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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.

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git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/logging/trunk@375631 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Robert Burrell Donkin
2006-02-07 15:38:22 +00:00
parent dff78fa049
commit 41863c3cc8
1 changed files with 65 additions and 1 deletions
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66
src/java/org/apache/commons/logging/impl/LogFactoryImpl.java
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@@ -839,6 +839,11 @@ public class LogFactoryImpl extends LogFactory {
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 @@ public class LogFactoryImpl extends LogFactory {
}
// 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) {