Module: Nagios::TimedParse

Included in:
Config, Objects, Status
Defined in:
lib/nagira/timed_parse.rb

Overview

Keep track of last parsed time and last changed time of the status/cache file to avoid parsing on each HTTP request.

Constant Summary collapse

TTL =

Set some minimum interval for re-parsing of the status file: even if file changes often, we do not want to parse it more often, then this number of seconds.

::DEFAULT[:ttl] || 0

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#last_parsed ⇒ Object

Returns the value of attribute last_parsed.



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# File 'lib/nagira/timed_parse.rb', line 58

def last_parsed
  @last_parsed
end

#parse_interval ⇒ Object

Returns the value of attribute parse_interval.



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# File 'lib/nagira/timed_parse.rb', line 58

def parse_interval
  @parse_interval
end

Class Method Details

.included(base) ⇒ Object

Override constructor and parse method from ::Nagios::Objects or ::Nagios::Status classes, add instance variables to handle modification and parseing times of status file. Original methods are aliased:

  • initialize -> constructor

  • parse -> parse!

See also www.ruby-forum.com/topic/969161



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# File 'lib/nagira/timed_parse.rb', line 22

def self.included(base)
  base.class_eval do
    alias_method :parse!, :parse
    alias_method :constructor, :initialize

    # @method initialize
    # Extend current constructor with some additional data to
    # track file change time
    #
    # @param [String] file Path to status file
    # @param [Fixnum] parse_interval Number of seconds between
    #     re-parsing of the file
    def initialize(file, parse_interval=TTL)
      constructor(file)

      # Time when status file was last time parsed, set it to 0 secs
      # epoch to make sure it will be parsed
      @last_parsed = Time.at(0)

      # Last time file was changed
      @last_changed = File.mtime(@path)
      @parse_interval = parse_interval
    end


    # Extend original parse method: parse file only if it needs
    # parsing and set time of parser run to current time.
    def parse
      if need_parsing?
        parse!
        @last_parsed = Time.now
      end
    end
  end
end

Instance Method Details

#changed? ⇒ Boolean

Return true if file is changed since it was parsed last time

Returns:

  • (Boolean) 


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# File 'lib/nagira/timed_parse.rb', line 65

def changed?
  self.last_changed > self.last_parsed
end

#last_changed ⇒ Object 



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# File 'lib/nagira/timed_parse.rb', line 60

def last_changed
  @last_changed = File.mtime(@path)
end

#need_parsing? ⇒ Boolean

Check if:

  • file changed?

  • was it parsed recently?

Returns:

  • (Boolean) 


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# File 'lib/nagira/timed_parse.rb', line 72

def need_parsing?
  changed? && ((Time.now - self.last_parsed) > @parse_interval)
end