Struct UndoSegmentHeader 

pub struct UndoSegmentHeader {
    pub state: UndoState,
    pub last_log: u16,
}

Parsed undo segment header (only on first page of undo segment).

Fields

state: UndoState

State of the undo segment.

last_log: u16

Offset of the last undo log header on the segment.

Implementations

impl UndoSegmentHeader

pub fn parse(page_data: &[u8]) -> Option<Self>

Parse an undo segment header from a full page buffer.

The segment header follows the page header at FIL_PAGE_DATA + TRX_UNDO_PAGE_HDR_SIZE.

Examples

use idb::innodb::undo::{UndoSegmentHeader, UndoState};
use byteorder::{BigEndian, ByteOrder};

// Need at least 38 (FIL header) + 18 (page header) + 30 (seg header) = 86 bytes.
let mut page = vec![0u8; 96];
let base = 38 + 18; // FIL_PAGE_DATA + TRX_UNDO_PAGE_HDR_SIZE

// State = CACHED (2) at base+0
BigEndian::write_u16(&mut page[base..], 2);
// Last log offset at base+2
BigEndian::write_u16(&mut page[base + 2..], 200);

let hdr = UndoSegmentHeader::parse(&page).unwrap();
assert_eq!(hdr.state, UndoState::Cached);
assert_eq!(hdr.last_log, 200);

Trait Implementations

impl Clone for UndoSegmentHeader

fn clone(&self) -> UndoSegmentHeader

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for UndoSegmentHeader

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Serialize for UndoSegmentHeader

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.