Package org.terrier.compression.bit

Class BitFileInMemory

  • All Implemented Interfaces:
    java.io.Closeable, java.lang.AutoCloseable, BitInSeekable
    public class BitFileInMemory
extends java.lang.Object
implements BitInSeekable
    Class which enables a bit compressed file to be read wholly into memory and accessed from there with lot latency. This class will fail if the file is larger than Integer.MAX_VALUE. Use BitFileInMemoryLarge instead.
    Author:
    Craig Macdonald

    • Field Summary

      Fields 
      Modifier and Type Field Description
      protected byte[] inBuffer
      buffer in memory for the entire compressed file
      protected static org.slf4j.Logger logger
      The logger used

    • Constructor Summary

      Constructors 
      Constructor Description
      BitFileInMemory​(byte[] buffer)
      Create an object using the specified data as the compressed data
      BitFileInMemory​(java.io.InputStream is, long length)
      Loads the entire specified inputstream into memory.
      BitFileInMemory​(java.lang.String filename)
      Loads the entire file represented by filename into memory

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void close()
      Close this object.
      BitIn readReset​(long startByteOffset, byte startBitOffset)
      Reads from the file a specific number of bytes and after this call, a sequence of read calls may follow.
      BitIn readReset​(long startByteOffset, byte startBitOffset, long endByteOffset, byte endBitOffset)
      Reads from the file a specific number of bytes and after this call, a sequence of read calls may follow.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Field Detail

      • logger

        protected static final org.slf4j.Logger logger
        The logger used

      • inBuffer

        protected final byte[] inBuffer
        buffer in memory for the entire compressed file

    • Constructor Detail

      • BitFileInMemory

        public BitFileInMemory​(java.lang.String filename)
                throws java.io.IOException
        Loads the entire file represented by filename into memory
        Parameters:
        filename - Location of bit file to read into memory
        Throws:
        java.io.IOException - if anything goes wrong reading the file

      • BitFileInMemory

        public BitFileInMemory​(java.io.InputStream is,
                       long length)
                throws java.io.IOException
        Loads the entire specified inputstream into memory. Length is assumed to be as specified.
        Parameters:
        is - InputStream containing the compressed bitfile
        length - Expected length of the input stream
        Throws:
        java.io.IOException - if anything goes wrong reading the inputstream

      • BitFileInMemory

        public BitFileInMemory​(byte[] buffer)
        Create an object using the specified data as the compressed data

    • Method Detail

      • readReset

        public BitIn readReset​(long startByteOffset,
                       byte startBitOffset,
                       long endByteOffset,
                       byte endBitOffset)
        Reads from the file a specific number of bytes and after this call, a sequence of read calls may follow. The offsets given as arguments are inclusive. For example, if we call this method with arguments 0, 2, 1, 7, it will read in a buffer the contents of the underlying file from the third bit of the first byte to the last bit of the second byte.
        Specified by:
        readReset in interface BitInSeekable
        Parameters:
        startByteOffset - the starting byte to read from
        startBitOffset - the bit offset in the starting byte
        endByteOffset - the ending byte
        endBitOffset - the bit offset in the ending byte. This bit is the last bit of this entry.
        Returns:
        Returns the BitIn object to use to read that data

      • readReset

        public BitIn readReset​(long startByteOffset,
                       byte startBitOffset)
        Reads from the file a specific number of bytes and after this call, a sequence of read calls may follow. The offsets given as arguments are inclusive. For example, if we call this method with arguments 0, 2, 1, 7, it will read in a buffer the contents of the underlying file from the third bit of the first byte to the last bit of the second byte.
        Specified by:
        readReset in interface BitInSeekable
        Parameters:
        startByteOffset - the starting byte to read from
        startBitOffset - the bit offset in the starting byte
        Returns:
        Returns the BitIn object to use to read that data

      • close

        public void close()
        Close this object. Does nothing.
        Specified by:
        close in interface java.lang.AutoCloseable
        Specified by:
        close in interface java.io.Closeable