Class: RRD::Data

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

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(rra, reader, header, data_start) ⇒ Data

Returns a new instance of Data.



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# File 'lib/rrd/data.rb', line 6

def initialize(rra, reader, header, data_start)
  @rra = rra
  @reader = reader
  @header = header
  @data_start = data_start

  header.setup_reader(reader) # update endianess and alignment
end

Instance Attribute Details

#data_start ⇒ Object (readonly)

Returns the value of attribute data_start.



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# File 'lib/rrd/data.rb', line 4

def data_start
  @data_start
end

#header ⇒ Object (readonly)

Returns the value of attribute header.



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# File 'lib/rrd/data.rb', line 4

def header
  @header
end

#reader ⇒ Object (readonly)

Returns the value of attribute reader.



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# File 'lib/rrd/data.rb', line 4

def reader
  @reader
end

#rra ⇒ Object (readonly)

Returns the value of attribute rra.



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# File 'lib/rrd/data.rb', line 4

def rra
  @rra
end

Instance Method Details

#fetch(options = {}, &block) ⇒ Object 



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# File 'lib/rrd/data.rb', line 33

def fetch(options = {}, &block)
  row = options[:start_row] || 0
  rows = [options[:rows] || rra.rows, rra.rows].min

  current_time = first_update
  columns = [:time] + header.datasources.map(&:name).map(&:to_sym)

  if options[:start_time]
    start_time = round_time(options[:start_time].to_i)

    if current_time < start_time
      row = ((start_time - current_time) / step_time).floor
      current_time = start_time
    end
  end

  if options[:end_time]
    end_time = round_time(options[:end_time].to_i)

    if end_time < last_update
      rows = ((end_time - current_time) / step_time).ceil
    end
  end

  if row < head
    reader.seek(base_position + ((rra.current_row + 1 + row) * row_size))
  end

  data = []
  while row < rows
    if head && row >= head
      reader.seek(base_position + (row - head) * row_size) # jump to beginning
      head = nil
    end

    current_time += step_time

    row_data = [current_time] + reader.read(row_size, unpack_formula)

    row_data = block.call(row_data, columns, options) if block

    data << row_data

    row += 1
  end

  data
end

#fetch_last ⇒ Object 



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# File 'lib/rrd/data.rb', line 27

def fetch_last
  reader.seek(base_position + rra.current_row * row_size)

  [last_update] + reader.read(row_size, unpack_formula)
end

#first_update ⇒ Object 



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# File 'lib/rrd/data.rb', line 15

def first_update
  @start_time = last_update - (rra.rows * step_time)
end

#last_update ⇒ Object 



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# File 'lib/rrd/data.rb', line 19

def last_update
  @last_update ||= round_time(header.last_update.to_i)
end

#step_time ⇒ Object 



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# File 'lib/rrd/data.rb', line 23

def step_time
  @step_time ||= header.step * rra.pdpr
end