_MSG, we may yet create the variable,
 	 * or otherwise generate our own error!
 	 */
@@ -2277,6 +2284,17 @@ TclObjUnsetVar2(interp, part1Ptr, part2, flags)
     }
 
     /*
+     * Try to avoid keeping the Var struct allocated due to a tclNsVarNameType 
+     * keeping a reference. This removes some additional exteriorisations of
+     * [Bug 736729], but may be a good thing independently of the bug.
+     */
+
+    if (part1Ptr->typePtr == &tclNsVarNameType) {
+	part1Ptr->typePtr->freeIntRepProc(part1Ptr);
+	part1Ptr->typePtr = NULL;
+    }
+
+    /*
      * Finally, if the variable is truly not in use then free up its Var
      * structure and remove it from its hash table, if any. The ref count of
      * its value object, if any, was decremented above.