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work::mod_perl-2.0.11:User:Contributed.Perl:DocumentatioApache2::ServerUtil(3)

NAME
       Apache2::ServerUtil - Perl API for Apache server	record utils

Synopsis
	 use Apache2::ServerUtil ();
	 $s = Apache2::ServerUtil->server;

	 # push	config
	 $s->add_config(['ServerTokens off']);

	 # add components to the Server	signature
	 $s->add_version_component("MyModule/1.234");

	 # access PerlSetVar/PerlAddVar	values
	 my $srv_cfg = $s->dir_config;

	 # check command line defines
	 print "this is	mp2"
	     if	Apache2::ServerUtil::exists_config_define('MODPERL2');

	 # get PerlChildExitHandler configured handlers
	 @handlers = @{	$s->get_handlers('PerlChildExitHandler') || []};

	 # server build	and version info:
	 $when_built = Apache2::ServerUtil::get_server_built();
	 $description =	Apache2::ServerUtil::get_server_description();
	 $version = Apache2::ServerUtil::get_server_version();
	 $banner = Apache2::ServerUtil::get_server_banner();

	 # ServerRoot value
	 $server_root =	Apache2::ServerUtil::server_root();

	 # get 'conf/' dir path	(avoid using this function!)
	 my $dir = Apache2::ServerUtil::server_root_relative($r->pool, 'conf');

	 # set child_exit handlers
	 $r->set_handlers(PerlChildExitHandler => \&handler);

	 # server level	PerlOptions flags lookup
	 $s->push_handlers(ChildExit =>	\&child_exit)
	     if	$s->is_perl_option_enabled('ChildExit');

	 # extend HTTP to support a new	method
	 $s->method_register('NEWGET');

	 # register server shutdown callback
	 Apache2::ServerUtil::server_shutdown_register_cleanup(sub { Apache2::Const::OK	});

	 # do something	only when the server restarts
	 my $cnt = Apache2::ServerUtil::restart_count();
	 do_something_once() if	$cnt > 1;

	 # get the resolved ids	from Group and User entries
	 my $user_id  =	Apache2::ServerUtil->user_id;
	 my $group_id =	Apache2::ServerUtil->group_id;

Description
       "Apache2::ServerUtil" provides the Apache server	object utilities API.

Methods	API
       "Apache2::ServerUtil" provides the following functions and/or methods:

   "add_config"
       Dynamically add Apache configuration:

	 $s->add_config($lines);

       obj: $s ( "Apache2::ServerRec object" )
       arg1: $lines ( ARRAY ref	)
	   An ARRAY reference containing configuration lines per element,
	   without the new line	terminators.

       ret: no return value
       since: 2.0.00

       See also: "$r->add_config"

       For example:

       Add a configuration section at the server startup (e.g. from
       startup.pl):

	 use Apache2::ServerUtil ();
	 my $conf = <<'EOC';
	 PerlModule Apache2::MyExample
	 <Location /perl>
	   SetHandler perl-script
	   PerlResponseHandler Apache2::MyExample
	 </Location>
	 EOC
	 Apache2::ServerUtil->server->add_config([split	/\n/, $conf]);

   "add_version_component"
       Add a component to the version string

	 $s->add_version_component($component);

       obj: $s ( "Apache2::ServerRec object" )
       arg1: $component	( string )
	   The string component	to add

       ret: no return value
       since: 2.0.00

       This function is	usually	used by	modules	to advertise themselves	to the
       world. It's picked up by	such statistics	collectors, like netcraft.com,
       which accomplish	that by	connecting to various servers and grabbing the
       server version response header ("Server"). Some servers choose to fully
       or partially conceal that header.

       This method should be invoked in	the "PerlPostConfigHandler" phase,
       which will ensure that the Apache core version number will appear
       first.

