Re: open a file non-blocking ?

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On 2018-02-26 17:41, Jeffrey R. Carter wrote:
>> On Saturday, February 24, 2018 at 2:42:30 PM UTC-5, 
>> pat...@spellingbeewinnars.org wrote:
>> There does not seem to be an option to open a file non-blocking. Is 
>> there a way?
> 
> I guess it depends on what you mean by non-blocking. Some of the 
> responses on here seem to think it means you can issue a write to the 
> file and it returns immediately, without waiting for the write to file 
> to complete.
> 
> If that's the case, the normal way to deal with this within Ada is 
> something like

[...]

No, to my understanding the question was about using OS asynchronous I/O 
facilities rather than mimicking them on top of Ada blocking tasks. 
Apart from wasting resources it is not even close to be asynchronous in 
the sense of I/O. The monitor solution you described does not actually 
multiplex I/O requests. It does single *blocking* request at a time.

As an example consider dealing with several sockets. With a socket 
selector all socket I/O is done concurrently. This is true asynchronous 
I/O. With a monitor task, only one socket can be serviced at a time. The 
difference in terms of data throughout and packet latencies will be 
gigantic.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de