Apache2::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 = $s->dir_config($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 = $s->dir_config($key);
If the $key argument is passed in the list context a list of all
matching values will be returned. This method is ineffective for big
tables, as it does a linear search of the table. Thefore avoid using
this way of calling dir_config() unless you know that there could be
more than one value for the wanted key and all the values are wanted.
$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.
"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(3) 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 v5.10.0 Apache2::ServerUtil(3)
Mac OS X 10.6 - Generated Thu Sep 17 20:10:32 CDT 2009