asterisk-rs-core 0.1.1

Shared types, error framework, and event bus for asterisk-rs
Documentation 
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//! Shared configuration types used across protocol crates.

use std::time::Duration;

/// reconnection policy with exponential backoff and jitter
#[derive(Debug, Clone)]
pub struct ReconnectPolicy {
    pub initial_delay: Duration,
    pub max_delay: Duration,
    pub max_retries: Option<u32>,
    /// multiplicative factor per retry (default 2.0)
    pub backoff_factor: f64,
    /// whether to add random jitter to prevent thundering herd
    pub jitter: bool,
}

impl ReconnectPolicy {
    /// create an exponential backoff policy
    pub fn exponential(initial: Duration, max: Duration) -> Self {
        Self {
            initial_delay: initial,
            max_delay: max,
            max_retries: None,
            backoff_factor: 2.0,
            jitter: true,
        }
    }

    /// create a fixed-interval retry policy
    pub fn fixed(interval: Duration) -> Self {
        Self {
            initial_delay: interval,
            max_delay: interval,
            max_retries: None,
            backoff_factor: 1.0,
            jitter: false,
        }
    }

    /// set maximum number of retries (default: unlimited)
    pub fn with_max_retries(mut self, n: u32) -> Self {
        self.max_retries = Some(n);
        self
    }

    /// disable retry entirely
    pub fn none() -> Self {
        Self {
            initial_delay: Duration::ZERO,
            max_delay: Duration::ZERO,
            max_retries: Some(0),
            backoff_factor: 1.0,
            jitter: false,
        }
    }

    /// compute delay for a given attempt number (0-indexed)
    pub fn delay_for_attempt(&self, attempt: u32) -> Duration {
        if self.max_retries.is_some_and(|max| attempt >= max) {
            return Duration::ZERO;
        }
        let base = self.initial_delay.as_secs_f64() * self.backoff_factor.powi(attempt as i32);
        let capped = base.min(self.max_delay.as_secs_f64());

        if self.jitter {
            // simple jitter: uniform random between 0.5x and 1.0x of computed delay
            // use a deterministic-ish approach without pulling in rand
            let jitter_factor = 0.5 + 0.5 * pseudo_random_factor(attempt);
            Duration::from_secs_f64(capped * jitter_factor)
        } else {
            Duration::from_secs_f64(capped)
        }
    }
}

impl Default for ReconnectPolicy {
    fn default() -> Self {
        Self::exponential(Duration::from_secs(1), Duration::from_secs(60))
    }
}

/// connection state for health monitoring
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ConnectionState {
    Disconnected,
    Connecting,
    Connected,
    Reconnecting,
}

impl std::fmt::Display for ConnectionState {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::Disconnected => write!(f, "disconnected"),
            Self::Connecting => write!(f, "connecting"),
            Self::Connected => write!(f, "connected"),
            Self::Reconnecting => write!(f, "reconnecting"),
        }
    }
}

/// cheap pseudo-random factor derived from attempt count
/// avoids pulling in the `rand` crate for jitter
fn pseudo_random_factor(seed: u32) -> f64 {
    // xorshift-inspired mixing
    let mut x = seed.wrapping_add(0x9E37_79B9);
    x ^= x << 13;
    x ^= x >> 17;
    x ^= x << 5;
    (x as f64) / (u32::MAX as f64)
}