| /* |
| * 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.datasketches.memory.internal; |
| |
| import java.lang.reflect.InvocationTargetException; |
| import java.lang.reflect.Method; |
| |
| /** |
| * Extracts a version-dependent reference to the `jdk.internal.misc.VM` into a standalone |
| * class. The package name for VM has changed in later versions. The appropriate |
| * class will be loaded by the class loader depending on the Java version that is used. |
| * For more information, see: https://openjdk.java.net/jeps/238 |
| */ |
| public final class VirtualMachineMemory { |
| |
| private static final Class<?> VM_CLASS; |
| private static final Method VM_IS_DIRECT_MEMORY_PAGE_ALIGNED_METHOD; |
| private static final boolean isPageAligned; |
| |
| static { |
| try { |
| VM_CLASS = Class.forName("jdk.internal.misc.VM"); |
| VM_IS_DIRECT_MEMORY_PAGE_ALIGNED_METHOD = VM_CLASS.getDeclaredMethod("isDirectMemoryPageAligned"); |
| VM_IS_DIRECT_MEMORY_PAGE_ALIGNED_METHOD.setAccessible(true); |
| isPageAligned = (boolean) VM_IS_DIRECT_MEMORY_PAGE_ALIGNED_METHOD.invoke(null); //static method |
| } catch (final ClassNotFoundException | NoSuchMethodException | IllegalAccessException |
| | IllegalArgumentException | InvocationTargetException | SecurityException e) { |
| throw new RuntimeException("Could not acquire jdk.internal.misc.VM: " + e.getClass()); |
| } |
| } |
| |
| /** |
| * Returns true if the direct buffers should be page aligned. |
| * @return flag that determines whether direct buffers should be page aligned. |
| */ |
| public static boolean getIsPageAligned() { |
| return isPageAligned; |
| } |
| } |