Module run 

The per-run journal machine.

Workflow code is deterministic between journal operations. Every operation the code starts (step, sleep, wait_for, child, now, …) takes the next sequence number, so an operation’s identity is the order in which the code called it. Results come back as deliveries, and the journal records deliveries in the order they were handed to the code. Replay hands recorded results back in exactly that order, one at a time, letting the code run until it is quiescent in between. Live completions that arrive while replay is still in progress are held until the recorded ones are all delivered. Live execution uses the same one-at-a-time rule, so a parallel branch can never observe a different interleaving after a crash.

Accepted updates are deliveries too: an update’s handler starts at the update’s place in the journal, so its operations take the same sequence numbers on every run.

The machine does no I/O. It tells the host which records to append and when a step function may run; the host (the embedded engine, a language binding or a remote worker) does the rest.

Structs

DeterminismError

The code did something its journal says it did not do the first time.

Outcome

What an operation resolves to.

RunInfo

Identity and input of a run, from its Start record.

RunMachine

StreamOpen

What RunMachine::stream_open tells the writer.

Enums

Arm

What the host must do after the code starts a sleep, wait or child.

AwaitStart

What the host must do after the code starts an async completion.

Completion

A live completion reported by the host.

LiveRecord

The record of a Next::DeliverLive, less what its outcome holds.

Next

The next thing to hand to the code.

OpKind

The kinds of journal operations workflow code can start.

StepStart

What the host must do after the code starts a step.

Functions

empty

The empty payload, shared on this thread (a clone, not an allocation).