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Added internal diagnostics

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git-svn-id: https://svn.apache.org/repos/asf/jakarta/commons/proper/logging/trunk@171301 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Simon Kitching
2005-05-22 10:43:52 +00:00
parent c485c20b1e
commit 110f2a234b
1 changed files with 183 additions and 29 deletions
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208
src/java/org/apache/commons/logging/impl/LogFactoryImpl.java
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@@ -76,6 +76,8 @@ public class LogFactoryImpl extends LogFactory {
*/
public LogFactoryImpl() {
super();
initDiagnostics(); // method on this object
logDiagnostic("Instance created.");
}
@@ -108,6 +110,11 @@ public class LogFactoryImpl extends LogFactory {
// ----------------------------------------------------- Instance Variables
/**
* The string prefixed to every message output by the logDiagnostic method.
*/
private String diagnosticPrefix;
/**
* Configuration attributes.
*/
@@ -160,7 +167,6 @@ public class LogFactoryImpl extends LogFactory {
// --------------------------------------------------------- Public Methods
/**
* Return the configuration attribute with the specified name (if any),
* or <code>null</code> if there is no such attribute.
@@ -250,6 +256,7 @@ public class LogFactoryImpl extends LogFactory {
*/
public void release() {
logDiagnostic("Releasing all known loggers");
instances.clear();
}
@@ -287,13 +294,90 @@ public class LogFactoryImpl extends LogFactory {
}
// ------------------------------------------------------
// Static Methods
//
// These methods only defined as workarounds for a java 1.2 bug;
// theoretically none of these are needed.
// ------------------------------------------------------
/**
* Gets the context classloader.
* This method is a workaround for a java 1.2 compiler bug.
*/
protected static ClassLoader getContextClassLoader() throws LogConfigurationException {
return LogFactory.getContextClassLoader();
}
/**
* Workaround for bug in Java1.2; in theory this method is not needed.
* See LogFactory.isInternalLoggingEnabled.
*/
protected static boolean isDiagnosticsEnabled() {
return LogFactory.isDiagnosticsEnabled();
}
/**
* Workaround for bug in Java1.2; in theory this method is not needed.
* See LogFactory.getClassLoader.
*/
protected static ClassLoader getClassLoader(Class clazz) {
return LogFactory.getClassLoader(clazz);
}
// ------------------------------------------------------ Protected Methods
/**
* Calculate and cache a string that uniquely identifies this instance,
* including which classloader the object was loaded from.
* <p>
* This string will later be prefixed to each "internal logging" message
* emitted, so that users can clearly see any unexpected behaviour.
* <p>
* Note that this method does not detect whether internal logging is
* enabled or not, nor where to output stuff if it is; that is all
* handled by the parent LogFactory class. This method just computes
* its own unique prefix for log messages.
*/
private void initDiagnostics() {
// It would be nice to include an identifier of the context classloader
// that this LogFactoryImpl object is responsible for. However that
// isn't possible as that information isn't available. It is possible
// to figure this out by looking at the logging from LogFactory to
// see the context & impl ids from when this object was instantiated,
// in order to link the impl id output as this object's prefix back to
// the context it is intended to manage.
Class clazz = this.getClass();
ClassLoader classLoader = getClassLoader(clazz);
diagnosticPrefix = clazz.getName() + "@" + classLoader.toString() + ":";
}
/**
* Output a diagnostic message to a user-specified destination (if the
* user has enabled diagnostic logging).
*
* @param msg
*/
protected void logDiagnostic(String msg) {
if (isDiagnosticsEnabled()) {
logRawDiagnostic(diagnosticPrefix + msg);
}
}
/**
* Return the fully qualified Java classname of the {@link Log}
* implementation we will be using.
* <p>
* This method looks in the following places:
* <ul>
* <li>Looks for an attribute LOG_PROPERTY or LOG_PROPERTY_OLD in the
* "attributes" associated with this class, as set earlier by method
* setAttribute.
* <li>Looks for a property LOG_PROPERTY or LOG_PROPERTY_OLD in the
* system properties.
* <li>Looks for log4j, jdk logging and jdk13lumberjack classes in
* the classpath.
