Trait ExecutorControl 

pub trait ExecutorControl:
    Send
    + Sync
    + 'static {
    // Required methods
    fn block_on<F>(&self, future: F) -> F::Output
       where F: Future;
    fn try_run(&self) -> bool;
    fn shutdown(&self);
    fn shutdown_timeout(&self, timeout: Duration);
    fn is_shutting_down(&self) -> bool;
    fn worker_count(&self) -> usize;
    fn load(&self) -> usize;
}

Provides control operations for executor lifecycle management.

This trait enables external systems to manage executor state transitions, perform health checks, and coordinate shutdown procedures.

Required Methods

fn block_on<F>(&self, future: F) -> F::Output

where F: Future,

Block the current thread until the future completes.

Behavior Guarantees

• Blocks calling thread until future resolves
• Supports nested async operations within the future
• Handles panic propagation from the future
• May deadlock if future depends on blocked thread

Performance Characteristics

• Optimal for CPU-bound futures with minimal I/O
• May block calling thread indefinitely
• Memory: Future size + execution context
• Suitable for main thread or dedicated blocking contexts

fn try_run(&self) -> bool

Attempt to run tasks without blocking.

Behavior Guarantees

• Non-blocking operation, returns immediately
• Returns true if any work was performed
• May perform multiple task executions in single call
• Suitable for integration with external event loops

Performance Characteristics

• O(1) operation, < 1μs typical latency
• Work stealing: Attempts to balance load across threads
• Suitable for event loops requiring non-blocking progress

fn shutdown(&self)

Shutdown the executor gracefully.

Behavior Guarantees

• Allows running tasks to complete naturally
• Prevents new tasks from being spawned
• Idempotent operation - safe to call multiple times
• Blocks until all worker threads have stopped
• Releases all resources and thread handles

Performance Characteristics

• Shutdown time: Depends on longest running task
• Resource cleanup: All memory and handles released
• Thread coordination: Uses efficient signaling

fn shutdown_timeout(&self, timeout: Duration)

Shutdown the executor with a timeout.

Behavior Guarantees

• Attempts graceful shutdown first
• Forces termination after timeout expires
• May result in task cancellation or abortion
• Guarantees executor stops within timeout + small overhead

Performance Characteristics

• Graceful phase: Same as shutdown()
• Forced phase: Immediate thread termination
• Timeout accuracy: ±10ms typical variance

fn is_shutting_down(&self) -> bool

Check if the executor is shutting down.

Behavior Guarantees

• Returns true once shutdown has been initiated
• Eventually consistent across all threads
• Remains true until executor is fully stopped

Performance Characteristics

• O(1) operation, < 10ns latency
• Non-blocking atomic read operation
• Memory ordering: Acquire semantics

fn worker_count(&self) -> usize

Get the number of worker threads.

Behavior Guarantees

• Returns configured number of worker threads
• Does not include async or blocking thread pools
• Constant value set during executor creation

Performance Characteristics

• O(1) operation, immediate return
• No synchronization overhead

fn load(&self) -> usize

Get the current load (number of pending tasks).

Behavior Guarantees

• Returns approximate pending task count
• Eventually consistent across distributed queues
• May include tasks currently being executed
• Does not include blocked or suspended tasks

Performance Characteristics

• O(1) operation for local queues
• May involve atomic reads across threads
• Latency: < 100ns typical

Dyn Compatibility

This trait is not dyn compatible.

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

Implementors