Struct LogWriter 

pub struct LogWriter {
    pub(crate) raw: NonNull<TlwWriter>,
}

One SQLite log being written by the C++ writer.

Create it, write the header, then the pages between begin_log and end_log. Dropping it closes the database; pages written since begin_log without an end_log are rolled back.

Fields

raw: NonNull<TlwWriter>

The C handle; never null, and owned: closed exactly once, in Drop.

Implementations

impl LogWriter

pub fn create( path: &Path, config: &Config, replace: bool, ) -> Result<Self, WriterError>

Creates a log at path for a tag with config, replacing an existing file when replace is true.

Errors

When the library was built from a different interface version, the path is not UTF-8 or contains a NUL, or the database cannot be created (the writer’s message says why).

pub fn write_header(&mut self, header: &LogHeader) -> Result<(), WriterError>

Writes header: its parts, then the info, calibration and state tables and the tag’s data tables. Call once, first.

The parts are passed one at a time (tlw_header_add) and written together (tlw_write_header), so the C side never needs a header message of its own and proto/ gains nothing for this interface. The parts accumulate in the handle: a second call would pass them again and the writer would fail creating tables that exist.

Errors

When a part is rejected or the writer fails, for example because the header’s tag type differs from the one given to create.

pub fn write_info( &mut self, field: &str, value: &str, ) -> Result<(), WriterError>

Adds a row to the info table, after the header.

Errors

When a string contains a NUL byte, or the writer fails.

pub fn begin_log(&mut self) -> Result<(), WriterError>

Starts the data log: the pages that follow are written in one transaction, committed by end_log.

Errors

When the transaction cannot be started.

pub fn write_log(&mut self, ack: &Ack) -> Result<usize, WriterError>

Decodes and writes one data-log page, the Ack as the tag returned it.

Returns how many log records the page consumed, which advances the index of the next page to request, or 0 at the end of the log. Both depend on the tag type, which is why the writer decides them, and why a download must call this synchronously, page by page: the next request cannot be formed until it returns.

Errors

When the writer rejects the page or the database write fails.

pub fn end_log(&mut self) -> Result<(), WriterError>

Commits the data log.

Errors

When the commit fails.

pub(crate) fn add_part( &mut self, kind: c_int, message: &impl Message, ) -> Result<(), WriterError>

Passes one header part to the writer.

Errors

When the library cannot parse the encoding (a version mismatch).

pub(crate) fn check(&self, status: c_int) -> Result<(), WriterError>

Turns a C status (1 success, 0 failure) into a Result.

Errors

When status is not 1, with the handle’s last error.

pub(crate) fn last_error(&self) -> WriterError

The handle’s last error, copied out of the library.

Trait Implementations

impl Drop for LogWriter

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.

impl Send for LogWriter