       For example let's add a component "Hikers, Inc/0.99999" to the server
       string at the server startup:

	 use Apache2::ServerUtil ();
	 use Apache2::Const -compile =>	'OK';

	 Apache2::ServerUtil->server->push_handlers(
	     PerlPostConfigHandler => \&add_my_version);

	 sub add_my_version {
	     my	($conf_pool, $log_pool,	$temp_pool, $s)	= @_;
	     $s->add_version_component("Hikers,	Inc/0.99999");
	     return Apache2::Const::OK;
	 }

       or of course you	could register the "PerlPostConfigHandler" handler
       directly	in httpd.conf

       Now when	the server starts, you will something like:

	 [Thu Jul 15 12:15:28 2004] [notice] Apache/2.0.51-dev (Unix)
	 mod_perl/1.99_15-dev Perl/v5.8.5 Hikers, Inc/0.99999
	 configured -- resuming	normal operations

       Also remember that the "ServerTokens" directive value controls whether
       the component information is displayed or not.

   "dir_config"
       "$s->dir_config()" provides an interface	for the	per-server variables
       specified by the	"PerlSetVar" and "PerlAddVar" directives, and also can
       be manipulated via the "APR::Table" methods.

	 $table	 = $s->dir_config();
	 $value	 = $s->dir_config($key);
	 @values = $s->dir_config->get($key);
	 $s->dir_config($key, $val);

       obj: $s ( "Apache2::ServerRec object" )
       opt arg2: $key (	string )
	   Key string

       opt arg3: $val (	string )
	   Value string

       ret: ...
	   Depends on the passed arguments, see	further	discussion

       since: 2.0.00

       The keys	are case-insensitive.

	 $t = $s->dir_config();

       dir_config() called in a	scalar context without the $key	argument
       returns a HASH reference	blessed	into the APR::Table class. This	object
       can be manipulated via the APR::Table methods. For available methods
       see APR::Table.

	 @values = $s->dir_config->get($key);

       To receive a list of values you must use	"get()"	method from the
       "APR::Table" class.

	 $value	= $s->dir_config($key);

       If the $key argument is passed in the scalar context only a single
       value will be returned. Since the table preserves the insertion order,
       if there	is more	than one value for the same key, the oldest value
       assosiated with the desired key is returned. Calling in the scalar
       context is also much faster, as it'll stop searching the	table as soon
       as the first match happens.

	 $s->dir_config($key =>	$val);

       If the $key and the $val	arguments are used, the	set() operation	will
       happen: all existing values associated with the key $key	(and the key
       itself) will be deleted and $value will be placed instead.

	 $s->dir_config($key =>	undef);

       If $val is undef	the unset() operation will happen: all existing	values
       associated with the key $key (and the key itself) will be deleted.

   "exists_config_define"
       Check for a definition from the server startup command line (e.g.
       "-DMODPERL2")

	 $result = Apache2::ServerUtil::exists_config_define($name);

       arg1: $name ( string )
	   The define string to	check for

       ret: $result ( boolean )
	   true	if defined, false otherwise

       since: 2.0.00

       For example:

	 print "this is	mp2"
	     if	Apache2::ServerUtil::exists_config_define('MODPERL2');

   "get_handlers"
       Returns a reference to a	list of	handlers enabled for a given phase.

	 $handlers_list	= $s->get_handlers($hook_name);

       obj: $s ( "Apache2::ServerRec object" )
       arg1: $hook_name	( string )
	   a string representing the phase to handle.

       ret: $handlers_list (ref	to an ARRAY of CODE refs)
	   a list of references	to the handler subroutines

       since: 2.0.00

       See also: "$r->add_config"

       For example:

       A list of handlers configured to	run at the child_exit phase:

	 @handlers = @{	$s->get_handlers('PerlChildExitHandler') || []};

   "get_server_built"
       Get the date and	time that the server was built

	 $when_built = Apache2::ServerUtil::get_server_built();

       ret: $when_built	( string )
	   The server build time string

       since: 2.0.00

   "get_server_version"
       Get the server version string

	 $version = Apache2::ServerUtil::get_server_version();

       ret: $version ( string )
	   The server version string

       since: 2.0.00

   "get_server_banner"
       Get the server banner

	$banner	= Apache2::ServerUtil::get_server_banner();

       ret: $banner ( string )
	   The server banner

       since: 2.0.4

   "get_server_description"
       Get the server description

	$description = Apache2::ServerUtil::get_server_description();

       ret: $description ( string )
	   The server description

       since: 2.0.4

   "group_id"
       Get the group id	corresponding to the "Group" directive in httpd.conf:

	 $gid =	Apache2::ServerUtil->group_id;

       obj: "Apache2::ServerUtil" (class name)
       ret: $gid ( integer )
	   On Unix platforms returns the gid corresponding to the value	used
	   in the "Group" directive in httpd.conf. On other platforms returns
	   0.

       since: 2.0.03

   "is_perl_option_enabled"
       check whether a server level "PerlOptions" flag is enabled or not.

