lock-owner Function

Summary

Returns the owner of a lock.

Package

mp

Signature

lock-owner lock => result

Arguments

lock⇩

A lock.

Values

result⇩

A process, t or :unknown.

Description

The function lock-owner returns the process that currently owns lock, or nil.

If lock is a "sharing" lock then lock-owner checks whether it is locked exclusively (see lock-owned-by-current-process-p).

If lock is locked then result is normally the process that locked it. If lock was locked while multiprocessing was not running then result is t. Also, if lock was locked by an unknown process (for example, the process is killed while holding lock) then result is :unknown.

result is nil if lock is not locked.

Examples

CL-USER 1 > (let ((lock (mp:make-lock :name
                                      "my lock")))
              (mp:lock-owner lock))
NIL
 
CL-USER 2 > (let ((lock (mp:make-lock :name
                                      "my lock")))
              (mp:with-lock (lock)
                (mp:lock-owner lock)))
#<MP:PROCESS Name "CAPI Execution Listener 1" Priority 0 State "Running">

See also

lock
lock-owned-by-current-process-p
make-lock
with-lock
process-lock
process-unlock
lock-name
lock-owned-by-current-process-p
19.4 Locks