--- /dev/null
+/*
+ * 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