Class BufferedIndexInput

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      private static class  BufferedIndexInput.SlicedIndexInput
      Implementation of an IndexInput that reads from a portion of a file.
    • Method Summary

      All Methods Static Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method Description
      static int bufferSize​(IOContext context)
      Returns default buffer sizes for the given IOContext
      private void checkBufferSize​(int bufferSize)  
      BufferedIndexInput clone()
      Returns a clone of this stream.
      protected int flushBuffer​(IndexOutput out, long numBytes)
      Flushes the in-memory buffer to the given output, copying at most numBytes.
      int getBufferSize()
      Returns buffer size.
      long getFilePointer()
      Returns the current position in this file, where the next read will occur.
      protected void newBuffer​(byte[] newBuffer)  
      byte readByte()
      Reads and returns a single byte.
      byte readByte​(long pos)
      Reads a byte at the given position in the file
      void readBytes​(byte[] b, int offset, int len)
      Reads a specified number of bytes into an array at the specified offset.
      void readBytes​(byte[] b, int offset, int len, boolean useBuffer)
      Reads a specified number of bytes into an array at the specified offset with control over whether the read should be buffered (callers who have their own buffer should pass in "false" for useBuffer).
      int readInt()
      Reads four bytes and returns an int.
      int readInt​(long pos)
      Reads an integer at the given position in the file
      protected abstract void readInternal​(byte[] b, int offset, int length)
      Expert: implements buffer refill.
      long readLong()
      Reads eight bytes and returns a long.
      long readLong​(long pos)
      Reads a long at the given position in the file
      short readShort()
      Reads two bytes and returns a short.
      short readShort​(long pos)
      Reads a short at the given position in the file
      int readVInt()
      Reads an int stored in variable-length format.
      long readVLong()
      Reads a long stored in variable-length format.
      private void refill()  
      void seek​(long pos)
      Sets current position in this file, where the next read will occur.
      protected abstract void seekInternal​(long pos)
      Expert: implements seek.
      void setBufferSize​(int newSize)
      Change the buffer size used by this IndexInput
      IndexInput slice​(java.lang.String sliceDescription, long offset, long length)
      Creates a slice of this index input, with the given description, offset, and length.
      static BufferedIndexInput wrap​(java.lang.String sliceDescription, IndexInput other, long offset, long length)
      Wraps a portion of another IndexInput with buffering.
      • Methods inherited from class java.lang.Object

        equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
    • Field Detail

      • BUFFER_SIZE

        public static final int BUFFER_SIZE
        Default buffer size set to 1024.
        See Also:
        Constant Field Values
      • MIN_BUFFER_SIZE

        public static final int MIN_BUFFER_SIZE
        Minimum buffer size allowed
        See Also:
        Constant Field Values
      • MERGE_BUFFER_SIZE

        public static final int MERGE_BUFFER_SIZE
        A buffer size for merges set to 4096.
        See Also:
        Constant Field Values
      • bufferSize

        private int bufferSize
      • buffer

        protected byte[] buffer
      • bufferStart

        private long bufferStart
      • bufferLength

        private int bufferLength
      • bufferPosition

        private int bufferPosition
    • Constructor Detail

      • BufferedIndexInput

        public BufferedIndexInput​(java.lang.String resourceDesc)
      • BufferedIndexInput

        public BufferedIndexInput​(java.lang.String resourceDesc,
                                  IOContext context)
      • BufferedIndexInput

        public BufferedIndexInput​(java.lang.String resourceDesc,
                                  int bufferSize)
        Inits BufferedIndexInput with a specific bufferSize
    • Method Detail

      • setBufferSize

        public final void setBufferSize​(int newSize)
        Change the buffer size used by this IndexInput
      • newBuffer

        protected void newBuffer​(byte[] newBuffer)
      • getBufferSize

        public final int getBufferSize()
        Returns buffer size. @see #setBufferSize
      • checkBufferSize

        private void checkBufferSize​(int bufferSize)
      • readBytes

        public final void readBytes​(byte[] b,
                                    int offset,
                                    int len)
                             throws java.io.IOException
        Description copied from class: DataInput
        Reads a specified number of bytes into an array at the specified offset.
        Specified by:
        readBytes in class DataInput
        Parameters:
        b - the array to read bytes into
        offset - the offset in the array to start storing bytes
        len - the number of bytes to read
        Throws:
        java.io.IOException
        See Also:
        DataOutput.writeBytes(byte[],int)
      • readBytes

