On 2009 Feb 27, at 4:25, Colin Paul Adams wrote:
Anyway, the POSIX spec indicates the EOF condition as return -1 with errno == ECONNRESET; this should not be taken as anything but the limited expressiveness of a C-based API. We should map this return to Nothing.
Johan> I'm not sure I agree. I think using exceptions in this case is fine as Johan> loosing the connection is indeed an exceptional condition and the best Johan> thing a program can do in this case is probably to abort processing of Johan> the disconnected client.
I guess this depends upon how exceptional you want an exception to be.
To my mind, a lost connection is a fairly normal condition (FAR to normal for my teleworking situation :-( ). That is, I would expect the exception to occur rather than not, during one run of a program. On that basis, I would suggest Nothing is better than an exception.
Actually, thinking about this, ECONNRESET can be a normal end-of- connection for TCP, but for UDP should never happen (on recv(); on send() it is surely an exception). But at the same time, if you're using recv() with TCP you are probably not working with a higher level protocol that simply shuts down the connection when it's done: it's more of a stream-oriented behavior, and the stream-oriented read() handles it as such. That said I have heard of cases where recv() is used for stream protocols for efficiency reasons. I don't know if the efficiency argument relates to anything newer than a PDP11 or VAX 750, though.... -- brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allbery@kf8nh.com system administrator [openafs,heimdal,too many hats] allbery@ece.cmu.edu electrical and computer engineering, carnegie mellon university KF8NH