Class: Fluent::ThrottleFilter

Inherits:
Filter
  • Object
show all
Defined in:
lib/fluent/plugin/filter_throttle.rb

Defined Under Namespace

Classes: Group

Instance Method Summary collapse

Instance Method Details

#configure(conf) ⇒ Object 



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# File 'lib/fluent/plugin/filter_throttle.rb', line 21

def configure(conf)
  super

  @group_key_path = group_key.split(".")

  raise "group_bucket_period_s must be > 0" \
    unless @group_bucket_period_s > 0

  raise "group_bucket_limit must be > 0" \
    unless @group_bucket_limit > 0

  @group_rate_limit = (@group_bucket_limit / @group_bucket_period_s)

  @group_reset_rate_s = @group_rate_limit \
    if @group_reset_rate_s == nil

  raise "group_reset_rate_s must be >= -1" \
    unless @group_reset_rate_s >= -1
  raise "group_reset_rate_s must be <= group_bucket_limit / group_bucket_period_s" \
    unless @group_reset_rate_s <= @group_rate_limit

  raise "group_warning_delay_s must be >= 1" \
    unless @group_warning_delay_s >= 1
end

#extract_group(record) ⇒ Object 



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# File 'lib/fluent/plugin/filter_throttle.rb', line 111

def extract_group(record)
  record.dig(*@group_key_path)
end

#filter(tag, time, record) ⇒ Object 



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# File 'lib/fluent/plugin/filter_throttle.rb', line 57

def filter(tag, time, record)
  now = Time.now
  group = extract_group(record)
  counter = @counters.fetch(group, nil)
  counter = @counters[group] = Group.new(
    0, now, 0, 0, now, nil) if counter == nil

  counter.rate_count += 1

  since_last_rate_reset = now - counter.rate_last_reset
  if since_last_rate_reset >= 1
    # compute and store rate/s at most every seconds.
    counter.aprox_rate = (counter.rate_count / since_last_rate_reset).round()
    counter.rate_count = 0
    counter.rate_last_reset = now
  end

  if (now.to_i / @group_bucket_period_s) \
      > (counter.bucket_last_reset.to_i / @group_bucket_period_s)
    # next time period reached.

    # wait until rate drops back down (if enabled).
    if counter.bucket_count == -1 and @group_reset_rate_s != -1
      if counter.aprox_rate < @group_reset_rate_s
        log_rate_back_down(now, group, counter)
      else
        log_rate_limit_exceeded(now, group, counter)
        return nil
      end
    end

    # reset counter for the rest of time period.
    counter.bucket_count = 0
    counter.bucket_last_reset = now
  else
    # if current time period credit is exhausted, drop the record.
    if counter.bucket_count == -1
      log_rate_limit_exceeded(now, group, counter)
      return nil
    end
  end

  counter.bucket_count += 1

  # if we are out of credit, we drop logs for the rest of the time period.
  if counter.bucket_count > @group_bucket_limit
    log_rate_limit_exceeded(now, group, counter)
    counter.bucket_count = -1
    return nil
  end

  record
end

#log_items(now, group, counter) ⇒ Object 



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# File 'lib/fluent/plugin/filter_throttle.rb', line 128

def log_items(now, group, counter)
  since_last_reset = now - counter.bucket_last_reset
  rate = (counter.bucket_count / since_last_reset).round()
  aprox_rate = counter.aprox_rate
  rate = aprox_rate if aprox_rate > rate

  {'group_key': group,
   'rate_s': rate,
   'period_s': @group_bucket_period_s,
   'limit': @group_bucket_limit,
   'rate_limit_s': @group_rate_limit,
   'reset_rate_s': @group_reset_rate_s}
end

#log_rate_back_down(now, group, counter) ⇒ Object 



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# File 'lib/fluent/plugin/filter_throttle.rb', line 124

def log_rate_back_down(now, group, counter)
  $log.info("rate back down", log_items(now, group, counter))
end

#log_rate_limit_exceeded(now, group, counter) ⇒ Object 



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# File 'lib/fluent/plugin/filter_throttle.rb', line 115

def log_rate_limit_exceeded(now, group, counter)
  emit = counter.last_warning == nil ? true \
    : (now - counter.last_warning) >= @group_warning_delay_s
  if emit
    $log.warn("rate exceeded", log_items(now, group, counter))
    counter.last_warning = now
  end
end

#shutdown ⇒ Object 



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# File 'lib/fluent/plugin/filter_throttle.rb', line 52

def shutdown
  $log.info("counters summary: #{@counters}")
  super
end

#start ⇒ Object 



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# File 'lib/fluent/plugin/filter_throttle.rb', line 46

def start
  super

  @counters = Hash.new()
end