Class: FluidFeatures::AppState

Inherits:
Object
  • Object
show all
Defined in:
lib/fluidfeatures/app/state.rb

Constant Summary collapse

USER_ID_NUMERIC = 
/^\d+$/
ETAG_WAIT =

Request to FluidFeatures API to long-poll for max 30 seconds. The API may choose a different duration. If not change in this time, API will return HTTP 304.

ENV["FF_DEV"] ? 5 : 30
WAIT_BETWEEN_FETCH_SUCCESS =

Hard max of 2 req/sec

0.5
WAIT_BETWEEN_SEND_SUCCESS_NEXT_WAITING =

Hard max of 10 req/sec

0.1
WAIT_BETWEEN_FETCH_FAILURES =

If we are failing to communicate with the FluidFeautres API then wait for this long between requests.

5

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(app) ⇒ AppState

seconds



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# File 'lib/fluidfeatures/app/state.rb', line 30

def initialize(app)
  raise "app invalid : #{app}" unless app.is_a? ::FluidFeatures::App
  configure(app)
  run_loop
end

Instance Attribute Details

#app ⇒ Object

Returns the value of attribute app.



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# File 'lib/fluidfeatures/app/state.rb', line 11

def app
  @app
end

Instance Method Details

#configure(app) ⇒ Object 



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# File 'lib/fluidfeatures/app/state.rb', line 36

def configure(app)
  @app = app
  @features = features_storage.list
  @features_lock = ::Mutex.new
end

#feature_version_enabled_for_user(feature_name, version_name, user_id, user_attributes = {}) ⇒ Object 



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# File 'lib/fluidfeatures/app/state.rb', line 107

def feature_version_enabled_for_user(feature_name, version_name, user_id, user_attributes={})
  raise "feature_name invalid : #{feature_name}" unless feature_name.is_a? String
  version_name ||= ::FluidFeatures::DEFAULT_VERSION_NAME
  raise "version_name invalid : #{version_name}" unless version_name.is_a? String

  #assert(isinstance(user_id, basestring))

  user_attributes ||= {}
  user_attributes["user"] = user_id.to_s
  if user_id.is_a? Integer
    user_id_hash = user_id
  elsif USER_ID_NUMERIC.match(user_id)
    user_id_hash = user_id.to_i
  else
    user_id_hash = Digest::SHA1.hexdigest(user_id)[-10, 10].to_i(16)
  end
  enabled = false

  feature = features[feature_name]
  version = feature["versions"][version_name]
  modulus = user_id_hash % feature["num_parts"]
  enabled = version["parts"].include? modulus

  feature["versions"].each_pair do |other_version_name, other_version|
    if other_version
      version_attributes = (other_version["enabled"] || {})["attributes"]
      if version_attributes
        user_attributes.each_pair do |attr_key, attr_id|
          version_attribute = version_attributes[attr_key.to_s]
          if version_attribute and version_attribute.include? attr_id.to_s
            if other_version_name == version_name
              # explicitly enabled for this version
              return true
            else
              # explicitly enabled for another version
              return false
            end
          end
        end
      end
    end
  end

  enabled
end

#features ⇒ Object 



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# File 'lib/fluidfeatures/app/state.rb', line 46

def features
  f = nil
  @features_lock.synchronize do
    f = @features
  end
  f
end

#features=(f) ⇒ Object 



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# File 'lib/fluidfeatures/app/state.rb', line 54

def features= f
  return unless f.is_a? Hash
  @features_lock.synchronize do
    features_storage.replace(f) unless @features == f
    @features = f
  end
end

#features_storage ⇒ Object 



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# File 'lib/fluidfeatures/app/state.rb', line 42

def features_storage
  @features_storage ||= FluidFeatures::Persistence::Features.create(FluidFeatures.config["cache"])
end

#load_state ⇒ Object 



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# File 'lib/fluidfeatures/app/state.rb', line 94

def load_state
  success, state = app.get("/features", { :verbose => true, :etag_wait => ETAG_WAIT }, true)
  if success and state
    state.each_pair do |feature_name, feature|
      feature["versions"].each_pair do |version_name, version|
        # convert parts to a Set for quick lookup
        version["parts"] = Set.new(version["parts"] || [])
      end
    end
  end
  return success, state
end

#run_loop ⇒ Object 



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# File 'lib/fluidfeatures/app/state.rb', line 62

def run_loop
  Thread.new do
    while true
      begin

        success, state = load_state

        # Note, success could be true, but state might be nil.
        # This occurs with 304 (no change)
        if success and state
          # switch out current state with new one
          self.features = state
        elsif not success
          # If service is down, then slow our requests
          # within this thread
          sleep WAIT_BETWEEN_FETCH_FAILURES
        end

        # What ever happens never make more than N requests
        # per second
        sleep WAIT_BETWEEN_FETCH_SUCCESS

      rescue Exception => err
        # catch errors, so that we do not affect the rest of the application
        app.logger.error "load_state failed : #{err.message}\n#{err.backtrace.join("\n")}"
        # hold off for a little while and try again
        sleep WAIT_BETWEEN_FETCH_FAILURES
      end
    end
  end
end