Module: Cirron

Defined in:
lib/tracer.rb,
lib/injector.rb,
lib/collector.rb

Defined Under Namespace

Classes: Injector

Class Method Summary collapse

Class Method Details

.calculate_overhead ⇒ Object 



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# File 'lib/collector.rb', line 51

def self.calculate_overhead
  10.times do
    counter = collector(measure_overhead: false) {}
    Counter.members.each do |field|
      @overhead[field] = [@overhead[field], counter[field]].compact.min
    end
  end
end

.collector(measure_overhead: true, &blk) ⇒ Object 



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# File 'lib/collector.rb', line 72

def self.collector(measure_overhead: true, &blk)
  calculate_overhead if measure_overhead && @overhead.empty?

  counter = Counter.new
  ret_val = self.start

  yield

  self.end(ret_val, counter)

  if measure_overhead && !@overhead.empty?
    Counter.members.each do |field|
      counter[field] = [counter[field] - @overhead[field], 0].max
    end
  end

  counter
end

.end(fd, counter) ⇒ Object 



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# File 'lib/collector.rb', line 68

def self.end(fd, counter)
  CirronInterOp.end(fd, counter)
end

.injector ⇒ Object 



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# File 'lib/injector.rb', line 61

def self.injector
  Injector.new
end

.start ⇒ Object 



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# File 'lib/collector.rb', line 60

def self.start
  ret_val = CirronInterOp.start
  if ret_val == -1
    raise "Failed to start collector"
  end
  ret_val
end

.to_tef(parsed_events) ⇒ Object 



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# File 'lib/tracer.rb', line 131

def self.to_tef(parsed_events)
  events = parsed_events.map do |event|
    case event
    when Syscall
      start_ts = event.timestamp.to_f * 1_000_000
      duration_us = event.duration.to_f * 1_000_000
      {
        name: event.name,
        ph: "X",
        ts: start_ts,
        dur: duration_us,
        pid: event.pid.to_i,
        tid: event.pid.to_i,
        args: { args: event.args, retval: event.retval }
      }
    when TraceSignal
      ts = event.timestamp.to_f * 1_000_000
      {
        name: "Signal: #{event.name}",
        ph: "i",
        s: "g",
        ts: ts,
        pid: event.pid.to_i,
        tid: event.pid.to_i,
        args: { details: event.details }
      }
    end
  end

  JSON.pretty_generate(events)
end

.tracer(timeout = 10, &block) ⇒ Object 



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# File 'lib/tracer.rb', line 88

def self.tracer(timeout = 10, &block)
  trace_file = Tempfile.new('cirron')
  trace_file.close
  parent_pid = Process.pid
  cmd = "strace --quiet=attach,exit -f -T -ttt -o #{trace_file.path} -p #{parent_pid}"
  
  strace_proc = spawn(cmd, :out => "/dev/null", :err => "/dev/null")
  
  # Wait for the trace file to be created
  deadline = Time.now + timeout
  begin
    until File.exist?(trace_file.path)
      if Time.now > deadline
        raise Timeout::Error, "Failed to start strace within #{timeout}s."
      end
    end
    # :(
    sleep 0.1

    # We use this dummy fstat to recognize when we start executing the block
    File.stat(trace_file.path + ".dummy") rescue nil

    yield if block_given?

    # Same here, to recognize when we're done executing the block
    File.stat(trace_file.path + ".dummy") rescue nil
  ensure
    Process.kill('INT', strace_proc) rescue nil
    Process.wait(strace_proc) rescue nil
  end

  # Parse the trace file into a list of events
  trace = File.open(trace_file.path, 'r') do |file|
    parse_strace(file)
  end

  trace = filter_trace(trace, trace_file.path + ".dummy")

  trace_file.unlink

  trace
end