* </ul>
*/
protected String getLogClassName() {
@@ -302,14 +386,19 @@ public class LogFactoryImpl extends LogFactory {
return logClassName;
}
logDiagnostic("Determining the name for the Log implementation.");
logDiagnostic("Trying to get log class from attribute " + LOG_PROPERTY);
logClassName = (String) getAttribute(LOG_PROPERTY);
if (logClassName == null) { // @deprecated
logDiagnostic("Trying to get log class from attribute " + LOG_PROPERTY_OLD);
logClassName = (String) getAttribute(LOG_PROPERTY_OLD);
}
if (logClassName == null) {
try {
logDiagnostic("Trying to get log class from system property " + LOG_PROPERTY);
logClassName = System.getProperty(LOG_PROPERTY);
} catch (SecurityException e) {
;
@@ -318,12 +407,15 @@ public class LogFactoryImpl extends LogFactory {
if (logClassName == null) { // @deprecated
try {
logDiagnostic("Trying to get log class from system property " + LOG_PROPERTY_OLD);
logClassName = System.getProperty(LOG_PROPERTY_OLD);
} catch (SecurityException e) {
;
}
}
// no need for internalLog calls below; they are done inside the
// various isXXXAvailable methods.
if ((logClassName == null) && isLog4JAvailable()) {
logClassName = "org.apache.commons.logging.impl.Log4JLogger";
}
@@ -340,6 +432,7 @@ public class LogFactoryImpl extends LogFactory {
logClassName = "org.apache.commons.logging.impl.SimpleLog";
}
logDiagnostic("Using log class " + logClassName);
return (logClassName);
}
@@ -368,24 +461,48 @@ public class LogFactoryImpl extends LogFactory {
String logClassName = getLogClassName();
// Attempt to load the Log implementation class
//
// Question: why is the loginterface being loaded dynamically?
// Isn't the code below exactly the same as this?
// Class logInterface = Log.class;
Class logClass = null;
Class logInterface = null;
try {
ClassLoader cl = this.getClass().getClassLoader();
// handle the case if getClassLoader() returns null
// It may mean this class was loaded from the bootstrap classloader
logInterface = (cl == null) ? loadClass(LOG_INTERFACE) :
cl.loadClass(LOG_INTERFACE);
ClassLoader cl = getClassLoader(this.getClass());
if (cl == null) {
// we are probably in Java 1.1, but may also be running in
// some sort of embedded system..
logInterface = loadClass(LOG_INTERFACE);
} else {
// normal situation
logInterface = cl.loadClass(LOG_INTERFACE);
}
logClass = loadClass(logClassName);
if (logClass == null) {
logDiagnostic(
"Unable to find any class named [" + logClassName + "]"
+ " in either the context classloader"
+ " or the classloader that loaded this class.");
throw new LogConfigurationException
("No suitable Log implementation for " + logClassName);
}
if (!logInterface.isAssignableFrom(logClass)) {
LogConfigurationException ex = reportInvalidLogAdapter(logInterface, logClass);
// oops, we need to cast this logClass we have loaded into
// a Log object in order to return it. But we won't be
// able to. See method reportInvalidLogAdapter for more
// information.
LogConfigurationException ex =
reportInvalidLogAdapter(logInterface, logClass);
throw ex;
}
} catch (Throwable t) {
logDiagnostic(
"An unexpected problem occurred while loading the"
+ " log adapter class: " + t.getMessage());
throw new LogConfigurationException(t);
}
@@ -411,9 +528,23 @@ public class LogFactoryImpl extends LogFactory {
/**
* Report a problem loading the log adapter, then <i>always</i> throw
* a LogConfigurationException.
* <p>
* There are two possible reasons why we successfully loaded the
* specified log adapter class then failed to cast it to a Log object:
* <ol>
* <li>the specific class just doesn't implement the Log interface
* (user screwed up), or
* <li> the specified class has bound to a Log class loaded by some other
* classloader; Log@classloaderX cannot be cast to Log@classloaderY.
* </ol>
* <p>
* Here we try to figure out which case has occurred so we can give the
* user some reasonable feedback.
*
* @param logInterface
* @param logClass
* @param logInterface is the class that this LogFactoryImpl class needs
* to return the adapter as.
* @param logClass is the adapter class we successfully loaded (but which
* could not be cast to type logInterface).
