/*
* WorldEdit, a Minecraft world manipulation toolkit
* Copyright (C) sk89q <http://www.sk89q.com>
* Copyright (C) WorldEdit team and contributors
*
* This program is free software: you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by the
* Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package com.sk89q.worldedit.util.io;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Throwables;
import java.io.Closeable;
import java.io.IOException;
import java.lang.reflect.Method;
import java.util.ArrayDeque;
import java.util.Deque;
import java.util.logging.Level;
import java.util.logging.Logger;
import static com.google.common.base.Preconditions.checkNotNull;
public final class Closer implements Closeable {
private static final Logger logger = Logger.getLogger(Closer.class.getCanonicalName());
/**
* The suppressor implementation to use for the current Java version.
*/
private static final Suppressor SUPPRESSOR = SuppressingSuppressor.isAvailable()
? SuppressingSuppressor.INSTANCE
: LoggingSuppressor.INSTANCE;
/**
* Creates a new {@link Closer}.
*/
public static Closer create() {
return new Closer(SUPPRESSOR);
}
@VisibleForTesting
final Suppressor suppressor;
// only need space for 2 elements in most cases, so try to use the smallest array possible
private final Deque<Closeable> stack = new ArrayDeque<Closeable>(4);
private Throwable thrown;
@VisibleForTesting Closer(Suppressor suppressor) {
this.suppressor = checkNotNull(suppressor); // checkNotNull to satisfy null tests
}
/**
* Registers the given {@code closeable} to be closed when this {@code Closer} is
* {@linkplain #close closed}.
*
* @return the given {@code closeable}
*/
// close. this word no longer has any meaning to me.
public <C extends Closeable> C register(C closeable) {
stack.push(closeable);
return closeable;
}
/**
* Stores the given throwable and rethrows it. It will be rethrown as is if it is an
* {@code IOException}, {@code RuntimeException} or {@code Error}. Otherwise, it will be rethrown
* wrapped in a {@code RuntimeException}. <b>Note:</b> Be sure to declare all of the checked
* exception types your try block can throw when calling an overload of this method so as to avoid
* losing the original exception type.
*
* <p>This method always throws, and as such should be called as
* {@code throw closer.rethrow(e);} to ensure the compiler knows that it will throw.
*
* @return this method does not return; it always throws
* @throws IOException when the given throwable is an IOException
*/
public RuntimeException rethrow(Throwable e) throws IOException {
thrown = e;
Throwables.propagateIfPossible(e, IOException.class);
throw Throwables.propagate(e);
}
/**
* Stores the given throwable and rethrows it. It will be rethrown as is if it is an
* {@code IOException}, {@code RuntimeException}, {@code Error} or a checked exception of the
* given type. Otherwise, it will be rethrown wrapped in a {@code RuntimeException}. <b>Note:</b>
* Be sure to declare all of the checked exception types your try block can throw when calling an
* overload of this method so as to avoid losing the original exception type.
*
* <p>This method always throws, and as such should be called as
* {@code throw closer.rethrow(e, ...);} to ensure the compiler knows that it will throw.
*
* @return this method does not return; it always throws
* @throws IOException when the given throwable is an IOException
* @throws X when the given throwable is of the declared type X
*/
public <X extends Exception> RuntimeException rethrow(Throwable e,
Class<X> declaredType) throws IOException, X {
thrown = e;
Throwables.propagateIfPossible(e, IOException.class);
Throwables.propagateIfPossible(e, declaredType);
throw Throwables.propagate(e);
}
/**
* Stores the given throwable and rethrows it. It will be rethrown as is if it is an
* {@code IOException}, {@code RuntimeException}, {@code Error} or a checked exception of either
* of the given types. Otherwise, it will be rethrown wrapped in a {@code RuntimeException}.
* <b>Note:</b> Be sure to declare all of the checked exception types your try block can throw
* when calling an overload of this method so as to avoid losing the original exception type.
*
* <p>This method always throws, and as such should be called as
* {@code throw closer.rethrow(e, ...);} to ensure the compiler knows that it will throw.
*
* @return this method does not return; it always throws
* @throws IOException when the given throwable is an IOException
* @throws X1 when the given throwable is of the declared type X1
* @throws X2 when the given throwable is of the declared type X2
*/
public <X1 extends Exception, X2 extends Exception> RuntimeException rethrow(
Throwable e, Class<X1> declaredType1, Class<X2> declaredType2) throws IOException, X1, X2 {
thrown = e;
Throwables.propagateIfPossible(e, IOException.class);
Throwables.propagateIfPossible(e, declaredType1, declaredType2);
throw Throwables.propagate(e);
}
/**
* Closes all {@code Closeable} instances that have been added to this {@code Closer}. If an
* exception was thrown in the try block and passed to one of the {@code exceptionThrown} methods,
* any exceptions thrown when attempting to close a closeable will be suppressed. Otherwise, the
* <i>first</i> exception to be thrown from an attempt to close a closeable will be thrown and any
* additional exceptions that are thrown after that will be suppressed.
*/
@Override
public void close() throws IOException {
Throwable throwable = thrown;
// close closeables in LIFO order
while (!stack.isEmpty()) {
Closeable closeable = stack.pop();
try {
closeable.close();
} catch (Throwable e) {
if (throwable == null) {
throwable = e;
} else {
suppressor.suppress(closeable, throwable, e);
}
}
}
if (thrown == null && throwable != null) {
Throwables.propagateIfPossible(throwable, IOException.class);
throw new AssertionError(throwable); // not possible
}
}
/**
* Suppression strategy interface.
*/
@VisibleForTesting interface Suppressor {
/**
* Suppresses the given exception ({@code suppressed}) which was thrown when attempting to close
* the given closeable. {@code thrown} is the exception that is actually being thrown from the
* method. Implementations of this method should not throw under any circumstances.
*/
void suppress(Closeable closeable, Throwable thrown, Throwable suppressed);
}
/**
* Suppresses exceptions by logging them.
*/
@VisibleForTesting static final class LoggingSuppressor implements Suppressor {
static final LoggingSuppressor INSTANCE = new LoggingSuppressor();
@Override
public void suppress(Closeable closeable, Throwable thrown, Throwable suppressed) {
// log to the same place as Closeables
logger.log(Level.WARNING, "Suppressing exception thrown when closing " + closeable, suppressed);
}
}
/**
* Suppresses exceptions by adding them to the exception that will be thrown using JDK7's
* addSuppressed(Throwable) mechanism.
*/
@VisibleForTesting static final class SuppressingSuppressor implements Suppressor {
static final SuppressingSuppressor INSTANCE = new SuppressingSuppressor();
static boolean isAvailable() {
return addSuppressed != null;
}
static final Method addSuppressed = getAddSuppressed();
private static Method getAddSuppressed() {
try {
return Throwable.class.getMethod("addSuppressed", Throwable.class);
} catch (Throwable e) {
return null;
}
}
@Override
public void suppress(Closeable closeable, Throwable thrown, Throwable suppressed) {
// ensure no exceptions from addSuppressed
if (thrown == suppressed) {
return;
}
try {
addSuppressed.invoke(thrown, suppressed);
} catch (Throwable e) {
// if, somehow, IllegalAccessException or another exception is thrown, fall back to logging
LoggingSuppressor.INSTANCE.suppress(closeable, thrown, suppressed);
}
}
}
}