## Function: SB-THREAD:CONDITION-WAIT
[![package](https://img.shields.io/badge/Package-SB--THREAD-5f9ea0.svg?style=social&colorA=999999)](../) [![type](https://img.shields.io/badge/Type-Function-5f9ea0.svg?style=social&colorA=999999)](../#function) [![github](https://img.shields.io/badge/GitHub-View_the_source-5f9ea0.svg?style=social&colorA=999999&logo=github)](https://github.com/sbcl/sbcl/blob/master/src/code/target-thread.lisp/) 

> Atomically release MUTEX and start waiting on QUEUE until another thread
> wakes us up using either CONDITION-NOTIFY or CONDITION-BROADCAST on
> QUEUE, at which point we re-acquire MUTEX and return T.
> 
> Spurious wakeups are possible.
> 
> If TIMEOUT is given, it is the maximum number of seconds to wait,
> including both waiting for the wakeup and the time to re-acquire
> MUTEX. When neither a wakeup nor a re-acquisition occurs within the
> given time, returns NIL without re-acquiring MUTEX.
> 
> If CONDITION-WAIT unwinds, it may do so with or without MUTEX being
> held.
> 
> Important: Since CONDITION-WAIT may return without CONDITION-NOTIFY or
> CONDITION-BROADCAST having occurred, the correct way to write code
> that uses CONDITION-WAIT is to loop around the call, checking the
> associated data:
> 
> (defvar *data* nil)
> (defvar *queue* (make-waitqueue))
> (defvar *lock* (make-mutex))
> 
> ;; Consumer
> (defun pop-data (&optional timeout)
> (with-mutex (*lock*)
> (loop until *data*
> do (or (condition-wait *queue* *lock* :timeout timeout)
> ;; Lock not held, must unwind without touching *data*.
> (return-from pop-data nil)))
> (pop *data*)))
> 
> ;; Producer
> (defun push-data (data)
> (with-mutex (*lock*)
> (push data *data*)
> (condition-notify *queue*)))

### Lambda list
```cl
(sb-thread::queue sb-thread:mutex &key sb-thread::timeout)
```