ek-core 0.4.3

//! 注册表(内部):单表统一 add / get / typed get / remove;
//! 状态原子 CAS;能力索引(svc_id → 提供方列表)+ 改版世代计数 + services 现场缓存;
//! start 拓扑序。
//!
//! 0.2.0 变更:
//! - `svc_index`:add 时从 `services()` 抽 id 织入(宿主只存「谁会什么 id」,
//!   宿主最小知识);removal 修剪、Quarantined 保留(条目=能力声明,非可用性);
//! - `revision` 世代:登记簿任何变动 +1,memoize 缓存按世代核对(审核 F4);
//! - `svc_cache`:services() 现场取回的透明性能缓存,非登记事实。
//! - `revision` 为字段名:`gen` 在 Rust 2024 是保留字。

use crate::error::PluginError;
use crate::main_engine::{PluginInfo, PluginState};
use crate::service::ServiceDesc;
use ek_event::{Event, HandlerId};
use std::any::Any;
use std::collections::{HashMap, VecDeque};
use std::sync::atomic::{AtomicBool, AtomicU8, AtomicU64, Ordering};
use std::sync::{Arc, Mutex, RwLock};
use std::thread::JoinHandle;

use crossbeam_channel::Sender;

/// 每插件运行统计(供宿主查询/测试断言/告警)。
#[derive(Default)]
pub(crate) struct EntryStats {
    /// forwarder 溢出丢弃累计(邮箱满)。
    pub spilled: AtomicU64,
    /// handler panic 累计。
    pub panics: AtomicU64,
    /// worker 退出标志(join-with-deadline 用,D4)。
    pub done: AtomicBool,
}

/// 注册表的一条记录(内部,不公开)。
pub(crate) struct PluginEntry {
    pub name: String,
    /// 供 worker/on_mail 与生命周期钩子调用的 trait 对象。
    pub plugin: Arc<dyn crate::plugin::Plugin>,
    /// 指向同一分配的 `Arc<dyn Any + Send + Sync>`:get_typed 的 downcast 底座。
    pub any: Arc<dyn Any + Send + Sync>,
    pub state: PluginStateCell,
    pub mailbox_cap: usize,
    pub deps: Vec<String>,
    /// 宿主侧邮箱发端(持有一份;close 第③步置 None → 全部 Sender 消费尽 → 断连)。
    pub mailbox: Mutex<Option<Sender<Event>>>,
    /// start 装配的 forwarder 注册 id(close/remove 第①步逐个卸)。
    pub forwarder_ids: Mutex<Vec<HandlerId>>,
    /// worker 句柄(close 第⑤步 join,超时则弃-剥离)。
    pub worker: Mutex<Option<JoinHandle<()>>>,
    pub stats: Arc<EntryStats>,
}

/// 插件状态(AtomicU8 CAS 迁移,非法迁移拒绝)。
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum PluginStateCode {
    Ready = 0,
    Running = 1,
    Stopping = 2,
    Exited = 3,
    Quarantined = 4,
}

/// 状态原子单元(锁-free;Clone 共享同一原子底座)。
#[derive(Clone)]
pub(crate) struct PluginStateCell(Arc<AtomicU8>);

impl PluginStateCell {
    pub fn new(s: PluginStateCode) -> Self {
        Self(Arc::new(AtomicU8::new(s as u8)))
    }
    pub fn get(&self) -> PluginState {
        PluginState::from_code(self.0.load(Ordering::Acquire))
    }
    pub(crate) fn cas(&self, from: PluginStateCode, to: PluginStateCode) -> bool {
        self.0
            .compare_exchange(from as u8, to as u8, Ordering::AcqRel, Ordering::Acquire)
            .is_ok()
    }
    /// worker 自然结束:Running/Stopping → Exited。
    pub(crate) fn finish(&self) -> bool {
        self.cas(PluginStateCode::Running, PluginStateCode::Exited)
            || self.cas(PluginStateCode::Stopping, PluginStateCode::Exited)
    }
}

/// 内部注册表集中区。
pub(crate) struct RegistryInner {
    pub entries: HashMap<String, Arc<PluginEntry>>,
    /// 注册顺序(确定性、拓扑并列时的排序依据)。
    pub order: Vec<String>,
}

/// services() 现场取回的缓存条目:(登记世代快照,现场目录)。
type SvcCacheEntry = (u64, Arc<Vec<ServiceDesc>>);

pub(crate) struct Registry {
    pub state_of: RwLock<RegistryInner>,
    /// 能力索引:svc_id → 提供方名单(注册序;removal 修剪、Quarantined 保留)。
    pub(crate) svc_index: RwLock<HashMap<String, Vec<String>>>,
    /// 改版世代:登记簿任何变动 +1(缓存失效用,审核 F4)。
    revision: AtomicU64,
    /// services() 现场取回的透明缓存(性能件,非登记事实)。
    svc_cache: Mutex<HashMap<String, SvcCacheEntry>>,
}

impl Registry {
    pub fn new() -> Self {
        Self {
            state_of: RwLock::new(RegistryInner {
                entries: HashMap::new(),
                order: Vec::new(),
            }),
            svc_index: RwLock::new(HashMap::new()),
            revision: AtomicU64::new(1),
            svc_cache: Mutex::new(HashMap::new()),
        }
    }

    pub fn revision(&self) -> u64 {
        self.revision.load(Ordering::Acquire)
    }

    pub fn bump(&self) {
        self.revision.fetch_add(1, Ordering::AcqRel);
    }

    /// 织入/刷新某提供方的索引条目(add 与 publish_services 共用)。
    pub fn index_put(&self, name: &str, ids: &[String]) {
        let mut w = self.svc_index.write().unwrap();
        for list in w.values_mut() {
            list.retain(|n| n != name);
        }
        w.retain(|_, l| !l.is_empty());
        for id in ids {
            let entry = w.entry(id.clone()).or_default();
            if !entry.iter().any(|n| n == name) {
                entry.push(name.to_string());
            }
        }
    }

