br-pgsql 0.1.29

use crate::config::Config;
use crate::connect::Connect;
use crate::error::PgsqlError;
use log::{error, info, warn};
use std::collections::VecDeque;
use std::sync::{Arc, Condvar, Mutex, MutexGuard, PoisonError, Weak};
use std::thread;
use std::time::Duration;

/// 空闲连接最大存活时间（5分钟），超过则丢弃而非归还池
const MAX_IDLE_SECS: u64 = 300;
/// 连接最大生命周期（30分钟），超过则丢弃，防止长期连接累积服务端状态
const MAX_CONN_LIFETIME_SECS: u64 = 1800;
struct PoolInner {
    idle: VecDeque<Connect>,
    total: usize,
    max: usize,
    /// 当前被事务持有的连接数
    txn_total: usize,
    /// 事务连接上限（防止事务饿死普通查询）
    txn_max: usize,
}

/// 预占位守卫：Create/GotConn-rebuild 路径中，如果 Connect::new() panic，
/// drop 时自动归还 total 计数并唤醒等待者，防止 total 永久膨胀。
struct SlotGuard<'a> {
    mutex: &'a Mutex<PoolInner>,
    condvar: &'a Condvar,
    active: bool,
    for_transaction: bool,
}

impl<'a> SlotGuard<'a> {
    fn new(mutex: &'a Mutex<PoolInner>, condvar: &'a Condvar, for_transaction: bool) -> Self {
        Self {
            mutex,
            condvar,
            active: true,
            for_transaction,
        }
    }

    /// 标记成功，不再需要回滚
    fn disarm(&mut self) {
        self.active = false;
    }
}

impl Drop for SlotGuard<'_> {
    fn drop(&mut self) {
        if self.active {
            let mut pool = lock_inner(self.mutex);
            pool.total = pool.total.saturating_sub(1);
            if self.for_transaction {
                pool.txn_total = pool.txn_total.saturating_sub(1);
            }
            drop(pool);
            self.condvar.notify_one();
        }
    }
}
#[derive(Clone)]
pub struct Pools {
    pub config: Config,
    inner: Arc<(Mutex<PoolInner>, Condvar)>,
}
fn lock_inner(mutex: &Mutex<PoolInner>) -> MutexGuard<'_, PoolInner> {
    mutex.lock().unwrap_or_else(PoisonError::into_inner)
}
pub struct ConnectionGuard {
    pool: Pools,
    conn: Option<Connect>,
}
impl ConnectionGuard {
    pub fn new(pool: Pools) -> Result<Self, PgsqlError> {
        let conn = pool.get_connect()?;
        Ok(Self {
            pool,
            conn: Some(conn),
        })
    }
    pub fn conn(&mut self) -> &mut Connect {
        self.conn.as_mut().expect("connection already released")
    }
    /// 丢弃连接（不归还到池），用于连接已断开的场景
    pub fn discard(&mut self) {
        if let Some(_conn) = self.conn.take() {
            let (ref mutex, ref condvar) = *self.pool.inner;
            let mut pool = lock_inner(mutex);
            pool.total = pool.total.saturating_sub(1);
            drop(pool);
            condvar.notify_one();
        }
    }
}
impl Drop for ConnectionGuard {
    fn drop(&mut self) {
        if let Some(conn) = self.conn.take() {
            self.pool.release_conn(conn);
        }
    }
}
impl Pools {
    pub fn get_guard(&self) -> Result<ConnectionGuard, PgsqlError> {
        ConnectionGuard::new(self.clone())
    }
    pub fn new(config: Config, size: usize) -> Result<Self, PgsqlError> {
        let init_size = 2.min(size);
        let mut idle = VecDeque::with_capacity(size);
        let mut created = 0;
        for _ in 0..init_size {
            match Connect::new(config.clone()) {
                Ok(conn) => {
                    idle.push_back(conn);
                    created += 1;
                }
                Err(e) => warn!("初始化连接失败: {e}"),
            }
        }
        let txn_max = (size / 3).max(1);
        let inner = PoolInner {
            idle,
            total: created,
            max: size,
            txn_total: 0,
            txn_max,
        };

        let arc = Arc::new((Mutex::new(inner), Condvar::new()));

        // 后台空闲连接回收线程（每60秒清理一次，Weak 引用自动退出）
        let weak = Arc::downgrade(&arc);
        thread::spawn(move || {
            Self::reaper_loop(weak);
        });

