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The Apache Log4j Implementation
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache license, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the license for the specific language governing permissions and
* limitations under the license.
*/
package org.apache.logging.log4j.core.impl;
import java.io.Serializable;
import java.net.URL;
import java.security.CodeSource;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.Stack;
import org.apache.logging.log4j.core.util.Loader;
import org.apache.logging.log4j.status.StatusLogger;
import org.apache.logging.log4j.util.ReflectionUtil;
import org.apache.logging.log4j.util.Strings;
/**
* Wraps a Throwable to add packaging information about each stack trace element.
*
*
* A proxy is used to represent a throwable that may not exist in a different class loader or JVM. When an application
* deserializes a ThrowableProxy, the throwable may not be set, but the throwable's information is preserved in other
* fields of the proxy like the message and stack trace.
*
*
*
* TODO: Move this class to org.apache.logging.log4j.core because it is used from LogEvent.
*
*
* TODO: Deserialize: Try to rebuild Throwable if the target exception is in this class loader?
*
*/
public class ThrowableProxy implements Serializable {
private static final String CAUSED_BY_LABEL = "Caused by: ";
private static final String SUPPRESSED_LABEL = "Suppressed: ";
private static final String WRAPPED_BY_LABEL = "Wrapped by: ";
/**
* Cached StackTracePackageElement and ClassLoader.
*
* Consider this class private.
*
*/
static class CacheEntry {
private final ExtendedClassInfo element;
private final ClassLoader loader;
public CacheEntry(final ExtendedClassInfo element, final ClassLoader loader) {
this.element = element;
this.loader = loader;
}
}
private static final ThrowableProxy[] EMPTY_THROWABLE_PROXY_ARRAY = new ThrowableProxy[0];
private static final char EOL = '\n';
private static final long serialVersionUID = -2752771578252251910L;
private final ThrowableProxy causeProxy;
private int commonElementCount;
private final ExtendedStackTraceElement[] extendedStackTrace;
private final String localizedMessage;
private final String message;
private final String name;
private final ThrowableProxy[] suppressedProxies;
private final transient Throwable throwable;
/**
* For JSON and XML IO via Jackson.
*/
@SuppressWarnings("unused")
private ThrowableProxy() {
this.throwable = null;
this.name = null;
this.extendedStackTrace = null;
this.causeProxy = null;
this.message = null;
this.localizedMessage = null;
this.suppressedProxies = EMPTY_THROWABLE_PROXY_ARRAY;
}
/**
* Constructs the wrapper for the Throwable that includes packaging data.
*
* @param throwable
* The Throwable to wrap, must not be null.
*/
public ThrowableProxy(final Throwable throwable) {
this(throwable, null);
}
/**
* Constructs the wrapper for the Throwable that includes packaging data.
*
* @param throwable
* The Throwable to wrap, must not be null.
* @param visited
* The set of visited suppressed exceptions.
*/
private ThrowableProxy(final Throwable throwable, final Set visited) {
this.throwable = throwable;
this.name = throwable.getClass().getName();
this.message = throwable.getMessage();
this.localizedMessage = throwable.getLocalizedMessage();
final Map map = new HashMap<>();
final Stack> stack = ReflectionUtil.getCurrentStackTrace();
this.extendedStackTrace = this.toExtendedStackTrace(stack, map, null, throwable.getStackTrace());
final Throwable throwableCause = throwable.getCause();
final Set causeVisited = new HashSet<>(1);
this.causeProxy = throwableCause == null ? null : new ThrowableProxy(throwable, stack, map, throwableCause, visited, causeVisited);
this.suppressedProxies = this.toSuppressedProxies(throwable, visited);
}
/**
* Constructs the wrapper for a Throwable that is referenced as the cause by another Throwable.
*
* @param parent
* The Throwable referencing this Throwable.
* @param stack
* The Class stack.
* @param map
* The cache containing the packaging data.
* @param cause
* The Throwable to wrap.
