Hi Elias,
given that hardly anybody uses shared variables these days this discussion
is more on the theoretical side than of practical relevance.
For that reason I would like the solution to be as simple as possible.
The extra things needed as you state below make things more complicated
and raise new problems, e.g. unlink the socket while it is still used
and the like.
Also I have not found a reliable way to figure if a connection is closed
or not.
For example if I do *kill -9* of a process that is connected to
*APserver* then
*APserver* does not detect this in its *select()* loop.
/// Jürgen
On 07/24/2014 01:34 PM, Elias Mårtenson wrote:
I did not know about that feature. Interesting. Also interesting that
it's not supported on OSX.
That said, I still think Unix domain sockets are good in this case.
There are just a few things that needs to be done in order to make
them solid. I think I did most of those things in the native code for
the Emacs mode.
These things include:
* Call unlink() on the socket file before creating it (in case there
is one lingering from before).
* Call unlink() on the socket when shitting down (we want everything
to be clean after shutdown).
* When automatically starting the backend (as opposed to manually
creating it), compute the filename so that it's reasonably unique.
I.e. append the process ID to it or something.
What do you think of this?
Regards,
Elias
On 24 July 2014 19:26, Juergen Sauermann
<juergen.sauerm...@t-online.de <mailto:juergen.sauerm...@t-online.de>>
wrote:
Hi Elias,
the idea is this:
man 7 unix says:
/abstract: an abstract socket address is distinguished by the
fact//
// that sun_path[0] is a null byte ('\0'). The
socket's address in//
// this namespace is given by the additional bytes in
sun_path that are//
// covered by the specified length of the address
structure. (Null//
// bytes in the name have no special significance.)/
So I *memset()* the entire socket address first and then copy the
name to *sun_path,*
but starting at *sun_path[1]* so that *sun_path[0]* remains *0
*(making it an abstract
socket).
man 7 unix also says:
/The abstract socket namespace is a nonportable Linux extension./
That's why I *#define ABSTRACT_OFFSET* to 1 if your OS supports it and
you can change it to 0 if not. In the latter case you have to
provide a file
*/tmp/GNU-APL/APserver* manually with proper permissions.
This file is having the file permissions that you were after
earlier. I am
not creating that file because I expect more problems with it than
benefits
(who owns it, who installs it, what if one user creates it with
wrong permissions etc.).
My general feeling is that TCP on localhost is much cleaner and
maybe I should make
that the default.
/// Jürgen
