process-lock Function

Summary

Locks a lock for the current process.

Package

mp

Signature

process-lock lock &optional whostate timeout => result

Arguments

lock⇩	A lock.
whostate⇩	A string or nil.
timeout⇩	A non-negative real or nil.

Values

result⇩

A boolean.

Description

The function process-lock attempts to lock lock and returns t if successful, or nil if timed out.

If lock is already locked and its owner is the same as the result of get-current-process, then the value of recursivep in lock (see make-lock) controls what happens. If recursivep is true, then lock remains locked and an internal count is incremented (this is called recursive locking). Otherwise, an error is signaled.

The Lisp process sleeps until the lock can be locked or the timeout period specified by timeout in seconds expires. If timeout is nil (the default) then process-lock waits indefinitely.

If whostate is non-nil, it is used as the wait reason while waiting for lock.

result is t if lock was successfully locked, and nil otherwise.

Notes

process-lock is guaranteed to return if it locked process, but may throw before locking, as described in 19.4.3 Guarantees and limitations when locking and unlocking.

Examples

(process-lock *my-lock* "waiting to lock" 10)

See also

make-lock
process-exclusive-lock
process-unlock
with-lock
19.4 Locks