* @param suppressedVisited TODO
* @param causeVisited TODO
*/
private ThrowableProxy(final Throwable parent, final Stack> stack, final Map map,
final Throwable cause, final Set suppressedVisited, final Set causeVisited) {
causeVisited.add(cause);
this.throwable = cause;
this.name = cause.getClass().getName();
this.message = this.throwable.getMessage();
this.localizedMessage = this.throwable.getLocalizedMessage();
this.extendedStackTrace = this.toExtendedStackTrace(stack, map, parent.getStackTrace(), cause.getStackTrace());
final Throwable causeCause = cause.getCause();
this.causeProxy = causeCause == null || causeVisited.contains(causeCause) ? null : new ThrowableProxy(parent,
stack, map, causeCause, suppressedVisited, causeVisited);
this.suppressedProxies = this.toSuppressedProxies(cause, suppressedVisited);
}
@Override
public boolean equals(final Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (this.getClass() != obj.getClass()) {
return false;
}
final ThrowableProxy other = (ThrowableProxy) obj;
if (this.causeProxy == null) {
if (other.causeProxy != null) {
return false;
}
} else if (!this.causeProxy.equals(other.causeProxy)) {
return false;
}
if (this.commonElementCount != other.commonElementCount) {
return false;
}
if (this.name == null) {
if (other.name != null) {
return false;
}
} else if (!this.name.equals(other.name)) {
return false;
}
if (!Arrays.equals(this.extendedStackTrace, other.extendedStackTrace)) {
return false;
}
if (!Arrays.equals(this.suppressedProxies, other.suppressedProxies)) {
return false;
}
return true;
}
private void formatCause(final StringBuilder sb, final String prefix, final ThrowableProxy cause, final List ignorePackages) {
formatThrowableProxy(sb, prefix, CAUSED_BY_LABEL, cause, ignorePackages);
}
private void formatThrowableProxy(final StringBuilder sb, final String prefix, final String causeLabel,
final ThrowableProxy throwableProxy, final List ignorePackages) {
if (throwableProxy == null) {
return;
}
sb.append(prefix).append(causeLabel).append(throwableProxy).append(EOL);
this.formatElements(sb, prefix, throwableProxy.commonElementCount,
throwableProxy.getStackTrace(), throwableProxy.extendedStackTrace, ignorePackages);
this.formatSuppressed(sb, prefix + "\t", throwableProxy.suppressedProxies, ignorePackages);
this.formatCause(sb, prefix, throwableProxy.causeProxy, ignorePackages);
}
private void formatSuppressed(final StringBuilder sb, final String prefix, final ThrowableProxy[] suppressedProxies,
final List ignorePackages) {
if (suppressedProxies == null) {
return;
}
for (final ThrowableProxy suppressedProxy : suppressedProxies) {
final ThrowableProxy cause = suppressedProxy;
formatThrowableProxy(sb, prefix, SUPPRESSED_LABEL, cause, ignorePackages);
}
}
private void formatElements(final StringBuilder sb, final String prefix, final int commonCount,
final StackTraceElement[] causedTrace, final ExtendedStackTraceElement[] extStackTrace,
final List ignorePackages) {
if (ignorePackages == null || ignorePackages.isEmpty()) {
for (final ExtendedStackTraceElement element : extStackTrace) {
this.formatEntry(element, sb, prefix);
}
} else {
int count = 0;
for (int i = 0; i < extStackTrace.length; ++i) {
if (!this.ignoreElement(causedTrace[i], ignorePackages)) {
if (count > 0) {
appendSuppressedCount(sb, prefix, count);
count = 0;
}
this.formatEntry(extStackTrace[i], sb, prefix);
} else {
++count;
}
}
if (count > 0) {
appendSuppressedCount(sb, prefix, count);
}
}
if (commonCount != 0) {
sb.append(prefix).append("\t... ").append(commonCount).append(" more").append(EOL);
}
}
private void appendSuppressedCount(final StringBuilder sb, final String prefix, final int count) {
sb.append(prefix);
if (count == 1) {
sb.append("\t....").append(EOL);
} else {
sb.append("\t... suppressed ").append(count).append(" lines").append(EOL);
}
}
private void formatEntry(final ExtendedStackTraceElement extStackTraceElement, final StringBuilder sb, final String prefix) {
sb.append(prefix);
sb.append("\tat ");
sb.append(extStackTraceElement);
sb.append(EOL);
}
/**
* Formats the specified Throwable.
