/**

* 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.util;

import java.util.ArrayList;

import java.util.Collection;

import java.util.Collections;

import java.util.List;

/**

* Exception that is a composite of 1 or more other exceptions.

* <p>

* The <code>getMessage()</code> will return a concatenation of the composite exceptions.

*/

public final class CompositeException extends RuntimeException {

private static final long serialVersionUID = 3026362227162912146L;

private final List<Throwable> exceptions;

private final String message;

private final Throwable cause;

public CompositeException(String messagePrefix, Collection<Throwable> errors) {

List<Throwable> _exceptions = new ArrayList<Throwable>();

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<Throwable> errors) {

this(null, errors);

}

public List<Throwable> 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();

}

private static void attachCallingThreadStack(Throwable e, Throwable cause) {

while (e.getCause() != null) {

e = 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

}

}

private final static class CompositeExceptionCausalChain extends RuntimeException {

private static final long serialVersionUID = 3875212506787802066L;

@Override

public String getMessage() {

return "Chain of Causes for CompositeException In Order Received =>";

}

}

}