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+package DBI::ProfileDumper::Apache;
+
+use strict;
+
+=head1 NAME
+
+DBI::ProfileDumper::Apache - capture DBI profiling data from Apache/mod_perl
+
+=head1 SYNOPSIS
+
+Add this line to your F<httpd.conf>:
+
+  PerlSetEnv DBI_PROFILE 2/DBI::ProfileDumper::Apache
+
+(If you're using mod_perl2, see L</When using mod_perl2> for some additional notes.)
+
+Then restart your server.  Access the code you wish to test using a
+web browser, then shutdown your server.  This will create a set of
+F<dbi.prof.*> files in your Apache log directory.
+
+Get a profiling report with L<dbiprof|dbiprof>:
+
+  dbiprof /path/to/your/apache/logs/dbi.prof.*
+
+When you're ready to perform another profiling run, delete the old files and start again.
+
+=head1 DESCRIPTION
+
+This module interfaces DBI::ProfileDumper to Apache/mod_perl.  Using
+this module you can collect profiling data from mod_perl applications.
+It works by creating a DBI::ProfileDumper data file for each Apache
+process.  These files are created in your Apache log directory.  You
+can then use the dbiprof utility to analyze the profile files.
+
+=head1 USAGE
+
+=head2 LOADING THE MODULE
+
+The easiest way to use this module is just to set the DBI_PROFILE
+environment variable in your F<httpd.conf>:
+
+  PerlSetEnv DBI_PROFILE 2/DBI::ProfileDumper::Apache
+
+The DBI will look after loading and using the module when the first DBI handle
+is created.
+
+It's also possible to use this module by setting the Profile attribute
+of any DBI handle:
+
+  $dbh->{Profile} = "2/DBI::ProfileDumper::Apache";
+
+See L<DBI::ProfileDumper> for more possibilities, and L<DBI::Profile> for full
+details of the DBI's profiling mechanism.
+
+=head2 WRITING PROFILE DATA
+
+The profile data files will be written to your Apache log directory by default.
+
+The user that the httpd processes run as will need write access to the
+directory.  So, for example, if you're running the child httpds as user 'nobody'
+and using chronolog to write to the logs directory, then you'll need to change
+the default.
+
+You can change the destination directory either by specifying a C<Dir> value
+when creating the profile (like C<File> in the L<DBI::ProfileDumper> docs),
+or you can use the C<DBI_PROFILE_APACHE_LOG_DIR> env var to change that. For example:
+
+  PerlSetEnv DBI_PROFILE_APACHE_LOG_DIR /server_root/logs
+
+=head3 When using mod_perl2
+
+Under mod_perl2 you'll need to either set the C<DBI_PROFILE_APACHE_LOG_DIR> env var,
+or enable the mod_perl2 C<GlobalRequest> option, like this:
+
+  PerlOptions +GlobalRequest
+
+to the global config section you're about test with DBI::ProfileDumper::Apache.
+If you don't do one of those then you'll see messages in your error_log similar to:
+
+  DBI::ProfileDumper::Apache on_destroy failed: Global $r object is not available. Set:
+    PerlOptions +GlobalRequest in httpd.conf at ..../DBI/ProfileDumper/Apache.pm line 144
+
+=head3 Naming the files
+
+The default file name is inherited from L<DBI::ProfileDumper> via the
+filename() method, but DBI::ProfileDumper::Apache appends the parent pid and
+the current pid, separated by dots, to that name.
+
+=head3 Silencing the log
+
+By default a message is written to STDERR (i.e., the apache error_log file)
+when flush_to_disk() is called (either explicitly, or implicitly via DESTROY).
+
+That's usually very useful. If you don't want the log message you can silence
+it by setting the C<Quiet> attribute true.
+
+  PerlSetEnv DBI_PROFILE 2/DBI::ProfileDumper::Apache/Quiet:1
+
+  $dbh->{Profile} = "!Statement/DBI::ProfileDumper/Quiet:1";
+
+  $dbh->{Profile} = DBI::ProfileDumper->new(
+      Path => [ '!Statement' ]
+      Quiet => 1
+  );
+
+
+=head2 GATHERING PROFILE DATA
+
+Once you have the module loaded, use your application as you normally
+would.  Stop the webserver when your tests are complete.  Profile data
+files will be produced when Apache exits and you'll see something like
+this in your error_log:
+
+  DBI::ProfileDumper::Apache writing to /usr/local/apache/logs/dbi.prof.2604.2619
+
+Now you can use dbiprof to examine the data:
+
+  dbiprof /usr/local/apache/logs/dbi.prof.2604.*
+
+By passing dbiprof a list of all generated files, dbiprof will
+automatically merge them into one result set.  You can also pass
+dbiprof sorting and querying options, see L<dbiprof> for details.
+
+=head2 CLEANING UP
+
+Once you've made some code changes, you're ready to start again.
+First, delete the old profile data files:
+
+  rm /usr/local/apache/logs/dbi.prof.*
+
+Then restart your server and get back to work.
+
+=head1 OTHER ISSUES
+
+=head2 Memory usage
+
+DBI::Profile can use a lot of memory for very active applications because it
+collects profiling data in memory for each distinct query run.
+Calling C<flush_to_disk()> will write the current data to disk and free the
+memory it's using. For example:
+
+  $dbh->{Profile}->flush_to_disk() if $dbh->{Profile};
+
+or, rather than flush every time, you could flush less often:
+
+  $dbh->{Profile}->flush_to_disk()
+    if $dbh->{Profile} and ++$i % 100;
+
+=head1 AUTHOR
+
+Sam Tregar <sam@tregar.com>
+
+=head1 COPYRIGHT AND LICENSE
+
+Copyright (C) 2002 Sam Tregar
+
+This program is free software; you can redistribute it and/or modify
+it under the same terms as Perl 5 itself.
+
+=cut
+
+our $VERSION = sprintf("2.%06d", q$Revision: 14120 $ =~ /(\d+)/o);
+
+our @ISA = qw(DBI::ProfileDumper);
+
+use DBI::ProfileDumper;
+use File::Spec;
+
+my $initial_pid = $$;
+
+use constant MP2 => ($ENV{MOD_PERL_API_VERSION} and $ENV{MOD_PERL_API_VERSION} == 2) ? 1 : 0;
+
+my $server_root_dir;
+
+if (MP2) {
+    require Apache2::ServerUtil;
+    $server_root_dir = Apache2::ServerUtil::server_root();
+}
+else {
+    require Apache;
+    $server_root_dir = eval { Apache->server_root_relative('') } || "/tmp";
+}
+
+
+sub _dirname {
+    my $self = shift;
+    return $self->{Dir} ||= $ENV{DBI_PROFILE_APACHE_LOG_DIR}
+                        || File::Spec->catdir($server_root_dir, "logs");
+}
+
+
+sub filename {
+    my $self = shift;
+    my $filename = $self->SUPER::filename(@_);
+    return $filename if not $filename; # not set yet
+
+    # to be able to identify groups of profile files from the same set of
+    # apache processes, we include the parent pid in the file name
+    # as well as the pid.
+    my $group_pid = ($$ eq $initial_pid) ? $$ : getppid();
+    $filename .= ".$group_pid.$$";
+
+    return $filename if File::Spec->file_name_is_absolute($filename);
+    return File::Spec->catfile($self->_dirname, $filename);
+}
+
+
+sub flush_to_disk {
+    my $self = shift;
+
+    my $filename = $self->SUPER::flush_to_disk(@_);
+
+    print STDERR ref($self)." pid$$ written to $filename\n"
+        if $filename && not $self->{Quiet};
+
+    return $filename;
+}
+
+1;