Struct FileLogPersistence 

pub struct FileLogPersistence { /* private fields */ }

Two-slot, versioned and checksummed file store for one log’s snapshots, as FileAuditLogPersistence keeps an Audit Log’s.

Commits alternate between base.slot0 and base.slot1 by generation, and each one fully writes and synchronizes its slot, so a commit cut off part way leaves the other slot’s snapshot to load. The first commit to a slot also synchronizes its directory (on Unix; see durable).

Loading takes the newer valid slot. A slot that is damaged (truncated, a bad checksum, or contents that don’t decode or don’t hold together) is passed over for the other one, with a warning; loading fails when both are damaged. It also fails, without falling back, when a slot belongs to another object or uses a schema this build can’t read, when reading either slot fails, and when both slots hold different snapshots of one generation. It does not coordinate several processes.

Implementations

impl FileLogPersistence

pub fn new(base_path: impl AsRef<Path>) -> Result<Self, Error>

Use base_path.slot0 and base_path.slot1. An empty path is refused with Error::OutOfRange.

pub fn slot_paths(&self) -> [PathBuf; 2]

The two slot paths, for application backup and diagnostics.

Trait Implementations

impl Clone for FileLogPersistence

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for FileLogPersistence

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

Formats the value using the given formatter.

impl LogPersistence<BACnetEventLogRecord> for FileLogPersistence

fn load( &self, expected_object: ObjectIdentifier, ) -> Result<Option<LogSnapshot<BACnetEventLogRecord>>, Error>

Load the newest valid snapshot for expected_object, or None when storage holds none yet.

fn commit( &self, snapshot: &LogSnapshot<BACnetEventLogRecord>, ) -> Result<(), Error>

Durably store snapshot, whose generation is one past the last one committed (or loaded).

impl LogPersistence<BACnetLogMultipleRecord> for FileLogPersistence

fn load( &self, expected_object: ObjectIdentifier, ) -> Result<Option<LogSnapshot<BACnetLogMultipleRecord>>, Error>

Load the newest valid snapshot for expected_object, or None when storage holds none yet.

fn commit( &self, snapshot: &LogSnapshot<BACnetLogMultipleRecord>, ) -> Result<(), Error>

Durably store snapshot, whose generation is one past the last one committed (or loaded).

impl LogPersistence<BACnetLogRecord> for FileLogPersistence

fn load( &self, expected_object: ObjectIdentifier, ) -> Result<Option<LogSnapshot<BACnetLogRecord>>, Error>

Load the newest valid snapshot for expected_object, or None when storage holds none yet.

fn commit(&self, snapshot: &LogSnapshot<BACnetLogRecord>) -> Result<(), Error>

Durably store snapshot, whose generation is one past the last one committed (or loaded).