        public final void readBytes​(byte[] b,
                                    int offset,
                                    int len,
                                    boolean useBuffer)
                             throws java.io.IOException
        Description copied from class: DataInput
        Reads a specified number of bytes into an array at the specified offset with control over whether the read should be buffered (callers who have their own buffer should pass in "false" for useBuffer). Currently only BufferedIndexInput respects this parameter.
        Overrides:
        readBytes in class DataInput
        Parameters:
        b - the array to read bytes into
        offset - the offset in the array to start storing bytes
        len - the number of bytes to read
        useBuffer - set to false if the caller will handle buffering.
        Throws:
        java.io.IOException
        See Also:
        DataOutput.writeBytes(byte[],int)
      • readInt

        public final int readInt()
                          throws java.io.IOException
        Description copied from class: DataInput
        Reads four bytes and returns an int.
        Overrides:
        readInt in class DataInput
        Throws:
        java.io.IOException
        See Also:
        DataOutput.writeInt(int)
      • readVInt

        public final int readVInt()
                           throws java.io.IOException
        Description copied from class: DataInput
        Reads an int stored in variable-length format. Reads between one and five bytes. Smaller values take fewer bytes. Negative numbers are supported, but should be avoided.

        The format is described further in DataOutput.writeVInt(int).

        Overrides:
        readVInt in class DataInput
        Throws:
        java.io.IOException
        See Also:
        DataOutput.writeVInt(int)
      • readVLong

        public final long readVLong()
                             throws java.io.IOException
        Description copied from class: DataInput
        Reads a long stored in variable-length format. Reads between one and nine bytes. Smaller values take fewer bytes. Negative numbers are not supported.

        The format is described further in DataOutput.writeVInt(int).

        Overrides:
        readVLong in class DataInput
        Throws:
        java.io.IOException
        See Also:
        DataOutput.writeVLong(long)
      • refill

        private void refill()
                     throws java.io.IOException
        Throws:
        java.io.IOException
      • readInternal

        protected abstract void readInternal​(byte[] b,
                                             int offset,
                                             int length)
                                      throws java.io.IOException
        Expert: implements buffer refill. Reads bytes from the current position in the input.
        Parameters:
        b - the array to read bytes into
        offset - the offset in the array to start storing bytes
        length - the number of bytes to read
        Throws:
        java.io.IOException
      • seek

        public final void seek​(long pos)
                        throws java.io.IOException
        Description copied from class: IndexInput
        Sets current position in this file, where the next read will occur. If this is beyond the end of the file then this will throw EOFException and then the stream is in an undetermined state.
        Specified by:
        seek in class IndexInput
        Throws:
        java.io.IOException
        See Also:
        IndexInput.getFilePointer()
      • clone

        public BufferedIndexInput clone()
        Description copied from class: IndexInput
        Returns a clone of this stream.

        Clones of a stream access the same data, and are positioned at the same point as the stream they were cloned from.

        Expert: Subclasses must ensure that clones may be positioned at different points in the input from each other and from the stream they were cloned from.

        Warning: Lucene never closes cloned IndexInputs, it will only call IndexInput.close() on the original object.

        If you access the cloned IndexInput after closing the original object, any readXXX methods will throw AlreadyClosedException.

        This method is NOT thread safe, so if the current IndexInput is being used by one thread while clone is called by another, disaster could strike.

        Overrides:
        clone in class IndexInput
      • slice

        public IndexInput slice​(java.lang.String sliceDescription,
                                long offset,
                                long length)
                         throws java.io.IOException
        Description copied from class: IndexInput
        Creates a slice of this index input, with the given description, offset, and length. The slice is sought to the beginning.
        Specified by:
        slice in class IndexInput
        Throws:
        java.io.IOException
      • flushBuffer

        protected final int flushBuffer​(IndexOutput out,
                                        long numBytes)
                                 throws java.io.IOException
        Flushes the in-memory buffer to the given output, copying at most numBytes.

        NOTE: this method does not refill the buffer, however it does advance the buffer position.

        Returns:
        the number of bytes actually flushed from the in-memory buffer.
        Throws:
        java.io.IOException
      • bufferSize

        public static int bufferSize​(IOContext context)
        Returns default buffer sizes for the given IOContext
      • wrap

        public static BufferedIndexInput wrap​(java.lang.String sliceDescription,
                                              IndexInput other,
                                              long offset,
                                              long length)
        Wraps a portion of another IndexInput with buffering.

        Please note: This is in most cases ineffective, because it may double buffer!