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.distributed.impl;
  
  import java.io.IOException;
  import java.io.UncheckedIOException;
  import java.util.Objects;
  import java.util.function.Predicate;
  
  import com.google.common.io.Closeables;
  
  import org.apache.cassandra.io.util.File;
  import org.apache.cassandra.io.util.RandomAccessReader;
  import org.apache.cassandra.utils.AbstractIterator;
  import org.apache.cassandra.distributed.api.LogAction;
  import org.apache.cassandra.distributed.api.LineIterator;
  
  public class FileLogAction implements LogAction
  {
      private final File file;
  
      public FileLogAction(File file)
      {
          this.file = Objects.requireNonNull(file);
      }
  
      @Override
      public long mark()
      {
          return file.length();
      }
  
      @Override
      public LineIterator match(long startPosition, Predicate<String> fn)
      {
          RandomAccessReader reader;
          reader = RandomAccessReader.open(file);
          if (startPosition > 0) // -1 used to disable, so ignore any negative values or 0 (default offset)
          {
              reader.seek(startPosition);
          }
          return new FileLineIterator(reader, fn);
      }
  
      private static final class FileLineIterator extends AbstractIterator<String> implements LineIterator
      {
          private final RandomAccessReader reader;
          private final Predicate<String> fn;
  
          private FileLineIterator(RandomAccessReader reader, Predicate<String> fn)
          {
              this.reader = reader;
              this.fn = fn;
          }
  
          @Override
          public long mark()
          {
              return reader.getFilePointer();
          }
  
          @Override
          protected String computeNext()
          {
              try
              {
                  String s;
                  while ((s = reader.readLine()) != null)
                  {
                      if (fn.test(s))
                          return s;
                  }
                  return endOfData();
              }
              catch (IOException e)
              {
                  throw new UncheckedIOException(e);
              }
          }
  
          @Override
          public void close()
          {
              try
              {
                  Closeables.close(reader, true);
              }
              catch (IOException impossible)
              {
                  throw new AssertionError(impossible);
              }
          }
      }
  }
  