On 15.09.2015 08:58, Michael Van Canneyt wrote:
On Mon, 14 Sep 2015, Ondrej Pokorny wrote:
I've developed a "single/multiple instances" feature for the Lazarus
IDE. For this feature I need an IPC. First I tried to use simpleipc
but I have struggled on bugs and missing functionality.
Particularly what I found:
1.) BUG: You can register multiple servers on Windows with the same
name (with StartServer procedure).
2.) Small issue: simpleipc uses exceptions if something fails (e.g.
in StartServer procedure). I would prefer using a function with
boolean result (true = OK, false = fail).
3.) MISSING: Multiple clients (from different processes) talk to one
server.
4.) MISSING: Client is able to receive a response on a request.
5.) MISSING: (Optionally, not default) client sends a request to a
server that isn't running. The server is able to handle these
requests when it is started.
So I developed "advancedipc.pas" that does what I need. It can do
everything that is in simpleirc but a little bit differently (I
changed the exception behavior and also method names). The question
is now what to do?
1.) Include advancedipc.pas into FCL as a standalone unit.
2.) Make advancedipc.pas backwards compatible to simpleipc.pas and
use the new code in simpleipc.pas.
Well, both 1 and 2 are the way to go if you want it included in FPC :-)
I see no point in including duplicate functionality, it means
duplicate maintenance. You can keep it as separate units, just make
sure simpleipc runs on top of advancedipc.
As for no semaphores on linux: of course there are semaphores, they
exist since many many years, they are part of POSIX: "man sem_overview".
Michael.
Thanks a lot Michael!
I'll prepare it, write (unit) tests and some demo and then send them
over! Thanks also for the semaphore information. I couldn't find
anything on the internet, therefore I thought Lazarus doesn't support them.
Are there some high level crossplatform semaphore functions in the FCL?
The cthreads/cIntSemaphoreOpen etc. seem to be available on unix only.
What about OS/2?
What about Windows? It looks like semaphores are supported only since
XP:
https://msdn.microsoft.com/en-us/library/windows/desktop/ms682438(v=vs.85).aspx
. Is this a problem for the FCL? (Basically, semaphores are only needed
on unix due to the file locking. But I am still interested.)
If I'll have more questions, I'll write them here.
Ondrej
_______________________________________________
fpc-devel maillist - fpc-devel@lists.freepascal.org
http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-devel
