[support] Issues with initializing Variables on startup..

Tue Jan 29 22:01:14 UTC 2008

Really, I'm not trying to tell you that this is all your problem, but I
am trying to help you get to the bottom of what your problem is. I'm
also trying to make sure you understand how the api's are intended to be
used, so that you don't spend time beating your head against the wall
here.   

Saying  that you're not going to use the variable_set function to get
the value into the database, is saying you won't use the api that's
intended for doing just that. You've suggested it is a bug, and I'm here
to tell you it's by design.  It needs to be used or else you need to
circumvent all the caching that goes on, and yes that will be hard.
The static variable is part of the caching, and there is an additional
database cache that also is used.  You may try executing a DELETE FROM
CACHE statement from your SQL line to see if that's what is getting in
your way. 

I expect that unless you delete drupal's cache manually every time you
alter the database, you're going to have problems getting the value back
out, unless you use variable_set to get that value in the database.  All
the variables are cached, in multiple layers and multiple ways in order
to improve performance.  I would encourage you to use variable_set to
alter the database values, as that's what it's there for. 

I certainly had no way of knowing what php version you were running when
I sent you that bug reference, but I do know that the static variable is
not supposed to overwrite a global in any version of PHP, and that the
static $conf='' line is a normal accepted way of initializing a static
variable caching that's used throughout drupal. I've even used this in
several of my own PHP applications.  I'm trying to make sense as to why
when you changed the variable names, you get different behavior.  That's
why I thought of that bug.  There may be other reasons, such as you
haven't found all of the references to the global $conf in the drupal
source code. 

I can tell you that I have multiple sites running on php 5.2.2, php 5.1
and a remote hosted php 5.x and the variable_set/variable_get apis are
used extensively in all the modules that I have written.  I have not
used the settings.php override mechanism, but I can tell you that I have
extensive experience using the variable_get/variable_set successfully in
multiple versions of drupal on multiple versions of PHP.   Variable_init
as I've said, was not intended to be called directly. 

In summary if you don't feel you need to use the settings.php override
mechanism then use variable_set to change the value in the database, use
variable_get to get the last value set by variable_set (or the default
if variable_set has never been called)..   Any other manipulations
should be done using a different structure such as your own static,
global or session construct.  In multi-site hosting environments, where
you want the value of variable_get to be overridden because you've got
to make it dynamic based on the settings.php file in play, only then use
the settings.php override mechanism.  Don't bother with the database
value cause it shouldn't ever actually matter.   

If you continue to be disatisfied with the help being provided on this
list,  and you really believe that there is a drupal core bug here
(which I really haven't seen strong evidence of, but I've been wrong
before) then I'd encourage you to post an issue on drupal.org.  

Anyway, it sounds like you'd prefer to hear from others so, I'll stay
silent for a while and let others confirm or refute my expertise here.
(really either are welcome). 

Dave

________________________________

From: support-bounces at drupal.org [mailto:support-bounces at drupal.org] On
Behalf Of Scott Matthews
Sent: Tuesday, January 29, 2008 12:56 PM
To: support at drupal.org
Subject: Re: [support] Issues with initializing Variables on startup..

            I understand that this bug report seems to be the same
issue, but I'm a little troubled at the fact that I'm running PHP 5.2.3
and this is listed as having been fixed about a year and a half ago.  I
really do not mean to come off as being too forceful but can anyone on
this distribution say that with PHP 5.2.3 and Drupal 5.3 that they have
tried setting a variable in the database directly (not specifically
using variable_set or variable_init) and their application was able to
pick up the value using variable_get?  Or even, been able to follow the
suggested feature of setting the $conf array in settings.php to override
a variable set previously.

            I see this is a problem.  I see the code where it's
happening and I would like to know if this case has been done and it
really is only happening on the multiple machines as well as my local
that my application is deployed on.

Scott Matthews

Senior Developer

(w) 617-227-1855 x164

(m) 617-710-8430

(f) 617-224-5388

smatthews at optaros.com

On Jan 29, 2008, at 1:42 PM, Metzler, David wrote:

Ahh,  static variables are supposed to be local in scope to the function
that they are in.    And they behave a bit differently than normal
variables. 

static $conf='' assignment doesn't execute the second time the function
gets called.  It only executes at the initial creation of the static
variable.  This variable later gets converted to an array, but the next
time the function gets called it should retain the previous value of
$conf.  It would not be reset to a string. You actually need to set
static variables to this empty strings to get them to work properly with
arrays.  I've done that several times before. 

It's worth noting that this $conf SHOULD be completely independent of
the global $conf variable, and that doesn't appear to be the case for
you. 

It's possible this is a PHP bug, but I'm not really sure here. There are
some references to such a bug at: 

http://bugs.php.net/bug.php?id=38287

Is it possible that you are being bitten by one of these? 

 I have many modules that work as you want.  The variable_get call pulls
the database value without problem.   It's quite possible that once the
PHP bug is resolved, everything will work they way you initially tried
it. 

And, no you should not need to call variable_init. 

Hope that helps. 

Dave

________________________________

From: support-bounces at drupal.org [mailto:support-bounces at drupal.org] On
Behalf Of Scott Matthews
Sent: Tuesday, January 29, 2008 9:43 AM
To: support at drupal.org
Subject: Re: [support] Issues with initializing Variables on startup..

