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use blocking::unblock; use futures::lock::Mutex; use futures::TryStreamExt; use futures_timer::Delay; use log::trace; use mobc::{async_trait, Manager}; use reql::cmd::connect::Options; use reql::cmd::run::{self, Arg}; use reql::types::{Change, ServerStatus}; use reql::{r, Connection, Driver, Error, Query, Result}; use std::cmp::Ordering; use std::io; use std::net::{IpAddr, TcpStream}; use std::ops::Deref; use std::sync::Arc; use std::time::{Duration, Instant}; pub type Pool = mobc::Pool<SessionManager>; #[async_trait] pub trait GetSession { async fn session(&self) -> Result<Session>; } #[async_trait] impl GetSession for Pool { async fn session(&self) -> Result<Session> { Ok(Session { conn: self.get().await.map_err(to_reql)?, }) } } pub struct Session { conn: mobc::Connection<SessionManager>, } impl Deref for Session { type Target = reql::Session; fn deref(&self) -> &Self::Target { &self.conn } } impl AsRef<reql::Session> for Session { fn as_ref(&self) -> &reql::Session { self.deref() } } impl Arg for &Session { fn into_run_opts(self) -> Result<(Connection, run::Options)> { self.deref().into_run_opts() } } #[derive(Debug, Clone, Eq)] struct Server { name: String, addresses: Vec<IpAddr>, port: u16, latency: Duration, } impl Ord for Server { fn cmp(&self, other: &Server) -> Ordering { self.latency.cmp(&other.latency) } } impl PartialOrd for Server { fn partial_cmp(&self, other: &Server) -> Option<Ordering> { Some(self.cmp(other)) } } impl PartialEq for Server { fn eq(&self, other: &Server) -> bool { self.name == other.name } } impl Server { fn from_status(status: ServerStatus) -> Self { let network = status.network; let addresses = network.canonical_addresses.into_iter().map(move |x| x.host); Self { name: status.name, addresses: addresses.collect(), port: network.reql_port, latency: Duration::from_millis(u64::MAX), } } } #[derive(Clone)] pub struct SessionManager { opts: Options, servers: Arc<Mutex<Vec<Server>>>, pool: Option<Pool>, } impl SessionManager { pub fn new(opts: Options) -> Self { Self { opts, servers: Arc::new(Mutex::new(Vec::new())), pool: None, } } pub async fn discover_hosts(mut self) { self.pool = Some(Pool::builder().max_open(2).build(self.clone())); let mut wait = 0; loop { if let Err(error) = self.listen_for_hosts(&mut wait).await { trace!( "listening for host changes; error: {}, wait: {}s", error, wait ); Delay::new(Duration::from_secs(wait)).await; wait = 300.min(wait + 1); } } } async fn listen_for_hosts(&self, wait: &mut u64) -> Result<()> { let conn = self.pool.as_ref().unwrap().session().await?; let mut query = server_status() .changes(()) .run::<_, Change<ServerStatus, ServerStatus>>(&conn); while query.try_next().await?.is_some() { let servers = self.get_servers().await?; *self.servers.lock().await = servers; *wait = 0; } Ok(()) } async fn get_servers(&self) -> Result<Vec<Server>> { let mut servers = Vec::new(); let conn = self.pool.as_ref().unwrap().session().await?; let mut query = server_status().run(&conn); while let Some(status) = query.try_next().await? { servers.push(Server::from_status(status)); } set_latency(&mut servers).await; servers.sort(); Ok(servers) } } async fn set_latency(servers: &mut Vec<Server>) { for server in servers { let port = server.port; for (i, host) in server.addresses.iter().enumerate() { let host = *host; let latency = unblock(move || { let start = Instant::now(); if TcpStream::connect((host, port)).is_ok() { return Some(start.elapsed()); } None }) .await; if let Some(latency) = latency { if latency > server.latency || i == 0 { server.latency = latency; } } } } } fn server_status() -> Query { r.db("rethinkdb").table("server_status") } #[async_trait] impl Manager for SessionManager { type Connection = reql::Session; type Error = Error; async fn connect(&self) -> Result<Self::Connection> { let opts = &self.opts; let servers = &self.servers.lock().await; if servers.is_empty() { trace!( "no discovered servers; host: {}, port: {}", opts.host, opts.port ); return r.connect(opts.clone()).await; } else { for server in servers.iter() { for host in &server.addresses { trace!( "discovered server {}; host: {}, port: {}", server.name, host, server.port ); let addr = (*host, server.port); if let Ok(conn) = r.connect(r.args((addr, opts.clone()))).await { return Ok(conn); } } } } Err(io::Error::new( io::ErrorKind::ConnectionRefused, "no RethinkDB servers available", ) .into()) } async fn check(&self, conn: Self::Connection) -> Result<Self::Connection> { let msg = 200; match r.expr(msg).run(&conn).try_next().await? { Some(res) => verify(res, msg)?, None => { return Err(Driver::ConnectionBroken.into()); } } Ok(conn) } fn validate(&self, conn: &mut Self::Connection) -> bool { !conn.is_broken() } } fn verify(res: u32, msg: u32) -> Result<()> { if res != msg { return Err(Driver::ConnectionBroken.into()); } Ok(()) } fn to_reql(error: mobc::Error<Error>) -> Error { match error { mobc::Error::Inner(error) => error, mobc::Error::Timeout => io::Error::from(io::ErrorKind::TimedOut).into(), mobc::Error::BadConn => Driver::ConnectionBroken.into(), } }