Made Tcl_AsyncDelete() more tolerant when called after all thread TSD

has been garbage-collected.

2 files changed, 28 insertions, 14 deletions

diff --git a/ChangeLog b/ChangeLog
index b2b53d1..5164c49 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2006-07-11  Zoran Vasiljevic <vasiljevic@users.sourceforge.net>
+
+	* generic/tclAsync.c: Made Tcl_AsyncDelete() more tolerant
+	when called after all thread TSD has been garbage-collected.
+
 2006-07-05  Don Porter  <dgp@users.sourceforge.net>
 
 	* generic/tclParseExpr.c:	Completely new expression parser
diff --git a/generic/tclAsync.c b/generic/tclAsync.c
index 5c3a535..f53e9fa 100644
--- a/generic/tclAsync.c
+++ b/generic/tclAsync.c
@@ -11,7 +11,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclAsync.c,v 1.9 2005/11/07 15:19:29 dkf Exp $
+ * RCS: @(#) $Id: tclAsync.c,v 1.10 2006/07/11 14:29:14 vasiljevic Exp $
  */
 
 #include "tclInt.h"
@@ -270,20 +270,29 @@ Tcl_AsyncDelete(
     AsyncHandler *asyncPtr = (AsyncHandler *) async;
     AsyncHandler *prevPtr;
 
+    /*
+     * Conservatively check the existence of the linked list of
+     * registered handlers, as we may come at this point even
+     * when the TSD's for the current thread have been already
+     * garbage-collected.
+     */
+
     Tcl_MutexLock(&tsdPtr->asyncMutex);
-    if (tsdPtr->firstHandler == asyncPtr) {
-	tsdPtr->firstHandler = asyncPtr->nextPtr;
-	if (tsdPtr->firstHandler == NULL) {
-	    tsdPtr->lastHandler = NULL;
-	}
-    } else {
-	prevPtr = tsdPtr->firstHandler;
-	while (prevPtr->nextPtr != asyncPtr) {
-	    prevPtr = prevPtr->nextPtr;
-	}
-	prevPtr->nextPtr = asyncPtr->nextPtr;
-	if (tsdPtr->lastHandler == asyncPtr) {
-	    tsdPtr->lastHandler = prevPtr;
+    if (tsdPtr->firstHandler != NULL ) {
+	if (tsdPtr->firstHandler == asyncPtr) {
+	    tsdPtr->firstHandler = asyncPtr->nextPtr;
+	    if (tsdPtr->firstHandler == NULL) {
+		tsdPtr->lastHandler = NULL;
+	    }
+	} else {
+	    prevPtr = tsdPtr->firstHandler;
+	    while (prevPtr->nextPtr != asyncPtr) {
+		prevPtr = prevPtr->nextPtr;
+	    }
+	    prevPtr->nextPtr = asyncPtr->nextPtr;
+	    if (tsdPtr->lastHandler == asyncPtr) {
+		tsdPtr->lastHandler = prevPtr;
+	    }
 	}
     }
     Tcl_MutexUnlock(&tsdPtr->asyncMutex);