Class: Innodb::Page::FspHdrXdes

A specialized class for FSP_HDR (filespace header) and XDES (extent descriptor) page types. Each tablespace always has an FSP_HDR page as its first page (page 0), and has repeating XDES pages every 16,384 pages after that (page 16384, 32768, …). The FSP_HDR and XDES page structure is completely identical, with the exception that the FSP header structure is zero-filled on XDES pages, but populated on FSP_HDR pages.

The basic structure of FSP_HDR and XDES pages is: FIL header, FSP header, an array of 256 XDES entries, empty (unused) space, and FIL trailer.

Methods

decode_flags dump each_list each_region each_xdes entries_in_xdes_array fsp_header pos_fsp_header pos_xdes_array shift_page_size size_fsp_header size_xdes_array size_xdes_entry

Constants

FLAGS_PAGE_SIZE_SHIFT = 9 A value added to the adjusted exponent stored in the page size field of the flags in the FSP header.

Public Class methods

decode_flags(flags)

Decode the "flags" field in the FSP header, returning a hash of useful decodings of the flags (based on MySQl 5.6 definitions). The flags are:

Offset Size Description 0 1 Post-Antelope Flag. 1 4 Compressed Page Size (zip_size). This is stored as a

                  power of 2, minus 9. Since 0 is reserved to mean "not
                  compressed", the minimum value is 1, thus making the
                  smallest page size 1024 (2 ** (9 + 1)).

5 1 Atomic Blobs Flag. 6 4 System Page Size (innodb_page_size, UNIV_PAGE_SIZE).

                  The setting of the system page size when the tablespace
                  was created, stored in the same format as the compressed
                  page size above.

10 1 Data Directory Flag.

shift_page_size(page_size_shifted)

Public Instance methods

dump()

Dump the contents of a page for debugging purposes.

each_list() {|key, value if value.is_a?(Innodb::List)| ...}

Iterate through all lists in the file space.

each_region() {|region| ...}

each_xdes() {|Innodb::Xdes.new(self, c)| ...}

Iterate through all XDES entries in order. This is useful for debugging, but each of these entries is actually a node in some other list. The state field in the XDES entry indicates which type of list it is present in, although not necessarily which list (e.g. :fseg).

entries_in_xdes_array()

The number of entries in the XDES array. Defined as page size divided by extent size.

fsp_header()

Read the FSP (filespace) header, which contains a few counters and flags, as well as list base nodes for each list maintained in the filespace.

pos_fsp_header()

The FSP header immediately follows the FIL header.

pos_xdes_array()

The XDES entry array immediately follows the FSP header.

size_fsp_header()

The FSP header contains six 32-bit integers, one 64-bit integer, and 5 list base nodes.

size_xdes_array()

size_xdes_entry()