Conf_init calls conf_path.  the first line in conf path is:

  static $conf = '';

As I said, once I globally changed the intended array variable to
something other than $conf ($config_vars for instance) it worked as
expected.

Now, as I mentioned before, before I tried to initialize in the
settings.php file, I just relied on the database value that I set.  This
was not being retrieved when I called variables_get() and
variables_get() was only returning the value I had as the default.  The
only thing I can think of from what you are saying is that in my module
I have to specifically call variables_init() for it to work.  Is that
true?  when in the stack is variables_init called?

Scott Matthews

Senior Developer

(w) 617-227-1855 x164

(m) 617-710-8430

(f) 617-224-5388

smatthews at optaros.com

On Jan 29, 2008, at 12:04 PM, Metzler, David wrote:

Yes true, I was mistaken about the variables being instatitated. But
these values are initially loaded from the database by the variable_init
function, called in the drupal bootstrap process before settings.php is
loaded.  Yes you can override these in settings.php, in which case the
database value doesn't matter, but hey are still meant to be site
configuration values that do not change.  As the settings.php file
indicates you don't normally use this method, unless you're rally trying
to something vhost specific.  They are not intended to house global
variables that you intend to change during the page load.   Variable_set
is designed to change the database given values and is functioning as
designed.  It's used by the admin pages to alter the site specific
values.   

90% of all use cases are handled using variable_get() to get the site
specific configuration settings from the database and loaded in cache.
It's only in weird multi-site hosting cases that you would ever be
overriding the values retrieved by variable_get in settings.php.  It is
not the preferred method of handling values that you expect to change
during a page load or between page loads on a site. 

Conf_init() in my inspection of the source code on drupal_api
initializes conf to an array() not a string. Where do you see this
behavior? 

Dave

________________________________

From: support-bounces at drupal.org [mailto:support-bounces at drupal.org] On
Behalf Of Scott Matthews
Sent: Tuesday, January 29, 2008 8:19 AM
To: support at drupal.org
Subject: Re: [support] Issues with initializing Variables on startup..

I don't believe you fully understood me.

First off, variable_get does NOT retrieve from the database.  if you
look in the code it ONLY retrieves from that $conf variable that
variable_set stores the variable in when it sets to the database.  If,
as you suggest David, it really should retrieve from the database then
it is not working as defined.

function variable_get($name, $default) {

  global $conf;

  return isset($conf[$name]) ? $conf[$name] : $default;

}

Second, according to the comments in the settings.php, you can initially
override any variables stored in the database in the settings.php file
by setting the same variable that variable_get and variable_set uses:

/**

 * Variable overrides:

 *

 * To override specific entries in the 'variable' table for this site,

 * set them here. You usually don't need to use this feature. This is

 * useful in a configuration file for a vhost or directory, rather than

 * the default settings.php. Any configuration setting from the
'variable'

 * table can be given a new value.

 *

 * Remove the leading hash signs to enable.

 *

/# $conf = array(

#   'site_name' => 'My Drupal site',

#   'theme_default' => 'minnelli',

#   'anonymous' => 'Visitor',

# );

Scott Matthews

Senior Developer

(w) 617-227-1855 x164

(m) 617-710-8430

(f) 617-224-5388

smatthews at optaros.com

On Jan 29, 2008, at 11:04 AM, Metzler, David wrote:

I think you're confusing two completely independent constructs.  

Variable_get and variable_set are used to store system wide settings
that should persist in the database.  They are never (to my knowledge)
instantiated as PHP variables. The caching structure is meant to reduce
the number of database hits involved in loading variables, and should
not generally be accessed directly.  Multiple calls to variable_get
should leverage the cached variables as appropriate. 

The variables in settings.php can be used, you can define your own
global variables there, but if you want them to persist between page
loads you need to do that yourself.  IN your hooks you can reference
these variables after defining them as globals, but be careful with
namespace collisions.  I usually create a global variable that has the
same name as my module and store everying inside it (as an associative
array).  

Finally session variables can be used and will persist in the database
for the duration of a session.  

Hope that clarifies things.  It sounds like drupal is behaving as
designed here. 

Dave

________________________________

From: support-bounces at drupal.org [mailto:support-bounces at drupal.org] On
Behalf Of Scott Matthews
Sent: Tuesday, January 29, 2008 7:37 AM
To: support at drupal.org
Cc: Ron Trevarrow
Subject: [support] Issues with initializing Variables on startup..

I found what Appears to be a bug (or two) with initializing variables in
Drupal.

It is suggested that you can uncomment and set initial variable values
in settings.php with the $conf array.  In doing so, and not seeing my
variables set when retrieving using variable_get, I discovered that
conf_init(), when called to initialize the configure file path, it sets
$conf to a string.  I know that since it initializes settings.php within
the context it conceptually SHOULD reset it to a variable, but it
doesn't.   I proved this by changing the variable array name in
settings.php, variable_get, variable_set, variable_init and conf_init to
$config_vars and the values I initialized in settings.php were reflected
when my application later retrieved them using variable_get.

This bug is currently hindering the flexibility of an application that
I'm writing that will be deployed to different environments.  I
initially tried to set the variables in the 'variable' table of the
Database in order to retrieve them with variable_get but that method
only accesses the cached variables in $conf (or in my case,
$config_vars.  Is this on purpose?  I see that variable_set will not
only set the cached variable but will also set into the database.  This
seems to be a bug as well to me.  Can someone clarify this for me?

Scott Matthews

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