	 $result = $s->is_perl_option_enabled($flag);

       obj: $s ( "Apache2::ServerRec object" )
       arg1: $flag ( string )
       ret: $result ( boolean )
       since: 2.0.00

       For example to check whether the	"ChildExit" hook is enabled (which can
       be disabled with	"PerlOptions -ChildExit") and configure	some handlers
       to run if enabled:

	 $s->push_handlers(ChildExit =>	\&child_exit)
	     if	$s->is_perl_option_enabled('ChildExit');

       See also: PerlOptions and the equivalent	function for directory level
       PerlOptions flags.

   "method_register"
       Register	a new request method, and return the offset that will be
       associated with that method.

	 $offset = $s->method_register($methname);

       obj: $s ( "Apache2::ServerRec object" )
       arg1: $methname ( string	)
	   The name of the new method to register (in addition to the already
	   supported "GET", "HEAD", etc.)

       ret: $offset ( integer )
	   An int value	representing an	offset into a bitmask. You can
	   probably ignore it.

       since: 2.0.00

       This method allows you to extend	the HTTP protocol to support new
       methods,	which fit the HTTP paradigm.  Of course	you will need to write
       a client	that understands that protocol extension.  For a good example,
       refer to	the "MyApache2::SendEmail" example presented in	"the
       PerlHeaderParserHandler section", which demonstrates how	a new method
       "EMAIL" is registered and used.

   "push_handlers"
       Add one or more handlers	to a list of handlers to be called for a given
       phase.

	 $ok = $s->push_handlers($hook_name => \&handler);
	 $ok = $s->push_handlers($hook_name => [\&handler, \&handler2]);

       obj: $s ( "Apache2::ServerRec object" )
       arg1: $hook_name	( string )
	   the phase to	add the	handlers to

       arg2: $handlers ( CODE ref or SUB name or an ARRAY ref )
	   a single handler CODE reference or just a name of the subroutine
	   (fully qualified unless defined in the current package).

	   if more than	one passed, use	a reference to an array	of CODE	refs
	   and/or subroutine names.

       ret: $ok	( boolean )
	   returns a true value	on success, otherwise a	false value

       since: 2.0.00

       See also: "$r->add_config"

       Examples:

       A single	handler:

	 $s->push_handlers(PerlChildExitHandler	=> \&handler);

       Multiple	handlers:

	 $s->push_handlers(PerlChildExitHandler	=> ['Foo::Bar::handler', \&handler2]);

       Anonymous functions:

	 $s->push_handlers(PerlLogHandler => sub { return Apache2::Const::OK });

   "restart_count"
       How many	times the server was restarted.

	 $restart_count	= Apache2::ServerUtil::restart_count();

       ret: "restart_count" ( number )
       since: 2.0.00

       The following demonstration should make it clear	what values to expect
       from this function. Let's add the following code	to startup.pl, so it's
       run every time httpd.conf is parsed:

	 use Apache2::ServerUtil ();
	 my $cnt = Apache2::ServerUtil::restart_count();
	 open my $fh, ">>/tmp/out" or die "$!";
	 print $fh "cnt: $cnt\n";
	 close $fh;

       Now let's run a series of server	starts and restarts and	look at	what
       is logged into /tmp/out:

	 % httpd -k start
	 cnt: 1
	 cnt: 2

	 % httpd -k graceful
	 cnt: 1
	 cnt: 3

	 % httpd -k graceful
	 cnt: 1
	 cnt: 4

	 % httpd -k stop
	 cnt: 1

       Remembering that	Apache restarts	itself immediately after starting, we
       can see that the	"restart_count"	goes from 1 to 2 during	the server
       start. Moreover we can see that every operation forces the parsing of
       httpd.conf and therefore	reinitialization of mod_perl (and running all
       the code	found in httpd.conf). This happens even	when the server	is
       shutdown	via "httpd -k stop".

