ByteBuffer readBytes()

in mavibot/src/main/java/org/apache/directory/mavibot/btree/RecordManager.java [1294:1363]
52 lines of code
5 McCabe index (conditional complexity)

    /* no qualifier */ByteBuffer readBytes( PageIO[] pageIos, long position )
    {
        // Read the byte[] length first
        int length = readInt( pageIos, position );
        position += INT_SIZE;

        // Compute the page in which we will store the data given the
        // current position
        int pageNb = computePageNb( position );

        // Compute the position in the current page
        int pagePos = ( int ) ( position + ( pageNb + 1 ) * LONG_SIZE + INT_SIZE ) - pageNb * pageSize;

        // Check that the length is correct : it should fit in the provided pageIos
        int pageEnd = computePageNb( position + length );

        if ( pageEnd > pageIos.length )
        {
            // This is wrong...
            LOG.error( "Wrong size : {}, it's larger than the number of provided pages {}", length, pageIos.length );
            throw new ArrayIndexOutOfBoundsException();
        }

        ByteBuffer pageData = pageIos[pageNb].getData();
        int remaining = pageData.capacity() - pagePos;

        if ( length == 0 )
        {
            // No bytes to read : return null;
            return null;
        }
        else
        {
            ByteBuffer bytes = ByteBuffer.allocate( length );

            while ( length > 0 )
            {
                if ( length <= remaining )
                {
                    pageData.mark();
                    pageData.position( pagePos );
                    int oldLimit = pageData.limit();
                    pageData.limit( pagePos + length );
                    bytes.put( pageData );
                    pageData.limit( oldLimit );
                    pageData.reset();
                    bytes.rewind();

                    return bytes;
                }

                pageData.mark();
                pageData.position( pagePos );
                int oldLimit = pageData.limit();
                pageData.limit( pagePos + remaining );
                bytes.put( pageData );
                pageData.limit( oldLimit );
                pageData.reset();
                pageNb++;
                pagePos = LINK_SIZE;
                pageData = pageIos[pageNb].getData();
                length -= remaining;
                remaining = pageData.capacity() - pagePos;
            }

            bytes.rewind();

            return bytes;
        }
    }