robotrt-middleware-core 0.1.0-beta.2

RobotRT modular robotics runtime and middleware components.
Documentation 
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use std::collections::HashMap;

use core_types::{SessionId, Timestamp, TransportDomain};

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct ReconnectBackoffPolicy {
    pub base_delay_ms: u64,
    pub max_delay_ms: u64,
}

impl Default for ReconnectBackoffPolicy {
    fn default() -> Self {
        Self {
            base_delay_ms: 200,
            max_delay_ms: 5_000,
        }
    }
}

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum SessionLifecycle {
    Connecting,
    Connected,
    Reconnecting,
    Closed,
}

#[derive(Clone, Debug, Eq, PartialEq)]
pub struct SessionRecord {
    pub id: SessionId,
    pub domain: TransportDomain,
    pub target: String,
    pub opened_at: Timestamp,
    pub lifecycle: SessionLifecycle,
    pub reconnect_attempts: u32,
    pub reconnect_backoff_ms: u64,
    pub next_retry_at: Option<Timestamp>,
    pub last_error: Option<String>,
}

#[derive(Clone, Copy, Debug, Default, Eq, PartialEq)]
pub struct SessionLifecycleCounts {
    pub connecting: usize,
    pub connected: usize,
    pub reconnecting: usize,
    pub closed: usize,
}

pub trait SessionManager {
    fn open_session(&mut self, domain: TransportDomain, target: impl Into<String>) -> SessionId;
    fn get_session(&self, id: SessionId) -> Option<&SessionRecord>;
    fn set_backoff_policy(&mut self, policy: ReconnectBackoffPolicy);
    fn mark_connected(&mut self, id: SessionId);
    fn mark_reconnecting(&mut self, id: SessionId, reason: impl Into<String>);
    fn mark_closed(&mut self, id: SessionId);
}

#[derive(Default)]
pub struct SimpleSessionManager {
    next_id: u64,
    policy: ReconnectBackoffPolicy,
    sessions: HashMap<SessionId, SessionRecord>,
}

impl SimpleSessionManager {
    pub fn lifecycle_counts(&self) -> SessionLifecycleCounts {
        let mut out = SessionLifecycleCounts::default();
        for record in self.sessions.values() {
            match record.lifecycle {
                SessionLifecycle::Connecting => out.connecting += 1,
                SessionLifecycle::Connected => out.connected += 1,
                SessionLifecycle::Reconnecting => out.reconnecting += 1,
                SessionLifecycle::Closed => out.closed += 1,
            }
        }
        out
    }
}

impl SessionManager for SimpleSessionManager {
    fn open_session(&mut self, domain: TransportDomain, target: impl Into<String>) -> SessionId {
        self.next_id += 1;
        let id = SessionId::new(self.next_id);
        self.sessions.insert(
            id,
            SessionRecord {
                id,
                domain,
                target: target.into(),
                opened_at: Timestamp::now(),
                lifecycle: SessionLifecycle::Connecting,
                reconnect_attempts: 0,
                reconnect_backoff_ms: 0,
                next_retry_at: None,
                last_error: None,
            },
        );
        id
    }

    fn get_session(&self, id: SessionId) -> Option<&SessionRecord> {
        self.sessions.get(&id)
    }

    fn set_backoff_policy(&mut self, policy: ReconnectBackoffPolicy) {
        self.policy = policy;
    }

    fn mark_connected(&mut self, id: SessionId) {
        if let Some(record) = self.sessions.get_mut(&id) {
            record.lifecycle = SessionLifecycle::Connected;
            record.reconnect_backoff_ms = 0;
            record.next_retry_at = None;
            record.last_error = None;
        }
    }

    fn mark_reconnecting(&mut self, id: SessionId, reason: impl Into<String>) {
        let policy = self.policy;
        if let Some(record) = self.sessions.get_mut(&id) {
            record.lifecycle = SessionLifecycle::Reconnecting;
            record.reconnect_attempts += 1;
            let shift = record.reconnect_attempts.saturating_sub(1).min(16);
            let factor = 1u64 << shift;
            let backoff = policy
                .base_delay_ms
                .saturating_mul(factor)
                .min(policy.max_delay_ms);
            record.reconnect_backoff_ms = backoff;
            record.next_retry_at = Some(Timestamp(
                Timestamp::now().0 + (backoff as u128) * 1_000_000,
            ));
            record.last_error = Some(reason.into());
        }
    }

    fn mark_closed(&mut self, id: SessionId) {
        if let Some(record) = self.sessions.get_mut(&id) {
            record.lifecycle = SessionLifecycle::Closed;
        }
    }
}