pjfanning commented on code in PR #2020: URL: https://github.com/apache/pekko/pull/2020#discussion_r2273309092
########## actor/src/main/java/org/apache/pekko/io/ByteBufferCleaner.java: ########## @@ -0,0 +1,128 @@ +/* + * 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.pekko.io; + +import java.lang.invoke.MethodHandle; +import java.lang.invoke.MethodHandles; +import java.lang.reflect.Field; +import java.lang.reflect.Method; +import java.nio.ByteBuffer; + +import static java.lang.invoke.MethodType.methodType; + +/** + * Cleans a direct {@link ByteBuffer}. Without manual intervention, direct ByteBuffers will be + * cleaned eventually upon garbage collection. However, this should not be relied upon since it may + * not occur in a timely fashion - especially since off heap ByteBuffers don't put pressure on the + * garbage collector. + * + * <p><strong>Warning:</strong> Do not attempt to use a direct {@link ByteBuffer} that has been + * cleaned or bad things will happen. Don't use this class unless you can ensure that the cleaned + * buffer will not be accessed anymore. + * + * <p>See <a href=https://bugs.openjdk.java.net/browse/JDK-4724038>JDK-4724038</a> + */ +final class ByteBufferCleaner { + + // adapted from + // https://github.com/apache/commons-io/blob/441115a4b5cd63ae808dd4c40fc238cb52c8048f/src/main/java/org/apache/commons/io/input/ByteBufferCleaner.java + + private interface Cleaner { + void clean(ByteBuffer buffer) throws Throwable; + } + + private static final class Java8Cleaner implements Cleaner { + + private final Method cleanerMethod; + private final Method cleanMethod; + + private Java8Cleaner() throws ReflectiveOperationException, SecurityException { + cleanMethod = Class.forName("sun.misc.Cleaner").getMethod("clean"); + cleanerMethod = Class.forName("sun.nio.ch.DirectBuffer").getMethod("cleaner"); + } + + @Override + public void clean(final ByteBuffer buffer) throws Throwable { + final Object cleaner = cleanerMethod.invoke(buffer); + if (cleaner != null) { + cleanMethod.invoke(cleaner); + } + } + } + + private static final class Java9Cleaner implements Cleaner { + + private final MethodHandle invokeCleaner; + + private Java9Cleaner() throws ReflectiveOperationException, SecurityException { + final Class<?> unsafeClass = Class.forName("sun.misc.Unsafe"); + final Field field = unsafeClass.getDeclaredField("theUnsafe"); + field.setAccessible(true); + final Object theUnsafe = field.get(null); + MethodHandles.Lookup lookup = MethodHandles.lookup(); + MethodHandle invokeCleaner = + lookup.findVirtual( + unsafeClass, "invokeCleaner", methodType(void.class, ByteBuffer.class)); + this.invokeCleaner = invokeCleaner.bindTo(theUnsafe); + } + + @Override + public void clean(final ByteBuffer buffer) throws Throwable { + invokeCleaner.invokeExact(buffer); + } + } + + private static final Cleaner INSTANCE = getCleaner(); + + /** + * Releases memory held by the given {@link ByteBuffer}. + * + * @param buffer to release. + * @throws IllegalStateException on internal failure. + */ + static void clean(final ByteBuffer buffer) { + try { + INSTANCE.clean(buffer); + } catch (final Throwable t) { + throw new IllegalStateException("Failed to clean direct buffer.", t); Review Comment: It isn't an unsupported exception if it gets here - INSTANCE is null if it is unsupported. I check for this at runtime. This is not a public API. It is not even a public class. It only needs to suit the way that I use it internally. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: notifications-unsubscr...@pekko.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: notifications-unsubscr...@pekko.apache.org For additional commands, e-mail: notifications-h...@pekko.apache.org
