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import java.io.FileInputStream;
import java.io.IOException;
import java.nio.CharBuffer;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class LogSearch {
	public static void FindLogEntry(String search) {
		// Construct regex dynamically from user string
		String regex = "(.*? +public\\[\\d+\\] +.*" + search + ".*)";
		Pattern keywordPattern = Pattern.compile(regex);
		try (FileInputStream fis = new FileInputStream("log.txt")) {
			FileChannel channel = fis.getChannel();
			// Get the file's size and map it into memory
			long size = channel.size();
			final MappedByteBuffer mappedBuffer = channel.map(
					FileChannel.MapMode.READ_ONLY, 0, size);
			Charset charset = Charset.forName("ISO-8859-15");
			final CharsetDecoder decoder = charset.newDecoder();
			// Read file into char buffer
			CharBuffer log = decoder.decode(mappedBuffer);
			Matcher logMatcher = keywordPattern.matcher(log);
			while (logMatcher.find()) {
				String match = logMatcher.group(1);
				if (match != null) {
				  System.out.println(match);
				}
			}
		} catch (IOException ex) {
			System.err.println("thrown exception: " + ex.toString());
			Throwable[] suppressed = ex.getSuppressed();
			for (int i = 0; i < suppressed.length; i++) {
				System.err.println("suppressed exception: "
						+ suppressed[i].toString());
			}
		} 
		return;
	}
	public static void main(String[] args) {
		FindLogEntry(args[0]);
	}
}

public class Keywords {
  private static ScheduledExecutorService scheduler
      = Executors.newSingleThreadScheduledExecutor();
  private static CharBuffer log;
  private static final Object lock = new Object();

  // Map log file into memory, and periodically reload
  static {
    try {
      FileChannel channel = new FileInputStream(
          "path").getChannel();

      // Get the file's size and map it into memory
      int size = (int) channel.size();
      final MappedByteBuffer mappedBuffer = channel.map(
          FileChannel.MapMode.READ_ONLY, 0, size);

      Charset charset = Charset.forName("ISO-8859-15");
      final CharsetDecoder decoder = charset.newDecoder();

      log = decoder.decode(mappedBuffer); // Read file into char buffer

      Runnable periodicLogRead = new Runnable() {
        @Override public void run() {
          synchronized(lock) { 
            try {
              log = decoder.decode(mappedBuffer);
            } catch (CharacterCodingException e) {
              // Forward to handler 
            } 
          }
        }
      };
      scheduler.scheduleAtFixedRate(periodicLogRead, 
                                    0, 5, TimeUnit.SECONDS);
    } catch (Throwable t) {
      // Forward to handler
    }
  }


  public static Set<String> suggestSearches(String search) {
    synchronized(lock) {
      Set<String> searches = new HashSet<String>();

      // Construct regex dynamically from user string
      String regex = "(.*? +public\\[\\d+\\] +.*" + search + ".*)";
  
      Pattern keywordPattern = Pattern.compile(regex);
      Matcher logMatcher = keywordPattern.matcher(log);
      while (logMatcher.find()) {
        String found = logMatcher.group(1);
        searches.add(found);
      }
      return searches;
    }  
  }

}