        Ok(Self { config, inner: arc })
    }

    /// 内部统一获取连接逻辑
    fn acquire_connect(&self, for_transaction: bool) -> Result<Connect, PgsqlError> {
        let mut attempts = 0;
        let (ref mutex, ref condvar) = *self.inner;
        let label = if for_transaction { "事务" } else { "" };
        #[cfg(not(test))]
        const BASE_SLEEP_MS: u64 = 200;
        #[cfg(test)]
        const BASE_SLEEP_MS: u64 = 1;
        #[cfg(not(test))]
        const MAX_SLEEP_MS: u64 = 2000;
        #[cfg(test)]
        const MAX_SLEEP_MS: u64 = 5;
        #[cfg(not(test))]
        const WAIT_TIMEOUT: Duration = Duration::from_secs(2);
        #[cfg(test)]
        const WAIT_TIMEOUT: Duration = Duration::from_millis(5);

        let timeout_msg = if for_transaction {
            "无法获取事务连接，重试超时"
        } else {
            "无法连接数据库，重试超时"
        };

        loop {
            if attempts >= 5 {
                return Err(PgsqlError::Pool(timeout_msg.into()));
            }

            let action = {
                let mut pool = lock_inner(mutex);
                // 事务连接受 txn_max 限制，防止饿死普通查询
                if for_transaction && pool.txn_total >= pool.txn_max && pool.total >= pool.max {
                    Action::Wait
                } else if let Some(conn) = pool.idle.pop_front() {
                    if for_transaction {
                        pool.txn_total += 1;
                    }
                    Action::GotConn(Box::new(conn))
                } else if pool.total < pool.max {
                    pool.total += 1; // 预占位
                    if for_transaction {
                        pool.txn_total += 1;
                    }
                    Action::Create
                } else {
                    Action::Wait
                }
            };

            match action {
                Action::GotConn(mut conn) => {
                    // 超过最大生命周期的连接直接丢弃
                    if conn.age().as_secs() > MAX_CONN_LIFETIME_SECS {
                        {
                            let mut pool = lock_inner(mutex);
                            pool.total = pool.total.saturating_sub(1);
                            if for_transaction {
                                pool.txn_total = pool.txn_total.saturating_sub(1);
                            }
                        }
                        log::debug!("{}连接存活超过{}秒，已丢弃", label, MAX_CONN_LIFETIME_SECS);
                        continue;
                    }
                    // 锁外做健康检查（is_valid 含懒 SELECT 1）
                    if conn.is_valid() {
                        conn.touch();
                        return Ok(*conn);
                    }
                    // 连接失效，丢弃并重新循环（不消耗重试次数，参考 mysql crate 模式）
                    {
                        let mut pool = lock_inner(mutex);
                        pool.total = pool.total.saturating_sub(1);
                        if for_transaction {
                            pool.txn_total = pool.txn_total.saturating_sub(1);
                        }
                    }
                    warn!(
                        "{}连接失效已丢弃，当前总连接数量: {}",
                        label,
                        self.total_connections()
                    );
                    // 不增加 attempts，直接重新循环获取连接
                    continue;
                }

