Class: NewRelic::Agent::WorkerLoop

Inherits:
Object
  • Object
show all
Defined in:
lib/new_relic/agent/worker_loop.rb

Overview

A worker loop executes a set of registered tasks on a single thread. A task is a proc or block with a specified call period in seconds.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(opts = {}) ⇒ WorkerLoop

Optional argument :duration (in seconds) for how long the worker loop runs or :limit (integer) for max number of iterations



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# File 'lib/new_relic/agent/worker_loop.rb', line 17

def initialize(opts={})
  @should_run = true
  @next_invocation_time = Time.now
  @period = 60.0
  @duration = opts[:duration] if opts[:duration]
  @limit = opts[:limit] if opts[:limit]
  @iterations = 0
  @propagate_errors = opts.fetch(:propagate_errors, false)
end

Instance Attribute Details

#period ⇒ Object

Returns the value of attribute period.



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# File 'lib/new_relic/agent/worker_loop.rb', line 13

def period
  @period
end

#propagate_errors ⇒ Object

Returns the value of attribute propagate_errors.



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# File 'lib/new_relic/agent/worker_loop.rb', line 13

def propagate_errors
  @propagate_errors
end

Instance Method Details

#keep_running? ⇒ Boolean

a simple accessor for @should_run

Returns:

  • (Boolean) 


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# File 'lib/new_relic/agent/worker_loop.rb', line 61

def keep_running?
  @should_run && under_duration? && under_limit?
end

#run(period = nil, &block) ⇒ Object

Run infinitely, calling the registered tasks at their specified call periods. The caller is responsible for creating the thread that runs this worker loop. This will run the task immediately.



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# File 'lib/new_relic/agent/worker_loop.rb', line 42

def run(period=nil, &block)
  setup(period, block)
  while keep_running? do
    sleep_time = schedule_next_invocation
    sleep(sleep_time) if sleep_time > 0
    run_task if keep_running?
    @iterations += 1
  end
end

#run_task ⇒ Object

Executes the block given to the worker loop, and handles many possible errors. Also updates the execution time so that the next run occurs on schedule, even if we execute at some odd time



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# File 'lib/new_relic/agent/worker_loop.rb', line 81

def run_task
  if @propagate_errors
    @task.call
  else
    begin
      @task.call
    rescue ServerError => e
      ::NewRelic::Agent.logger.debug "Server Error:", e
    rescue NewRelic::Agent::ForceRestartException, NewRelic::Agent::ForceDisconnectException
      # blow out the loop
      raise
    rescue RuntimeError => e
      # This is probably a server error which has been logged in the server along
      # with your account name.
      ::NewRelic::Agent.logger.error "Error running task in worker loop, likely a server error:", e
    rescue Timeout::Error, NewRelic::Agent::ServerConnectionException
      # Want to ignore these because they are handled already
    rescue SystemExit, NoMemoryError, SignalException
      raise
    rescue => e
      # Don't blow out the stack for anything that hasn't already propagated
      ::NewRelic::Agent.logger.error "Error running task in Agent Worker Loop:", e
    end
  end
end

#schedule_next_invocation ⇒ Object 



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# File 'lib/new_relic/agent/worker_loop.rb', line 52

def schedule_next_invocation
  now = Time.now
  while @next_invocation_time <= now && @period > 0
    @next_invocation_time += @period
  end
  @next_invocation_time - Time.now
end

#setup(period, task) ⇒ Object

Reset state that is changed by running the worker loop



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# File 'lib/new_relic/agent/worker_loop.rb', line 28

def setup(period, task)
  @task = task
  @period = period if period
  @should_run = true
  @iterations = 0

  now = Time.now
  @deadline = now + @duration if @duration
  @next_invocation_time = (now + @period)
end

#stop ⇒ Object

Sets @should_run to false. Returns false



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# File 'lib/new_relic/agent/worker_loop.rb', line 74

def stop
  @should_run = false
end

#under_duration? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/new_relic/agent/worker_loop.rb', line 65

def under_duration?
  !@deadline || Time.now < @deadline
end

#under_limit? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/new_relic/agent/worker_loop.rb', line 69

def under_limit?
  @limit.nil? || @iterations < @limit
end