Module: Aeternitas::Pollable

Extended by:
ActiveSupport::Concern
Defined in:
lib/aeternitas/pollable.rb,
lib/aeternitas/pollable/dsl.rb,
lib/aeternitas/pollable/configuration.rb

Overview

Note:

Can only be used by classes inheriting from ActiveRecord::Base

Mixin that enables the frequent polling of the receiving class. Classes including this method must implement the .poll method. Polling behaviour can be configured via pollable_options.

Examples:

class MyWebsitePollable < ActiveRecord::Base
  includes Aeternitas::Pollable

  polling_options do
    polling_frequency :daily
    lock_key ->(obj) {obj.url}
  end

  def poll
    response = HTTParty.get(self.url)
    raise StandardError, "#{self.url} responded with #{response.status}" unless response.success?
    HttpSource.create!(content: response.parsed_response)
  end
end

Defined Under Namespace

Classes: Configuration, Dsl

Instance Method Summary collapse

Instance Method Details

#add_source(raw_content) ⇒ Aeternitas::Source

Creates a new source with the given content if it does not exist

Examples:

#...
def poll
  response = HTTParty.get("http://example.com")
  add_source(response.parsed_response)
end
#...

Parameters:

  • raw_content (String) —

    the sources raw content

Returns:



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# File 'lib/aeternitas/pollable.rb', line 124

def add_source(raw_content)
  source = sources.create(raw_content: raw_content)
  return nil unless source.persisted?

  Aeternitas::Metrics.log(:sources_created, self.class)
  source
end

#execute_poll ⇒ Object

This method runs the polling workflow



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# File 'lib/aeternitas/pollable.rb', line 51

def execute_poll
  _before_poll

  begin
    guard.with_lock { poll }
  rescue Aeternitas::Guard::GuardIsLocked
    # Do not transition to the 'errored' state for a guard lock.
    raise
  rescue => e
    if pollable_configuration.deactivation_errors.include?(e.class)
      disable_polling(e)
      return false
    elsif pollable_configuration.ignored_errors.include?(e.class)
      pollable_meta_data.has_errored!
      raise Aeternitas::Errors::Ignored, e
    else
      pollable_meta_data.has_errored!
      raise e
    end
  end

  _after_poll
rescue => e
  begin
    log_poll_error(e)
  ensure
    raise e
  end
end

#guard ⇒ Object 



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# File 'lib/aeternitas/pollable.rb', line 100

def guard
  guard_key = pollable_configuration.guard_options[:key].call(self)
  guard_timeout = pollable_configuration.guard_options[:timeout]
  guard_cooldown = pollable_configuration.guard_options[:cooldown]
  Aeternitas::Guard.new(guard_key, guard_cooldown, guard_timeout)
end

#poll ⇒ Object

This method is abstract.

This method must be implemented when Aeternitas::Pollable is included

This method implements the class specific polling behaviour. It is only called after the lock was acquired successfully.

Raises:

  • (NotImplementedError) 


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# File 'lib/aeternitas/pollable.rb', line 85

def poll
  raise NotImplementedError, "#{self.class.name} does not implement #poll, required by Aeternitas::Pollable"
end

#pollable_configuration ⇒ Aeternitas::Pollable::Configuration

Access the Pollables configuration

Returns:



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# File 'lib/aeternitas/pollable.rb', line 110

def pollable_configuration
  self.class.pollable_configuration
end

#register_pollable ⇒ Object

Note:

Manual registration is only needed if the object was created before Aeternitas::Pollable was included. Otherwise it is done automatically after creation.

Registers the instance as pollable.



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# File 'lib/aeternitas/pollable.rb', line 93

def register_pollable
  self.pollable_meta_data ||= create_pollable_meta_data(
    state: "waiting",
    pollable_class: self.class.name
  )
end