Performance improvement for Lucene.net with memory mapped files (bis)

[Van Den Berghe, Vincent]

Further testing has indicated that mapped memory accessors will throw an 
exception if the position argument is already at the end, even if zero bytes 
are read.
The methods mentioned previously therefore become:

              public override ByteBuffer Get(byte[] dst, int offset, int length)
              {
                     CheckBounds(offset, length, dst.Length);
                     if (length > Remaining)
                           throw new BufferUnderflowException();
                     // we need to check for 0-length reads, since ReadArray 
will throw an ArgumentOutOfRange exception if position is at the end
                     // even when nothing is read
                     if (length > 0)
                           _accessor.ReadArray(Ix(NextGetIndex(length)), dst, 
offset, length);
                     return this;
              }


And

              public override ByteBuffer Put(byte[] src, int offset, int length)
              {
                     CheckBounds(offset, length, src.Length);
                     if (length > Remaining)
                           throw new BufferOverflowException();
                     // we need to check for 0-length writes, since ReadArray 
will throw an ArgumentOutOfRange exception if position is at the end
                     // even when nothing is read
                     if (length > 0)
                           _accessor.WriteArray(Ix(NextPutIndex(length)), src, 
offset, length);
                     return this;
              }


Vincent