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ExecutionBackend

zeph_durable::backend

Trait ExecutionBackend 

Source 
pub trait ExecutionBackend:
    Journal
    + Send
    + Sync
    + Sealed {
    // Required methods
    fn capabilities(&self) -> BackendCapabilities;
    fn lookup_committed_result(
        &self,
        id: ExecutionId,
        idem_key: IdempotencyKey,
    ) -> impl Future<Output = Result<Option<JournalEntry>, DurableError>> + Send;
}
Expand description

A durable-execution persistence backend.

ExecutionBackend is the closed set of journal engines Zeph ships. It is sealed via [crate::sealed::Sealed]: external crates cannot implement it and must dispatch through DurableBackendEnum. Every backend is also a Journal, so the append/read/finalize/prune surface is available uniformly.

§Contract for implementors

  • capabilities MUST return a stable description of the backend; callers cache it and adapt their journaling strategy to it.
  • The Journal half MUST serialize writes through a single connection so appends receive a monotonic JournalSeq.

Additional entry points (execution open, promise resolution, timer scan) are added as the higher layers land; because the trait is sealed, those additions do not break callers.

Required Methods§

Source

fn capabilities(&self) -> BackendCapabilities

Return this backend’s stable capability description.

Source

fn lookup_committed_result( &self, id: ExecutionId, idem_key: IdempotencyKey, ) -> impl Future<Output = Result<Option<JournalEntry>, DurableError>> + Send

Look up a committed StepResult anywhere in an execution by its IdempotencyKey.

This is the point-lookup behind INV-13: after a DurableError::ReplayDivergence the execution restarts fresh, but a guarded effect that already committed its result must not re-fire. Before invoking a guarded operation the durable step consults this lookup; a Some result means the effect already succeeded and its journaled value is returned instead. The key uniquely locates the row via the idx_durable_journal_idem_key index, so the lookup is O(log n).

§Errors

Returns DurableError::Decode if the located row cannot be reconstructed, or DurableError::Storage if the query fails.

Dyn Compatibility§

This trait is not dyn compatible.

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

Implementors§