    /// 摘除某提供方的全部索引条目(removal;Quarantined 不动)。
    pub fn index_remove(&self, name: &str) {
        let mut w = self.svc_index.write().unwrap();
        for list in w.values_mut() {
            list.retain(|n| n != name);
        }
        w.retain(|_, l| !l.is_empty());
    }

    /// 某服务的全部提供方(注册序)。
    pub fn index_providers(&self, svc: &str) -> Vec<String> {
        self.svc_index
            .read()
            .unwrap()
            .get(svc)
            .cloned()
            .unwrap_or_default()
    }

    /// publish_services 的登记侧:重织索引 + 失效缓存(+bump)。
    /// 返回该插件当前申报版本(插件不存在 → 空串)。
    pub(crate) fn publish(&self, name: &str, list: Vec<ServiceDesc>) -> String {
        let Some(entry) = self.get(name) else {
            return String::new();
        };
        let mut ids: Vec<String> = Vec::with_capacity(list.len());
        for d in &list {
            if !ids.contains(&d.id) {
                ids.push(d.id.clone());
            }
        }
        self.index_put(name, &ids);
        self.invalidate(name);
        entry.plugin.version().into_owned()
    }

    /// services() 现场取 + 世代核对 + memoize(F4):宿主存的是性能缓存而非登记事实。
    pub fn services_of(&self, name: &str) -> Option<Arc<Vec<ServiceDesc>>> {
        let entry = self.get(name)?;
        let revision = self.revision();
        if let Some((rev, list)) = self.svc_cache.lock().unwrap().get(name) {
            if *rev == revision {
                return Some(Arc::clone(list));
            }
        }
        let list = Arc::new(entry.plugin.services());
        self.svc_cache
            .lock()
            .unwrap()
            .insert(name.to_string(), (revision, Arc::clone(&list)));
        Some(list)
    }

    /// 信息快照(get_plugin / ctx.plugins() 共用:单一披露面,审核 F5)。
    pub(crate) fn info_of(&self, name: &str) -> Option<PluginInfo> {
        self.get(name).map(|e| PluginInfo {
            name: e.name.clone(),
            version: e.plugin.version().into_owned(),
            state: e.state.get(),
            deps: e.deps.clone(),
        })
    }

    pub fn get(&self, name: &str) -> Option<Arc<PluginEntry>> {
        self.state_of.read().unwrap().entries.get(name).cloned()
    }

    pub fn remove(&self, name: &str) -> Option<Arc<PluginEntry>> {
        let mut w = self.state_of.write().unwrap();
        w.entries.remove(name).inspect(|_| {
            if let Some(i) = w.order.iter().position(|n| n == name) {
                w.order.remove(i);
            }
        })
    }

    pub fn names(&self) -> Vec<String> {
        self.state_of.read().unwrap().order.clone()
    }

    pub fn any_depends_on(&self, target: &str) -> Vec<String> {
        let r = self.state_of.read().unwrap();
        r.order
            .iter()
            .filter_map(|n| r.entries.get(n))
            .filter(|e| e.deps.iter().any(|d| d == target))
            .map(|e| e.name.clone())
            .collect()
    }

    pub fn clear(&self) {
        let mut w = self.state_of.write().unwrap();
        w.entries.clear();
        w.order.clear();
        drop(w);
        self.svc_index.write().unwrap().clear();
        self.svc_cache.lock().unwrap().clear();
        self.bump();
    }

    /// add/remove/publish 等变动时统一让缓存失效(F4)。
    pub fn invalidate(&self, name: &str) {
        self.svc_cache.lock().unwrap().remove(name);
        self.bump();
    }

    /// start() 的依赖拓扑序(Kahn;并列按注册序;环 → Err)。
    /// deps 存在性在此把关(新 D1:add 期不校验,悬空依赖按缺失报错)。
    pub fn topo_order(&self) -> Result<Vec<Arc<PluginEntry>>, PluginError> {
        let r = self.state_of.read().unwrap();
        let mut indeg: HashMap<String, usize> = HashMap::new();
        let mut dependents: HashMap<String, Vec<String>> = HashMap::new();
        for name in &r.order {
            indeg.entry(name.clone()).or_insert(0);
        }
        for name in &r.order {
            let e = &r.entries[name];
            for d in &e.deps {
                if !r.entries.contains_key(d) {
                    return Err(PluginError::UnknownDep(d.clone()));
                }
                *indeg.entry(name.clone()).or_insert(0) += 1;
                dependents.entry(d.clone()).or_default().push(name.clone());
            }
        }
        let mut queue: VecDeque<String> =
            r.order.iter().filter(|n| indeg[*n] == 0).cloned().collect();
        let mut out = Vec::with_capacity(r.order.len());
        while let Some(n) = queue.pop_front() {
            let e = Arc::clone(&r.entries[&n]);
            out.push(e);
            if let Some(deps_list) = dependents.get(&n) {
                for dep_name in deps_list {
                    let d = indeg.get_mut(dep_name).unwrap();
                    *d -= 1;
                    if *d == 0 {
                        queue.push_back(dep_name.clone());
                    }
                }
            }
        }
        if out.len() < r.order.len() {
            let cycle: Vec<String> = r.order.iter().filter(|n| indeg[*n] > 0).cloned().collect();
            return Err(PluginError::DepCycle(cycle));
        }
        Ok(out)
    }
}