Function

Summary

Returns the owner of a lock.

Package

mp

Signature

lock-owner lock => result

Arguments

lock

A lock object

Values

result

A process, t or :unknown

Description

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

If lock is a "sharing" lock then lock-owner checks for an exclusive lock (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 the lock) then result is :unknown.

result is nil if lock is not locked.

Example

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