       What conclusions	can be drawn from this demonstration:

       o   "Apache2::ServerUtil::restart_count()" returns 1 every time some
	   "-k"	command	is passed to Apache (or	"kill -USR1" or	some
	   alternative signal is received).

       o   At all other	times the count	will be	2 or higher. So	for example on
	   graceful restart the	count will be 3	or higher.

       For example if you want to run something	every time "httpd -k" is run
       you just	need to	check whether "restart_count()"	returns	1:

	 my $cnt = Apache2::ServerUtil::restart_count();
	 do_something()	if $cnt	== 1;

       To do something only when server	restarts ("httpd -k start" or "httpd
       -k graceful)", check whether "restart_count()" is bigger	than 1:

	 my $cnt = Apache2::ServerUtil::restart_count();
	 do_something()	if $cnt	> 1;

   "server"
       Get the main server's object

	 $main_s = Apache2::ServerUtil->server();

       obj: "Apache2::ServerUtil" (class name)
       ret: $main_s ( "Apache2::ServerRec object" )
       since: 2.0.00

   "server_root"
       returns the value set by	the top-level "ServerRoot" directive.

	 $server_root =	Apache2::ServerUtil::server_root();

       ret: $server_root ( string )
       since: 2.0.00

   "server_root_relative"
       Returns the canonical form of the filename made absolute	to
       "ServerRoot":

	 $path = Apache2::ServerUtil::server_root_relative($pool, $fname);

       arg1: $pool ( "APR::Pool	object"	)
	   Make	sure that you read the following explanation and understand
	   well	which pool object you need to pass before using	this function.

       opt arg2: $fname	( string )
       ret: $path ( string )
	   The concatenation of	"ServerRoot" and the $fname.

	   If $fname is	not specified, the value of "ServerRoot" is returned
	   with	a trailing "/".	(it's the same as using	'' as $fname's value).

       since: 2.0.00

       $fname is appended to the value of "ServerRoot" and returned. For
       example:

	 my $dir = Apache2::ServerUtil::server_root_relative($r->pool, 'logs');

       You must	be extra-careful when using this function. If you aren't sure
       what you	are doing don't	use it.

       It's much safer to build	the path by yourself using use
       "Apache2::ServerUtil::server_root()", For example:

	 use File::Spec::Functions qw(catfile);
	 my $path = catfile Apache2::ServerUtil::server_root, qw(t logs);

       In this example,	no memory allocation happens on	the Apache-side	and
       you aren't risking to get a memory leak.

       The problem with	"server_root_relative" is that Apache allocates	memory
       to concatenate the path string. The memory is allocated from the	pool
       object. If you call this	method on the server pool object it'll
       allocate	the memory from	it.  If	you do that at the server startup,
       it's perfectly right, since you will do that only once. However if you
       do that from within a request or	a connection handler, you create a
       memory leak every time it is called -- as the memory gets allocated
       from the	server pool, it	will be	freed only when	the server is
       shutdown. Therefore if you need to build	a relative to the root server
       path for	the duration of	the request, use the request pool:

	 use Apache2::RequestRec ();
	 Apache2::ServerUtil::server_root_relative($r->pool, $fname);

       If you need to have the path for	the duration of	a connection (e.g.
       inside a	protocol handler), you should use:

	 use Apache2::Connection ();
	 Apache2::ServerUtil::server_root_relative($c->pool, $fname);

       And if you want it for the scope	of the server file:

	 use Apache2::Process ();
	 use Apache2::ServerUtil ();
	 Apache2::ServerUtil::server_root_relative($s->process->pool, $fname);

       Moreover, you could have	encountered the	opposite problem, where	you
       have used a short-lived pool object to construct	the path, but tried to
       use the resulting path variable,	when that pool has been	destructed
       already.	In order to avoid mysterious segmentation faults, mod_perl
       does a wasteful copy of the path	string when returning it to you	--
       another reason to avoid using this function.

