Re: [thread] Expected behaviour of condition variable wait when the mutex is not locked

> ----- Original Message -----
> From: "Anthony Williams" <anthony@...>
> To: <threads-devel@...>
> Sent: Monday, April 14, 2008 5:34 PM
> Subject: Re: [Threads-devel] [boost] Expected behaviour of condition
> variable wait when unique_lock is not locked
>
>
>> Quoting "vicente.botet" <vicente.botet@...>:
>>
>>> which is the expected behaviour of condition variable wait when
>>> unique_lock is not locked
>>
>> Undefined behaviour: a precondition has not been met.
>
> IMO this is not satisfactory. At least an exception should be thrown. And
> the C++0x recomendation states this.
>
> "void wait(unique_lock<mutex>& lock);
> Precondition:
>     lock is locked by the current thread, and either:
>     No other thread is waiting on this condition_variable object, or
>     The lock arguments supplied by all concurrently waiting threads (via
> wait or timed_wait) return the same value for lock.mutex().
> Effects:
>     Atomically calls lock.unlock() and blocks on *this.
>     When unblocked, calls lock.lock() (possibly blocking on the lock) and
> returns.
>     The function will unblock when this thread is signaled by a call to
> this->notify_one(), a call to this->notify_all(), or spuriously.
>     If the function exits via an exception, lock.lock() will still be called
> prior to exiting the function scope.
> Postconditions:
>     lock is locked by the current thread.
> Throws:
>     system_error when the effects or postconditions cannot be achieved.
> "