Class: Gitlab::Metrics::Samplers::BaseSampler

Inherits:
Daemon
  • Object
show all
Defined in:
lib/gitlab/metrics/samplers/base_sampler.rb

Instance Attribute Summary collapse

Attributes inherited from Daemon

#thread

Instance Method Summary collapse

Methods inherited from Daemon

#enabled?, initialize_instance, instance, #start, #stop, #thread?, #thread_name

Constructor Details

#initialize(interval: nil, logger: Logger.new($stdout), warmup: false, **options) ⇒ BaseSampler

interval - The sampling interval in seconds. warmup - When true, takes a single sample eagerly before entering the sampling loop.

This can be useful to ensure that all metrics files exist after `start` returns,
since prometheus-client-mmap creates them lazily upon first access.



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# File 'lib/gitlab/metrics/samplers/base_sampler.rb', line 15

def initialize(interval: nil, logger: Logger.new($stdout), warmup: false, **options)
  interval ||= ENV[interval_env_key]&.to_i
  interval ||= self.class::DEFAULT_SAMPLING_INTERVAL_SECONDS
  interval_half = interval.to_f / 2

  @interval = interval
  @interval_steps = (-interval_half..interval_half).step(0.1).to_a

  @logger = logger
  @warmup = warmup

  super(**options)
end

Instance Attribute Details

#interval ⇒ Object (readonly)

Returns the value of attribute interval.



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# File 'lib/gitlab/metrics/samplers/base_sampler.rb', line 9

def interval
  @interval
end

Instance Method Details

#safe_sample ⇒ Object 



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# File 'lib/gitlab/metrics/samplers/base_sampler.rb', line 29

def safe_sample
  sample
rescue StandardError => e
  @logger.warn("#{self.class}: #{e}, stopping")
  stop
end

#sample ⇒ Object

Raises:

  • (NotImplementedError) 


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# File 'lib/gitlab/metrics/samplers/base_sampler.rb', line 36

def sample
  raise NotImplementedError
end

#sleep_interval ⇒ Object

Returns the sleep interval with a random adjustment.

The random adjustment is put in place to ensure we:

  1. Don’t generate samples at the exact same interval every time (thus potentially missing anything that happens in between samples).

  2. Don’t sample data at the same interval two times in a row.



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# File 'lib/gitlab/metrics/samplers/base_sampler.rb', line 47

def sleep_interval
  while step = @interval_steps.sample
    next if step == @last_step

    @last_step = step

    return @interval + @last_step
  end
end