NAME

Apache::Log -- Perl API for Apache Logging Methods

Synopsis

  #in startup.pl
  #-------------
  use Apache::Log;
  my $s = Apache->server;
  
  $s->log_error("server: log_error");
  
  $s->log_serror(Apache::LOG_MARK, Apache::LOG_ERR,
                 0, "log_serror logging at err level");
  
  $s->log_serror(Apache::LOG_MARK, Apache::LOG_DEBUG,
                 APR::ENOTIME, "debug print");

  #in a handler
  #------------
  use Apache::Log;
  sub handler{
      my $r = shift;
      $r->log_error("request: log_error");
  
      my $rlog = $r->log;
      for my $level qw(emerg alert crit error warn notice info debug) {
          no strict 'refs';
          $rlog->$level($package, "request: $level log level");
      }

      # can use server methods as well
      my $s = $r->server;
      $s->log_error("server: log_error");
  
      $r->log_rerror(Apache::LOG_MARK, Apache::LOG_DEBUG,
                     APR::ENOTIME, "in debug");
  
      $s->log_serror(Apache::LOG_MARK, Apache::LOG_INFO, 0,
                     "server info");
  
      $s->log_serror(Apache::LOG_MARK, Apache::LOG_ERR,
                     APR::ENOTIME, "fatal error");

      $s->warn('routine server warning');
      Apache->warn("routine warning");

  }

Description

Apache::Log provides the Perl API for Apache logging methods.

Constants

The following constants (sorted from the most severe level to the least severe) are used in logging methods to specify the log level at which the message should be logged:

• Apache::LOG_EMERG

• Apache::LOG_ALERT

• Apache::LOG_CRIT

• Apache::LOG_ERR

• Apache::LOG_WARNING

• Apache::LOG_NOTICE

• Apache::LOG_INFO

• Apache::LOG_DEBUG

For example if the current LogLevel is set to warning, only messages with log level of the level warning or higher (err, crit, elert and emerg) will be logged. Therefore this:

  $r->log_rerror(Apache::LOG_MARK, Apache::LOG_WARNING,
                 APR::ENOTIME, "warning!");

will log the message, but this one won't:

  $r->log_rerror(Apache::LOG_MARK, Apache::LOG_INFO,
                 APR::ENOTIME, "just an info");

It will be logged only if the server log level is set to info or debug. (either in the configuration file or using the $s->loglevel() method.)

Other constants:

• Apache::LOG_LEVELMASK

  used to mask off the level value, to make sure that the log level's value is within the proper bits range. e.g.:

   $loglevel &= LOG_LEVELMASK;

• Apache::LOG_TOCLIENT

  used to give content handlers the option of including the error text in the ErrorDocument sent back to the client. When Apache::LOG_TOCLIENT is passed to log_rerror() the error message will be saved in the $r's notes table, keyed to the string "error-notes", if and only if the severity level of the message is Apache::LOG_WARNING or greater and there are no other "error-notes" entry already set in the request record's notes table. Once the "error-notes" entry is set, it is up to the content handler to determine whether this text should be send back to the client. For example:

    $r->log_rerror(Apache::LOG_MARK, Apache::LOG_ERR|Apache::LOG_TOCLIENT,
                   APR::ENOTIME, "request log_rerror");

  now the log message can be retrieved via:

    $r->notes->get("error-notes");

  Remember that client generated text streams sent back to the client MUST be escaped to prevent CSS attacks.

• Apache::LOG_STARTUP

  is set only during the startup.

Server Logging Methods

$s->log_error()

  $s->log_error(@message);

just logs the supplied message. For example:

  $s->log_error("running low on memory");

$s->log_serror()

  log_serror($file, $line, $level, $status, @message);

where:

 * $file    The file in which this function is called
 * $line    The line number on which this function is called
 * $level   The level of this error message
 * $status  The status code from the previous command
 * @message The log message

This function provides a fine control of when the message is logged, gives an access to built-in status codes.

For example:

  $s->log_serror(Apache::LOG_MARK, Apache::LOG_ERR,
                 0, "log_serror logging at err level");
  
  $s->log_serror(Apache::LOG_MARK, Apache::LOG_DEBUG,
                 APR::ENOTIME, "debug print");

$s->log()

  my $slog = $s->log;

returns a handle which can be used to log messages of different level. See the next entry.

emerg(), alert(), crit(), error(), warn(), notice(), info(), debug()

  $s->log->emerg(@message);

after getting the log handle with $s->log, use these methods to control when messages should be logged.

For example:

  my $slog = $s->log;
  $slog->debug("just ", "some debug info");
  $slog->warn(@warnings);
  $slog->crit("dying");

Request Logging Methods

$r->log_error()

  $r->log_error(@message);

logs the supplied message (similar to $s->log_error). For example:

  $r->log_error("the request is about to end");

the same as $s->log_error.

$r->log_rerror()

  log_rerror($file, $line, $level, $status, @message);

same as $s->log_rerror. For example:

  $s->log_rerror(Apache::LOG_MARK, Apache::LOG_ERR,
                 0, "log_rerror logging at err level");
  
  $s->log_rerror(Apache::LOG_MARK, Apache::LOG_DEBUG,
                 APR::ENOTIME, "debug print");

$r->log()

  my $rlog = $r->log;

Similar to $s->log()

emerg(), alert(), crit(), error(), warn(), notice(), info(), debug()

Similar to the server's log functions with the same names.

For example:

  $rlog->debug("just ", "some debug info");
  $rlog->warn(@req_warnings);
  $rlog->crit("dying");

General Functions

Apache::LOG_MARK()

  my($file, $line) = Apache::LOG_MARK();

Though looking like a constant, this is a function, which returns a list of two items: (__FILE__, __LINE__), i.e. the file and the line where the function was called from.

Aliases

$s->warn()

  $s->warn(@warnings);

$s->warn() is an alias to $s->log->warn().

For example:

  $s->warn('routine server warning');

Apache->warn()

  Apache->warn(@warnings);

Apache->warn() is an alias to $s->log->warn().

cpanm mod_perl

perl -MCPAN -e shell
install mod_perl