GLogg - Another custom logging gem

• [github project] (https://github.com/geronime/glogg)

GLogg is another custom logging gem with multiple debug log levels.

Usage

Levels

List of available log levels:

GLogg::L_NIL = -1 # no logging at all
GLogg::L_FAT =  0 # fatal
GLogg::L_ERR =  1 # error
GLogg::L_WRN =  2 # warning
GLogg::L_INF =  3 # info
GLogg::L_DBG =  4 # debug level 1
GLogg::L_D2  =  5 # debug level 2
GLogg::L_D3  =  6 # debug level 3
GLogg::L_D4  =  7 # debug level 4

Configuration

Without setup GLogg prints messages to STDERR with up to GLogg::L_DBG verbosity.

To query/set different settings you can use:

current_level = GLogg.log_level
current_destination = GLogg.log_path
GLogg.log_level = level
GLogg.log_path = destination
GLogg.ini destination, level

• destination may be one of $stdout, $stderr, nil, log file path (nil is the default $stderr)
• level is one of previously listed log level

Logging

GLogg provides following methods:

• GLogg.log_f? to discover whether messages with GLogg::L_FAT verbosity get logged
  • continuing with log_e?,..., log_d?, log_d2?,...
• GLogg.log_f(msg) to log message with GLogg::L_FAT verbosity (unless configured log level is GLogg::L_NIL)
  • simmilarly methods log_e,...
• shortcut methods where the message is passed in block which is executed only if the message is to be logged in the end: GLogg.l_f{msg}, etc.

Examples

These two examples have the same behaviour:

GLogg.log_f? && GLogg.log_f("Fatal error!")

GLogg.l_f { "Fatal error!" }

The output would look like:

$ irb -r bundler/setup -r glogg
irb(main):001:0> GLogg.l_f { "Fatal error!" }
2012-08-12 12:24:52.618418 (CEST) - [30113] - [irb] - [FATAL]:
  Fatal error!

=> true

• in the log header the values in square brackets are PID, process name and message verbosity
• the message follows and is always terminated by an empty line

Under the hood

The appropriate anonymous logging method is selected during destination setup:

• for $stdout or $stderr the message gets printed using IO.write, and logging method always returns true
• for file logging the method is more elaborate:
  • log message is assembled first (to spend as little time with the file handle locked as possible)
  • the file is opened in append mode
  • handle is locked using handle.flock File::LOCK_EX waiting for the exclusive access
  • message gets logged using handle.write
  • handle is unlocked and closed
  • in case of SystemCallError the warning is issued and false returned
  • otherwise true is returned

In the logging process the proper logging method is always executed only after the message relevance was compared with the configured logging verbosity and it is decided the message is to be logged at all.

Changelog

• 0.0.2: shortcut methods with message in block, docs written
• 0.0.1: first revision

License

GLogg is copyright (c)2011 Jiri Nemecek, and released under the terms of the MIT license. See the LICENSE file for the gory details.