Class: Distem::Resource::Latency

Inherits:

VIface::VTraffic::Property

• Object
• VIface::VTraffic::Property
• Distem::Resource::Latency

show all

Defined in:

lib/distem/resource/latency.rb

Overview

Instance Attribute Summary (collapse)

• - (Object) delay readonly

  The delay (String at 'tc' form such as “3ms”).

Class Method Summary (collapse)

• + (Object) is_valid(latency)
• + (Object) to_secs(delay)

  converts the latency/delay to seconds (floating point) returns nil if not set.

Instance Method Summary (collapse)

• - (Latency) initialize(paramshash = {}) constructor

  Create a new Bandwidth ==== Attributes * paramshash The Hash of the parameters to set (in the form “paramname” => value).

• - (Object) limit_from_bandwidth(bandwidth)

  adjust 'limit' parameter to netem so that it works sensibly bandwidth is the rate that this link will emulate (in bytes/s) it can be nil, then we assume it is 1Gbit/s.

• - (Object) parse_params(paramshash)

  Parameters parsing method.

• - (Object) tc_params(bandwidth)
• - (Object) to_secs

Methods inherited from VIface::VTraffic::Property

#to_s

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# File 'lib/distem/resource/latency.rb', line 13

def initialize(paramshash={})
  super()
  @delay = nil
  parse_params(paramshash)
end

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# File 'lib/distem/resource/latency.rb', line 8

def delay
  @delay
end

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# File 'lib/distem/resource/latency.rb', line 65

def self.is_valid(latency)
  begin
    self.to_secs(latency)
    return true
  rescue ArgumentError
    return false
  end
end

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# File 'lib/distem/resource/latency.rb', line 46

def self.to_secs(delay)
  return nil if delay.nil?
  m = /^(\d+)(\w*)$/.match(delay)
  raise ArgumentError if m.nil?
  digits, units = m.captures
  mult = case units
    when 's', 'sec', 'secs' then 1.0 # seconds
    when 'ms', 'msec', 'msecs' then 0.001 # milliseconds
    when 'us', 'usec', 'usecs', '' then 0.000001 # microseconds
    else nil
  end
  raise ArgumentError if mult.nil?
  return (digits.to_i * mult)
end

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# File 'lib/distem/resource/latency.rb', line 28

def limit_from_bandwidth(bandwidth)
  bandwidth = (1024 ** 3) if bandwidth.nil?
  capacity = bandwidth * to_secs()
  # on average the packet has ~ 1500 bytes (Ethernet MTU?)
  packets = capacity / 1500.0
  # we give additional space (10%), just in case
  limit = (packets * 1.1).to_i
  limit = 1000 if limit < 1000
  return limit
end

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# File 'lib/distem/resource/latency.rb', line 20

def parse_params(paramshash)
  super(paramshash)
  @delay = paramshash['delay']
end

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# File 'lib/distem/resource/latency.rb', line 39

def tc_params(bandwidth)
    return { 'delay' => @delay } if @delay.nil?
    return { 'delay' => @delay, 'limit' => limit_from_bandwidth(bandwidth) } 
end

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# File 'lib/distem/resource/latency.rb', line 61

def to_secs
  Latency.to_secs(@delay)
end