                Action::Create => {
                    // SlotGuard 保护 Create 路径的 total 预占位
                    let mut guard = SlotGuard::new(mutex, condvar, for_transaction);
                    match Connect::new(self.config.clone()) {
                        Ok(new_conn) => {
                            guard.disarm();
                            return Ok(new_conn);
                        }
                        Err(e) => {
                            // guard drop 会自动 total -= 1 + notify
                            drop(guard);
                            let sleep_ms = BASE_SLEEP_MS
                                .saturating_mul(1u64 << attempts.min(3))
                                .min(MAX_SLEEP_MS);
                            attempts += 1;
                            error!("创建{}连接失败({}ms后重试): {}", label, sleep_ms, e);
                            thread::sleep(Duration::from_millis(sleep_ms));
                        }
                    }
                }
                Action::Wait => {
                    let pool = lock_inner(mutex);
                    let (_pool, timeout) = condvar
                        .wait_timeout(pool, WAIT_TIMEOUT)
                        .unwrap_or_else(PoisonError::into_inner);
                    drop(_pool);
                    if timeout.timed_out() {
                        attempts += 1;
                    }
                }
            }
        }
    }
    pub fn get_connect(&self) -> Result<Connect, PgsqlError> {
        self.acquire_connect(false)
    }
    /// 事务专用连接，不归还到池
    pub fn get_connect_for_transaction(&self) -> Result<Connect, PgsqlError> {
        self.acquire_connect(true)
    }
    pub fn release_transaction_conn(&self) {
        let (ref mutex, ref condvar) = *self.inner;
        let mut pool = lock_inner(mutex);
        pool.total = pool.total.saturating_sub(1);
        pool.txn_total = pool.txn_total.saturating_sub(1);
        drop(pool);
        condvar.notify_one();
    }
    /// 归还事务连接到连接池（而非销毁），同时递减 txn_total
    pub fn release_transaction_conn_with_conn(&self, conn: Connect) {
        let (ref mutex, _) = *self.inner;
        {
            let mut pool = lock_inner(mutex);
            pool.txn_total = pool.txn_total.saturating_sub(1);
        }
        self.release_conn(conn);
    }
    pub fn release_conn(&self, conn: Connect) {
        let (ref mutex, ref condvar) = *self.inner;
        if !conn.peer_valid() {
            let mut pool = lock_inner(mutex);
            pool.total = pool.total.saturating_sub(1);
            drop(pool);
            condvar.notify_one();
            warn!("释放时检测到坏连接，已丢弃");
            return;
        }
        if conn.age().as_secs() > MAX_CONN_LIFETIME_SECS {
            let mut pool = lock_inner(mutex);
            pool.total = pool.total.saturating_sub(1);
            drop(pool);
            condvar.notify_one();
            log::debug!("释放时连接存活超过{}秒，已丢弃", MAX_CONN_LIFETIME_SECS);
            return;
        }
        if conn.idle_elapsed().as_secs() > MAX_IDLE_SECS {
            let mut pool = lock_inner(mutex);
            pool.total = pool.total.saturating_sub(1);
            drop(pool);
            condvar.notify_one();
            log::debug!("连接空闲超过{}秒，已丢弃", MAX_IDLE_SECS);
            return;
        }
        let mut pool = lock_inner(mutex);
        if pool.idle.len() < pool.max {
            pool.idle.push_back(conn);
        } else {
            pool.total = pool.total.saturating_sub(1);
            warn!("连接池已满，丢弃连接");
        }
        drop(pool);
        condvar.notify_one();
    }
    pub fn idle_pool_size(&self) -> usize {
        let (ref mutex, _) = *self.inner;
        let pool = lock_inner(mutex);
        pool.idle.len()
    }
    pub fn total_connections(&self) -> usize {
        let (ref mutex, _) = *self.inner;
        let pool = lock_inner(mutex);
        pool.total
    }
    pub fn borrowed_connections(&self) -> usize {
        let (ref mutex, _) = *self.inner;
        let pool = lock_inner(mutex);
        pool.total.saturating_sub(pool.idle.len())
    }
    /// 清空池中所有空闲连接（failover 场景：所有连接同时死亡时调用）
    pub fn flush_idle(&self) {
        let (ref mutex, _) = *self.inner;
        let mut pool = lock_inner(mutex);
        let flushed = pool.idle.len();
        pool.total = pool.total.saturating_sub(flushed);
        pool.idle.clear();
        if flushed > 0 {
            warn!("清空池中 {flushed} 个空闲连接（疑似批量失效）");
        }
    }
    pub fn cleanup_idle_connections(&self) {
        let (ref mutex, _) = *self.inner;
        let mut pool = lock_inner(mutex);
        let before = pool.idle.len();
        pool.idle.retain(|conn| {
            let peer_ok = conn.peer_valid();
            let idle_ok = conn.idle_elapsed().as_secs() <= MAX_IDLE_SECS;
            let lifetime_ok = conn.age().as_secs() <= MAX_CONN_LIFETIME_SECS;
            if !peer_ok {
                log::debug!("检测到无效连接，已移除");
            } else if !idle_ok {
                log::debug!("检测到空闲超时连接，已移除");
            } else if !lifetime_ok {
                log::debug!("检测到超过最大生命周期连接，已移除");
            }
            peer_ok && idle_ok && lifetime_ok
        });
        let removed = before - pool.idle.len();
        pool.total = pool.total.saturating_sub(removed);
        if removed > 0 {
            log::debug!(
                "空闲连接清理完成: 移除 {removed} 个，剩余 {} 个",
                pool.idle.len()
            );
        }
    }
    /// 后台回收线程主循环：每60秒清理空闲/过期连接，Weak 引用失效时自动退出
    fn reaper_loop(weak: Weak<(Mutex<PoolInner>, Condvar)>) {
        #[cfg(not(test))]
        const INTERVAL: Duration = Duration::from_secs(60);
        #[cfg(test)]
        const INTERVAL: Duration = Duration::from_millis(50);
        loop {
            thread::sleep(INTERVAL);
            let arc = match weak.upgrade() {
                Some(a) => a,
                None => {
                    info!("连接池已释放，回收线程退出");
                    return;
                }
            };
            let (ref mutex, _) = *arc;
            let mut pool = lock_inner(mutex);
            let before = pool.idle.len();
            pool.idle.retain(|conn| {
                conn.peer_valid()
                    && conn.idle_elapsed().as_secs() <= MAX_IDLE_SECS
                    && conn.age().as_secs() <= MAX_CONN_LIFETIME_SECS
            });
            let removed = before - pool.idle.len();
            pool.total = pool.total.saturating_sub(removed);
            if removed > 0 {
                info!(
                    "后台回收: 移除 {removed} 个空闲连接，剩余 {} 个",
                    pool.idle.len()
                );
            }
        }
    }
}

