Package org.apache.nifi.util

Class NaiveSearchRingBuffer

java.lang.Object
org.apache.nifi.util.NaiveSearchRingBuffer
public class NaiveSearchRingBuffer extends Object

A RingBuffer that can be used to scan byte sequences for subsequences.

This class implements an efficient naive search algorithm, which allows the user of the library to identify byte sequences in a stream on-the-fly so that the stream can be segmented without having to buffer the data.

The intended usage paradigm is: 

 final byte[] searchSequence = ...;
 final CircularBuffer buffer = new CircularBuffer(searchSequence);
 while ((int nextByte = in.read()) > 0) {
      if ( buffer.addAndCompare(nextByte) ) {
          // This byte is the last byte in the given sequence
      } else {
          // This byte does not complete the given sequence
      }
 }

  • Field Details

    • lookingFor

      private final byte[] lookingFor

    • buffer

      private final int[] buffer

    • insertionPointer

      private int insertionPointer

    • bufferSize

      private long bufferSize

  • Constructor Details

    • NaiveSearchRingBuffer

      public NaiveSearchRingBuffer(byte[] lookingFor)

  • Method Details

    • getBufferContents

      public byte[] getBufferContents()
      Returns:
      the contents of the internal buffer, which represents the last X bytes added to the buffer, where X is the minimum of the number of bytes added to the buffer or the length of the byte sequence for which we are looking

    • getOldestByte

      public int getOldestByte()
      Returns:
      the oldest byte in the buffer

    • isFilled

      public boolean isFilled()
      Returns:
      true if the number of bytes that have been added to the buffer is at least equal to the length of the byte sequence for which we are searching

    • clear

      public void clear()
      Clears the internal buffer so that a new search may begin

    • addAndCompare

      public boolean addAndCompare(byte data)
      Add the given byte to the buffer and notify whether or not the byte completes the desired byte sequence.
      Parameters:
      data - the data to add to the buffer
      Returns:
      true if this byte completes the byte sequence, false otherwise.