## Macro: SB-THREAD:WITH-RECURSIVE-LOCK
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> Acquire MUTEX for the dynamic scope of BODY.
> 
> If WAIT-P is true (the default), and the MUTEX is not immediately available or
> held by the current thread, sleep until it is available.
> 
> If TIMEOUT is given, it specifies a relative timeout, in seconds, on how long
> the system should try to acquire the lock in the contested case.
> 
> If the mutex isn't acquired successfully due to either WAIT-P or TIMEOUT, the
> body is not executed, and WITH-RECURSIVE-LOCK returns NIL.
> 
> Otherwise body is executed with the mutex held by current thread, and
> WITH-RECURSIVE-LOCK returns the values of BODY.
> 
> Unlike WITH-MUTEX, which signals an error on attempt to re-acquire an already
> held mutex, WITH-RECURSIVE-LOCK allows recursive lock attempts to succeed.

### Lambda list
```cl
((sb-thread:mutex &key sb-thread::wait-p sb-thread::timeout) &body sb-thread::body)
```