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   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
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   *
   *     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,
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   * See the License for the specific language governing permissions and
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  package org.apache.cassandra.hints;
  
  import java.io.IOException;
  import java.io.InputStream;
  import java.nio.ByteBuffer;
  import java.nio.file.Files;
  import java.util.Iterator;
  import java.util.UUID;
  import java.util.concurrent.TimeUnit;
  import java.util.zip.CRC32;
  
  import com.google.common.collect.Iterables;
  
  import org.apache.cassandra.io.util.File;
  import org.junit.Test;
  
  import org.apache.cassandra.SchemaLoader;
  import org.apache.cassandra.db.Mutation;
  import org.apache.cassandra.db.RowUpdateBuilder;
  import org.apache.cassandra.db.rows.Cell;
  import org.apache.cassandra.db.rows.Row;
  import org.apache.cassandra.schema.KeyspaceParams;
  import org.apache.cassandra.schema.Schema;
  import org.apache.cassandra.schema.TableMetadata;
  import org.apache.cassandra.utils.FBUtilities;
  import org.apache.cassandra.utils.memory.MemoryUtil;
  
  import static org.apache.cassandra.Util.dk;
  import static org.apache.cassandra.utils.ByteBufferUtil.bytes;
  import static org.junit.Assert.assertEquals;
  import static org.junit.Assert.assertNotNull;
  import static org.junit.Assert.assertTrue;
  
  import static org.apache.cassandra.utils.Clock.Global.currentTimeMillis;
  
  public class HintsWriteThenReadTest
  {
      private static final String KEYSPACE = "hints_write_then_read_test";
      private static final String TABLE = "table";
  
      private static final int HINTS_COUNT = 10_000_000;
  
      @Test
      public void testWriteReadCycle() throws IOException
      {
          SchemaLoader.prepareServer();
          SchemaLoader.createKeyspace(KEYSPACE, KeyspaceParams.simple(1), SchemaLoader.standardCFMD(KEYSPACE, TABLE));
  
          HintsDescriptor descriptor = new HintsDescriptor(UUID.randomUUID(), currentTimeMillis());
  
          File directory = new File(Files.createTempDirectory(null));
          try
          {
              testWriteReadCycle(directory, descriptor);
          }
          finally
          {
              directory.deleteOnExit();
          }
      }
  
      private void testWriteReadCycle(File directory, HintsDescriptor descriptor) throws IOException
      {
          // write HINTS_COUNT hints to a file
          writeHints(directory, descriptor);
  
          // calculate the checksum of the file, then compare to the .crc32 checksum file content
          verifyChecksum(directory, descriptor);
  
          // iterate over the written hints, make sure they are all present
          verifyHints(directory, descriptor);
      }
  
      private void writeHints(File directory, HintsDescriptor descriptor) throws IOException
      {
          try (HintsWriter writer = HintsWriter.create(directory, descriptor))
          {
              write(writer, descriptor.timestamp);
          }
      }
  
      private static void verifyChecksum(File directory, HintsDescriptor descriptor) throws IOException
      {
          File hintsFile = descriptor.file(directory);
          File checksumFile = descriptor.checksumFile(directory);
  
          assertTrue(checksumFile.exists());
  
          String actualChecksum = Integer.toHexString(calculateChecksum(hintsFile));
          String expectedChecksum = Files.readAllLines(checksumFile.toPath()).iterator().next();
  
          assertEquals(expectedChecksum, actualChecksum);
      }
  
      private void verifyHints(File directory, HintsDescriptor descriptor)
      {
          long baseTimestamp = descriptor.timestamp;
          int index = 0;
  
          try (HintsReader reader = HintsReader.open(descriptor.file(directory)))
          {
              for (HintsReader.Page page : reader)
              {
                  Iterator<Hint> hints = page.hintsIterator();
                  while (hints.hasNext())
                  {
                      Hint hint = hints.next();
  
                      long timestamp = baseTimestamp + index;
                      Mutation mutation = hint.mutation;
  
                      assertEquals(timestamp, hint.creationTime);
                      assertEquals(dk(bytes(index)), mutation.key());
  
                      Row row = mutation.getPartitionUpdates().iterator().next().iterator().next();
                      assertEquals(1, Iterables.size(row.cells()));
                      assertEquals(bytes(index), toByteBuffer(row.clustering().get(0)));
                      Cell<?> cell = row.cells().iterator().next();
                      assertNotNull(cell);
                      assertEquals(bytes(index), toByteBuffer(cell.value()));
                      assertEquals(timestamp * 1000, cell.timestamp());
  
                      index++;
                  }
              }
          }
  
          assertEquals(index, HINTS_COUNT);
      }
  
      private void write(HintsWriter writer, long timestamp) throws IOException
      {
          ByteBuffer buffer = ByteBuffer.allocateDirect(256 * 1024);
          try (HintsWriter.Session session = writer.newSession(buffer))
          {
              write(session, timestamp);
          }
          MemoryUtil.clean(buffer);
      }
  
      private void write(HintsWriter.Session session, long timestamp) throws IOException
      {
          for (int i = 0; i < HINTS_COUNT; i++)
              session.append(createHint(i, timestamp));
      }
  
      private static Hint createHint(int idx, long baseTimestamp)
      {
          long timestamp = baseTimestamp + idx;
          return Hint.create(createMutation(idx, TimeUnit.MILLISECONDS.toMicros(timestamp)), timestamp);
      }
  
      private static Mutation createMutation(int index, long timestamp)
      {
          TableMetadata table = Schema.instance.getTableMetadata(KEYSPACE, TABLE);
          return new RowUpdateBuilder(table, timestamp, bytes(index))
                 .clustering(bytes(index))
                 .add("val", bytes(index))
                 .build();
      }
  
      private static int calculateChecksum(File file) throws IOException
      {
          CRC32 crc = new CRC32();
          byte[] buffer = new byte[FBUtilities.MAX_UNSIGNED_SHORT];
  
          try (InputStream in = Files.newInputStream(file.toPath()))
          {
              int bytesRead;
              while((bytesRead = in.read(buffer)) != -1)
                  crc.update(buffer, 0, bytesRead);
          }
  
          return (int) crc.getValue();
      }
  
      private ByteBuffer toByteBuffer(Object obj)
      {
          if (obj instanceof ByteBuffer)
             return (ByteBuffer) obj;
  
          return ByteBuffer.wrap((byte[]) obj);
      }
  }
  