Apache::LogFormat::Compiler(3pm)

NAME
Apache::LogFormat::Compiler - Compile a log format string to perl-code

SYNOPSIS
  use Apache::LogFormat::Compiler;

  my $log_handler = Apache::LogFormat::Compiler->new("combined");
  my $log = $log_handler->log_line(
      $env,
      $res,
      $length,
      $reqtime,
      $time
  );

DESCRIPTION
Compile a log format string to perl-code. For faster generation of access_log lines.

METHOD

new($fmt:String)
    Takes a format string (or a preset template "combined" or "custom") to specify the log format. This module implements a subset of Apache's LogFormat templates <http://httpd.apache.org/docs/2.0/mod/mod_log_config.html>:

       %%    a percent sign
       %h    REMOTE_ADDR from the PSGI environment, or -
       %l    remote logname not implemented (currently always -)
       %u    REMOTE_USER from the PSGI environment, or -
       %t    [local timestamp, in default format]
       %r    REQUEST_METHOD, REQUEST_URI and SERVER_PROTOCOL from the PSGI environment
       %s    the HTTP status code of the response
       %b    content length of the response
       %T    custom field for handling times in subclasses
       %D    custom field for handling sub-second times in subclasses
       %v    SERVER_NAME from the PSGI environment, or -
       %V    HTTP_HOST or SERVER_NAME from the PSGI environment, or -
       %p    SERVER_PORT from the PSGI environment
       %P    the worker's process id
       %m    REQUEST_METHOD from the PSGI environment
       %U    PATH_INFO from the PSGI environment
       %q    QUERY_STRING from the PSGI environment
       %H    SERVER_PROTOCOL from the PSGI environment

    In addition, custom values can be referenced, using "%{name}", with one of the mandatory modifier flags "i", "o" or "t":

       %{variable-name}i    HTTP_VARIABLE_NAME value from the PSGI environment
       %{header-name}o      header-name header in the response
       %{time-format]t      localtime in the specified strftime format

log_line($env:HashRef, $res:ArrayRef, $length:Integer, $reqtime:Integer, $time:Integer): $log:String
    Generates log line.

      $env      PSGI env request HashRef
      $res      PSGI response ArrayRef
      $length   Content-Length
      $reqtime  The time taken to serve request in microseconds. optional
      $time     Time the request was received. optional. If $time is undefined. current timestamp is used.

    Sample psgi

      use Plack::Builder;
      use Time::HiRes;
      use Apache::LogFormat::Compiler;

      my $log_handler = Apache::LogFormat::Compiler->new(
          '%h %l %u %t "%r" %>s %b "%{Referer}i" "%{User-agent}i" %D'
      );
      my $compile_log_app = builder {
          enable sub {
              my $app = shift;
              sub {
                  my $env = shift;
                  my $t0 = [gettimeofday];
                  my $res = $app->();
                  my $reqtime = int(Time::HiRes::tv_interval($t0) * 1_000_000);
                  $env->{psgi.error}->print($log_handler->log_line(
                      $env,$res,6,$reqtime, $t0->[0]));
              }
          };
          $app
      };

ABOUT POSIX::strftime::Compiler
This module uses POSIX::strftime::Compiler for generate datetime string. POSIX::strftime::Compiler provides GNU C library compatible strftime(3). But this module will not affected by the system locale. This feature is useful when you want to write loggers, servers and portable applications.

ADD CUSTOM FORMAT STRING
Apache::LogFormat::Compiler allows one to add a custom format string

  my $log_handler = Apache::LogFormat::Compiler->new(
      '%z %{HTTP_X_FORWARDED_FOR|REMOTE_ADDR}Z',
      char_handlers => +{
          'z' => sub {
              my ($env,$req) = @_;
              return $env->{HTTP_X_FORWARDED_FOR};
          }
      },
      block_handlers => +{
          'Z' => sub {
              my ($block,$env,$req) = @_;
              # block eq 'HTTP_X_FORWARDED_FOR|REMOTE_ADDR'
              my ($main, $alt) = split('\|', $args);
              return exists $env->{$main} ? $env->{$main} : $env->{$alt};
          }
      },
  );

Any single letter can be used, other than those already defined by Apache::LogFormat::Compiler. Your sub is called with two or three arguments: the content inside the "{}" from the format (block_handlers only), the PSGI environment ($env), and the ArrayRef of the response. It should return the string to be logged.

AUTHOR
Masahiro Nagano <kazeburo@gmail.com>

SEE ALSO
Plack::Middleware::AccessLog, <http://httpd.apache.org/docs/2.2/mod/mod_log_config.html>

LICENSE
Copyright (C) Masahiro Nagano

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.