/// acquire_connect 内部决策
enum Action {
    GotConn(Box<Connect>),
    Create,
    Wait,
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::io::{Read as IoRead, Write as IoWrite};
    use std::net::TcpListener;
    use std::sync::atomic::{AtomicBool, Ordering};

    fn pg_msg(tag: u8, payload: &[u8]) -> Vec<u8> {
        let mut m = Vec::with_capacity(5 + payload.len());
        m.push(tag);
        m.extend(&((payload.len() as u32 + 4).to_be_bytes()));
        m.extend_from_slice(payload);
        m
    }

    fn pg_auth(auth_type: u32, extra: &[u8]) -> Vec<u8> {
        let mut body = Vec::new();
        body.extend(&auth_type.to_be_bytes());
        body.extend_from_slice(extra);
        pg_msg(b'R', &body)
    }

    fn post_auth_ok() -> Vec<u8> {
        let mut v = Vec::new();
        v.extend(pg_auth(0, &[]));
        v.extend(pg_msg(b'S', b"server_version\x0015.0\x00"));
        let mut k = Vec::new();
        k.extend(&1u32.to_be_bytes());
        k.extend(&2u32.to_be_bytes());
        v.extend(pg_msg(b'K', &k));
        v.extend(pg_msg(b'Z', b"I"));
        v
    }

    fn simple_query_response() -> Vec<u8> {
        let mut r = Vec::new();
        r.extend(pg_msg(b'1', &[]));
        r.extend(pg_msg(b'2', &[]));
        let mut rd = Vec::new();
        rd.extend(&1u16.to_be_bytes());
        rd.extend(b"c\x00");
        rd.extend(&0u32.to_be_bytes());
        rd.extend(&1u16.to_be_bytes());
        rd.extend(&23u32.to_be_bytes());
        rd.extend(&4i16.to_be_bytes());
        rd.extend(&(-1i32).to_be_bytes());
        rd.extend(&0u16.to_be_bytes());
        r.extend(pg_msg(b'T', &rd));
        let mut dr = Vec::new();
        dr.extend(&1u16.to_be_bytes());
        dr.extend(&1u32.to_be_bytes());
        dr.push(b'1');
        r.extend(pg_msg(b'D', &dr));
        r.extend(pg_msg(b'C', b"SELECT 1\x00"));
        r.extend(pg_msg(b'Z', b"I"));
        r
    }

