Class: Judoscale::RequestMetrics

Inherits:
Object
  • Object
show all
Defined in:
lib/judoscale/request_metrics.rb

Constant Summary collapse

MILLISECONDS_CUTOFF = 
Time.new(2000, 1, 1).to_i * 1000
MICROSECONDS_CUTOFF = 
MILLISECONDS_CUTOFF * 1000
NANOSECONDS_CUTOFF = 
MICROSECONDS_CUTOFF * 1000

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(env, config = Config.instance) ⇒ RequestMetrics

Returns a new instance of RequestMetrics.



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# File 'lib/judoscale/request_metrics.rb', line 11

def initialize(env, config = Config.instance)
  @config = config
  @request_id = env["HTTP_X_REQUEST_ID"]
  @size = env["rack.input"].respond_to?(:size) ? env["rack.input"].size : 0
  @network_time = env["puma.request_body_wait"].to_i
  @request_start_header = env["HTTP_X_REQUEST_START"]
end

Instance Attribute Details

#network_time ⇒ Object (readonly)

Returns the value of attribute network_time.



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# File 'lib/judoscale/request_metrics.rb', line 9

def network_time
  @network_time
end

#request_id ⇒ Object (readonly)

Returns the value of attribute request_id.



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# File 'lib/judoscale/request_metrics.rb', line 9

def request_id
  @request_id
end

#size ⇒ Object (readonly)

Returns the value of attribute size.



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# File 'lib/judoscale/request_metrics.rb', line 9

def size
  @size
end

Instance Method Details

#elapsed_time ⇒ Object 



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# File 'lib/judoscale/request_metrics.rb', line 34

def elapsed_time
  start = Process.clock_gettime(Process::CLOCK_MONOTONIC)
  response = yield
  finish = Process.clock_gettime(Process::CLOCK_MONOTONIC)

  elapsed = ((finish - start) * 1000).to_i
  [elapsed, response]
end

#queue_time(now = Time.now) ⇒ Object 



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# File 'lib/judoscale/request_metrics.rb', line 23

def queue_time(now = Time.now)
  queue_time = ((now.utc - started_at.utc) * 1000).to_i

  # Subtract the time Puma spent waiting on the request body, i.e. the network time. It's irrelevant to
  # capacity-related queue time. Without this, slow clients and large request payloads will skew queue time.
  queue_time -= network_time

  # Safeguard against negative queue times (should not happen in practice)
  (queue_time > 0) ? queue_time : 0
end

#track_queue_time? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/judoscale/request_metrics.rb', line 19

def track_queue_time?
  @request_start_header && !ignore_large_request?
end