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Apache2::ServerUtil - Perl API for Apache server record utils | ||||
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add_config
add_version_component
dir_config
exists_config_define
get_handlers
get_server_built
get_server_version
get_server_banner
get_server_description
group_id
is_perl_option_enabled
method_register
push_handlers
restart_count
server
server_root
server_root_relative
server_shutdown_cleanup_register
set_handlers
user_id
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;
add_config
Dynamically add Apache configuration:
$s->add_config($lines);
$s
( Apache2::ServerRec object
)
$lines
( ARRAY ref )
An ARRAY reference containing configuration lines per element, without the new line terminators.
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);
$s
( Apache2::ServerRec object
)
$component
( string )
The string component to add
This function is usually used by modules to advertise themselves to
the world. It's picked up by such statistics collectors, like
netcraft.com, which accomplish that by connecting to various servers
and grabbing the server version response header (Server
). Some
servers choose to fully or partially conceal that header.
This method should be invoked in the
PerlPostConfigHandler
phase, which will ensure that the Apache core version number will
appear first.
For example let's add a component "Hikers, Inc/0.99999" to the server string at the server startup:
use Apache2::ServerUtil (); use Apache2::Const -compile => 'OK'; Apache2::ServerUtil->server->push_handlers( PerlPostConfigHandler => \&add_my_version); sub add_my_version { my ($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);
$s
( Apache2::ServerRec object
)
$key
( string )
Key string
$val
( string )
Value string
Depends on the passed arguments, see further discussion
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);
$name
( string )
The define string to check for
$result
( boolean )
true if defined, false otherwise
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);
$s
( Apache2::ServerRec object
)
$hook_name
( string )
a string representing the phase to handle.
$handlers_list
(ref to an ARRAY of CODE refs)
a list of references to the handler subroutines
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();
get_server_version
Get the server version string
$version = Apache2::ServerUtil::get_server_version();
get_server_description
Get the server description
$description = Apache2::ServerUtil::get_server_description();
group_id
Get the group id corresponding to the Group
directive in
httpd.conf:
$gid = Apache2::ServerUtil->group_id;
Apache2::ServerUtil
(class name)
$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.
is_perl_option_enabled
check whether a server level PerlOptions
flag is enabled or not.
$result = $s->is_perl_option_enabled($flag);
$s
( Apache2::ServerRec object
)
$flag
( string )
$result
( boolean )
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);
$s
( Apache2::ServerRec object
)
$methname
( string )
The name of the new method to register (in addition to the already
supported GET
, HEAD
, etc.)
$offset
( integer )
An int value representing an offset into a bitmask. You can probably ignore it.
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]);
$s
( Apache2::ServerRec object
)
$hook_name
( string )
the phase to add the handlers to
$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.
$ok
( boolean )
returns a true value on success, otherwise a false value
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();
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:
Apache2::ServerUtil::restart_count()
returns 1 every time some -k
command is passed to Apache (or kill -USR1
or some alternative
signal is received).
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();
Apache2::ServerUtil
(class name)
$main_s
( Apache2::ServerRec object
)
server_root
returns the value set by the top-level ServerRoot
directive.
$server_root = Apache2::ServerUtil::server_root();
server_root_relative
Returns the canonical form of the filename made absolute to
ServerRoot
:
$path = Apache2::ServerUtil::server_root_relative($pool, $fname);
$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.
$fname
( string )
$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).
$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);
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);
$s
( Apache2::ServerRec object
)
$hook_name
( string )
the phase to set the handlers in
$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.
$ok
( boolean )
returns a true value on success, otherwise a false value
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;
Apache2::ServerUtil
(class name)
$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.
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();
$s
( Apache2::ServerRec object
)
The current server
This method may prove useful if you want to start redirecting STDERR to the error_log file before Apache does that on the startup.
mod_perl 2.0 and its core modules are copyrighted under The Apache Software License, Version 2.0.
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