*/
private LogConfigurationException reportInvalidLogAdapter(
Class logInterface, Class logClass) {
@@ -421,6 +552,21 @@ public class LogFactoryImpl extends LogFactory {
Class interfaces[] = logClass.getInterfaces();
for (int i = 0; i < interfaces.length; i++) {
if (LOG_INTERFACE.equals(interfaces[i].getName())) {
if (isDiagnosticsEnabled()) {
ClassLoader logInterfaceClassLoader = getClassLoader(logInterface);
ClassLoader logAdapterClassLoader = getClassLoader(logClass);
Class logAdapterInterface = interfaces[i];
ClassLoader logAdapterInterfaceClassLoader = getClassLoader(logAdapterInterface);
logDiagnostic(
"Class " + logClassName + " was found in classloader "
+ objectId(logAdapterClassLoader)
+ " but it implements the Log interface as loaded"
+ " from classloader " + objectId(logAdapterInterfaceClassLoader)
+ " not the one loaded by this class's classloader "
+ objectId(logInterfaceClassLoader));
}
throw new LogConfigurationException
("Invalid class loader hierarchy. " +
"You have more than one version of '" +
@@ -434,15 +580,6 @@ public class LogFactoryImpl extends LogFactory {
LOG_INTERFACE + "'.");
}
/**
* Gets the context classloader.
* This method is a workaround for a java 1.2 compiler bug.
*/
protected static ClassLoader getContextClassLoader() throws LogConfigurationException {
return LogFactory.getContextClassLoader();
}
/**
* MUST KEEP THIS METHOD PRIVATE.
*
@@ -453,7 +590,10 @@ public class LogFactoryImpl extends LogFactory {
* </p>
*
* Load a class, try first the thread class loader, and
* if it fails use the loader that loaded this class.
* if it fails use the loader that loaded this class. Actually, as
* the thread (context) classloader should always be the same as or a
* child of the classloader that loaded this class, the fallback should
* never be used.
*/
private static Class loadClass( final String name )
throws ClassNotFoundException
@@ -489,12 +629,17 @@ public class LogFactoryImpl extends LogFactory {
*/
protected boolean isJdk13LumberjackAvailable() {
// note: the algorithm here is different from isLog4JAvailable.
// I think isLog4JAvailable is correct....see bugzilla#31597
logDiagnostic("Checking for Jdk13Lumberjack.");
try {
loadClass("java.util.logging.Logger");
loadClass("org.apache.commons.logging.impl.Jdk13LumberjackLogger");
return (true);
logDiagnostic("Found Jdk13Lumberjack.");
return true;
} catch (Throwable t) {
return (false);
logDiagnostic("Did not find Jdk13Lumberjack.");
return false;
}
}
@@ -508,6 +653,9 @@ public class LogFactoryImpl extends LogFactory {
*/
protected boolean isJdk14Available() {
// note: the algorithm here is different from isLog4JAvailable.
// I think isLog4JAvailable is correct....
logDiagnostic("Checking for Jdk14.");
try {
loadClass("java.util.logging.Logger");
loadClass("org.apache.commons.logging.impl.Jdk14Logger");
@@ -515,9 +663,11 @@ public class LogFactoryImpl extends LogFactory {
if (throwable.getDeclaredMethod("getStackTrace", null) == null) {
return (false);
}
return (true);
logDiagnostic("Found Jdk14.");
return true;
} catch (Throwable t) {
return (false);
logDiagnostic("Did not find Jdk14.");
return false;
}
}
@@ -527,12 +677,16 @@ public class LogFactoryImpl extends LogFactory {
*/
protected boolean isLog4JAvailable() {
logDiagnostic("Checking for Log4J");
try {
loadClass("org.apache.commons.logging.impl.Log4JLogger").getClassLoader()
.loadClass("org.apache.log4j.Logger" );
return (true);
Class adapterClass = loadClass("org.apache.commons.logging.impl.Log4JLogger");
ClassLoader cl = getClassLoader(adapterClass);
Class loggerClass = cl.loadClass("org.apache.log4j.Logger" );
logDiagnostic("Found Log4J");
return true;
} catch (Throwable t) {
return (false);
logDiagnostic("Did not find Log4J");
return false;
}
}