Trait persist::storage::Log[−][src]

pub trait Log {
    fn write_sync(&mut self, buf: Vec<u8>) -> Result<SeqNo, Error>;

    fn snapshot<F>(&self, logic: F) -> Result<Range<SeqNo>, Error>
    where
        F: FnMut(SeqNo, &[u8]) -> Result<(), Error>;

    fn truncate(&mut self, upper: SeqNo) -> Result<(), Error>;

    fn close(&mut self) -> Result<bool, Error>;
}
Expand description

An abstraction over an append-only bytes log.

Each written entry is assigned a unique, incrementing SeqNo, which can be later used when draining data back out of the log.

  • Invariant: Implementations are responsible for ensuring that they are exclusive writers to this location.

Required methods

Synchronously appends an entry.

TODO: Figure out our async story so we can batch up multiple of these into one disk flush.

Returns a consistent snapshot of all written but not yet truncated entries.

  • Invariant: all returned entries must have a sequence number within the declared [lower, upper) range of sequence numbers.

Removes all entries with a SeqNo strictly less than the given upper bound.

Synchronously closes the log, releasing exclusive-writer locks and causing all future commands to error.

Implementations must be idempotent. Returns true if the log had not previously been closed.

Implementors