    fn spawn_multi_server(stop: Arc<AtomicBool>) -> u16 {
        let listener = TcpListener::bind("127.0.0.1:0").unwrap();
        let port = listener.local_addr().unwrap().port();
        thread::spawn(move || {
            listener.set_nonblocking(true).unwrap();
            while !stop.load(Ordering::Relaxed) {
                match listener.accept() {
                    Ok((s, _)) => {
                        s.set_nonblocking(false).ok();
                        let stop2 = stop.clone();
                        thread::spawn(move || {
                            s.set_read_timeout(Some(Duration::from_secs(5))).ok();
                            let mut s = s;
                            let mut buf = [0u8; 4096];
                            if s.read(&mut buf).unwrap_or(0) == 0 {
                                return;
                            }
                            let _ = s.write_all(&pg_auth(3, &[]));
                            if s.read(&mut buf).unwrap_or(0) == 0 {
                                return;
                            }
                            let _ = s.write_all(&post_auth_ok());
                            while !stop2.load(Ordering::Relaxed) {
                                match s.read(&mut buf) {
                                    Ok(0) | Err(_) => break,
                                    Ok(_) => {
                                        let _ = s.write_all(&simple_query_response());
                                    }
                                }
                            }
                        });
                    }
                    Err(ref e) if e.kind() == std::io::ErrorKind::WouldBlock => {
                        thread::sleep(Duration::from_millis(5));
                    }
                    Err(_) => break,
                }
            }
        });
        thread::sleep(Duration::from_millis(50));
        port
    }

    fn mock_config(port: u16) -> Config {
        Config {
            debug: false,
            hostname: "127.0.0.1".into(),
            hostport: port as i32,
            username: "u".into(),
            userpass: "p".into(),
            database: "d".into(),
            charset: "utf8".into(),
            pool_max: 5,
            sslmode: "disable".into(),
        }
    }

    #[test]
    fn pools_all_paths() {
        let stop = Arc::new(AtomicBool::new(false));
        let port = spawn_multi_server(stop.clone());
        let cfg = mock_config(port);

        // 基本创建 + 计数
        let pools = Pools::new(cfg.clone(), 10).unwrap();
        assert_eq!(pools.total_connections(), 2);
        assert_eq!(pools.idle_pool_size(), 2);
        assert_eq!(pools.borrowed_connections(), 0);

        // 借出一个
        let conn1 = pools.get_connect().unwrap();
        assert_eq!(pools.idle_pool_size(), 1);
        assert!(pools.borrowed_connections() > 0);

        // 归还
        let idle_before = pools.idle_pool_size();
        pools.release_conn(conn1);
        assert!(pools.idle_pool_size() > idle_before);

        // 借出后 drop（不归还到池，total 不变因为 drop 不通知池）
        let conn2 = pools.get_connect().unwrap();
        drop(conn2);

        // 归还坏连接 → total 减少
        let mut conn3 = pools.get_connect().unwrap();
        let total_before = pools.total_connections();
        conn3._close();
        pools.release_conn(conn3);
        assert!(pools.total_connections() <= total_before);

        // cleanup
        pools.cleanup_idle_connections();

        // ConnectionGuard
        {
            let mut guard = pools.get_guard().unwrap();
            let qr = guard.conn().query("SELECT 1");
            assert!(qr.is_ok());
        }
        assert!(pools.idle_pool_size() > 0);

        // 事务连接
        let pools2 = Pools::new(cfg.clone(), 10).unwrap();
        let txn = pools2.get_connect_for_transaction().unwrap();
        let total_before = pools2.total_connections();
        pools2.release_transaction_conn();
        assert_eq!(pools2.total_connections(), total_before - 1);
        drop(txn);

        // pool_max=1 → 池满时 get_connect 超时
        let pools3 = Pools::new(cfg.clone(), 1).unwrap();
        let held = pools3.get_connect().unwrap();
        let result = pools3.get_connect();
        assert!(result.is_err());
        drop(held);

        // 坏配置 → 0 连接
        let bad_cfg = mock_config(1);
        let pools4 = Pools::new(bad_cfg.clone(), 5).unwrap();
        assert_eq!(pools4.total_connections(), 0);

        // 坏配置 get_connect 失败
        let pools5 = Pools::new(bad_cfg.clone(), 5).unwrap();
        let result = pools5.get_connect();
        assert!(result.is_err());

        // 坏配置 get_connect_for_transaction 失败
        let pools6 = Pools::new(bad_cfg.clone(), 5).unwrap();
        let result = pools6.get_connect_for_transaction();
        assert!(result.is_err());

        // pool_max=1 初始化
        let pools7 = Pools::new(cfg.clone(), 1).unwrap();
        assert_eq!(pools7.total_connections(), 1);

        stop.store(true, Ordering::Relaxed);
    }
}