ralph/lock/
owner.rs

1//! Lock owner metadata.
2//!
3//! Responsibilities:
4//! - Define lock owner metadata and parse/render helpers.
5//! - Read and write owner files for lock directories.
6//! - Identify task sidecar owner files and supervising labels.
7//!
8//! Not handled here:
9//! - Lock acquisition policy or stale-lock decisions.
10//! - PID liveness detection.
11//!
12//! Invariants/assumptions:
13//! - Owner files are small text blobs with one `key: value` pair per line.
14//! - Task owner sidecars use the `owner_task_` filename prefix.
15
16use crate::fsutil::sync_dir_best_effort;
17use anyhow::{Context, Result, anyhow};
18use std::fs;
19use std::io::Write;
20use std::path::Path;
21
22pub(crate) const OWNER_FILE_NAME: &str = "owner";
23pub const TASK_OWNER_PREFIX: &str = "owner_task_";
24
25/// Lock owner metadata parsed from the owner file.
26#[derive(Debug, Clone)]
27pub struct LockOwner {
28    pub pid: u32,
29    pub started_at: String,
30    pub command: String,
31    pub label: String,
32}
33
34impl LockOwner {
35    pub(crate) fn render(&self) -> String {
36        format!(
37            "pid: {}\nstarted_at: {}\ncommand: {}\nlabel: {}\n",
38            self.pid, self.started_at, self.command, self.label
39        )
40    }
41}
42
43pub fn read_lock_owner(lock_dir: &Path) -> Result<Option<LockOwner>> {
44    let owner_path = lock_dir.join(OWNER_FILE_NAME);
45    let raw = match fs::read_to_string(&owner_path) {
46        Ok(raw) => raw,
47        Err(err) if err.kind() == std::io::ErrorKind::NotFound => return Ok(None),
48        Err(err) => {
49            return Err(anyhow!(err))
50                .with_context(|| format!("read lock owner {}", owner_path.display()));
51        }
52    };
53    Ok(parse_lock_owner(&raw))
54}
55
56pub(crate) fn write_lock_owner(owner_path: &Path, owner: &LockOwner) -> Result<()> {
57    log::debug!("writing lock owner: {}", owner_path.display());
58    let mut file = fs::File::create(owner_path)
59        .with_context(|| format!("create lock owner {}", owner_path.display()))?;
60    file.write_all(owner.render().as_bytes())
61        .context("write lock owner")?;
62    file.flush().context("flush lock owner")?;
63    file.sync_all().context("sync lock owner")?;
64    if let Some(parent) = owner_path.parent() {
65        sync_dir_best_effort(parent);
66    }
67    Ok(())
68}
69
70pub(crate) fn parse_lock_owner(raw: &str) -> Option<LockOwner> {
71    let mut pid = None;
72    let mut started_at = None;
73    let mut command = None;
74    let mut label = None;
75
76    for line in raw.lines() {
77        let trimmed = line.trim();
78        if trimmed.is_empty() {
79            continue;
80        }
81        if let Some((key, value)) = trimmed.split_once(':') {
82            let value = value.trim().to_string();
83            match key.trim() {
84                "pid" => {
85                    pid = value
86                        .parse::<u32>()
87                        .inspect_err(|error| {
88                            log::debug!("Lock file has invalid pid '{}': {}", value, error)
89                        })
90                        .ok()
91                }
92                "started_at" => started_at = Some(value),
93                "command" => command = Some(value),
94                "label" => label = Some(value),
95                _ => {}
96            }
97        }
98    }
99
100    let pid = pid?;
101    Some(LockOwner {
102        pid,
103        started_at: started_at.unwrap_or_else(|| "unknown".to_string()),
104        command: command.unwrap_or_else(|| "unknown".to_string()),
105        label: label.unwrap_or_else(|| "unknown".to_string()),
106    })
107}
108
109pub(crate) fn command_line() -> String {
110    let joined = std::env::args().collect::<Vec<_>>().join(" ");
111    let trimmed = joined.trim();
112    if trimmed.is_empty() {
113        "unknown".to_string()
114    } else {
115        trimmed.to_string()
116    }
117}
118
119pub(crate) fn is_supervising_label(label: &str) -> bool {
120    matches!(label, "run one" | "run loop")
121}
122
123pub fn is_task_owner_file(name: &str) -> bool {
124    name.starts_with(TASK_OWNER_PREFIX)
125}
126
127pub(crate) fn is_task_sidecar_owner(owner_path: &Path) -> bool {
128    owner_path
129        .file_name()
130        .and_then(|name| name.to_str())
131        .map(is_task_owner_file)
132        .unwrap_or(false)
133}
ralph/lock/owner.rs

ralph/lock/
owner.rs
