Trait AtomicJournal

Source

pub trait AtomicJournal: Send + Sync {
    // Required method
    fn append_atomic<'life0, 'life1, 'async_trait>(
        &'life0 self,
        run: RunId,
        epoch: Epoch,
        work: &'life1 dyn AtomicWork,
    ) -> Pin<Box<dyn Future<Output = Result<Vec<Record>, StoreError>> + Send + 'async_trait>>
       where Self: 'async_trait,
             'life0: 'async_trait,
             'life1: 'async_trait;
}

Expand description

A store whose own transaction a co-located resource can join.

Reached through JournalStore::atomic, which answers None for a backend that cannot offer this. Absence is the honest answer and it is checked where it is cheap — at registration, not at commit.

Required Methods§

Source

fn append_atomic<'life0, 'life1, 'async_trait>( &'life0 self, run: RunId, epoch: Epoch, work: &'life1 dyn AtomicWork, ) -> Pin<Box<dyn Future<Output = Result<Vec<Record>, StoreError>> + Send + 'async_trait>>
where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Run work and append what it returns, in one transaction, fenced by epoch exactly as an ordinary append is.

The run is named rather than read from the records, because the fence is taken before the work runs. Deriving it afterwards would execute a displaced writer’s statements and only then discover it had no right to — harmless for a transaction, and a bad habit to build a fence on.

The fence is not optional here and not weaker: a displaced writer that could commit a resource change because it arrived wrapped in a transaction would be a fence with a hole in it shaped like this feature.