   "server_shutdown_cleanup_register"
       Register	server shutdown	cleanup	callback:

	 Apache2::ServerUtil::server_shutdown_cleanup_register($sub);

       arg1: $sub ( CODE ref or	SUB name )
       ret: no return value
       since: 2.0.00

       This function can be used to register a callback	to be run once at the
       server shutdown (compared to "PerlChildExitHandler" which will execute
       the callback for	each exiting child process).

       For example in order to arrange the function "do_my_cleanups()" to be
       run every time the server shuts down (or	restarts), run the following
       code at the server startup:

	 Apache2::ServerUtil::server_shutdown_cleanup_register(\&do_my_cleanups);

       It's necessary to run this code at the server startup (normally
       startup.pl). The	function will croak if run after the
       "PerlPostConfigHandler" phase.

       Values returned from cleanup functions are ignored. If a	cleanup	dies
       the exception is	stringified and	passed to "warn()". Usually, this
       results in printing it to the error_log.

   "set_handlers"
       Set a list of handlers to be called for a given phase. Any previously
       set handlers are	forgotten.

	 $ok = $s->set_handlers($hook_name => \&handler);
	 $ok = $s->set_handlers($hook_name => [\&handler, \&handler2]);
	 $ok = $s->set_handlers($hook_name => []);
	 $ok = $s->set_handlers($hook_name => undef);

       obj: $s ( "Apache2::ServerRec object" )
       arg1: $hook_name	( string )
	   the phase to	set the	handlers in

       arg2: $handlers ( CODE ref or SUB name or an ARRAY ref )
	   a reference to a single handler CODE	reference or just a name of
	   the subroutine (fully qualified unless defined in the current
	   package).

	   if more than	one passed, use	a reference to an array	of CODE	refs
	   and/or subroutine names.

	   if the argument is "undef" or "[]" the list of handlers is reset to
	   zero.

       ret: $ok	( boolean )
	   returns a true value	on success, otherwise a	false value

       since: 2.0.00

       See also: "$r->add_config"

       Examples:

       A single	handler:

	 $r->set_handlers(PerlChildExitHandler => \&handler);

       Multiple	handlers:

	 $r->set_handlers(PerlFixupHandler => ['Foo::Bar::handler', \&handler2]);

       Anonymous functions:

	 $r->set_handlers(PerlLogHandler => sub	{ return Apache2::Const::OK });

       Reset any previously set	handlers:

	 $r->set_handlers(PerlCleanupHandler =>	[]);

       or

	 $r->set_handlers(PerlCleanupHandler =>	undef);

   "user_id"
       Get the user id corresponding to	the "User" directive in	httpd.conf:

	 $uid =	Apache2::ServerUtil->user_id;

       obj: "Apache2::ServerUtil" (class name)
       ret: $uid ( integer )
	   On Unix platforms returns the uid corresponding to the value	used
	   in the "User" directive in httpd.conf. On other platforms returns
	   0.

       since: 2.0.03

Unsupported API
       "Apache2::ServerUtil" also provides auto-generated Perl interface for a
       few other methods which aren't tested at	the moment and therefore their
       API is a	subject	to change. These methods will be finalized later as a
       need arises. If you want	to rely	on any of the following	methods	please
       contact the the mod_perl	development mailing list so we can help	each
       other take the steps necessary to shift the method to an	officially
       supported API.

   "error_log2stderr"
       Start sending STDERR to the error_log file

	 $s->error_log2stderr();

       obj: $s ( "Apache2::ServerRec object" )
	   The current server

       ret: no return value
       since: 2.0.00

       This method may prove useful if you want	to start redirecting STDERR to
       the error_log file before Apache	does that on the startup.

See Also
       mod_perl	2.0 documentation.

Copyright
       mod_perl	2.0 and	its core modules are copyrighted under The Apache
       Software	License, Version 2.0.

Authors
       The mod_perl development	team and numerous contributors.

perl v5.32.0	      work::mod_perl-2.0.11::docs::api::Apache2::ServerUtil(3)

NAME | Synopsis | Description | Methods API | Unsupported API | See Also | Copyright | Authors

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