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.cassandra.io.util;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.util.Random;
  
  import org.junit.Test;
  
  import static org.apache.cassandra.io.util.PageAware.PAGE_SIZE;
  import static org.junit.Assert.assertEquals;
  
  public class PageAwareTest
  {
      @Test
      public void pageLimit()
      {
          assertEquals(PAGE_SIZE, PageAware.pageLimit(0));
          assertEquals(2 * PAGE_SIZE, PageAware.pageLimit(PAGE_SIZE));
          assertEquals(3 * PAGE_SIZE, PageAware.pageLimit(2 * PAGE_SIZE));
  
          assertEquals(PAGE_SIZE, PageAware.pageLimit(PAGE_SIZE / 3));
          assertEquals(PAGE_SIZE, PageAware.pageLimit(PAGE_SIZE - 1));
          assertEquals(PAGE_SIZE, PageAware.pageLimit(1));
  
          assertEquals(2 * PAGE_SIZE, PageAware.pageLimit(PAGE_SIZE + PAGE_SIZE / 3));
          assertEquals(2 * PAGE_SIZE, PageAware.pageLimit(PAGE_SIZE + PAGE_SIZE - 1));
          assertEquals(2 * PAGE_SIZE, PageAware.pageLimit(PAGE_SIZE + 1));
      }
  
      @Test
      public void bytesLeftInPage()
      {
          assertEquals(PAGE_SIZE, PageAware.bytesLeftInPage(0));
          assertEquals(PAGE_SIZE, PageAware.bytesLeftInPage(PAGE_SIZE));
          assertEquals(PAGE_SIZE, PageAware.bytesLeftInPage(2 * PAGE_SIZE));
  
          assertEquals(PAGE_SIZE - (PAGE_SIZE / 3), PageAware.bytesLeftInPage(PAGE_SIZE / 3));
          assertEquals(1, PageAware.bytesLeftInPage(PAGE_SIZE - 1));
          assertEquals(PAGE_SIZE - 1, PageAware.bytesLeftInPage(1));
  
          assertEquals(PAGE_SIZE - (PAGE_SIZE / 3), PageAware.bytesLeftInPage(PAGE_SIZE + PAGE_SIZE / 3));
          assertEquals(1, PageAware.bytesLeftInPage(PAGE_SIZE + PAGE_SIZE - 1));
          assertEquals(PAGE_SIZE - 1, PageAware.bytesLeftInPage(PAGE_SIZE + 1));
      }
  
      @Test
      public void pageStart()
      {
          assertEquals(0, PageAware.pageStart(0));
          assertEquals(PAGE_SIZE, PageAware.pageStart(PAGE_SIZE));
          assertEquals(2 * PAGE_SIZE, PageAware.pageStart(2 * PAGE_SIZE));
  
          assertEquals(0, PageAware.pageStart(PAGE_SIZE / 3));
          assertEquals(0, PageAware.pageStart(PAGE_SIZE - 1));
          assertEquals(0, PageAware.pageStart(1));
  
          assertEquals(PAGE_SIZE, PageAware.pageStart(PAGE_SIZE + PAGE_SIZE / 3));
          assertEquals(PAGE_SIZE, PageAware.pageStart(PAGE_SIZE + PAGE_SIZE - 1));
          assertEquals(PAGE_SIZE, PageAware.pageStart(PAGE_SIZE + 1));
      }
  
      @Test
      public void padded()
      {
          assertEquals(0, PageAware.padded(0));
          assertEquals(PAGE_SIZE, PageAware.padded(PAGE_SIZE));
          assertEquals(2 * PAGE_SIZE, PageAware.padded(2 * PAGE_SIZE));
  
          assertEquals(PAGE_SIZE, PageAware.padded(PAGE_SIZE / 3));
          assertEquals(PAGE_SIZE, PageAware.padded(PAGE_SIZE - 1));
          assertEquals(PAGE_SIZE, PageAware.padded(1));
  
          assertEquals(2 * PAGE_SIZE, PageAware.padded(PAGE_SIZE + PAGE_SIZE / 3));
          assertEquals(2 * PAGE_SIZE, PageAware.padded(PAGE_SIZE + PAGE_SIZE - 1));
          assertEquals(2 * PAGE_SIZE, PageAware.padded(PAGE_SIZE + 1));
      }
  
