Class: Hitimes::Metric

Inherits:
Object
  • Object
show all
Defined in:
lib/hitimes/metric.rb

Overview

Metric hold the common meta information for all derived metric classes

All metrics hold the meta information of:

  • The name of the metric

  • The time of day the first measurement is taken

  • The time of day the last measurement is taken

  • additional data

Each derived class is assumed to set the sampling_start_time and sampling_stop_time appropriately.

Metric itself should generally not be used. Only use the derived classes.

Direct Known Subclasses

TimedMetric, TimedValueMetric, ValueMetric

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name, additional_data = {}) ⇒ Metric

:call-seq:

Metric.new( 'my_metric' ) -> Metric
Metric.new( 'my_metric', 'foo' => 'bar', 'this' => 42 ) -> Metric

Create a new ValueMetric giving it a name and additional data.

additional_data may be anything that follows the to_hash protocol. name may be anything that follows the to_s protocol.



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# File 'lib/hitimes/metric.rb', line 44

def initialize( name, additional_data = {} )
  @sampling_start_time     = nil
  @sampling_start_interval = nil
  @sampling_delta          = 0

  @name                = name.to_s
  @additional_data     = additional_data.to_hash
end

Instance Attribute Details

#additional_data ⇒ Object (readonly)

An additional hash of data to associate with the metric



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# File 'lib/hitimes/metric.rb', line 29

def additional_data
  @additional_data
end

#name ⇒ Object (readonly)

The ‘name’ to associate with the metric



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# File 'lib/hitimes/metric.rb', line 32

def name
  @name
end

#sampling_delta ⇒ Object (readonly)

the number of seconds as a float since the sampling_start_time



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# File 'lib/hitimes/metric.rb', line 26

def sampling_delta
  @sampling_delta
end

Instance Method Details

#sampling_start_time ⇒ Object

:call-seq: 

metric.sampling_start_time -> Float or nil

The time at which the first sample was taken. This is the number of microseconds since UNIX epoch UTC as a Float

If the metric has not started measuring then the start time is nil.



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# File 'lib/hitimes/metric.rb', line 62

def sampling_start_time
  if @sampling_start_interval then
    @sampling_start_time ||= self.utc_microseconds()
  else
    nil
  end
end

#sampling_stop_time ⇒ Object

:call-seq:

metric.sampling_stop_time -> Float or nil

The time at which the last sample was taken This is the number of microseconds since UNIX epoch UTC as a Float

If the metric has not completely measured at least one thing then stop time is nil.

Because accessing the actual ‘time of day’ is an expesive operation, we only get the time of day at the beginning of the first measurement and we keep track of the offset from that point in @sampling_delta.

When sampling_stop_time is called, the actual time of day is caculated.



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# File 'lib/hitimes/metric.rb', line 86

def sampling_stop_time
  if @sampling_delta > 0 then
    (self.sampling_start_time + (@sampling_delta * 1_000_000))
  else 
    nil
  end
end

#to_hash ⇒ Object

:call-seq:

metric.to_hash -> Hash
metric.to_hash

Convert the metric to a Hash.



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# File 'lib/hitimes/metric.rb', line 101

def to_hash
  { 'sampling_start_time' => self.sampling_start_time,
    'sampling_stop_time'  => self.sampling_stop_time,
    'additional_data'     => self.additional_data,
    'name'                => self.name }
end

#utc_microseconds ⇒ Object

:call-seq:

metric.utc_microseconds -> Float

The current time in microseconds from the UNIX Epoch in the UTC



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# File 'lib/hitimes/metric.rb', line 114

def utc_microseconds
  Time.now.gmtime.to_f * 1_000_000
end