This fixes all warnings for "make examples" for:
-Wunused-parameter
-Wshadow
-Wformat-security
-Wenum-conversion
Some remaining warnings include:
-Wdeprecated-delcarations
This is the local socket for windows, analogous to AF_UNIX.
`Efl_Net_Socket_Windows` is the base class doing `ReadFile()` and
`WriteFile()` using overlapped I/O, as well as the close procedure
(`FlushFileBuffers()`, `DisconnectNamedPipe()` and
`CloseHandle()`). These are done on top of an existing HANDLE that is
set by `Efl_Net_Dialer_Windows` (from `CreateFile()`) or
`Efl_Net_Server_Windows` (from `CreateNamedPipe()`).
The overlapped I/O will return immediately, either with operation
completed or `ERROR_IO_PENDING`, which means the kernel will execute
that asynchronously and will later `SetEvent(overlapped.hEvent)` which
is an event we wait on our main loop. That `overlapped` handle must
exist during the call lifetime, thus cannot be bound to `pd`, as we
may call `CancelIo()` but there is no guarantee the memory won't be
touched, in that case we keep the overlapped around, but without an
associated object.
Windows provides no notification "can read without blocking" or
non-blocking calls that returns partial data. The way to go is to use
these overlapped I/O, with an initial `ReadFile()` to an internal
buffer, once that operation finishes, we callback the user to says
there is something to read (`efl_io_reader_can_read_set()`) and wait
until `efl_io_reader_read()` is called to consume the available data,
then `ReadFile()` is called again to read more data to the same
internal buffer.
Likewise, there is no "can write without blocking" or non-blocking
calls that sends only partial data. The way to go is to get user bytes
in `efl_io_writer_write()` and copy them in an internal buffer, then
call `WriteFile()` on that and inform the user nothing else can be
written until that operation completes
(`efl_io_writer_can_write_set()`).
This is cumbersome since we say we "sent" stuff when we actually
didn't, it's still in our internal buffer (`pd->send.bytes`), but
nonetheless the kernel and the other peer may be adding even more
buffers, in this case we need to do a best effort to get it
delivery. A particular case is troublesome: `write() -> close()`, this
may result in `WriteFile()` pending, in this case we wait using
`GetOverlappedResult()`, *this is nasty and may block*, but it's the
only way I see to cope with such common use case.
Other operations, like ongoing `ReadFile()` or `ConnectNamedPipe()`
will be canceled using `CancelIo()`.
Q: Why no I/O Completion Port (IOCP) was used? Why no
CreateThreadpoolIo()? These perform much better!
A: These will call back from secondary threads, but in EFL we must
report back to the user in order to process incoming data or get
more data to send. That is, we serialize everything to the main
thread, making it impossible to use the benefits of IOCP and
similar such as CreateThreadpoolIo(). Since we'd need to wakeup the
main thread anyways, using `OVERLAPPED.hEvent` with
`ecore_main_win32_handler_add()` does the job as we expect.
Thanks to Vincent Torri (vtorri) for his help getting this code done
with an example on how to do the NamedPipe handling on Windows.
Working directly with Eina_Slice is easier than a pointer to it,
requires no validation of the pointers and is cheap since it's just
putting together size_t + void*.
However we can't hint the user of 'const(Eina.Slice)' properties as
Eolian is incorrectly generating getters as:
const Eina_Slice class_property_get(...)
which is makes compilers complain about ignored qualifiers:
../src/lib/ecore/efl_io_copier.eo.h:329:7: warning: 'const' type qualifier on return type has no effect [-Wignored-qualifiers]
Leave some TODO so @q66 can fix those.
Previously we couldn't return a slice, instead required the user to
pass a slice and we'd fill it since Eolian couldn't generate fallbacks
for structures.
Since @q66 fixed eolian, we can now return the structure itself as
initially wanted, ditching some TODO from the code.
The low level I/O primitives are powerful but adds some complexity to
use, for bi-directional streaming communication one ends creating two
Efl.Io.Queue and two Efl.Io.Copier to pipe data to socket when it can
operate.
Then encapsulate the socket using the new Efl.Io.Buffered_Stream, this
will allow the socket, be a dialer or a server client, to be operated
as a single handle that internally carries about the buffering for
you.
As one can see in the examples, compared to their "manual"
alternatives they are very easy to use, ressembling
Ecore_Con_Server/Ecore_Con_Client, but also offers line-based
delimiters and the possibility to let the socket to handle queueing
for you in case you received partial messages (just do not
read/clear/discard the received data).
Xavi Artigas
Mike Blumenkrantz
Cedric BAIL
Carsten Haitzler
Jean-Philippe Andre
Gustavo Sverzut Barbieri