Module executor 

Workflow execution engine.

Parallel Fan-out / Fan-in

WorkflowExecutor::execute automatically discovers independent groups of tasks — tasks whose dependencies are all satisfied at the same time — and launches them concurrently. When all tasks in a fan-out group complete the join point (fan-in) tasks are unblocked. This happens naturally through the dependency-tracking loop; no explicit graph analysis is required.

Scheduling correctness

A task whose dependencies are not yet satisfied is retried on the next pass, never dropped: the scheduler repeatedly rescans the set of not-yet-dispatched tasks (a fixpoint loop) until every task has either run to completion, been synthetically completed from a checkpoint, or been skipped. WorkflowState::Completed is returned only when that fixpoint is reached with an empty failure set. A real task failure, or a dependency that can never be satisfied because an upstream task failed or was skipped, is reported as WorkflowState::Failed (or a scheduling WorkflowError if no task can ever become ready again) — never silently downgraded to a fabricated success.

Pause / Resume

Call WorkflowExecutor::pause to signal the executor to stop launching new tasks after the current wave completes. The checkpoint is serialised to a JSON string containing the completed task IDs and execution context variables. Pass that string to WorkflowExecutor::resume_from_checkpoint to reconstruct the state and continue.

Structs

DefaultTaskExecutor

Default task executor implementation.

ExecutionCheckpoint

Serializable checkpoint for pause/resume of workflow execution.

ExecutionContext

Execution context shared across task executions.

ExecutionResult

Workflow execution result.

StatusUpdate

A buffered status update pending persistence.

WorkflowExecutor

Workflow executor.

Enums

WorkflowControl

High-level control signal for a running WorkflowExecutor.

Traits

TaskExecutor

Task executor trait.

Functions

parse_condition

Parse and evaluate a single condition expression against the execution context.