*
* @param sb
* StringBuilder to contain the formatted Throwable.
* @param cause
* The Throwable to format.
*/
public void formatWrapper(final StringBuilder sb, final ThrowableProxy cause) {
this.formatWrapper(sb, cause, null);
}
/**
* Formats the specified Throwable.
*
* @param sb
* StringBuilder to contain the formatted Throwable.
* @param cause
* The Throwable to format.
* @param packages
* The List of packages to be suppressed from the trace.
*/
@SuppressWarnings("ThrowableResultOfMethodCallIgnored")
public void formatWrapper(final StringBuilder sb, final ThrowableProxy cause, final List packages) {
final Throwable caused = cause.getCauseProxy() != null ? cause.getCauseProxy().getThrowable() : null;
if (caused != null) {
this.formatWrapper(sb, cause.causeProxy);
sb.append(WRAPPED_BY_LABEL);
}
sb.append(cause).append(EOL);
this.formatElements(sb, "", cause.commonElementCount,
cause.getThrowable().getStackTrace(), cause.extendedStackTrace, packages);
}
public ThrowableProxy getCauseProxy() {
return this.causeProxy;
}
/**
* Format the Throwable that is the cause of this Throwable.
*
* @return The formatted Throwable that caused this Throwable.
*/
public String getCauseStackTraceAsString() {
return this.getCauseStackTraceAsString(null);
}
/**
* Format the Throwable that is the cause of this Throwable.
*
* @param packages
* The List of packages to be suppressed from the trace.
* @return The formatted Throwable that caused this Throwable.
*/
public String getCauseStackTraceAsString(final List packages) {
final StringBuilder sb = new StringBuilder();
if (this.causeProxy != null) {
this.formatWrapper(sb, this.causeProxy);
sb.append(WRAPPED_BY_LABEL);
}
sb.append(this.toString());
sb.append(EOL);
this.formatElements(sb, "", 0, this.throwable.getStackTrace(), this.extendedStackTrace, packages);
return sb.toString();
}
/**
* Return the number of elements that are being omitted because they are common with the parent Throwable's stack
* trace.
*
* @return The number of elements omitted from the stack trace.
*/
public int getCommonElementCount() {
return this.commonElementCount;
}
/**
* Gets the stack trace including packaging information.
*
* @return The stack trace including packaging information.
*/
public ExtendedStackTraceElement[] getExtendedStackTrace() {
return this.extendedStackTrace;
}
/**
* Format the stack trace including packaging information.
*
* @return The formatted stack trace including packaging information.
*/
public String getExtendedStackTraceAsString() {
return this.getExtendedStackTraceAsString(null);
}
/**
* Format the stack trace including packaging information.
*
* @param ignorePackages
* List of packages to be ignored in the trace.
* @return The formatted stack trace including packaging information.
*/
public String getExtendedStackTraceAsString(final List ignorePackages) {
final StringBuilder sb = new StringBuilder(this.name);
final String msg = this.message;
if (msg != null) {
sb.append(": ").append(msg);
}
sb.append(EOL);
final StackTraceElement[] causedTrace = this.throwable != null ? this.throwable.getStackTrace() : null;
this.formatElements(sb, "", 0, causedTrace, this.extendedStackTrace, ignorePackages);
this.formatSuppressed(sb, "\t", this.suppressedProxies, ignorePackages);
this.formatCause(sb, "", this.causeProxy, ignorePackages);
return sb.toString();
}
public String getLocalizedMessage() {
return this.localizedMessage;
}
public String getMessage() {
return this.message;
}
/**
* Return the FQCN of the Throwable.
