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Date: Tue, 24 Nov 2009 15:00:14 -0500
Message-ID: <cc67648e0911241200v2c724299mbcf5a930e22eea0@mail.gmail.com>
Subject: Re: svn commit: r883712 - /httpd/httpd/trunk/docs/manual/mod/core.xml
From: Jeff Trawick <trawick@gmail.com>
To: dev@httpd.apache.org
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On Tue, Nov 24, 2009 at 1:58 PM, William A. Rowe Jr.
<wrowe@rowe-clan.net> wrote:
> Jeff Trawick wrote:
>>
>> What about an optional third argument to Mutex to indicate that the
>> pid should be omitted?
>>
>> Mutex default sysvsem
>> Mutex ssl-cache file:/mnt/sesscachedir OmitPid
>> etc.
>
> That seems sensible, but I'm left wondering how many different naming
> conventions we can fit on one directive line. =A0Perhaps bOmitPID instead=
 ;-)
> This really becomes harder to follow than the existing multiple-syntaxes.
>
> Is there any reason not to name these mutexes in MixedCase?

I like having the mutex type name as of the filename, and mixed case
filenames are unexpected.  Beyond that, MixedCase and the "." before
the pid suffix don't totally resolve readability.  Modules like
mod_watchdog with multi-instance mutexes provide an instance string
which gets inserted as "-" string prior to the . pid suffix.

If the watchdog names are heartbeat and dialup (wild guess; I didn't
look closely or try to configure the thing), the files would be

logs/watchdog-callback-heartbeat.1359
logs/watchdog-callback-dialup.1359

(These are both instances of the "watchdog-callback" type, which is
what would be specified on the Mutex directive.)

> Is there any reason we can't invert the arg order, so that we have
>
> Mutex mutextype:name Resource [Resource ...] [OmitPid]

Maybe it would be clearer if the optional OmitPid came before the list
of mutexes?

>
> Of course, default could be assumed here. =A0So the above becomes
>
> Mutex SysVSem
> Mutex file:/mnt/sesscachedir SSLSessionCache OmitPid
>
> (note the Resource tag can be the actual directive being mutexed, instead
> of an alt-name).
>
> Thoughts?

I'm fine with putting the mechanism:dir first followed by a list of
mutex type names.  I'm not sure about where to put the OmitPid though.
 I guess you get used to either after a while.

(Joe suggested "Mutex name1,name2,name3 mechanism:dir"; I didn't get
around to splitting up the first arg to implement that.)

>> In the ssl-cache example, the name of the mutex will be simply
>> /mnt/sesscachedir/ssl-cache
>>
>> Does that meet the special SSLMutex requirement?
>
> Well, it's not strictly SSLMutex,

understood that its a general capability

> but any other shared-resource that
> requires cross process/cross machine mutexing.

The SSL session cache mutex is the only use case we have now.

At any rate, I take that as a "yes" answer ;)  (user somehow says
omit-the-pid on the Mutex directive, case closed)