Class: Process::Metrics::Processor

Inherits:
Object
  • Object
show all
Defined in:
lib/process/metrics/processor.rb

Overview

Computes interval CPU utilization from cumulative process metrics.

Defined Under Namespace

Classes: Sample, Snapshot

Instance Method Summary collapse

Constructor Details

#initialize(capture: General.method(:capture)) ⇒ Processor

Initialize a process metrics sampler.



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# File 'lib/process/metrics/processor.rb', line 23

def initialize(capture: General.method(:capture))
	@capture = capture
	@snapshots = {}
end

Instance Method Details

#sample(process_ids) ⇒ Object

Sample CPU utilization for the given processes. The first observation of each process establishes a baseline and does not produce a sample.



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# File 'lib/process/metrics/processor.rb', line 32

def sample(process_ids)
	processes = @capture.call(pid: process_ids, memory: false)
	timestamp = now
	return {} unless finite?(timestamp)
	
	samples = {}
	snapshots = {}
	
	processes.each do |process_id, process|
		start_time = process.start_time
		processor_time = process.processor_time
		next unless finite?(start_time) && finite?(processor_time)
		
		current = Snapshot.new(start_time, processor_time, timestamp)
		snapshots[process_id] = current
		
		if previous = @snapshots[process_id]
			next unless previous.start_time == current.start_time
			
			duration = current.timestamp - previous.timestamp
			processor_time = current.processor_time - previous.processor_time
			next unless finite?(duration) && duration > 0.0
			next unless finite?(processor_time) && processor_time >= 0.0
			
			utilization = processor_time / duration
			next unless finite?(utilization)
			
			samples[process_id] = Sample.new(process_id, duration, processor_time, utilization).freeze
		end
	end
	
	@snapshots = snapshots
	
	return samples
end