cadrumo.core.pid_liveness module

Cross-platform PID-liveness probe shared by the crash-recoverable locks.

Both the bucket lockfile (adapters.persistence.storage.bucket) and the auth-acquisition lock (application.auth) reclaim a stale lock by asking the OS whether the recorded holder PID is still a live process. This module is the single home for that probe so the two lock subsystems cannot diverge on Windows failure-mode handling: a probe failure other than “PID does not exist” MUST be treated as alive, never as grounds to reclaim a lock this process cannot actually inspect.

pid_is_alive(pid)

Return whether pid is a live process, per a best-effort OS probe.

Returns True when the OS reports pid as a live process and False when the OS reports it as gone (or pid is not a valid process id). A permission error probing the PID (it exists but belongs to another user, or this process lacks the query right) is treated as alive: from the caller’s perspective a lock held by that PID cannot be safely reclaimed.

On Windows the probe distinguishes ERROR_INVALID_PARAMETER (87, returned by OpenProcess for a PID that no longer exists) from every other OpenProcess failure (access-denied against a foreign or protected process, a PID recycled onto a process this call cannot query, etc.). Only the former is treated as dead; every other failure is treated as alive so a lock is never wrongly reclaimed just because this process could not inspect its holder.

Return type:

bool

Parameters:

pid (int)