Class: CPU::UsageSampler

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

Constant Summary collapse

CPU =

This regular expression is used to parse cpu times from the /proc/stat kernel file.

/^cpu(\d+)#{'\s+(\d+)' * 4}/
USER_HZ =

This value is used to convert cpu times from jiffies into seconds.

100

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ UsageSampler

Creates a new UsageSampler instance.



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# File 'lib/cpu/usage_sampler.rb', line 4

def initialize
  sample
end

Instance Attribute Details

#usages ⇒ Object (readonly)

Return all CPU::Usage instances stored in this UsageSampler, if any.



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# File 'lib/cpu/usage_sampler.rb', line 9

def usages
  @usages
end

Instance Method Details

#sample ⇒ Object

Take one sample of CPU usage data for every processor in this computer and store them in the usages attribute.



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# File 'lib/cpu/usage_sampler.rb', line 26

def sample
  total, @usages = nil, {}
  timestamp = Time.now
  File.foreach('/proc/stat') do |line|
    case line
    when /^cpu[^\d]/
      next
    when CPU
      times = $~.captures
      processor_id = times[0] = times[0].to_i
      (1...times.size).each { |i| times[i] = times[i].to_f / USER_HZ }
      times << timestamp << timestamp
      @usages[processor_id] = Usage.new(self, *times)
    else
      break
    end
  end
  if @usages.empty?
    raise NoSampleDataError, "could not sample measurement data"
  end
  self
end

#sum_usages ⇒ Object

Returns a CPU::Usage instance, that sums up all CPU::Usage instances for all processors in this computer.



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# File 'lib/cpu/usage_sampler.rb', line 13

def sum_usages
  @usages and @usages.values.inject(&:+)
end