asyn-rs 0.24.0

Rust port of EPICS asyn - async device I/O framework
Documentation 
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use std::sync::atomic::{AtomicU64, Ordering};
use std::time::Duration;

use crate::services::PortServices;

/// C `pasynBase->autoConnectTimeout` (asynManager.c:110), initialised to
/// `DEFAULT_AUTOCONNECT_TIMEOUT` = 0.5 s (:49, :507) and rewritten by
/// `asynSetAutoConnectTimeout` (:2370-2377).
///
/// Process-global on purpose: C has exactly one `pasynBase`, and each port
/// registration reads the value that is current *then* (:2135). Microseconds,
/// so the shell's `double` seconds survives the round trip.
static AUTO_CONNECT_TIMEOUT_US: AtomicU64 = AtomicU64::new(500_000);

/// The registration connect-wait every new port gets — C's
/// `pasynBase->autoConnectTimeout` read at :2135.
pub fn auto_connect_timeout() -> Duration {
    Duration::from_micros(AUTO_CONNECT_TIMEOUT_US.load(Ordering::Relaxed))
}

/// C `pasynManager->setAutoConnectTimeout(double)` — the iocsh
/// `asynSetAutoConnectTimeout`. Applies to ports registered after this call,
/// exactly as in C. A negative or NaN value collapses to zero (no wait), which
/// is what C's `epicsEventWaitWithTimeout` does with one.
pub fn set_auto_connect_timeout(timeout: Duration) {
    AUTO_CONNECT_TIMEOUT_US.store(timeout.as_micros() as u64, Ordering::Relaxed);
}

/// Configuration for a port runtime.
#[derive(Debug, Clone)]
pub struct RuntimeConfig {
    /// Channel capacity for the command channel.
    pub channel_capacity: usize,
    /// Auto-connect on startup.
    pub auto_connect: bool,
    /// Backoff configuration for auto-connect retries.
    pub connect_backoff: BackoffConfig,
    /// Supervision policy.
    pub supervision: SupervisionPolicy,
    /// How long port creation waits for an `auto_connect` port to come up
    /// before returning — C `waitConnect(pport->pconnectUser,
    /// pasynBase->autoConnectTimeout)` at the end of registration
    /// (asynManager.c:2135), with `DEFAULT_AUTOCONNECT_TIMEOUT` = 0.5 s (:49,
    /// :507). It bounds the wait; it does not decide the outcome — a port that
    /// has not connected by then keeps retrying on its own timer, exactly as C's
    /// does, and registration still succeeds.
    pub auto_connect_timeout: Duration,
    /// The trace configuration and exception list the port is created with —
    /// C's `pasynBase`. Defaults to the process-wide
    /// [`PortServices::global()`], so a port built with a default config is
    /// still traceable and still announces exceptions; a
    /// [`crate::manager::PortManager`] carrying its own `TraceManager`
    /// substitutes its own here.
    pub services: PortServices,
}

impl Default for RuntimeConfig {
    fn default() -> Self {
        Self {
            channel_capacity: 1024,
            auto_connect: true,
            connect_backoff: BackoffConfig::default(),
            supervision: SupervisionPolicy::default(),
            auto_connect_timeout: auto_connect_timeout(),
            services: PortServices::global(),
        }
    }
}

/// Backoff configuration for retries.
#[derive(Debug, Clone)]
pub struct BackoffConfig {
    pub initial: Duration,
    pub max: Duration,
    pub multiplier: f64,
}

impl Default for BackoffConfig {
    fn default() -> Self {
        Self {
            initial: Duration::from_millis(100),
            max: Duration::from_secs(30),
            multiplier: 2.0,
        }
    }
}

/// Supervision policy for runtime actors.
#[derive(Debug, Clone)]
pub struct SupervisionPolicy {
    /// Maximum restart attempts before giving up.
    pub max_restarts: usize,
    /// Window in which max_restarts is counted.
    pub restart_window: Duration,
}

impl Default for SupervisionPolicy {
    fn default() -> Self {
        Self {
            max_restarts: 5,
            restart_window: Duration::from_secs(60),
        }
    }
}