/*
   * Copyright 2017 The Netty Project
   *
   * The Netty Project 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:
   *
   *   https://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.netty.util.internal;
  
  import io.netty.util.internal.logging.InternalLogger;
  import io.netty.util.internal.logging.InternalLoggerFactory;
  import sun.misc.Unsafe;
  
  import java.lang.invoke.MethodHandle;
  import java.lang.invoke.MethodHandles;
  import java.nio.ByteBuffer;
  import java.security.AccessController;
  import java.security.PrivilegedAction;
  
  import static java.lang.invoke.MethodType.methodType;
  
  /**
   * Provide a way to clean a ByteBuffer on Java9+.
   */
  final class CleanerJava9 implements Cleaner {
      private static final InternalLogger logger = InternalLoggerFactory.getInstance(CleanerJava9.class);
  
      private static final MethodHandle INVOKE_CLEANER;
  
      static {
          final MethodHandle method;
          final Throwable error;
          if (PlatformDependent0.hasUnsafe()) {
              final ByteBuffer buffer = ByteBuffer.allocateDirect(1);
              Object maybeInvokeMethod = AccessController.doPrivileged(new PrivilegedAction<Object>() {
                  @Override
                  public Object run() {
                      try {
                          // See https://bugs.openjdk.java.net/browse/JDK-8171377
                          Class<? extends Unsafe> unsafeClass = PlatformDependent0.UNSAFE.getClass();
                          MethodHandles.Lookup lookup = MethodHandles.lookup();
                          MethodHandle invokeCleaner = lookup.findVirtual(
                                  unsafeClass, "invokeCleaner", methodType(void.class, ByteBuffer.class));
                          invokeCleaner = invokeCleaner.bindTo(PlatformDependent0.UNSAFE);
                          invokeCleaner.invokeExact(buffer);
                          return invokeCleaner;
                      } catch (Throwable e) {
                          return e;
                      }
                  }
              });
  
              if (maybeInvokeMethod instanceof Throwable) {
                  method = null;
                  error = (Throwable) maybeInvokeMethod;
              } else {
                  method = (MethodHandle) maybeInvokeMethod;
                  error = null;
              }
          } else {
              method = null;
              error = new UnsupportedOperationException("sun.misc.Unsafe unavailable");
          }
          if (error == null) {
              logger.debug("java.nio.ByteBuffer.cleaner(): available");
          } else {
              logger.debug("java.nio.ByteBuffer.cleaner(): unavailable", error);
          }
          INVOKE_CLEANER = method;
      }
  
      static boolean isSupported() {
          return INVOKE_CLEANER != null;
      }
  
      @Override
      public CleanableDirectBuffer allocate(int capacity) {
          return new CleanableDirectBufferImpl(ByteBuffer.allocateDirect(capacity));
      }
  
      @Deprecated
      @Override
      public void freeDirectBuffer(ByteBuffer buffer) {
          freeDirectBufferStatic(buffer);
      }
  
      private static void freeDirectBufferStatic(ByteBuffer buffer) {
          // Try to minimize overhead when there is no SecurityManager present.
          // See https://bugs.openjdk.java.net/browse/JDK-8191053.
          if (System.getSecurityManager() == null) {
              try {
                 INVOKE_CLEANER.invokeExact(buffer);
             } catch (Throwable cause) {
                 PlatformDependent0.throwException(cause);
             }
         } else {
             freeDirectBufferPrivileged(buffer);
         }
     }
 
     private static void freeDirectBufferPrivileged(final ByteBuffer buffer) {
         Throwable error = AccessController.doPrivileged(new PrivilegedAction<Throwable>() {
             @Override
             public Throwable run() {
                 try {
                     INVOKE_CLEANER.invokeExact(buffer);
                 } catch (Throwable e) {
                     return e;
                 }
                 return null;
             }
         });
         if (error != null) {
             PlatformDependent0.throwException(error);
         }
     }
 
     private static final class CleanableDirectBufferImpl implements CleanableDirectBuffer {
         private final ByteBuffer buffer;
 
         private CleanableDirectBufferImpl(ByteBuffer buffer) {
             this.buffer = buffer;
         }
 
         @Override
         public ByteBuffer buffer() {
             return buffer;
         }
 
         @Override
         public void clean() {
             freeDirectBufferStatic(buffer);
         }
     }
 }