Class BlockAllocationTableWriter

  • All Implemented Interfaces:
    BATManaged, BlockWritable

    public class BlockAllocationTableWriter
    extends Object
    implements BlockWritable, BATManaged
    This class manages and creates the Block Allocation Table, which is basically a set of linked lists of block indices.

    Each block of the filesystem has an index. The first block, the header, is skipped; the first block after the header is index 0, the next is index 1, and so on.

    A block's index is also its index into the Block Allocation Table. The entry that it finds in the Block Allocation Table is the index of the next block in the linked list of blocks making up a file, or it is set to -2: end of list.

    Author:
    Marc Johnson (mjohnson at apache dot org)
    • Constructor Detail

      • BlockAllocationTableWriter

        public BlockAllocationTableWriter()
        create a BlockAllocationTableWriter
    • Method Detail

      • createBlocks

        public int createBlocks​(int size)
        Create the BATBlocks we need
        Returns:
        start block index of BAT blocks
      • allocateSpace

        public int allocateSpace​(int blockCount)
        Allocate space for a block of indices
        Parameters:
        blockCount - the number of blocks to allocate space for
        Returns:
        the starting index of the blocks
      • getStartBlock

        public int getStartBlock()
        get the starting block
        Returns:
        the starting block index
      • writeBlocks

        public void writeBlocks​(OutputStream stream)
                         throws IOException
        Write the storage to an OutputStream
        Specified by:
        writeBlocks in interface BlockWritable
        Parameters:
        stream - the OutputStream to which the stored data should be written
        Throws:
        IOException - on problems writing to the specified stream
      • countBlocks

        public int countBlocks()
        Return the number of BigBlock's this instance uses
        Specified by:
        countBlocks in interface BATManaged
        Returns:
        count of BigBlock instances
      • setStartBlock

        public void setStartBlock​(int start_block)
        Set the start block for this instance
        Specified by:
        setStartBlock in interface BATManaged
        Parameters:
        start_block -