Struct UndoPageHeader 

pub struct UndoPageHeader {
    pub page_type: UndoPageType,
    pub start: u16,
    pub free: u16,
}

Parsed undo log page header.

Fields

page_type: UndoPageType

Type of undo log (INSERT or UPDATE).

start: u16

Offset of the start of undo log records on this page.

free: u16

Offset of the first free byte on this page.

Implementations

impl UndoPageHeader

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

Parse an undo page header from a full page buffer.

The undo page header starts at FIL_PAGE_DATA (byte 38).

Examples

use idb::innodb::undo::{UndoPageHeader, UndoPageType};
use byteorder::{BigEndian, ByteOrder};

// Build a minimal page buffer (at least 38 + 18 = 56 bytes).
let mut page = vec![0u8; 64];
let base = 38; // FIL_PAGE_DATA

// Undo page type = UPDATE (2) at offset base+0
BigEndian::write_u16(&mut page[base..], 2);
// Start offset at base+2
BigEndian::write_u16(&mut page[base + 2..], 80);
// Free offset at base+4
BigEndian::write_u16(&mut page[base + 4..], 160);

let hdr = UndoPageHeader::parse(&page).unwrap();
assert_eq!(hdr.page_type, UndoPageType::Update);
assert_eq!(hdr.start, 80);
assert_eq!(hdr.free, 160);

Trait Implementations

impl Clone for UndoPageHeader

fn clone(&self) -> UndoPageHeader

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for UndoPageHeader

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

Formats the value using the given formatter.

impl Serialize for UndoPageHeader

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

where __S: Serializer,

Serialize this value into the given Serde serializer.