brokerd, memoryd, gatewayd: a lock file keeps each to one instance

Co-Authored-By: ornith-1.5-35b-a3b <agent@wntrmute.dev>

crates/memoryd/src/main.rs

@@ -5,6 +5,7 @@ use std::path::PathBuf;
 use std::process::ExitCode;
 use std::sync::Arc;
 
+use bxcore::instance;
 use memoryd::config::Config;
 use memoryd::serve;
 
@@ -24,6 +25,17 @@ fn main() -> ExitCode {
             return ExitCode::from(1);
         }
     };
+    // One memoryd per home (M5b spec, section 9a). The lock comes before anything under the home
+    // is made or bound, so a second copy never takes the sockets of the one that runs. Held until
+    // the process ends.
+    let lock_path = config.paths.home.join("run/memoryd.lock");
+    let _instance = match instance::lock(&lock_path) {
+        Ok(held) => held,
+        Err(e) => {
+            eprintln!("{}", e.line("memoryd", &lock_path));
+            return ExitCode::from(1);
+        }
+    };
     let log: serve::Log = Arc::new(|line: &str| eprintln!("{line}"));
     let running = match serve::start(config, log) {
         Ok(running) => running,

crates/memoryd/tests/instance.rs

@@ -0,0 +1,223 @@
+//! One `memoryd` per home (M5b spec, section 9a): a second `memoryd serve` against the same home is
+//! refused with the lock's line, and the first keeps serving; once the first is killed, a new one
+//! removes the stale sockets and serves. Every wait has a deadline, and every process is killed
+//! and every path removed by a guard (tip T44). Do not edit.
+
+#[path = "support/tmp.rs"]
+mod tmp;
+
+use std::os::unix::fs::PermissionsExt;
+use std::os::unix::net::UnixStream;
+use std::path::{Path, PathBuf};
+use std::process::{Child, Command, Stdio};
+use std::time::{Duration, Instant};
+
+use bxcore::{Empty, Envelope, Message, PROTOCOL_VERSION, read_frame, write_frame};
+use tmp::TempDir;
+
+const POINTER: &str = "see docs/runbook.md#already-running";
+const SOCKETS: [&str; 3] = [
+    "run/loop-memory/memory.sock",
+    "run/broker-memory/memory.sock",
+    "run/owner-memory/admin.sock",
+];
+
+struct Home {
+    dir: TempDir,
+    config: PathBuf,
+}
+
+impl Home {
+    fn new(tag: &str) -> Home {
+        let dir = TempDir::new(tag);
+        let soul = dir.write("etc/soul.md", "You are Boxmaker.\n");
+        let text = format!(
+            "[paths]\nhome = \"{}\"\n[memory]\nsoul_starter = \"{}\"\n",
+            dir.path().display(),
+            soul.display()
+        );
+        let config = dir.write("memoryd.toml", &text);
+        Home { dir, config }
+    }
+
+    fn path(&self, relative: &str) -> PathBuf {
+        self.dir.path().join(relative)
+    }
+
+    fn command(&self) -> Command {
+        let mut command = Command::new(env!("CARGO_BIN_EXE_memoryd"));
+        command
+            .args(["serve", "--config"])
+            .arg(&self.config)
+            .stdin(Stdio::null())
+            .stdout(Stdio::null());
+        command
+    }
+
+    /// `memoryd serve` with its stderr in `<home>/<name>.err`, for the messages of a failing test.
+    fn start(&self, name: &str) -> Daemon {
+        let err = std::fs::File::create(self.path(&format!("{name}.err"))).unwrap();
+        Daemon(self.command().stderr(Stdio::from(err)).spawn().unwrap())
+    }
+
+    fn stderr_of(&self, name: &str) -> String {
+        std::fs::read_to_string(self.path(&format!("{name}.err"))).unwrap_or_default()
+    }
+
+    /// Runs `memoryd serve` to its end, at most 10 s (then it is killed), and gives its exit code
+    /// (`None` if it had to be killed) and its stderr.
+    fn run_to_end(&self) -> (Option<i32>, String) {
+        let mut child = Daemon(self.command().stderr(Stdio::piped()).spawn().unwrap());
+        let deadline = Instant::now() + Duration::from_secs(10);
+        let mut code = None;
+        while Instant::now() < deadline {
+            if let Ok(Some(status)) = child.0.try_wait() {
+                code = status.code();
+                break;
+            }
+            std::thread::sleep(Duration::from_millis(20));
+        }
+        let _ = child.0.kill();
+        let _ = child.0.wait();
+        let mut stderr = String::new();
+        if let Some(mut pipe) = child.0.stderr.take() {
+            let _ = std::io::Read::read_to_string(&mut pipe, &mut stderr);
+        }
+        (code, stderr)
+    }
+
+    fn inodes(&self) -> Vec<u64> {
+        SOCKETS.iter().map(|s| inode(&self.path(s))).collect()
+    }
+}
+
+/// A running `memoryd serve`, killed and waited for when dropped. Declared after the `Home`, so it
+/// drops first.
+struct Daemon(Child);
+
+impl Drop for Daemon {
+    fn drop(&mut self) {
+        let _ = self.0.kill();
+        let _ = self.0.wait();
+    }
+}
+
+impl Daemon {
+    fn running(&mut self) -> bool {
+        matches!(self.0.try_wait(), Ok(None))
+    }
+}
+
+/// True when `memoryd` answers on `socket`, `loopd`'s: `memory_block` gets the block. Any other
+/// answer, or none within 5 s, is false.
+fn answers(socket: &Path) -> bool {
+    let Ok(mut stream) = UnixStream::connect(socket) else {
+        return false;
+    };
+    let limit = Some(Duration::from_secs(5));
+    if stream.set_read_timeout(limit).is_err() || stream.set_write_timeout(limit).is_err() {
+        return false;
+    }
+    let ask = Envelope {
+        v: PROTOCOL_VERSION,
+        id: 1,
+        r#final: true,
+        msg: Message::MemoryBlock(Empty {}),
+    };
+    if write_frame(&mut stream, &ask).is_err() {
+        return false;
+    }
+    matches!(
+        read_frame(&mut stream),
+        Ok(Envelope {
+            msg: Message::MemoryBlockReply(_),
+            ..
+        })
+    )
+}
+
+/// Waits up to 10 s for `memoryd` to answer on `loopd`'s socket and to listen on the other two.
+fn wait_until_it_answers(home: &Home) -> bool {
+    let deadline = Instant::now() + Duration::from_secs(10);
+    while Instant::now() < deadline {
+        if answers(&home.path(SOCKETS[0]))
+            && SOCKETS[1..]
+                .iter()
+                .all(|s| UnixStream::connect(home.path(s)).is_ok())
+        {
+            return true;
+        }
+        std::thread::sleep(Duration::from_millis(20));
+    }
+    false
+}
+
+fn inode(path: &Path) -> u64 {
+    use std::os::unix::fs::MetadataExt;
+    std::fs::symlink_metadata(path)
+        .map(|m| m.ino())
+        .unwrap_or(0)
+}
+
+#[test]
+fn a_second_memoryd_on_the_same_home_is_refused_and_the_first_keeps_serving() {
+    let home = Home::new("inst-twice");
+    let mut first = home.start("first");
+    assert!(
+        wait_until_it_answers(&home),
+        "the first memoryd never answered; stderr: {}",
+        home.stderr_of("first")
+    );
+    let before = home.inodes();
+
+    let (code, stderr) = home.run_to_end();
+    let line = format!(
+        "memoryd: another memoryd is running (it holds {}); {POINTER}",
+        home.path("run/memoryd.lock").display()
+    );
+    assert_eq!(code, Some(1), "the second memoryd: {stderr}");
+    assert_eq!(
+        stderr,
+        format!("{line}\n"),
+        "the lock's line, and nothing else"
+    );
+
+    assert!(first.running(), "the first memoryd is still running");
+    assert_eq!(home.inodes(), before, "the first's sockets are still there");
+    assert!(
+        answers(&home.path(SOCKETS[0])),
+        "the first memoryd still answers; its stderr: {}",
+        home.stderr_of("first")
+    );
+}
+
+#[test]
+fn after_the_first_is_killed_a_new_memoryd_removes_the_stale_sockets_and_serves() {
+    let home = Home::new("inst-restart");
+    let mut first = home.start("first");
+    assert!(
+        wait_until_it_answers(&home),
+        "the first memoryd never answered; stderr: {}",
+        home.stderr_of("first")
+    );
+    let _ = first.0.kill();
+    let _ = first.0.wait();
+    assert!(
+        SOCKETS.iter().all(|s| home.path(s).exists()),
+        "a killed memoryd leaves its sockets"
+    );
+    assert!(
+        !answers(&home.path(SOCKETS[0])),
+        "nobody serves the stale socket"
+    );
+
+    let _next = home.start("next");
+    assert!(
+        wait_until_it_answers(&home),
+        "the new memoryd never answered; stderr: {}",
+        home.stderr_of("next")
+    );
+    let lock = home.path("run/memoryd.lock");
+    let mode = std::fs::metadata(&lock).map(|m| m.permissions().mode() & 0o777);
+    assert_eq!(mode.ok(), Some(0o600), "the lock file, mode 0600");
+}