Author: rdonkin
Date: Tue Feb 7 07:38:22 2006
New Revision: 375631
URL: http://svn.apache.org/viewcvs?rev=375631&view=rev
Log:
Please check this long addition carefully. Hopefully the in-code comments
should describe the reasons for this change but I'll outline them here as well.
ClassLoader#getParent can return null to indicate the bootstrap classloader.
Sun's implementations do not but this behaviour might be encountered in other
JVMs. I haven't been able to test this patch so please check this very
carefully.
Modified:
jakarta/commons/proper/logging/trunk/src/java/org/apache/commons/logging/impl/LogFactoryImpl.java
Modified:
jakarta/commons/proper/logging/trunk/src/java/org/apache/commons/logging/impl/LogFactoryImpl.java
URL:
http://svn.apache.org/viewcvs/jakarta/commons/proper/logging/trunk/src/java/org/apache/commons/logging/impl/LogFactoryImpl.java?rev=375631&r1=375630&r2=375631&view=diff
==============================================================================
---
jakarta/commons/proper/logging/trunk/src/java/org/apache/commons/logging/impl/LogFactoryImpl.java
(original)
+++
jakarta/commons/proper/logging/trunk/src/java/org/apache/commons/logging/impl/LogFactoryImpl.java
Tue Feb 7 07:38:22 2006
@@ -839,6 +839,11 @@
Class logAdapterClass = null;
ClassLoader currentCL = getBaseClassLoader();
+ //
+ // This variable is used to ensure that the system classloader
+ // is tried only once when getParent is null.
+ boolean systemClassloaderTried = false;
+
for(;;) {
// Loop through the classloader hierarchy trying to find
// a viable classloader.
@@ -934,7 +939,66 @@
}
// try the parent classloader
- currentCL = currentCL.getParent();
+ final ClassLoader parentCL = currentCL.getParent();
+
+ //
+ // getParent may return null to indicate that the parent
+ // is the 'bootstrap classloader'. This term is difficult.
+ // A reasonable way to interpret this is as
+ // the system classloader which is provided as a base
+ // for delegating classloaders.
+ //
+ // Note that this functionality cannot be easily tested
+ // since it depends upon an optional behaviour of the basic
+ // java libraries. The Sun libraries do not behave in this
+ // fashion. It may be possible to create a test that
+ // uses a customized boot classpath containing a special
+ // implementation but this approach
+ // would need to wait until an open source Java implementation
+ // exists. So sadly, this code path is not unit tested.
+ //
+ if (parentCL == null) {
+ if (systemClassloaderTried == true)
+ {
+ logDiagnostic("Parent classloader is NULL. But System
ClassLoader has already been tried.");
+ break;
+ }
+ // try system classloader
+ try {
+ final ClassLoader systemClassLoader =
ClassLoader.getSystemClassLoader();
+ if (systemClassLoader == null) {
+ logDiagnostic("System classloader is NULL. Cannot find
parent of classloader "
+ + objectId(currentCL));
+ break;
+ } else if (systemClassLoader.equals(currentCL)) {
+ // the system classloader has already been tried and
failed
+ logDiagnostic("System classloader tried and failed.");
+ break;
+ } else {
+ // the parent is null indicating that the parent is
the boot classloader
+ // so retry with system classloader
+ currentCL = systemClassLoader;
+
+ //
+ // avoid infinite loops by trying the system loader
only the
+ // first time a classloader
+ systemClassloaderTried = true;
+ logDiagnostic("Parent classloader is NULL. Trying
System ClassLoader.");
+ }
+ } catch (Throwable t) {
+ // getSystemClassLoader is allowed to fail in
+ // many strange ways: so need to catch everything
+ // including errors
+ logDiagnostic("Failed to get system classloader: '"
+ + t.getMessage()
+ + "'. Cannot find parent of
classloader "
+ + objectId(currentCL));
+ break;
+ }
+ } else {
+ currentCL = parentCL;
+ }
+
}
if ((logAdapter != null) && affectState) {
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