Class: DynamoAutoscale::TableTracker

Inherits:
Object
  • Object
show all
Includes:
Logger
Defined in:
lib/dynamo-autoscale/table_tracker.rb

Constant Summary collapse

TIME_WINDOW =

TODO: This time window may need changing.

7.days

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Logger

included, logger, #logger, logger=

Constructor Details

#initialize(name) ⇒ TableTracker

Returns a new instance of TableTracker.



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 10

def initialize name
  @name = name
  clear_data
end

Instance Attribute Details

#data ⇒ Object (readonly)

Returns the value of attribute data.



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 8

def data
  @data
end

#name ⇒ Object (readonly)

Returns the value of attribute name.



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 8

def name
  @name
end

#scale_events ⇒ Object (readonly)

Returns the value of attribute scale_events.



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 8

def scale_events
  @scale_events
end

#triggered_rules ⇒ Object (readonly)

Returns the value of attribute triggered_rules.



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 8

def triggered_rules
  @triggered_rules
end

Instance Method Details

#all_times ⇒ Object

Returns an array of all of the time points that have data present in them. Example:

table.tick(Time.now, { ... })
table.tick(Time.now, { ... })

table.all_times
#=> Array with the 2 time values above in it



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 225

def all_times
  @data.keys
end

#clear_data ⇒ Object 



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 15

def clear_data
  @data            = RBTree.new
  @triggered_rules = RBTree.new
  @scale_events    = RBTree.new
end

#earliest_data_time ⇒ Object

Returns the earliest point in time that we have tracked data for.



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 230

def earliest_data_time
  all_times.first
end

#graph!(opts = {}) ⇒ Object 



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 271

def graph! opts = {}
  data_tmp = File.join(Dir.tmpdir, 'data.csv')
  png_tmp  = opts[:path] || File.join(Dir.tmpdir, 'graph.png')
  r_script = File.join(DynamoAutoscale.root, 'rlib', 'dynamodb_graph.r')

  to_csv!(path: data_tmp)

  `r --no-save --args #{data_tmp} #{png_tmp} < #{r_script}`

  if $? != 0
    logger.error "[table] Failed to create graph."
    return false
  else
    if opts[:open]
      `open #{png_tmp}`
      if $? != 0
        logger.error "[table] Failed to open graph."
        return false
      else
        return png_tmp
      end
    end
  end
end

#last(value, metric) ⇒ Object

Useful method for querying the last N points, or the last points in a time range. For example:

table.last 5. :consumed_writes
#=> [ array of last 5 data points ]

table.last 5.minutes, :provisioned_reads
#=> [ array containing the last 5 minutes of provisioned read data ]

If there are no points present, or no points in your time range, the return value will be an empty array.



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 113

def last value, metric
  if value.is_a? ActiveSupport::Duration
    value = value.to_i
    to_return = []
    now = Time.now.to_i

    @data.reverse_each do |time, datum|
      value -= now - time.to_i
      now    = time.to_i
      break if value < 0

      to_return << datum[metric]
    end

    to_return
  else
    @data.reverse_each.take(value).map { |time, datum| datum[metric] }
  end
end

#last_consumed_for(metric, opts = {}) ⇒ Object

Gets the last amount of consumed throughput for whatever metric you pass in. Example:

table.last_consumed_for :writes
#=> 54.3456



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 85

def last_consumed_for metric, opts = {}
  key = case metric
  when :reads, :provisioned_reads, :consumed_reads
    :consumed_reads
  when :writes, :provisioned_writes, :consumed_writes
    :consumed_writes
  end

  @data.reverse_each do |time, datum|
    if opts[:at].nil? or time <= opts[:at]
      return datum[key] if datum[key]
    end
  end

  return nil
end

#last_provisioned_for(metric, opts = {}) ⇒ Object

Gets the last amount of provisioned throughput for whatever metric you pass in. Example:

table.last_provisioned_for :writes
#=> 600.0



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 63

def last_provisioned_for metric, opts = {}
  key = case metric
  when :reads, :provisioned_reads, :consumed_reads
    :provisioned_reads
  when :writes, :provisioned_writes, :consumed_writes
    :provisioned_writes
  end

  @data.reverse_each do |time, datum|
    if opts[:at].nil? or time <= opts[:at]
      return datum[key] if datum[key]
    end
  end

  return nil
end

#latest_data_time ⇒ Object

Returns the latest point in time that we have tracked data for.



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 235

def latest_data_time
  all_times.last
end

#lost_read_percent ⇒ Object 



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 213

def lost_read_percent
  (lost_read_units / total_read_units) * 100.0
end

#lost_read_units ⇒ Object

Whenever the consumed units goes above the provisioned, we refer to the overflow as “lost” units.



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 165

def lost_read_units
  @data.inject(0) do |memo, (_, datum)|
    if datum[:consumed_reads] > datum[:provisioned_reads]
      memo += datum[:consumed_reads] - datum[:provisioned_reads]
    end

    memo
  end
end

#lost_write_percent ⇒ Object 



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 209

def lost_write_percent
  (lost_write_units / total_write_units) * 100.0
end

#lost_write_units ⇒ Object

Whenever the consumed units goes above the provisioned, we refer to the overflow as “lost” units.



