Trait Ledger 

pub trait Ledger {
    // Required method
    fn append(&mut self, draft: EventDraft) -> Result<EventRef, AxError>;

    // Provided method
    fn append_all(
        &mut self,
        drafts: Vec<EventDraft>,
    ) -> Result<Vec<EventRef>, AxError> { ... }
}

The only write entrance to history.

Required Methods

fn append(&mut self, draft: EventDraft) -> Result<EventRef, AxError>

Provided Methods

fn append_all( &mut self, drafts: Vec<EventDraft>, ) -> Result<Vec<EventRef>, AxError>

Every draft in one wave, answered positionally.

A durable write costs one disk barrier, and a barrier costs the same whether one record or fifty ride on it. Measured on one windows-x86_64 NVMe machine: 585 µs per record at one record per barrier against 13 µs at fifty, of which the write itself is about 2.5 µs. A caller that already holds a wave therefore pays forty times what the disk asks by handing it over one at a time.

The contract of Ledger::append holds for every element: when this answers Ok, every record in it is durable, and the refs come back in the order the drafts were given. The default implementation appends one at a time, which is correct and is what a store with no batch of its own can honestly offer.

Errors

The first refusal ends the wave. Records before it may already be durable, which is the same promise a single append makes when the one after it fails.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors