Struct PidLockGuard 

pub struct PidLockGuard { /* private fields */ }

Exclusive, flock(2)-backed guard on a pid file.

Acquiring the lock writes the current process PID to the file. Dropping the guard unlinks the file and then closes the file descriptor, releasing the lock.

The fd inheritance invariant: the file is opened with O_CLOEXEC, so child processes spawned via Command do NOT inherit the lock. If you re-exec the binary, the new process must call PidLockGuard::acquire independently.

Examples

use zeph_common::pidfile::PidLockGuard;

let path = std::env::temp_dir().join(format!("zeph-pidfile-doctest-{}.pid", std::process::id()));
let guard = PidLockGuard::acquire(&path).expect("no other instance running");
assert_eq!(guard.path(), path.as_path());
drop(guard); // releases the lock and removes the pid file
assert!(!path.exists());

Implementations

impl PidLockGuard

pub fn acquire(path: &Path) -> Result<Self, PidLockError>

Open (or create) the pid file at path and acquire an exclusive advisory lock.

The sequence is:

1. open(O_RDWR | O_CREAT | O_CLOEXEC, 0o644) — atomic create-or-open.
2. flock(LOCK_EX | LOCK_NB) — fails immediately if already locked.
3. ftruncate(0) + write current PID.

Errors

• PidLockError::AlreadyRunning if another process holds the lock.
• PidLockError::Io for filesystem errors.

pub fn path(&self) -> &Path

Path to the locked pid file.

Trait Implementations

impl Debug for PidLockGuard

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Drop for PidLockGuard

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.