[cp-patches] RFC: Full stacktrace on glib/gtk errors and warnings

[Mark Wielaard]

Hi,

While working with the native gtk+ awt peers I often need to find out
where precisely a warning or error message is comming from. The
following patch installs a default log handler that dumps a stacktrace
whenever we encounter such a situation. It is careful about only
installing it when gtk+ (> 2.4) supports it and that it isn't swallowing
any pending exceptions.

2005-06-25  Mark Wielaard  <address@hidden>

        * native/jni/gtk-peer/gnu_java_awt_peer_gtk_GtkToolkit.c
        (glog_func): New static function.
        (Java_gnu_java_awt_peer_gtk_GtkToolkit_gtkInit): Install glog_func as
        default log handler.
        * native/jni/gtk-peer/Makefile.am (libgtkpeer_la_LIBADD): Add jcl.

This generates things like:

java.lang.InternalError: GdkPixbuf: gdk_pixbuf_loader_close: assertion 
`priv->closed == FALSE' failed
   at gnu.java.awt.peer.gtk.GdkPixbufDecoder.finish (Native Method)
   at gnu.java.awt.peer.gtk.GdkPixbufDecoder.finalize 
(GdkPixbufDecoder.java:182)

(Which indeed is a bug that I recently introduces, sorry. We should be
more careful in the finalizer manipulating the native state.)

The stack trace generation is only conditional on it being something
that already generates output on stderr by default. Since I think that
none of these error/warning messages should ever occur in our code (it
means we are feeding the native side bogus data from java-'user-space')
I think this is the right thing to do. And it really helps with
debugging.

Comments?

Cheers,

Mark

Index: native/jni/gtk-peer/Makefile.am
===================================================================
RCS file: /cvsroot/classpath/classpath/native/jni/gtk-peer/Makefile.am,v
retrieving revision 1.23
diff -u -r1.23 Makefile.am
--- native/jni/gtk-peer/Makefile.am     2 Jun 2005 13:18:10 -0000       1.23
+++ native/jni/gtk-peer/Makefile.am     25 Jun 2005 13:24:51 -0000
@@ -51,7 +51,8 @@
                        gtkcairopeer.h \
                        gtkpeer.h
 
-libgtkpeer_la_LIBADD = $(top_builddir)/native/jni/classpath/native_state.lo
+libgtkpeer_la_LIBADD = $(top_builddir)/native/jni/classpath/native_state.lo \
+                      $(top_builddir)/native/jni/classpath/jcl.lo
 
 AM_LDFLAGS = @CLASSPATH_MODULE@ @GTK_LIBS@ @CAIRO_LIBS@ @PANGOFT2_LIBS@ 
@X_LIBS@ -lXtst
 AM_CPPFLAGS = @CLASSPATH_INCLUDES@
Index: native/jni/gtk-peer/gnu_java_awt_peer_gtk_GtkToolkit.c
===================================================================
RCS file: 
/cvsroot/classpath/classpath/native/jni/gtk-peer/gnu_java_awt_peer_gtk_GtkToolkit.c,v
retrieving revision 1.14
diff -u -r1.14 gnu_java_awt_peer_gtk_GtkToolkit.c
--- native/jni/gtk-peer/gnu_java_awt_peer_gtk_GtkToolkit.c      3 May 2005 
23:57:49 -0000       1.14
+++ native/jni/gtk-peer/gnu_java_awt_peer_gtk_GtkToolkit.c      25 Jun 2005 
13:24:51 -0000
@@ -39,6 +39,7 @@
 #include "gtkpeer.h"
 #include "gnu_java_awt_peer_gtk_GtkToolkit.h"
 #include "gthread-jni.h"
+#include "jcl.h"
 
 #include <sys/time.h>
 
@@ -102,6 +103,14 @@
 static void dpi_changed_cb (GtkSettings  *settings,
                             GParamSpec   *pspec);
 
+#if GTK_MINOR_VERSION > 4
+static GLogFunc old_glog_func;
+static void glog_func (const gchar *log_domain,
+                      GLogLevelFlags log_level,
+                      const gchar *message,
+                      gpointer user_data);
+#endif
+
 /*
  * Call gtk_init.  It is very important that this happen before any other
  * gtk calls.
@@ -177,6 +186,11 @@
   g_free (argv[0]);
   g_free (argv);
 
+  /* On errors or warning print a whole stacktrace. */
+#if GTK_MINOR_VERSION > 4
+  old_glog_func = g_log_set_default_handler (&glog_func, NULL);
+#endif
+
   /* setup cached IDs for posting GTK events to Java */
 
   window = (*env)->FindClass (env, "java/awt/Window");
@@ -362,6 +376,31 @@
   return milliseconds_elapsed < 100;
 }
 
+#if GTK_MINOR_VERSION > 4
+static void
+glog_func (const gchar *log_domain,
+          GLogLevelFlags log_level,
+          const gchar *message,
+          gpointer user_data)
+{
+  old_glog_func (log_domain, log_level, message, user_data);
+  if (log_level & (G_LOG_LEVEL_ERROR
+                  | G_LOG_LEVEL_CRITICAL
+                  | G_LOG_LEVEL_WARNING))
+    {
+      JNIEnv *env = gdk_env ();
+      jthrowable *exc = (*env)->ExceptionOccurred(env);
+      gchar *detail = g_strconcat (log_domain, ": ", message, NULL);
+      JCL_ThrowException (env, "java/lang/InternalError", detail);
+      g_free (detail);
+      (*env)->ExceptionDescribe (env);
+      if (exc != NULL)
+       (*env)->Throw (env, exc);
+      else
+       (*env)->ExceptionClear (env);
+    }
+}
+#endif
 
 JNIEXPORT void JNICALL 
 Java_gnu_java_awt_peer_gtk_GtkToolkit_iterateNativeQueue

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