-/*
- * Copyright 2019-present Open Networking Foundation
- *
- * 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 io.atomix.storage.journal;
-
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-import java.io.IOException;
-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 java.security.AccessController;
-import java.security.PrivilegedAction;
-import java.util.Objects;
-
-import static java.lang.invoke.MethodHandles.constant;
-import static java.lang.invoke.MethodHandles.dropArguments;
-import static java.lang.invoke.MethodHandles.filterReturnValue;
-import static java.lang.invoke.MethodHandles.guardWithTest;
-import static java.lang.invoke.MethodHandles.lookup;
-import static java.lang.invoke.MethodType.methodType;
-
-/**
- * Utility class which allows explicit calls to the DirectByteBuffer cleaner method instead of relying on GC.
- */
-public class BufferCleaner {
-
- private static final Logger LOGGER = LoggerFactory.getLogger(BufferCleaner.class);
-
- /**
- * Reference to a Cleaner that does unmapping; no-op if not supported.
- */
- private static final Cleaner CLEANER;
-
- static {
- final Object hack = AccessController.doPrivileged((PrivilegedAction<Object>) BufferCleaner::unmapHackImpl);
- if (hack instanceof Cleaner) {
- CLEANER = (Cleaner) hack;
- LOGGER.debug("java.nio.DirectByteBuffer.cleaner(): available");
- } else {
- CLEANER = (ByteBuffer buffer) -> {
- // noop
- };
- LOGGER.debug("java.nio.DirectByteBuffer.cleaner(): unavailable: {}", hack);
- }
- }
-
- private static Object unmapHackImpl() {
- final MethodHandles.Lookup lookup = lookup();
- try {
- try {
- // *** sun.misc.Unsafe unmapping (Java 9+) ***
- final Class<?> unsafeClass = Class.forName("sun.misc.Unsafe");
- // first check if Unsafe has the right method, otherwise we can give up
- // without doing any security critical stuff:
- final MethodHandle unmapper = lookup.findVirtual(unsafeClass, "invokeCleaner",
- methodType(void.class, ByteBuffer.class));
- // fetch the unsafe instance and bind it to the virtual MH:
- final Field f = unsafeClass.getDeclaredField("theUnsafe");
- f.setAccessible(true);
- final Object theUnsafe = f.get(null);
- return newBufferCleaner(ByteBuffer.class, unmapper.bindTo(theUnsafe));
- } catch (SecurityException se) {
- // rethrow to report errors correctly (we need to catch it here, as we also catch RuntimeException below!):
- throw se;
- } catch (ReflectiveOperationException | RuntimeException e) {
- // *** sun.misc.Cleaner unmapping (Java 8) ***
- final Class<?> directBufferClass = Class.forName("java.nio.DirectByteBuffer");
-
- final Method m = directBufferClass.getMethod("cleaner");
- m.setAccessible(true);
- final MethodHandle directBufferCleanerMethod = lookup.unreflect(m);
- final Class<?> cleanerClass = directBufferCleanerMethod.type().returnType();
-
- /* "Compile" a MH that basically is equivalent to the following code:
- * void unmapper(ByteBuffer byteBuffer) {
- * sun.misc.Cleaner cleaner = ((java.nio.DirectByteBuffer) byteBuffer).cleaner();
- * if (Objects.nonNull(cleaner)) {
- * cleaner.clean();
- * } else {
- * noop(cleaner); // the noop is needed because MethodHandles#guardWithTest always needs ELSE
- * }
- * }
- */
- final MethodHandle cleanMethod = lookup.findVirtual(cleanerClass, "clean", methodType(void.class));
- final MethodHandle nonNullTest = lookup.findStatic(Objects.class, "nonNull", methodType(boolean.class, Object.class))
- .asType(methodType(boolean.class, cleanerClass));
- final MethodHandle noop = dropArguments(constant(Void.class, null).asType(methodType(void.class)), 0, cleanerClass);
- final MethodHandle unmapper = filterReturnValue(directBufferCleanerMethod, guardWithTest(nonNullTest, cleanMethod, noop))
- .asType(methodType(void.class, ByteBuffer.class));
- return newBufferCleaner(directBufferClass, unmapper);
- }
- } catch (SecurityException se) {
- return "Unmapping is not supported, because not all required permissions are given to the Lucene JAR file: "
- + se + " [Please grant at least the following permissions: RuntimePermission(\"accessClassInPackage.sun.misc\") "
- + " and ReflectPermission(\"suppressAccessChecks\")]";
- } catch (ReflectiveOperationException | RuntimeException e) {
- return "Unmapping is not supported on this platform, because internal Java APIs are not compatible with this Atomix version: " + e;
- }
- }
-
- private static Cleaner newBufferCleaner(final Class<?> unmappableBufferClass, final MethodHandle unmapper) {
- return (ByteBuffer buffer) -> {
- if (!buffer.isDirect()) {
- return;
- }
- if (!unmappableBufferClass.isInstance(buffer)) {
- throw new IllegalArgumentException("buffer is not an instance of " + unmappableBufferClass.getName());
- }
- final Throwable error = AccessController.doPrivileged((PrivilegedAction<Throwable>) () -> {
- try {
- unmapper.invokeExact(buffer);
- return null;
- } catch (Throwable t) {
- return t;
- }
- });
- if (error != null) {
- throw new IOException("Unable to unmap the mapped buffer", error);
- }
- };
- }
-
- /**
- * Free {@link ByteBuffer} if possible.
- */
- public static void freeBuffer(ByteBuffer buffer) throws IOException {
- CLEANER.freeBuffer(buffer);
- }
-}
Code Review / controller.git / blobdiff