Struct WalFileHeader 

pub struct WalFileHeader {
    pub page_size: u32,
    pub checkpoint_seq: u32,
    pub salt: WalSalt,
}

R858-B18 — the 32-byte -wal file header, read straight off disk with no engine open. Ground truth about which WAL generation is on disk and how far it has been written, independent of anything turso caches.

Only the three fields that move are kept. The rest of the header (magic, format version, the two header checksums) is either constant for a given build or a function of these; a change to any of it that did not move one of these three would not be a change this crate can act on.

Fields

page_size: u32

Page size the WAL’s frames carry (bytes 8..12).

checkpoint_seq: u32

Checkpoint sequence (bytes 12..16) — the field tail_frames used to key restart detection on before WalGeneration paired it with the salt.

salt: WalSalt

The generation’s salt (bytes 16..24).

Implementations

impl WalFileHeader

pub const SIZE: usize = 32

SQLite’s WAL header is exactly this many bytes, ahead of frame 1.

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

Parse a WAL header out of the first Self::SIZE bytes of a -wal file. None for anything shorter — a truncated or freshly-created WAL has no generation to name yet, which is an honest unknown rather than an error (see WalGeneration’s salt: None).

pub fn read(db_path: &str) -> Result<Option<Self>>

Read {db_path}-wal’s header. Ok(None) when the sidecar is absent (WAL folded and deleted, or journal_mode != WAL) or too short to parse.

Trait Implementations

impl Clone for WalFileHeader

fn clone(&self) -> WalFileHeader

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for WalFileHeader

impl Debug for WalFileHeader

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

Formats the value using the given formatter.

impl Eq for WalFileHeader

impl PartialEq for WalFileHeader

fn eq(&self, other: &WalFileHeader) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for WalFileHeader