      @Test
      public void numPages()
      {
          assertEquals(0, PageAware.numPages(0));
          assertEquals(1, PageAware.numPages(PAGE_SIZE));
          assertEquals(2, PageAware.numPages(2 * PAGE_SIZE));
  
          assertEquals(1, PageAware.numPages(PAGE_SIZE / 3));
          assertEquals(1, PageAware.numPages(PAGE_SIZE - 1));
          assertEquals(1, PageAware.numPages(1));
  
          assertEquals(2, PageAware.numPages(PAGE_SIZE + PAGE_SIZE / 3));
          assertEquals(2, PageAware.numPages(PAGE_SIZE + PAGE_SIZE - 1));
          assertEquals(2, PageAware.numPages(PAGE_SIZE + 1));
      }
  
      @Test
      public void pageNum()
      {
          assertEquals(0, PageAware.pageNum(0));
          assertEquals(1, PageAware.pageNum(PAGE_SIZE));
          assertEquals(2, PageAware.pageNum(2 * PAGE_SIZE));
  
          assertEquals(0, PageAware.pageNum(PAGE_SIZE / 3));
          assertEquals(0, PageAware.pageNum(PAGE_SIZE - 1));
          assertEquals(0, PageAware.pageNum(1));
  
          assertEquals(1, PageAware.pageNum(PAGE_SIZE + PAGE_SIZE / 3));
          assertEquals(1, PageAware.pageNum(PAGE_SIZE + PAGE_SIZE - 1));
          assertEquals(1, PageAware.pageNum(PAGE_SIZE + 1));
      }
  
      @Test
      public void pad() throws IOException
      {
          testPad(0, 0);
          testPad(PAGE_SIZE, PAGE_SIZE);
          testPad(2 * PAGE_SIZE, 2 * PAGE_SIZE);
  
          testPad(PAGE_SIZE, PAGE_SIZE / 3);
          testPad(PAGE_SIZE, PAGE_SIZE - 1);
          testPad(PAGE_SIZE, 1);
  
          testPad(2 * PAGE_SIZE, PAGE_SIZE + PAGE_SIZE / 3);
          testPad(2 * PAGE_SIZE, PAGE_SIZE + PAGE_SIZE - 1);
          testPad(2 * PAGE_SIZE, PAGE_SIZE + 1);
      }
  
      private void testPad(int expectedSize, int currentSize) throws IOException
      {
          ByteBuffer expectedBuf = ByteBuffer.allocate(expectedSize);
          try (DataOutputBuffer out = new DataOutputBuffer())
          {
              for (int i = 0; i < currentSize; i++)
              {
                  expectedBuf.put((byte) 1);
                  out.write(1);
              }
              for (int i = currentSize; i < expectedSize; i++)
              {
                  expectedBuf.put((byte) 0);
              }
  
              PageAware.pad(out);
              out.flush();
  
              assertEquals(expectedBuf.rewind(), out.asNewBuffer());
          }
      }
  
      @Test
      public void randomizedTest()
      {
          Random rand = new Random();
          for (int i = 0; i < 100000; ++i)
          {
              long pos = rand.nextLong() & ((1L << rand.nextInt(64)) - 1);    // positive long with random length
              long pageStart = (pos / PAGE_SIZE) * PAGE_SIZE;
              long pageLimit = pageStart + PAGE_SIZE;
              assertEquals(pageLimit, PageAware.pageLimit(pos));
              assertEquals(pageStart, PageAware.pageStart(pos));
              assertEquals(pageLimit - pos, PageAware.bytesLeftInPage(pos));
              assertEquals(pos == pageStart ? pageStart : pageLimit, PageAware.padded(pos));
          }
      }
  }