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/**
* Copyright 2014 Netflix, Inc.
*
* Licensed 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 rx.exceptions;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
/**
* Exception that is a composite of 1 or more other exceptions.
*
* Use getMessage() to retrieve a concatenation of the composite exceptions.
*/
public final class CompositeException extends RuntimeException {
private static final long serialVersionUID = 3026362227162912146L;
private final List exceptions;
private final String message;
private final Throwable cause;
public CompositeException(String messagePrefix, Collection errors) {
List _exceptions = new ArrayList();
CompositeExceptionCausalChain _cause = new CompositeExceptionCausalChain();
int count = 0;
for (Throwable e : errors) {
count++;
attachCallingThreadStack(_cause, e);
_exceptions.add(e);
}
this.exceptions = Collections.unmodifiableList(_exceptions);
this.message = count + " exceptions occurred. See them in causal chain below.";
this.cause = _cause;
}
public CompositeException(Collection errors) {
this(null, errors);
}
/**
* Retrieves the list of exceptions that make up the {@code CompositeException}
*
* @return the exceptions that make up the {@code CompositeException}, as a {@link List} of
* {@link Throwable}s
*/
public List getExceptions() {
return exceptions;
}
@Override
public String getMessage() {
return message;
}
@Override
public synchronized Throwable getCause() {
return cause;
}
@SuppressWarnings("unused")
// useful when debugging but don't want to make part of publicly supported API
private static String getStackTraceAsString(StackTraceElement[] stack) {
StringBuilder s = new StringBuilder();
boolean firstLine = true;
for (StackTraceElement e : stack) {
if (e.toString().startsWith("java.lang.Thread.getStackTrace")) {
// we'll ignore this one
continue;
}
if (!firstLine) {
s.append("\n\t");
}
s.append(e.toString());
firstLine = false;
}
return s.toString();
}
/* package-private */ static void attachCallingThreadStack(Throwable e, Throwable cause) {
Set seenCauses = new HashSet();
while (e.getCause() != null) {
e = e.getCause();
if (seenCauses.contains(e.getCause())) {
break;
} else {
seenCauses.add(e.getCause());
}
}
// we now have 'e' as the last in the chain
try {
e.initCause(cause);
} catch (Throwable t) {
// ignore
// the javadocs say that some Throwables (depending on how they're made) will never
// let me call initCause without blowing up even if it returns null
}
}
/* package-private */ final static class CompositeExceptionCausalChain extends RuntimeException {
private static final long serialVersionUID = 3875212506787802066L;
/* package-private */ static String MESSAGE = "Chain of Causes for CompositeException In Order Received =>";
@Override
public String getMessage() {
return MESSAGE;
}
}
}