*
* @return The FQCN of the Throwable.
*/
public String getName() {
return this.name;
}
public StackTraceElement[] getStackTrace() {
return this.throwable == null ? null : this.throwable.getStackTrace();
}
/**
* Gets proxies for suppressed exceptions.
*
* @return proxies for suppressed exceptions.
*/
public ThrowableProxy[] getSuppressedProxies() {
return this.suppressedProxies;
}
/**
* Format the suppressed Throwables.
*
* @return The formatted suppressed Throwables.
*/
public String getSuppressedStackTrace() {
final ThrowableProxy[] suppressed = this.getSuppressedProxies();
if (suppressed == null || suppressed.length == 0) {
return Strings.EMPTY;
}
final StringBuilder sb = new StringBuilder("Suppressed Stack Trace Elements:").append(EOL);
for (final ThrowableProxy proxy : suppressed) {
sb.append(proxy.getExtendedStackTraceAsString());
}
return sb.toString();
}
/**
* The throwable or null if this object is deserialized from XML or JSON.
*
* @return The throwable or null if this object is deserialized from XML or JSON.
*/
public Throwable getThrowable() {
return this.throwable;
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + (this.causeProxy == null ? 0 : this.causeProxy.hashCode());
result = prime * result + this.commonElementCount;
result = prime * result + (this.extendedStackTrace == null ? 0 : Arrays.hashCode(this.extendedStackTrace));
result = prime * result + (this.suppressedProxies == null ? 0 : Arrays.hashCode(this.suppressedProxies));
result = prime * result + (this.name == null ? 0 : this.name.hashCode());
return result;
}
private boolean ignoreElement(final StackTraceElement element, final List ignorePackages) {
final String className = element.getClassName();
for (final String pkg : ignorePackages) {
if (className.startsWith(pkg)) {
return true;
}
}
return false;
}
/**
* Loads classes not located via Reflection.getCallerClass.
*
* @param lastLoader
* The ClassLoader that loaded the Class that called this Class.
* @param className
* The name of the Class.
* @return The Class object for the Class or null if it could not be located.
*/
private Class loadClass(final ClassLoader lastLoader, final String className) {
// XXX: this is overly complicated
Class clazz;
if (lastLoader != null) {
try {
clazz = Loader.initializeClass(className, lastLoader);
if (clazz != null) {
return clazz;
}
} catch (final Throwable ignore) {
// Ignore exception.
}
}
try {
clazz = Loader.loadClass(className);
} catch (final ClassNotFoundException ignored) {
return initializeClass(className);
} catch (final NoClassDefFoundError ignored) {
return initializeClass(className);
}
return clazz;
}
private Class initializeClass(final String className) {
try {
return Loader.initializeClass(className, this.getClass().getClassLoader());
} catch (final ClassNotFoundException ignore) {
return null;
} catch (final NoClassDefFoundError ignore) {
return null;
}
}
/**
* Construct the CacheEntry from the Class's information.
*
* @param stackTraceElement
* The stack trace element
* @param callerClass
* The Class.
* @param exact
* True if the class was obtained via Reflection.getCallerClass.
*
* @return The CacheEntry.
*/
private CacheEntry toCacheEntry(final StackTraceElement stackTraceElement, final Class callerClass,
final boolean exact) {
String location = "?";
String version = "?";
ClassLoader lastLoader = null;
if (callerClass != null) {
try {
final CodeSource source = callerClass.getProtectionDomain().getCodeSource();
if (source != null) {
final URL locationURL = source.getLocation();
if (locationURL != null) {
final String str = locationURL.toString().replace('\\', '/');
int index = str.lastIndexOf("/");
if (index >= 0 && index == str.length() - 1) {
index = str.lastIndexOf("/", index - 1);
location = str.substring(index + 1);
} else {
location = str.substring(index + 1);
}
}
}
} catch (final Exception ex) {
// Ignore the exception.
