With that, also fixed bug #68297 (Application Popup provides too few
information) as a better error message is provided to the event log.
In the second case, the condition for display_startup_error was removed. The
condition was added as a fix for bug #30760 which was preventing the
MessageBox to appear. When display_startup_error=on, the error will be seen
on the console. But when running under a webserver it'll probably get lost,
so we need to log it other way into the event log (would be done automatically
when message box was used, but that would eventually cause issues of blocked
execution).
Generally speaking - any MessageBox or other graphical element is a potential
issue and that was repeatedly reported. Graphical elements shouldn't be used
in the core. Even being a rare one it can cause a bad situation where the
server is blocked. Yet some places have to cleaned up.
This loop can block for some minutes, theoretically. Practially
however, this is a 99% non issue for a normal use case. This is
required because read() is synchronous. The PHP streams API wants
to fill its internal buffers, therefore it might try to read some
more data than user has demanded. Also, for a case where we want
to read X bytes, but neither enough data nor EOF arrives, read()
will block until it could fill the buffer. If a counterpart station
runs slowly or delivers not all the data at once, read() would
still be waiting. If we quit too early, we possibly could loose
some data from the pipe. Thus it has to emulate the read()
behaviour, but obviously not completely, just to some grade.
Reading big data amount is for sure an issue on any platforms, it
depends on the pipe buffer size, which is controlled by the system.
On Windows, the buffer size seems to be way too small, which causes
buffer congestion and a dead lock. It is essential to read the pipe
descriptors simultaneously and possibly in the same order as the
opposite writes them.
Thus, this will work with smaller buffer data sizes passed through
pipes. As MSDN states, anonymous pipes don't support asynchronous
operations. Neither anonymous pipes do support select() as they are
not SOCKETs but file descriptors. Consequently - bigger data sizes
will need a better solution based on threads. However it is much
more expencive. Maybe a better solution could be exporting a part
of the internal doing as a userspace function which could perform
some kind of lookahead operation on the pipe descriptor.
This is just the first stone, depending on the user feedback we
might go for further improvements in this area.
