cassandra-trunk/src/java/org/apache/cassandra/utils/Throwables.java
/*
* 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.cassandra.utils;

import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.util.Arrays;
import java.util.Iterator;
import java.util.Objects;
import java.util.Optional;
import java.util.concurrent.CompletionException;
import java.util.concurrent.ExecutionException;
import java.util.function.Predicate;
import java.util.stream.Stream;
import javax.annotation.Nonnull;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import com.google.common.collect.Iterables;

import org.apache.cassandra.io.FSReadError;
import org.apache.cassandra.io.FSWriteError;
import org.apache.cassandra.io.util.File;
import org.apache.cassandra.utils.concurrent.UncheckedInterruptedException;

public final class Throwables
{
    public enum FileOpType { READ, WRITE }

    public interface DiscreteAction<E extends Exception>
    {
        void perform() throws E;
    }

    public static boolean isCausedBy(Throwable t, Predicate<Throwable> cause)
    {
        return cause.test(t) || (t.getCause() != null && cause.test(t.getCause()));
    }

    public static boolean anyCauseMatches(Throwable t, Predicate<Throwable> cause)
    {
        do
        {
            if (cause.test(t))
                return true;
        } while ((t = t.getCause()) != null);
        return false;
    }

    public static <T extends Throwable> T merge(T existingFail, T newFail)
    {
        if (existingFail == null)
            return newFail;
        if (newFail == null)
            return existingFail;
        existingFail.addSuppressed(newFail);
        return existingFail;
    }

    public static void maybeFail(Throwable fail)
    {
        if (failIfCanCast(fail, null))
            throw new RuntimeException(fail);
    }

    public static <T extends Throwable> void maybeFail(Throwable fail, Class<T> checked) throws T
    {
        if (failIfCanCast(fail, checked))
            throw new RuntimeException(fail);
    }

    public static <T extends Throwable> boolean failIfCanCast(Throwable fail, Class<T> checked) throws T
    {
        if (fail == null)
            return false;

        if (fail instanceof Error)
            throw (Error) fail;

        if (fail instanceof RuntimeException)
            throw (RuntimeException) fail;

        if (fail instanceof InterruptedException)
            throw new UncheckedInterruptedException((InterruptedException) fail);

        if (checked != null && checked.isInstance(fail))
            throw checked.cast(fail);

        return true;
    }

    @SafeVarargs
    public static <E extends Exception> void maybeFail(DiscreteAction<? extends E> ... actions)
    {
        maybeFail(Throwables.perform(null, Stream.of(actions)));
    }

    @SafeVarargs
    public static <E extends Exception> void perform(DiscreteAction<? extends E> ... actions) throws E
    {
        Throwables.<E>perform(Stream.of(actions));
    }

    public static <E extends Exception> void perform(Stream<? extends DiscreteAction<? extends E>> stream, DiscreteAction<? extends E> ... extra) throws E
    {
        perform(Stream.concat(stream, Stream.of(extra)));
    }

    @SuppressWarnings("unchecked")
    public static <E extends Exception> void perform(Stream<DiscreteAction<? extends E>> actions) throws E
    {
        Throwable fail = perform(null, actions);
        if (failIfCanCast(fail, null))
            throw (E) fail;
    }

    public static Throwable perform(Throwable accumulate, DiscreteAction<?> ... actions)
    {
        return perform(accumulate, Arrays.stream(actions));
    }

    public static Throwable perform(Throwable accumulate, Stream<? extends DiscreteAction<?>> actions)
    {
        return perform(accumulate, actions.iterator());
    }

    public static Throwable perform(Throwable accumulate, Iterator<? extends DiscreteAction<?>> actions)
    {
        while (actions.hasNext())
        {
            DiscreteAction<?> action = actions.next();
            try
            {
                action.perform();
            }
            catch (Throwable t)
            {
                accumulate = merge(accumulate, t);
            }
        }
        return accumulate;
    }

    @SafeVarargs
    public static void perform(File against, FileOpType opType, DiscreteAction<? extends IOException> ... actions)
    {
        perform(against.path(), opType, actions);
    }

    @SafeVarargs
    public static void perform(String filePath, FileOpType opType, DiscreteAction<? extends IOException> ... actions)
    {
        maybeFail(perform(null, filePath, opType, actions));
    }

    @SafeVarargs
    public static Throwable perform(Throwable accumulate, String filePath, FileOpType opType, DiscreteAction<? extends IOException> ... actions)
    {
        return perform(accumulate, filePath, opType, Arrays.stream(actions));
    }

    public static Throwable perform(Throwable accumulate, String filePath, FileOpType opType, Stream<DiscreteAction<? extends IOException>> actions)
    {
        return perform(accumulate, actions.map((action) -> () ->
        {
            try
            {
                action.perform();
            }
            catch (IOException e)
            {
                throw (opType == FileOpType.WRITE) ? new FSWriteError(e, filePath) : new FSReadError(e, filePath);
            }
        }));
    }

