rskit-process 0.1.0-alpha.1

Process and subprocess execution with timeout and signal handling
Documentation 
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

use tokio::{process::Child, time::timeout};
use tokio_util::sync::CancellationToken;
use tracing::{debug, warn};

use crate::{AppError, AppResult, ErrorCode, ProcessConfig, ProcessSpec, signal::ProcessSignal};

pub(in crate::runner) struct Completion {
    pub(in crate::runner) exit_code: Option<i32>,
    pub(in crate::runner) timed_out: bool,
    pub(in crate::runner) cancelled: bool,
    pub(in crate::runner) synthetic_stderr: Option<String>,
}

pub(in crate::runner) async fn wait_for_completion(
    child: &mut Child,
    spec: &ProcessSpec,
    config: &ProcessConfig,
    cancel: CancellationToken,
) -> AppResult<Completion> {
    let pid = child.id();
    let (exit_code, timed_out, cancelled, synthetic_stderr) = if let Some(timeout_duration) =
        config.timeout
    {
        tokio::select! {
            _ = cancel.cancelled() => {
                debug!(program = %spec.program.display(), "process cancelled, sending SIGTERM");
                let (exit_code, stderr) = terminate_and_wait(child, pid, config, "cancellation").await;
                (exit_code, false, true, stderr)
            }
            wait_result = timeout(timeout_duration, child.wait()) => {
                match wait_result {
                    Ok(Ok(status)) => (status.code(), false, false, None),
                    Ok(Err(error)) => {
                        return Err(AppError::new(
                            ErrorCode::Internal,
                            format!("process execution error: {error}"),
                        ));
                    }
                    Err(_) => {
                        debug!(program = %spec.program.display(), timeout = ?timeout_duration, "process timeout, sending SIGTERM");
                        let (exit_code, stderr) = terminate_and_wait(child, pid, config, "timeout").await;
                        (exit_code, true, false, stderr)
                    }
                }
            }
        }
    } else {
        tokio::select! {
            _ = cancel.cancelled() => {
                debug!(program = %spec.program.display(), "process cancelled, sending SIGTERM");
                let (exit_code, stderr) = terminate_and_wait(child, pid, config, "cancellation").await;
                (exit_code, false, true, stderr)
            }
            wait_result = child.wait() => {
                match wait_result {
                    Ok(status) => (status.code(), false, false, None),
                    Err(error) => {
                        return Err(AppError::new(
                            ErrorCode::Internal,
                            format!("process execution error: {error}"),
                        ));
                    }
                }
            }
        }
    };

    Ok(Completion {
        exit_code,
        timed_out,
        cancelled,
        synthetic_stderr,
    })
}

async fn terminate_and_wait(
    child: &mut Child,
    pid: Option<u32>,
    config: &ProcessConfig,
    reason: &str,
) -> (Option<i32>, Option<String>) {
    if !terminate_process(pid, config, ProcessSignal::Terminate) {
        let _ = child.start_kill();
    }
    match timeout(config.signal.grace_period, child.wait()).await {
        Ok(Ok(status)) => (status.code(), None),
        Ok(Err(error)) => {
            warn!(
                signal = ProcessSignal::Terminate.name(),
                "error waiting for process after signal: {error}"
            );
            if !terminate_process(pid, config, ProcessSignal::Kill) {
                let _ = child.start_kill();
            }
            (
                None,
                Some(format!(
                    "process killed (error during grace period after {reason}: {error})"
                )),
            )
        }
        Err(_) => {
            debug!(
                signal = ProcessSignal::Kill.name(),
                "grace period expired, sending signal"
            );
            if !terminate_process(pid, config, ProcessSignal::Kill) {
                let _ = child.start_kill();
            }
            let _ = child.wait().await;
            (
                None,
                Some(format!("process killed by SIGKILL after {reason}")),
            )
        }
    }
}

fn terminate_process(pid: Option<u32>, config: &ProcessConfig, signal: ProcessSignal) -> bool {
    if let Some(pid) = pid {
        #[cfg(unix)]
        // SAFETY: `kill` targets either the child pid or the negated
        // process-group id created by the `pre_exec` hook. ESRCH means the
        // process already exited.
        unsafe {
            let target =
                if config.signal.create_process_group && config.signal.terminate_descendants {
                    -(pid as i32)
                } else {
                    pid as i32
                };
            let result = libc::kill(target, signal.as_raw());
            if result != 0 {
                let error = std::io::Error::last_os_error();
                if error.raw_os_error() != Some(libc::ESRCH) {
                    warn!(signal = signal.name(), "failed to send signal: {error}");
                    return false;
                }
            }
            return true;
        }
    }
    false
}