1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150

use std::collections::VecDeque;
use std::io;

use actix::actors::resolver::{Connect, Resolver};
use actix::prelude::*;
use actix_utils::oneshot;
use backoff::backoff::Backoff;
use backoff::ExponentialBackoff;
use futures_util::FutureExt;
use log::{error, info, warn};
use redis_async::error::Error as RespError;
use redis_async::resp::{RespCodec, RespValue};
use tokio::io::{split, WriteHalf};
use tokio::net::TcpStream;
use tokio_util::codec::FramedRead;

use crate::Error;

/// Command for send data to Redis
#[derive(Debug)]
pub struct Command(pub RespValue);

impl Message for Command {
    type Result = Result<RespValue, Error>;
}

/// Redis comminucation actor
pub struct RedisActor {
    addr: String,
    backoff: ExponentialBackoff,
    cell: Option<actix::io::FramedWrite<RespValue, WriteHalf<TcpStream>, RespCodec>>,
    queue: VecDeque<oneshot::Sender<Result<RespValue, Error>>>,
}

impl RedisActor {
    /// Start new `Supervisor` with `RedisActor`.
    pub fn start<S: Into<String>>(addr: S) -> Addr<RedisActor> {
        let addr = addr.into();

        let backoff = ExponentialBackoff {
            max_elapsed_time: None,
            ..Default::default()
        };

        Supervisor::start(|_| RedisActor {
            addr,
            cell: None,
            backoff,
            queue: VecDeque::new(),
        })
    }
}

impl Actor for RedisActor {
    type Context = Context<Self>;

    fn started(&mut self, ctx: &mut Context<Self>) {
        Resolver::from_registry()
            .send(Connect::host(self.addr.as_str()))
            .into_actor(self)
            .map(|res, act, ctx| match res {
                Ok(res) => match res {
                    Ok(stream) => {
                        info!("Connected to redis server: {}", act.addr);

                        let (r, w) = split(stream);

                        // configure write side of the connection
                        let framed = actix::io::FramedWrite::new(w, RespCodec, ctx);
                        act.cell = Some(framed);

                        // read side of the connection
                        ctx.add_stream(FramedRead::new(r, RespCodec));

                        act.backoff.reset();
                    }
                    Err(err) => {
                        error!("Can not connect to redis server: {}", err);
                        // re-connect with backoff time.
                        // we stop current context, supervisor will restart it.
                        if let Some(timeout) = act.backoff.next_backoff() {
                            ctx.run_later(timeout, |_, ctx| ctx.stop());
                        }
                    }
                },
                Err(err) => {
                    error!("Can not connect to redis server: {}", err);
                    // re-connect with backoff time.
                    // we stop current context, supervisor will restart it.
                    if let Some(timeout) = act.backoff.next_backoff() {
                        ctx.run_later(timeout, |_, ctx| ctx.stop());
                    }
                }
            })
            .wait(ctx);
    }
}

impl Supervised for RedisActor {
    fn restarting(&mut self, _: &mut Self::Context) {
        self.cell.take();
        for tx in self.queue.drain(..) {
            let _ = tx.send(Err(Error::Disconnected));
        }
    }
}

impl actix::io::WriteHandler<io::Error> for RedisActor {
    fn error(&mut self, err: io::Error, _: &mut Self::Context) -> Running {
        warn!("Redis connection dropped: {} error: {}", self.addr, err);
        Running::Stop
    }
}

impl StreamHandler<Result<RespValue, RespError>> for RedisActor {
    fn handle(&mut self, msg: Result<RespValue, RespError>, ctx: &mut Self::Context) {
        match msg {
            Err(e) => {
                if let Some(tx) = self.queue.pop_front() {
                    let _ = tx.send(Err(e.into()));
                }
                ctx.stop();
            }
            Ok(val) => {
                if let Some(tx) = self.queue.pop_front() {
                    let _ = tx.send(Ok(val));
                }
            }
        }
    }
}

impl Handler<Command> for RedisActor {
    type Result = ResponseFuture<Result<RespValue, Error>>;

    fn handle(&mut self, msg: Command, _: &mut Self::Context) -> Self::Result {
        let (tx, rx) = oneshot::channel();
        if let Some(ref mut cell) = self.cell {
            self.queue.push_back(tx);
            cell.write(msg.0);
        } else {
            let _ = tx.send(Err(Error::NotConnected));
        }

        Box::pin(rx.map(|res| match res {
            Ok(res) => res,
            Err(_) => Err(Error::Disconnected),
        }))
    }
}