Paranoid::Log(3p)

NAME
Paranoid::Log - Log Functions

VERSION
$Id: Log.pm,v 0.14 2010/06/03 19:03:32 acorliss Exp $

SYNOPSIS
  use Paranoid::Log;

  clearLogDist();
  initLogDist();

  $rv = enableFacility($name, $facility, $logLevel, $scope, @args);
  $rv = disableFacility($name);

  $rv = plog($severity, $message);
  $rv = psyslog($severity, $message);

  # The following functions are not exported by default
  clearLogDist();
  initLogDist();
  $timeStamp = ptimestamp();

DESCRIPTION
This module provides a unified interface and distribution for multiple logging mediums. By calling one function (plog) you can have that message stored in multiple mediums depending on what you've enabled at what severities. For instance, you could have a critical message not only automatically logged in a log file and syslog, but it could also generate an e-mail.

You can also use your own logging facility modules as long as you adhere to the expected API (detailed below). Just pass the name of the module as the facility in enableFacility.

SYMBOL TAG SETS
By default, only the following are exported:

  enableFacility
  disableFacility
  plog
  psyslog

You can get everything using :all, including:

  clearLogDist
  initLogDist
  ptimestamp

LOGGING FACILITIES
Each logging facility is implemented as separate module consisting of non-exported functions with conform to a a consistent API. Each facility module must have the following functions:

  Function        Description
  ------------------------------------------------------
  init            Called when module first loaded
  remove          Removes a named instance of the facility
  log             Logs the passed message
  dump            Dumps internal information

The init function is only called once -- the first time the module is used and accessed.

The remove function allows you to remove a specific named instance of the logging facility from use.

The log function is used to actually log an entry into the facility.

The dump function is used to dump pertinent internal data on the requested named instance. This is primarily intended for use with facilities like the log buffer, in which case it dumps the contents of the named buffer. Other uses for this is left to the developer of individual facility modules.

SUBROUTINES/METHODS

  clearLogDist
  clearLogDist();

This empties all enabled loggers from the distribution processor. It doesn't erase any named logging facilities already put into place, simply takes out of the distribution system so no further log entries will be processed.

This can be used to temporarily halt all logging.

  initLogDist
  initLogDist();

This goes through the list of named loggers and sets up the distribution processor to feed them the applicable log entries as they come in.

This can be used to re-enable logging.

  enableFacility
  $rv = enableFacility($name, $facility, $logLevel, $scope, @args);

This function enables the specified logging facility at the specified levels. Each facility (or permutation of) is associated with an arbitrary name. This name can be used to bypass log distribution and log only in the named facility.

The following facilities are available within Paranoid:

  facility        description
  =====================================================
  stderr          prints messages to STDERR
  buffer          stores messages in a named buffer
  file            prints messages to a file
  syslog          sends message to the syslog daemon
  email           sends message to an e-mail recipient

If you have your own custom facility that complies with the Paranoid::Log calling conventions you can pass this the name of the module (for example, Log::Foo). The first letter of the module will always be uppercased before attempting to load it.

Log levels are modeled after syslog:

  log level       description
  =====================================================
  emerg, panic,   system is unusable
  emergency
  alert           action must be taken immediately
  crit, critical  critical conditions
  err, error      error conditions
  warn, warning   warning conditions
  notice          normal but significant conditions
  info            informational
  debug           debug-level messages

If omitted level defaults to 'notice'.

Scope is defined with the following characters:

  character       definition
  =====================================================
  =               log only messages at this severity
  +               log only messages at this severity
                  or higher
  -               log only messages at this severity
                  or lower
  !               log at all levels but this severity

If omitted scope defaults to '+'.

Only the first two arguments are mandatory. What you put into the @args, and whether you need it at all, will depend on the facility you're using. The facilities provided directly by Paranoid are as follows:

  facility        arguments
  =====================================================
  stderr          none
  buffer          bufferSize (optional)
  file            filename
  syslog          none
  email           mailhost, recipient, sender (optional),
                  subject (optional)

  disableFacility
  $rv = disableFacility($name);

Removes the specified logging facility from the configuration and re-initializes the distribution processor.

  plog
  $rv = plog($severity, $message);

This call logs the passed message to all facilities enabled at the specified log level.

  ptimestamp
  $ts = ptimestamp();

This function returns a syslog-style timestamp string for the current time. You can optionally give it a value as returned by time() and the stamp will be for that timme.

  psyslog
  $rv = psyslog($severity, $message);

This function's name may be a bit misleading. This does not cause the message to be syslogged (that's the duty of the syslog facility), but rather the message is logged in a syslog-style format according to the following template:

  {timestamp} {hostname} {process}[{pid}]: {message}

You may want to use this if you're using, say, a file logging mechanism but you still want the logs in a syslog-styled format. More often than not, though, you do not want to use this function.

DEPENDENCIES

o   Paranoid::Debug

o   Paranoid::Input

o   Paranoid::Module

EXAMPLES
The following example provides the following behavior: debug messages go to a file, notice & above messages go to syslog, and critical and higher messages also go to console and e-mail.

  # Set up the logging facilities
  enableFacility("debug", "file", "debug", "=",
    "/var/log/myapp-debug.log");
  enableFacility("daemon", "syslog", "notice", "+", "myapp");
  enableFacility("console-err", "stderr", "critical", "+");
  enableFacility("smtp-err", "email", "critical", "+",
    "localhost", "root\@localhost", "myapp\@localhost",
    "MyApp Critical Alert");

  # Log some messages
  #
  # Since this is only going to the debug log, we'll use psyslog
  # so we get the timestamps, etc.
  psyslog("debug", "Starting application");

  # Log a notification
  plog("notice", "Uh, something happened...");

  # Log a critical error
  plog("emerg", "Ack! <choke... silence>");

SEE ALSO

o   Paranoid::Log::Buffer

o   Paranoid::Log::Email

o   Paranoid::Log::File

o   Paranoid::Log::Syslog

BUGS AND LIMITATIONS

AUTHOR
Arthur Corliss (corliss@digitalmages.com)

LICENSE AND COPYRIGHT
This software is licensed under the same terms as Perl, itself. Please see http://dev.perl.org/licenses/ for more information.

(c) 2005, Arthur Corliss (corliss@digitalmages.com)