Struct DrainManager 

pub struct DrainManager { /* private fields */ }

Manages graceful draining of workers in a distributed cluster.

Tasks are tracked per worker. When draining is requested the worker stops accepting new tasks and a WorkerState::Drained transition is triggered automatically once all in-flight tasks complete.

Implementations

impl DrainManager

pub fn new() -> Self

Create a new drain manager with no workers.

pub fn register(&mut self, worker_id: impl Into<String>)

Register a new worker in the Active state.

pub fn deregister(&mut self, worker_id: &str) -> bool

Deregister a worker. Returns true if it was present.

pub fn assign_task( &mut self, worker_id: &str, task_id: impl Into<String>, ) -> Result<(), DrainError>

Assign a task to a worker.

Fails with DrainError::WorkerDraining if the worker is draining or drained, and with DrainError::WorkerNotFound if unknown.

pub fn complete_task( &mut self, worker_id: &str, task_id: &str, ) -> Result<(), DrainError>

Mark a task as complete on a worker.

If the worker is draining and has no remaining in-flight tasks, it transitions to WorkerState::Drained automatically.

pub fn start_drain(&mut self, worker_id: &str) -> Result<(), DrainError>

Initiate graceful draining of a worker.

Returns DrainError::AlreadyDraining if already in progress. If the worker has no in-flight tasks it immediately becomes Drained.

pub fn force_drain( &mut self, worker_id: &str, ) -> Result<Vec<String>, DrainError>

Force-complete draining (e.g., after a timeout), discarding in-flight tasks.

pub fn state(&self, worker_id: &str) -> Option<&WorkerState>

Return the current state of a worker.

pub fn in_flight_count(&self, worker_id: &str) -> Option<usize>

Return the number of in-flight tasks on a worker.

pub fn drain_elapsed(&self, worker_id: &str) -> Option<Duration>

Return the time elapsed since draining started, if applicable.

pub fn timed_out_drains(&self, timeout: Duration) -> Vec<String>

Collect all workers whose drain has exceeded timeout.

These workers can then be force-drained to unblock rolling upgrades.

pub fn active_workers(&self) -> Vec<String>

Return ids of all Active workers (candidates to receive new tasks).

Trait Implementations

impl Debug for DrainManager

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for DrainManager

fn default() -> DrainManager

Returns the “default value” for a type.