org.apache.flink.runtime.io.network.partition.PageSizeUtil Maven / Gradle / Ivy
/*
* 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.flink.runtime.io.network.partition;
import org.apache.flink.util.ExceptionUtils;
import org.apache.flink.shaded.netty4.io.netty.util.internal.PlatformDependent;
import org.apache.flink.shaded.netty4.io.netty.util.internal.shaded.org.jctools.util.UnsafeAccess;
import sun.misc.Unsafe;
import javax.annotation.Nullable;
import java.security.AccessController;
import java.security.PrivilegedAction;
/**
* Utility for accessing the system page size.
*/
public final class PageSizeUtil {
/** Value indicating an unknown page size. */
public static final int PAGE_SIZE_UNKNOWN = -1;
/** The default page size on most systems. */
public static final int DEFAULT_PAGE_SIZE = 4 * 1024;
/** A conservative fallback value (64 KiBytes) that should be a multiple of the page size even
* in some uncommon cases of servers installations with larger-than-usual page sizes. */
public static final int CONSERVATIVE_PAGE_SIZE_MULTIPLE = 64 * 1024;
/**
* Tries to get the system page size. If the page size cannot be determined, this
* returns -1.
*
* This internally relies on the presence of "unsafe" and the resolution via some
* Netty utilities.
*/
public static int getSystemPageSize() {
try {
return PageSizeUtilInternal.getSystemPageSize();
}
catch (Throwable t) {
ExceptionUtils.rethrowIfFatalError(t);
return PAGE_SIZE_UNKNOWN;
}
}
/**
* Tries to get the system page size. If the page size cannot be determined, this
* returns the {@link #DEFAULT_PAGE_SIZE}.
*/
public static int getSystemPageSizeOrDefault() {
final int pageSize = getSystemPageSize();
return pageSize == PAGE_SIZE_UNKNOWN ? DEFAULT_PAGE_SIZE : pageSize;
}
/**
* Tries to get the system page size. If the page size cannot be determined, this
* returns the {@link #CONSERVATIVE_PAGE_SIZE_MULTIPLE}.
*/
public static int getSystemPageSizeOrConservativeMultiple() {
final int pageSize = getSystemPageSize();
return pageSize == PAGE_SIZE_UNKNOWN ? CONSERVATIVE_PAGE_SIZE_MULTIPLE : pageSize;
}
// ------------------------------------------------------------------------
/** This class is not meant to be instantiated. */
private PageSizeUtil() {}
// ------------------------------------------------------------------------
/**
* All unsafe related code must be in a separate class, so that loading the outer class
* does not implicitly try to resolve the unsafe class.
*/
@SuppressWarnings("all")
private static final class PageSizeUtilInternal {
static int getSystemPageSize() {
Unsafe unsafe = unsafe();
return unsafe == null ? PAGE_SIZE_UNKNOWN : unsafe.pageSize();
}
@Nullable
private static Unsafe unsafe() {
if (PlatformDependent.hasUnsafe()) {
return (Unsafe) AccessController.doPrivileged(
(PrivilegedAction