    /**
     * @see {@link #closeAndAddSuppressed(Throwable, Iterable)}
     */
    public static void closeAndAddSuppressed(@Nonnull Throwable t, AutoCloseable... closeables)
    {
        closeAndAddSuppressed(t, Arrays.asList(closeables));
    }

    /**
     * Do what {@link #closeAndAddSuppressed(Throwable, Iterable)} does, additionally filtering out all null closables.
     */
    public static void closeNonNullAndAddSuppressed(@Nonnull Throwable t, AutoCloseable... closeables)
    {
        closeAndAddSuppressed(t, Iterables.filter(Arrays.asList(closeables), Objects::nonNull));
    }

    /**
     * Closes all closables in the provided collections and accumulates the possible exceptions thrown when closing.
     *
     * @param accumulate non-null exception to accumulate errors thrown when closing the provided resources
     * @param closeables closeables to be closed
     */
    public static void closeAndAddSuppressed(@Nonnull Throwable accumulate, Iterable<AutoCloseable> closeables)
    {
        Preconditions.checkNotNull(accumulate);
        for (AutoCloseable closeable : closeables)
        {
            try
            {
                closeable.close();
            }
            catch (Throwable ex)
            {
                accumulate.addSuppressed(ex);
            }
        }
    }

    /**
     * See {@link #close(Throwable, Iterable)}
     */
    public static Throwable close(Throwable accumulate, AutoCloseable ... closeables)
    {
        return close(accumulate, Arrays.asList(closeables));
    }

    /**
     * Closes all the resources in the provided collections and accumulates the possible exceptions thrown when closing.
     *
     * @param accumulate the initial value for the exception accumulator, can be {@code null}
     * @param closeables closeables to be closed
     * @return {@code null}, {@param accumulate} or the first exception thrown when closing the provided resources
     */
    public static Throwable close(Throwable accumulate, Iterable<? extends AutoCloseable> closeables)
    {
        for (AutoCloseable closeable : closeables)
        {
            try
            {
                closeable.close();
            }
            catch (Throwable t)
            {
                accumulate = merge(accumulate, t);
            }
        }
        return accumulate;
    }

    public static Optional<IOException> extractIOExceptionCause(Throwable t)
    {
        if (t instanceof IOException)
            return Optional.of((IOException) t);
        Throwable cause = t;
        while ((cause = cause.getCause()) != null)
        {
            if (cause instanceof IOException)
                return Optional.of((IOException) cause);
        }
        return Optional.empty();
    }

    /**
     * If the provided throwable is a "wrapping" exception (see below), return the cause of that throwable, otherwise
     * return its argument untouched.
     * <p>
     * We call a "wrapping" exception in the context of that method an exception whose only purpose is to wrap another
     * exception, and currently this method recognize only 2 exception as "wrapping" ones: {@link ExecutionException}
     * and {@link CompletionException}.
     */
    public static Throwable unwrapped(Throwable t)
    {
        Throwable unwrapped = t;
        while (unwrapped instanceof CompletionException ||
               unwrapped instanceof ExecutionException ||
               unwrapped instanceof InvocationTargetException)
            unwrapped = unwrapped.getCause();

        // I don't think it make sense for those 2 exception classes to ever be used with null causes, but no point
        // in failing here if this happen. We still wrap the original exception if that happen so we get a sign
        // that the assumption of this method is wrong.
        return unwrapped == null
               ? new RuntimeException("Got wrapping exception not wrapping anything", t)
               : unwrapped;
    }

    /**
     * If the provided exception is unchecked, return it directly, otherwise wrap it into a {@link RuntimeException}
     * to make it unchecked.
     */
    public static RuntimeException unchecked(Throwable t)
    {
        return t instanceof RuntimeException ? (RuntimeException)t :
               t instanceof InterruptedException
               ? new UncheckedInterruptedException((InterruptedException) t)
               : new RuntimeException(t);
    }

    /**
     * throw the exception as a unchecked exception, wrapping if a checked exception, else rethroing as is.
     */
    public static RuntimeException throwAsUncheckedException(Throwable t)
    {
        if (t instanceof Error)
            throw (Error) t;
        throw unchecked(t);
    }

    /**
     * A shortcut for {@code unchecked(unwrapped(t))}. This is called "cleaned" because this basically removes the annoying
     * cruft surrounding an exception :).
     */
    public static RuntimeException cleaned(Throwable t)
    {
        return unchecked(unwrapped(t));
    }

    @VisibleForTesting
    public static void assertAnyCause(Throwable err, Class<? extends Throwable> cause)
    {
        if (!anyCauseMatches(err, cause::isInstance))
            throw new AssertionError("The exception is not caused by " + cause.getName(), err);
    }
}
