Patch 976520 reworks several of the details involved with

        startup/initialization of the Tcl library, focused on the
        activities of Tcl_FindExecutable().

        * generic/tclIO.c:      Removed bogus claim in comment that
        encoding "iso8859-1" is "built-in" to Tcl.

        * generic/tclInt.h:     Created a new struct ProcessGlobalValue,
        * generic/tclUtil.c:    routines Tcl(Get|Set)ProcessGlobalValue,
        and function type TclInitProcessGlobalValueProc.  Together, these
        take care of the housekeeping for "values" (things that can be
        held in a Tcl_Obj) that are global across a whole process.  That is,
        they are shared among multiple threads, and epoch and mutex
        protection must govern the validity of cached copies maintained
        in each thread.

        * generic/tclNotify.c:  Modified TclInitNotifier() to tolerate
        being called multiple times in the same thread.

        * generic/tclEvent.c:   Dropped the unused argv0 argument to
        TclInitSubsystems().  Removed machinery to unsure only one
        TclInitNotifier() call per thread, now that that is safe.
        Converted Tcl(Get|Set)LibraryPath to use a ProcessGlobalValue,
        and moved them to tclEncoding.c.
        * generic/tclBasic.c:   Updated caller.

        * generic/tclInt.h:     TclpFindExecutable now returns void.
        * unix/tclUnixFile.c:
        * win/tclWinFile.c:
        * win/tclWinPipe.c:

        * generic/tclEncoding.c: Built new encoding search initialization
        on a foundation of ProcessGlobalValues, exposing new routines
        Tcl(Get|Set)EncodingSearchPath.  A cache of a map from encoding name
        to directory pathname keeps track of where encodings are available
        for loading.  Tcl_FindExecutable greatly simplified into just
        three function calls.  The "library path" is now misnamed, as its
        only remaining purpose is as a foundation for the default encoding
        search path.

        * generic/tclInterp.c:  Inlined the initScript that is evaluated
        by Tcl_Init().  Added verification after initScript evaluation
        that Tcl can find its installed *.enc files, and that it has
        initialized [encoding system] in agreement with what the environment
        expects.  [tclInit] no longer driven by the value of $::tcl_libPath;
        it largely constructs its own search path now, rather than attempt
        to share one with the encoding system.

        * unix/tclUnixInit.c:   TclpSetInitialEncodings factored so that a new
        * win/tclWinInit.c:     routine TclpGetEncodingNameFromEnvironment
        can reveal that Tcl thinks the [encoding system] should be, even
        when an incomplete encoding search path, or a missing *.enc file
        won't allow that initialization to succeed.  TclpInitLibraryPath
        reworked as an initializer of a ProcessGlobalValue.

        * unix/tclUnixTest.c:   Update implementations of [testfindexecutable],
        [testgetdefenc], and [testsetdefenc].

        * tests/unixInit.test:  Corrected tests to operate properly even
        when a value of TCL_LIBRARY is required to find encodings.

        * generic/tclInt.decls: New internal stubs: TclGetEncodingSearchPath,
        TclSetEncodingSearchPath, TclpGetEncodingNameFromEnvironment.  These
        are candidates for public exposure by future TIPs.

        * generic/tclIntDecls.h:        make genstubs
        * generic/tclStubInit.c:

        * generic/tclTest.c:    Updated [testencoding] to use
        * tests/encoding.test:  Tcl(Get|Set)EncodingSearchPath.  Updated tests.

1 files changed, 16 insertions, 9 deletions

diff --git a/generic/tclNotify.c b/generic/tclNotify.c
index 3f62d1a..e5a438f 100644
--- a/generic/tclNotify.c
+++ b/generic/tclNotify.c
@@ -14,7 +14,7 @@
  * See the file "license.terms" for information on usage and redistribution
  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tclNotify.c,v 1.15 2004/07/15 21:17:03 vasiljevic Exp $
+ * RCS: @(#) $Id: tclNotify.c,v 1.16 2004/11/30 19:34:49 dgp Exp $
  */
 
 #include "tclInt.h"
@@ -81,7 +81,7 @@ static Tcl_ThreadDataKey dataKey;
  * be replaced with a hashtable.
  */
 
-static ThreadSpecificData *firstNotifierPtr;
+static ThreadSpecificData *firstNotifierPtr = NULL;
 TCL_DECLARE_MUTEX(listLock)
 
 /*
@@ -111,15 +111,22 @@ static void		QueueEvent _ANSI_ARGS_((ThreadSpecificData *tsdPtr,
 void
 TclInitNotifier()
 {
-    ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
+    ThreadSpecificData *tsdPtr;
+    Tcl_ThreadId threadId = Tcl_GetCurrentThread();
 
     Tcl_MutexLock(&listLock);
-
-    tsdPtr->threadId = Tcl_GetCurrentThread();
-    tsdPtr->clientData = tclStubs.tcl_InitNotifier();
-    tsdPtr->nextPtr = firstNotifierPtr;
-    firstNotifierPtr = tsdPtr;
-
+    for (tsdPtr = firstNotifierPtr; tsdPtr && tsdPtr->threadId != threadId;
+	     tsdPtr = tsdPtr->nextPtr) {
+	/* Empty loop body. */
+    }
+    if (NULL == tsdPtr) {
+	/* Notifier not yet initialized in this thread */
+	tsdPtr = TCL_TSD_INIT(&dataKey);
+	tsdPtr->threadId = threadId;
+	tsdPtr->clientData = tclStubs.tcl_InitNotifier();
+	tsdPtr->nextPtr = firstNotifierPtr;
+	firstNotifierPtr = tsdPtr;
+    }
     Tcl_MutexUnlock(&listLock);
 }