Patch: RFC: PR 9125

[Tom Tromey <tromey at redhat dot com>]

This patch fixes PR 9125 by adding a cache.  This lets us check
whether we've loaded a given shared library.

Anybody have any comments on this?
It doesn't try to do any kind of cache invalidation.  So, if you have
a long-running process and you install a new .so file, it might not
ever get loaded.  Do you think this a serious problem?

Tom

Index: ChangeLog
from  Tom Tromey  <tromey@redhat.com>
	Fix for PR libgcj/9125:
	* gnu/gcj/runtime/natVMClassLoader.cc (findClass): Find Runtime
	object outside of loop.  Use tried_libraries.
	* gnu/gcj/runtime/VMClassLoader.java (tried_libraries): New
	field.

Index: gnu/gcj/runtime/VMClassLoader.java
===================================================================
RCS file: /cvs/gcc/gcc/libjava/gnu/gcj/runtime/VMClassLoader.java,v
retrieving revision 1.9
diff -u -r1.9 VMClassLoader.java
--- gnu/gcj/runtime/VMClassLoader.java 9 Dec 2002 00:03:59 -0000 1.9
+++ gnu/gcj/runtime/VMClassLoader.java 15 Jan 2003 23:24:35 -0000
@@ -1,4 +1,4 @@
-/* Copyright (C) 1999, 2001, 2002  Free Software Foundation
+/* Copyright (C) 1999, 2001, 2002, 2003  Free Software Foundation
 
    This file is part of libgcj.
 
@@ -12,6 +12,7 @@
 
 import java.io.*;
 import java.util.StringTokenizer;
+import java.util.HashSet;
 import java.net.URL;
 
 public final class VMClassLoader extends java.net.URLClassLoader
@@ -67,6 +68,9 @@
   protected native Class findClass(String name) 
     throws java.lang.ClassNotFoundException;
 
+  // This keeps track of shared libraries we've already tried to load.
+  private HashSet tried_libraries = new HashSet();
+
   // The only VMClassLoader that can exist.
-  public static VMClassLoader instance = new VMClassLoader ();
+  public static VMClassLoader instance = new VMClassLoader();
 }
Index: gnu/gcj/runtime/natVMClassLoader.cc
===================================================================
RCS file: /cvs/gcc/gcc/libjava/gnu/gcj/runtime/natVMClassLoader.cc,v
retrieving revision 1.1
diff -u -r1.1 natVMClassLoader.cc
--- gnu/gcj/runtime/natVMClassLoader.cc 11 Dec 2002 03:15:14 -0000 1.1
+++ gnu/gcj/runtime/natVMClassLoader.cc 15 Jan 2003 23:24:35 -0000
@@ -1,6 +1,6 @@
 // Native code for VMClassLoader
 
-/* Copyright (C) 2002  Free Software Foundation
+/* Copyright (C) 2002, 2003  Free Software Foundation
 
    This file is part of libgcj.
 
@@ -18,6 +18,7 @@
 #include <java/lang/StringBuffer.h>
 #include <java/net/URLClassLoader.h>
 #include <java/lang/Runtime.h>
+#include <java/util/HashSet.h>
 
 jclass
 gnu::gcj::runtime::VMClassLoader::findClass (jstring name)
@@ -41,11 +42,17 @@
 	cn = name->substring (0, ci);
       jstring so_base_name = (sb->append (cn)->toString ())->replace ('.', '-');
 
+      using namespace ::java::lang;
+      Runtime *rt = Runtime::getRuntime();
+
       // Compare against `3' because that is the length of "lib".
       while (! klass && so_base_name && so_base_name->length() > 3)
 	{
-	  using namespace ::java::lang;
-	  Runtime *rt = Runtime::getRuntime();
+	  // If we've already tried this name, we're done.
+	  if (tried_libraries->contains(so_base_name))
+	    break;
+	  tried_libraries->add(so_base_name);
+
 	  jboolean loaded = rt->loadLibraryInternal (so_base_name);
 
 	  jint nd = so_base_name->lastIndexOf ('-');