content: /*
   * 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.spark.unsafe.array;
  
  import org.apache.spark.unsafe.Platform;
  import org.apache.spark.unsafe.memory.MemoryBlock;
  
  /**
   * An array of long values. Compared with native JVM arrays, this:
   * <ul>
   *   <li>supports using both in-heap and off-heap memory</li>
   *   <li>has no bound checking, and thus can crash the JVM process when assert is turned off</li>
   * </ul>
   */
  public final class LongArray {
  
    // This is a long so that we perform long multiplications when computing offsets.
    private static final long WIDTH = 8;
  
    private final MemoryBlock memory;
    private final Object baseObj;
    private final long baseOffset;
  
    private final long length;
  
    public LongArray(MemoryBlock memory) {
      assert memory.size() < (long) Integer.MAX_VALUE * 8: "Array size > 4 billion elements";
      this.memory = memory;
      this.baseObj = memory.getBaseObject();
      this.baseOffset = memory.getBaseOffset();
      this.length = memory.size() / WIDTH;
    }
  
    public MemoryBlock memoryBlock() {
      return memory;
    }
  
    public Object getBaseObject() {
      return baseObj;
    }
  
    public long getBaseOffset() {
      return baseOffset;
    }
  
    /**
     * Returns the number of elements this array can hold.
     */
    public long size() {
      return length;
    }
  
    /**
     * Fill this all with 0L.
     */
    public void zeroOut() {
      for (long off = baseOffset; off < baseOffset + length * WIDTH; off += WIDTH) {
        Platform.putLong(baseObj, off, 0);
      }
    }
  
    /**
     * Sets the value at position {@code index}.
     */
    public void set(int index, long value) {
      assert index >= 0 : "index (" + index + ") should >= 0";
      assert index < length : "index (" + index + ") should < length (" + length + ")";
      Platform.putLong(baseObj, baseOffset + index * WIDTH, value);
    }
  
    /**
     * Returns the value at position {@code index}.
     */
    public long get(int index) {
      assert index >= 0 : "index (" + index + ") should >= 0";
      assert index < length : "index (" + index + ") should < length (" + length + ")";
      return Platform.getLong(baseObj, baseOffset + index * WIDTH);
    }
  }
  