Op 13-5-2012 19:51, Till Oliver Knoll schreef: > Am 13.05.2012 um 18:36 schrieb Till Oliver Knoll<till.oliver.kn...@gmail.com>: > >> Hello, >> >> this seems to be an ever recurring topic: How does one get notified in a >> *child* process (started via QProcess) once there is data to be read on >> stdin (in a platform-independent matter - but for now mostly OS X)? > I came to realise that stdin/out are really *text*-based and trying to > re-open them in binary mode is also not guaranteed to work everywhere: > > http://bytes.com/topic/c/answers/213649-how-write-binary-data-stdout > > As I really want to send raw JPEG binary data from parent to child this IPC > solution is a dead-end anyway. > > > Next: QLocalServer/Socket. I assume in the parent process I start a > QLocalServer, start a child process via QProcess and pass along the "server > connect information" as arguments, and then in the child process connect to > the parent process' server. That should hopefully give me a bi-directional > (local socket or pipe) connection with "bytesAvailable" signals on both ends. > > It remains to be seen whether the parent process with *no* network > entitlement ("OS X sandboxing") can actually create a local server... > > If that would fail, what remains is QSharedMemory. But to my understanding > that would require to "poll some memory addresses" wheter the other process > wants to "send a message". Not to mention that I need to send data of > variable size (JPEG), so I would probably end up in a "memory-based block > read/write protocol": "I have written 1024 KBytes of JPEG data into the > shared memory block, more to follow (poll for ACK) - Ok, got it (poll for > more data) - Here is the next block of 1024 KBytes - Ok, bring it on... - > Here are the last 42 KBytes - Got it..." doh! > > I hope the local socket approach works... > How about using QSharedMemory for the actual JPEG data, and use either the QLocalServer/Socket or a StdIn/StdOut approach for the notifications that there is something to read? Seems more efficient than (de-) serializing images all the time. You could even use something like QxtRPCPeer[1] for the communication between the two programs.
André [1] http://libqxt.bitbucket.org/doc/0.6/qxtrpcpeer.html#details _______________________________________________ Interest mailing list Interest@qt-project.org http://lists.qt-project.org/mailman/listinfo/interest
