johnyangk commented on a change in pull request #223: [NEMO-388] Off-heap memory management (reuse ByteBuffer) URL: https://github.com/apache/incubator-nemo/pull/223#discussion_r306162724
########## File path: runtime/executor/src/main/java/org/apache/nemo/runtime/executor/data/MemoryChunk.java ########## @@ -0,0 +1,811 @@ +/* + * 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.nemo.runtime.executor.data; + +import java.lang.reflect.Field; +import java.nio.ByteBuffer; +import java.nio.ByteOrder; + + +/** + * This class represents chunk of memory residing in off-heap region + * managed by {@link MemoryPoolAssigner}, which is backed by {@link ByteBuffer}. + */ +public class MemoryChunk { + + @SuppressWarnings("restriction") + protected static final sun.misc.Unsafe UNSAFE = getUnsafe(); + @SuppressWarnings("restriction") + protected static final long BYTE_ARRAY_BASE_OFFSET = UNSAFE.arrayBaseOffset(byte[].class); + private static final boolean LITTLE_ENDIAN = (ByteOrder.nativeOrder() == ByteOrder.LITTLE_ENDIAN); + private final ByteBuffer buffer; + private long address; + private final long addressLimit; + private boolean isFree; + private final int size; + private final boolean sequential; + + /** + * Creates a new memory chunk that represents the off-heap memory at the absolute address. + * This class can be created in two modes: sequential access mode or random access mode. + * Sequential access mode supports convenient sequential access of {@link ByteBuffer}. + * Random access mode supports random access and manipulation of the data in the {@code ByteBuffer} using UNSAFE. + * No automatic tracking of position, limit, capacity, etc. of {@code ByteBuffer} for random access mode. + * + * @param offHeapAddress the address of the off-heap memory, {@link ByteBuffer}, of this MemoryChunk + * @param buffer the off-heap memory of this MemoryChunk + * @param sequential whether this MemoryChunk is in sequential mode or not. + */ + MemoryChunk(final long offHeapAddress, final ByteBuffer buffer, final boolean sequential) { + if (offHeapAddress <= 0) { + throw new IllegalArgumentException("negative pointer or size"); + } + if (offHeapAddress >= Long.MAX_VALUE - Integer.MAX_VALUE) { + throw new IllegalArgumentException("MemoryChunk initialized with too large address"); + } + this.buffer = buffer; + this.size = buffer.capacity(); + this.address = offHeapAddress; + this.addressLimit = this.address + this.size; + this.isFree = false; + this.sequential = sequential; + } + + /** + * Creates a new memory chunk that represents the off-heap memory at the absolute address. + * + * @param buffer the off-heap memory of this MemoryChunk + * @param sequential whether this MemoryChunk is in sequential mode or not. + */ + MemoryChunk(final ByteBuffer buffer, final boolean sequential) { + this(getAddress(buffer), buffer, sequential); + } + + /** + * Gets the {@link ByteBuffer} from this MemoryChunk. + * + * @return {@link ByteBuffer} + */ + public ByteBuffer getBuffer() { + return buffer; + } + + /** + * Returns the off-heap memory address of this MemoryChunk. + * + * @return absolute memory address outside the heap + */ + public long getAddress() { Review comment: Remove this unused method. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services