}
final Package pkg = callerClass.getPackage();
if (pkg != null) {
final String ver = pkg.getImplementationVersion();
if (ver != null) {
version = ver;
}
}
lastLoader = callerClass.getClassLoader();
}
return new CacheEntry(new ExtendedClassInfo(exact, location, version), lastLoader);
}
/**
* Resolve all the stack entries in this stack trace that are not common with the parent.
*
* @param stack
* The callers Class stack.
* @param map
* The cache of CacheEntry objects.
* @param rootTrace
* The first stack trace resolve or null.
* @param stackTrace
* The stack trace being resolved.
* @return The StackTracePackageElement array.
*/
ExtendedStackTraceElement[] toExtendedStackTrace(final Stack> stack, final Map map,
final StackTraceElement[] rootTrace, final StackTraceElement[] stackTrace) {
int stackLength;
if (rootTrace != null) {
int rootIndex = rootTrace.length - 1;
int stackIndex = stackTrace.length - 1;
while (rootIndex >= 0 && stackIndex >= 0 && rootTrace[rootIndex].equals(stackTrace[stackIndex])) {
--rootIndex;
--stackIndex;
}
this.commonElementCount = stackTrace.length - 1 - stackIndex;
stackLength = stackIndex + 1;
} else {
this.commonElementCount = 0;
stackLength = stackTrace.length;
}
final ExtendedStackTraceElement[] extStackTrace = new ExtendedStackTraceElement[stackLength];
Class clazz = stack.isEmpty() ? null : stack.peek();
ClassLoader lastLoader = null;
for (int i = stackLength - 1; i >= 0; --i) {
final StackTraceElement stackTraceElement = stackTrace[i];
final String className = stackTraceElement.getClassName();
// The stack returned from getCurrentStack may be missing entries for java.lang.reflect.Method.invoke()
// and its implementation. The Throwable might also contain stack entries that are no longer
// present as those methods have returned.
ExtendedClassInfo extClassInfo;
if (clazz != null && className.equals(clazz.getName())) {
final CacheEntry entry = this.toCacheEntry(stackTraceElement, clazz, true);
extClassInfo = entry.element;
lastLoader = entry.loader;
stack.pop();
clazz = stack.isEmpty() ? null : stack.peek();
} else {
final CacheEntry cacheEntry = map.get(className);
if (cacheEntry != null) {
final CacheEntry entry = cacheEntry;
extClassInfo = entry.element;
if (entry.loader != null) {
lastLoader = entry.loader;
}
} else {
final CacheEntry entry = this.toCacheEntry(stackTraceElement,
this.loadClass(lastLoader, className), false);
extClassInfo = entry.element;
map.put(stackTraceElement.toString(), entry);
if (entry.loader != null) {
lastLoader = entry.loader;
}
}
}
extStackTrace[i] = new ExtendedStackTraceElement(stackTraceElement, extClassInfo);
}
return extStackTrace;
}
@Override
public String toString() {
final String msg = this.message;
return msg != null ? this.name + ": " + msg : this.name;
}
private ThrowableProxy[] toSuppressedProxies(final Throwable thrown, Set suppressedVisited) {
try {
final Throwable[] suppressed = thrown.getSuppressed();
if (suppressed == null) {
return EMPTY_THROWABLE_PROXY_ARRAY;
}
final List proxies = new ArrayList<>(suppressed.length);
if (suppressedVisited == null) {
suppressedVisited = new HashSet<>(proxies.size());
}
for (int i = 0; i < suppressed.length; i++) {
final Throwable candidate = suppressed[i];
if (!suppressedVisited.contains(candidate)) {
suppressedVisited.add(candidate);
proxies.add(new ThrowableProxy(candidate, suppressedVisited));
}
}
return proxies.toArray(new ThrowableProxy[proxies.size()]);
} catch (final Exception e) {
StatusLogger.getLogger().error(e);
}
return null;
}
}