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
151
152

use crate::error::{FaucetResult, FucetError};
use std::{net::SocketAddr, path::Path};
use tokio::process::Child;
use tokio_stream::StreamExt;
use tokio_util::codec::{FramedRead, LinesCodec};

#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Debug)]
pub enum WorkerType {
    Plumber,
    Shiny,
}

struct Worker {
    /// The child process running the plumber worker.
    _child: Child,
    /// The address of the worker's socket.
    socket_addr: SocketAddr,
}

fn log_stdio(mut child: Child) -> FaucetResult<Child> {
    let pid = child.id().expect("Failed to get plumber worker PID");

    let mut stdout = FramedRead::new(
        child.stdout.take().ok_or(FucetError::Unknown(format!(
            "Unable to take stdout from PID {pid}"
        )))?,
        LinesCodec::new(),
    );

    let mut stderr = FramedRead::new(
        child.stderr.take().ok_or(FucetError::Unknown(format!(
            "Unable to take stderr from PID {pid}"
        )))?,
        LinesCodec::new(),
    );

    tokio::spawn(async move {
        let target = format!("Worker::{}", pid);
        while let Some(line) = stderr.next().await {
            if let Ok(line) = line {
                log::warn!(target: &target, "{line}");
            }
        }
    });

    tokio::spawn(async move {
        let target = format!("Worker::{}", pid);
        while let Some(line) = stdout.next().await {
            if let Ok(line) = line {
                log::info!(target: &target, "{line}");
            }
        }
    });

    Ok(child)
}

fn spawn_plumber_worker(workdir: impl AsRef<Path>, port: u16) -> FaucetResult<Child> {
    let command = format!(
        r#"
        options("plumber.port" = {port})
        plumber::pr_run(plumber::pr("plumber.R"))
        "#,
    );
    let child = tokio::process::Command::new("Rscript")
        // Set the current directory to the directory containing the entrypoint
        .current_dir(workdir)
        .arg("-e")
        .arg(command)
        .stdout(std::process::Stdio::piped())
        .stderr(std::process::Stdio::piped())
        // Set the port environment variable `PORT` to the port we want to use
        // This is needed to make sure the child process is killed when the parent is dropped
        .kill_on_drop(true)
        .spawn()?;

    log_stdio(child)
}

fn spawn_shiny_worker(workdir: impl AsRef<Path>, port: u16) -> FaucetResult<Child> {
    let command = format!(
        r#"
        options("shiny.port" = {port})
        shiny::runApp()
        "#,
    );
    let child = tokio::process::Command::new("Rscript")
        // Set the current directory to the directory containing the entrypoint
        .current_dir(workdir)
        .arg("-e")
        .arg(command)
        .stdout(std::process::Stdio::piped())
        .stderr(std::process::Stdio::piped())
        // Set the port environment variable `PORT` to the port we want to use
        // This is needed to make sure the child process is killed when the parent is dropped
        .kill_on_drop(true)
        .spawn()?;

    log_stdio(child)
}

fn get_available_socket() -> FaucetResult<SocketAddr> {
    use std::net::TcpListener;
    TcpListener::bind("127.0.0.1:0")?
        .local_addr()
        .map_err(Into::into)
}

impl Worker {
    pub fn new(worker_type: WorkerType, workdir: impl AsRef<Path>) -> FaucetResult<Self> {
        use WorkerType::*;
        let addr = get_available_socket()?;
        let child = match worker_type {
            Plumber => spawn_plumber_worker(workdir, addr.port())?,
            Shiny => spawn_shiny_worker(workdir, addr.port())?,
        };
        Ok(Self {
            _child: child,
            socket_addr: addr,
        })
    }
}

pub(crate) struct Workers {
    workers: Vec<Worker>,
    worker_type: WorkerType,
    workdir: Box<Path>,
}

impl Workers {
    pub(crate) fn new(worker_type: WorkerType, workdir: impl AsRef<Path>) -> Self {
        let workdir = workdir.as_ref();
        Self {
            workers: Vec::new(),
            worker_type,
            workdir: workdir.into(),
        }
    }
    pub(crate) fn spawn(&mut self, n: usize) -> FaucetResult<()> {
        for _ in 0..n {
            self.workers
                .push(Worker::new(self.worker_type, &self.workdir)?);
        }
        Ok(())
    }
    pub(crate) fn get_socket_addrs(&self) -> Vec<SocketAddr> {
        self.workers
            .iter()
            .map(|w| w.socket_addr)
            .collect::<Vec<_>>()
    }
}