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 177

def lost_write_units
  @data.inject(0) do |memo, (_, datum)|
    if datum[:consumed_writes] > datum[:provisioned_writes]
      memo += datum[:consumed_writes] - datum[:provisioned_writes]
    end

    memo
  end
end

#report! ⇒ Object 



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 312

def report!
  puts "         Table: #{name}"
  puts "Wasted r/units: #{wasted_read_units.round(2)} (#{wasted_read_percent.round(2)}%)"
  puts " Total r/units: #{total_read_units.round(2)}"
  puts "  Lost r/units: #{lost_read_units.round(2)} (#{lost_read_percent.round(2)}%)"
  puts "Wasted w/units: #{wasted_write_units.round(2)} (#{wasted_write_percent.round(2)}%)"
  puts " Total w/units: #{total_write_units.round(2)}"
  puts "  Lost w/units: #{lost_write_units.round(2)} (#{lost_write_percent.round(2)}%)"
  puts "      Upscales: #{DynamoAutoscale.actioners[self].upscales}"
  puts "    Downscales: #{DynamoAutoscale.actioners[self].downscales}"
end

#scatterplot_for!(metric) ⇒ Object 



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 296

def scatterplot_for! metric
  data_tmp = File.join(Dir.tmpdir, 'data.csv')
  png_tmp  = File.join(Dir.tmpdir, 'boxplot.png')
  r_script = File.join(DynamoAutoscale.root, 'rlib', 'dynamodb_boxplot.r')

  to_csv!(data_tmp)

  `r --no-save --args #{data_tmp} #{png_tmp} < #{r_script}`

  if $? != 0
    logger.error "[table] Failed to create graph."
  else
    `open #{png_tmp}`
  end
end

#tick(time, datum) ⇒ Object

‘tick` takes two arguments. The first is a Time object, the second is a hash. The tick method expects data in the following format for the second argument:

{:provisioned_writes=>600.0,
 :provisioned_reads=>800.0,
 :consumed_writes=>52.693333333333335,
 :consumed_reads=>342.4033333333333}



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 29

def tick time, datum
  if time < (Time.now.utc - TIME_WINDOW)
    logger.warn "[table] Attempted to insert data outside of the time window."
    return
  end

  # Sometimes there are gaps in the data pertaining to provisioned
  # amounts. These two conditional blocks fill in those gaps.
  if datum[:provisioned_writes].nil?
    datum[:provisioned_writes] = last_provisioned_for :writes, at: time

    if datum[:provisioned_writes]
      logger.debug "[table] Filled in gap in provisioned writes."
    end
  end
  if datum[:provisioned_reads].nil?
    datum[:provisioned_reads] = last_provisioned_for :reads, at: time

    if datum[:provisioned_reads]
      logger.debug "[table] Filled in gap in provisioned reads."
    end
  end

  @data[time] = datum
  remove_expired_data! @data
  remove_expired_data! @triggered_rules
  remove_expired_data! @scale_events
end

#to_csv!(opts = {}) ⇒ Object

Pricing is pretty difficult. This isn’t a good measure of success. Base calculations on how many units are wasted. def wasted_money

UnitCost.read(wasted_read_units) + UnitCost.write(wasted_write_units)

end



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 245

def to_csv! opts = {}
  path = opts[:path] or File.join(DynamoAutoscale.root, "#{self.name}.csv")

  CSV.open(path, 'w') do |csv|
    csv << [
      "time",
      "provisioned_reads",
      "provisioned_writes",
      "consumed_reads",
      "consumed_writes",
    ]

    @data.each do |time, datum|
      csv << [
        time.iso8601,
        datum[:provisioned_reads],
        datum[:provisioned_writes],
        datum[:consumed_reads],
        datum[:consumed_writes],
      ]
    end
  end

  path
end

#total_read_units ⇒ Object 



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 187

def total_read_units
  @data.inject(0) do |memo, (_, datum)|
    memo += datum[:provisioned_reads] if datum[:provisioned_reads]
    memo
  end
end

#total_write_units ⇒ Object 



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 194

def total_write_units
  @data.inject(0) do |memo, (_, datum)|
    memo += datum[:provisioned_writes] if datum[:provisioned_writes]
    memo
  end
end

#wasted_read_percent ⇒ Object 



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 201

def wasted_read_percent
  (wasted_read_units / total_read_units) * 100.0
end

#wasted_read_units ⇒ Object

Calculate how many read units have been wasted in the current set of tracked data.

table.wasted_read_units
#=> 244.4



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 138

def wasted_read_units
  @data.inject(0) do |memo, (_, datum)|
    # if datum[:provisioned_reads] and datum[:consumed_reads]
      memo += datum[:provisioned_reads] - datum[:consumed_reads]
    # end

    memo
  end
end

#wasted_write_percent ⇒ Object 



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 205

def wasted_write_percent
  (wasted_write_units / total_write_units) * 100.0
end

#wasted_write_units ⇒ Object

Calculate how many write units have been wasted in the current set of tracked data.

table.wasted_write_units
#=> 566.3



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# File 'lib/dynamo-autoscale/table_tracker.rb', line 153

def wasted_write_units
  @data.inject(0) do |memo, (_, datum)|
    # if datum[:provisioned_writes] and datum[:consumed_writes]
      memo += datum[:provisioned_writes] - datum[:consumed_writes]
    # end

    memo
  end
end