stdio line-streaming revisited

[Andrei Alexandrescu (See Website For Email)]

Sean Kelly wrote:
> Andrei Alexandrescu (See Website For Email) wrote:
>> Sean Kelly wrote:
>>> Andrei Alexandrescu (See Website For Email) wrote:
>>>> Bill Baxter wrote:
>>>>>
>>>>> I believe the current discussion is only about under-the-hood 
>>>>> implementation issues.  So I don't think you have to worry about 
>>>>> any D libraries exposing (good or bad) C/C++ design decisions to 
>>>>> users.  Tango is going to expose the same D interface no matter how 
>>>>> it's implemented under the hood.
>>>>
>>>> That's great, however the interface has a problem too: it does not 
>>>> produce atomic strings in multithreaded programs.
>>>
>>> Which interface?  And are you talking about input or output?
>>
>> Cout. The thing is that the design using the syntax Cout(a)(b) is 
>> conducive to two separate calls to the library. I recall this has been 
>> briefly discussed here.
> 
> Just making sure we were on the same page.  In my experience, raw output 
> is typically used for logging--that's about the only case I can think of 
> where the random interleaving of messages is acceptable.  Tango has a 
> separate logging facility which performs synchronization for exactly 
> this purpose: tango.util.log.  Perhaps this particular critique would be 
> more appropriately applied to the logging package?

I don't think so. For example, I have a multithreaded program that 
starts processes on multiple machines and outputs "stamped" lines to the 
standard output - lines with a prefix clarifying which machine the line 
comes from, and at what time. That output is gzipped for efficiency and 
transported via ethernet to a hub where the lines are demultiplexed and 
put into multiple files etc.

It is essential that lines are written atomically, but beyond that, the 
actual order does not matter.


Andrei