Class: FloodControl

Inherits:
Object
  • Object
show all
Defined in:
lib/flood.rb

Overview

Provides a means to limit events to a count/time ratio. This is a more or less straight port of the Perl Algorithm::FloodControl library by Vladi Belperchinov-Shabanski.

See README for more information and examples of use.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(max_events, interval) ⇒ FloodControl

Returns a new instance of FloodControl.



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# File 'lib/flood.rb', line 13

def initialize(max_events, interval)
  @flood = Hash.new
  @max_events = max_events
  @interval = interval
end

Instance Attribute Details

#flood ⇒ Object

Returns the value of attribute flood.



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# File 'lib/flood.rb', line 9

def flood
  @flood
end

#interval ⇒ Object

Returns the value of attribute interval.



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# File 'lib/flood.rb', line 9

def interval
  @interval
end

#max_events ⇒ Object

Returns the value of attribute max_events.



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# File 'lib/flood.rb', line 11

def max_events
  @max_events
end

Instance Method Details

#check(event = '', max_events = @max_events, interval = @interval) ⇒ Object

Check if an event can proceed.

If no event id is given as an argument, the name of the caller is used.

max_events and interval can be overridden on a per-call basis.

The return value is 0 if event can proceed, or a positive integer if the limit has been exceeded. The value represents the number of seconds to wait so the event will occur within the limit set.



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# File 'lib/flood.rb', line 54

def check(event='',max_events=@max_events, interval=@interval)

  #provide event key if not supplied
  if (event == '')
    # TEST: is this unique?
    event = caller[0].gsub(/\s/,'')
    # print STDERR "EN: $en\n";
  end
  
  # make empty flood array for this event key
  @flood[event] ||= Array.new;  
  
  event_count = @flood[event].length;
  
  if( event_count >= max_events )
    # flood array has enough events to do real flood check
    ot = @flood[event][0];      # oldest event timestamp in the flood array
    tp = Time.now.to_i - ot; # time period between current and oldest event
  
    # now calculate time in seconds until next allowed event
    wait = ot + ( event_count * interval / max_events ) - Time.now.to_i
    if( wait > 0 )
      # positive number of seconds means flood in progress
      # event_count should be rejected or postponed
      # print "WARNING: next event will be allowed in $wait seconds\n";
      return wait;
    end

    # negative or 0 seconds means that event should be accepted
    # oldest event is removed from the flood array
    @flood[event].shift;

  end
  # flood array is not full or oldest event is already removed
  # so current event has to be added

  @flood[event].push(Time.now.to_i);
  # event is ok
  return 0
end

#reset(event = nil) ⇒ Object

Reset the event count for a given event, or if no argument supplied reset the event count for all events.



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# File 'lib/flood.rb', line 21

def reset(event=nil)
  if event.nil?
    @flood.clear
  else
    @flood.delete(event)
  end
end

#storage ⇒ Object

Get flood data



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# File 'lib/flood.rb', line 96

def storage
  @flood
end

#storage=(flood) ⇒ Object

Set flood data



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# File 'lib/flood.rb', line 101

def storage=(flood)
  @flood=flood
end