Ricardo Garcia wrote:
> On Thu, Apr 17, 2008 at 6:02 PM, Jens Persson <[EMAIL PROTECTED]> wrote:
>> Buenas noches ppl!
>>
>> I ran into a little problem on IRC and am a bit clueless so I just pass
>> it on to the pros:
>>
>> <oberon> hi
>> <oberon> is there a keyword I can put in an .i file that will prevent a
>> daemon from restarting when a daemon is uses/needs restarts ?
>> <xerxes2> oberon: i'm not sure what you mean?
>> <oberon> when there is a daemon A that uses/needs daemon B - if B
>> restarts for whatever reason, A is forced to restart too
>> <oberon> I wonder if there is a way to prevent this forced restart
>> <xerxes2> hmm, i didnt know that.
>> <xerxes2> i'll take it up with ismaell later.
>> <xerxes2> sounds just stupid yes.
>> <oberon> it's reasonable, but there should be a way to prevent this
>> * Anathema` has quit (Read error: 110 (Connection timed out))
>> <xerxes2> ok
>> <xerxes2> as you said a keyword like "norestart" would solve it.
>> <xerxes2> dunno if that exists.
>> * fcr-sama has quit (Read error: 104 (Connection reset by peer))
>> <oberon> actually there should be two levels of "norestart"
>> <oberon> the simpler one is just "norestart;"
>> <oberon> the more complex one will accept exceptions
>> <xerxes2> hmm ok.
>> <oberon> ie, when a daemon depends on A and B, when A restarts you dont
>> want to restart, but whn B restarts you *do* want to restart
>> <oberon> I'll settle for a simple "norestart;" for now .. :-)
>> <xerxes2> ok. :D
>> <Ditegen> if A needs B and B restarts: there should be restart handler in A
>> <Ditegen> it either restarts or runs the script in restart handler
>> <Ditegen> most simple case is A sends itself SIGHUP in the script
>> * Anathema` ([EMAIL PROTECTED]) has joined #initng
>> * Pix` ([EMAIL PROTECTED]) has joined #initng
>> * Pix- ([EMAIL PROTECTED]) has joined #initng
>> * Pix has quit (Read error: 110 (Connection timed out))
>> * Pix- is now known as Pix
>> * Pix` has quit (Read error: 113 (No route to host))
>> <oberon> Ditegen, yeah, thats a better idea, but it will take a longer
>> time to implement
>> <oberon> that's why I said that I'll settle for a simple "norestart" for now
>>
>> Greets Jens
>
> I see a way to define the restarting... I think you might be barking
> at the wrong tree. I think that instead of specifying if a service
> should restart or not, we should specify whether a service or daemon
> should send a restart chain to its dependants. For this we can
> implement a "nochainrestart" (or "restartsfreely") directive. This
> would be wonderful for, say, setting up the random number generator
> for encryption services. They only need it to run once. It's also
> useful for other services that do only on-start setup chores, like the
> dkms autoinstaller present in some distros. Actually I tried to
> restart it once, and I ended up restarting the whole machine.
>
> The pseudocode for the handling would be (I haven't read the code, so
> please forgive me):
>
> service::onstop() {
> if(!restartsfreely) {
> send_dependency_down_events();
> }
> }
>
> But let's assume that specifying it on the other end is required. For
> this, I propose other directives: "needsonce" and "usesonce" (similar
> to php's include_once and require_once directives), which only depends
> on the service on startup (i.e. setting up a config file or
> something). This way we could specify which services should restart
> and which ones shouldn't.
>
> The alternative would be "norestartfor", in which we could list the
> services/daemons that we want to restart. If we want to generalize
> that, we could use a "*" meaning any.
>
> The pseudocode is pretty simple:
>
> service::ondependencydown(dependencyname) {
> if((not dependencyname in [norestartfor] ) and (norestartfor != "*" ) then {
> shutdownservice("waiting for dep");
> }
> }
>
> But I actually don't know how the real code is handled. Anyway, this
> is a very interesting subject B-)
A plugin could be written with both ideas quite easily, the main problem
at the moment there is no restart event to hook into, no way to tell a
restart event from a stopping event.
I started looking at this when I read the irc log, I'll try and add
something to SVN, and look into porting it to 0.6 if it works ok
--
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