Struct WalSource 

pub struct WalSource<S: Source, W: Source> { /* private fields */ }

A database file with its log read on top of it.

This is a Source, not a special case inside the reader: a page that the log holds a committed version of is served from there, everything else from the main file, and nothing above this line has to know that a log exists at all. The reader that walks b-trees is the same code either way.

Reads are split at page boundaries before being served, so a caller that asks for a range spanning two pages gets each half from wherever that page currently lives.

Implementations

impl<S: Source, W: Source> WalSource<S, W>

pub fn new(main: S, log: Option<W>) -> Result<WalSource<S, W>>

Put log on top of main. Pass None when there is no log file, which is the state sqlite leaves behind after a checkpoint.

pub fn has_log(&self) -> bool

Whether any page is actually being served from the log.

Trait Implementations

impl<S: Source, W: Source> Source for WalSource<S, W>

fn accounts_for_wal(&self) -> bool

This source reads the log, so a wal mode database read through it is complete by construction.

fn read_at(&self, offset: u64, buf: &mut [u8]) -> Result<()>

Read exactly buf.len() bytes at offset. Reading past the end is an error; short reads are never returned.

fn len(&self) -> Result<u64>

Size in bytes.

fn is_empty(&self) -> Result<bool>