class LaunchDarkly::LDClient

A client for LaunchDarkly. Client instances are thread-safe. Users should create a single client instance for the lifetime of the application.

Public Class Methods

new(sdk_key, config = Config.default, wait_for_sec = 5) click to toggle source

Creates a new client instance that connects to LaunchDarkly. A custom configuration parameter can also supplied to specify advanced options, but for most use cases, the default configuration is appropriate.

The client will immediately attempt to connect to LaunchDarkly and retrieve your feature flag data. If it cannot successfully do so within the time limit specified by `wait_for_sec`, the constructor will return a client that is in an uninitialized state. See {#initialized?} for more details.

@param sdk_key [String] the SDK key for your LaunchDarkly account @param config [Config] an optional client configuration object @param wait_for_sec [Float] maximum time (in seconds) to wait for initialization

@return [LDClient] The LaunchDarkly client instance

# File lib/ldclient-rb/ldclient.rb, line 35
def initialize(sdk_key, config = Config.default, wait_for_sec = 5)
  # Note that sdk_key is normally a required parameter, and a nil value would cause the SDK to
  # fail in most configurations. However, there are some configurations where it would be OK
  # (offline = true, *or* we are using LDD mode or the file data source and events are disabled
  # so we're not connecting to any LD services) so rather than try to check for all of those
  # up front, we will let the constructors for the data source implementations implement this
  # fail-fast as appropriate, and just check here for the part regarding events.
  if !config.offline? && config.send_events
    raise ArgumentError, "sdk_key must not be nil" if sdk_key.nil?
  end

  @sdk_key = sdk_key

  @event_factory_default = EventFactory.new(false)
  @event_factory_with_reasons = EventFactory.new(true)

  # We need to wrap the feature store object with a FeatureStoreClientWrapper in order to add
  # some necessary logic around updates. Unfortunately, we have code elsewhere that accesses
  # the feature store through the Config object, so we need to make a new Config that uses
  # the wrapped store.
  @store = Impl::FeatureStoreClientWrapper.new(config.feature_store)
  updated_config = config.clone
  updated_config.instance_variable_set(:@feature_store, @store)
  @config = updated_config

  get_flag = lambda { |key| @store.get(FEATURES, key) }
  get_segment = lambda { |key| @store.get(SEGMENTS, key) }
  @evaluator = LaunchDarkly::Impl::Evaluator.new(get_flag, get_segment, @config.logger)

  if !@config.offline? && @config.send_events && !@config.diagnostic_opt_out?
    diagnostic_accumulator = Impl::DiagnosticAccumulator.new(Impl::DiagnosticAccumulator.create_diagnostic_id(sdk_key))
  else
    diagnostic_accumulator = nil
  end

  if @config.offline? || !@config.send_events
    @event_processor = NullEventProcessor.new
  else
    @event_processor = EventProcessor.new(sdk_key, config, nil, diagnostic_accumulator)
  end

  if @config.use_ldd?
    @config.logger.info { "[LDClient] Started LaunchDarkly Client in LDD mode" }
    return  # requestor and update processor are not used in this mode
  end

  data_source_or_factory = @config.data_source || self.method(:create_default_data_source)
  if data_source_or_factory.respond_to? :call
    # Currently, data source factories take two parameters unless they need to be aware of diagnostic_accumulator, in
    # which case they take three parameters. This will be changed in the future to use a less awkware mechanism.
    if data_source_or_factory.arity == 3
      @data_source = data_source_or_factory.call(sdk_key, @config, diagnostic_accumulator)
    else
      @data_source = data_source_or_factory.call(sdk_key, @config)
    end
  else
    @data_source = data_source_or_factory
  end

  ready = @data_source.start
  if wait_for_sec > 0
    ok = ready.wait(wait_for_sec)
    if !ok
      @config.logger.error { "[LDClient] Timeout encountered waiting for LaunchDarkly client initialization" }
    elsif !@data_source.initialized?
      @config.logger.error { "[LDClient] LaunchDarkly client initialization failed" }
    end
  end
end

Public Instance Methods

alias(current_context, previous_context) click to toggle source

Associates a new and old user object for analytics purposes via an alias event.

@param current_context [Hash] The current version of a user. @param previous_context [Hash] The previous version of a user. @return [void]

# File lib/ldclient-rb/ldclient.rb, line 292
def alias(current_context, previous_context)
  if !current_context || current_context[:key].nil? || !previous_context || previous_context[:key].nil?
    @config.logger.warn("Alias called with nil user or nil user key!")
    return
  end
  sanitize_user(current_context)
  sanitize_user(previous_context)
  @event_processor.add_event(@event_factory_default.new_alias_event(current_context, previous_context))
end
all_flags(user) click to toggle source

Returns all feature flag values for the given user.

@deprecated Please use {#all_flags_state} instead. Current versions of the

client-side SDK will not generate analytics events correctly if you pass the
result of `all_flags`.

@param user [Hash] The end user requesting the feature flags @return [Hash] a hash of feature flag keys to values

# File lib/ldclient-rb/ldclient.rb, line 312
def all_flags(user)
  all_flags_state(user).values_map
end
all_flags_state(user, options={}) click to toggle source

Returns a {FeatureFlagsState} object that encapsulates the state of all feature flags for a given user, including the flag values and also metadata that can be used on the front end. This method does not send analytics events back to LaunchDarkly.

@param user [Hash] The end user requesting the feature flags @param options [Hash] Optional parameters to control how the state is generated @option options [Boolean] :client_side_only (false) True if only flags marked for use with the

client-side SDK should be included in the state. By default, all flags are included.

@option options [Boolean] :with_reasons (false) True if evaluation reasons should be included

in the state (see {#variation_detail}). By default, they are not included.

@option options [Boolean] :details_only_for_tracked_flags (false) True if any flag metadata that is

normally only used for event generation - such as flag versions and evaluation reasons - should be
omitted for any flag that does not have event tracking or debugging turned on. This reduces the size
of the JSON data if you are passing the flag state to the front end.

@return [FeatureFlagsState] a {FeatureFlagsState} object which can be serialized to JSON

# File lib/ldclient-rb/ldclient.rb, line 333
def all_flags_state(user, options={})
  return FeatureFlagsState.new(false) if @config.offline?

  unless user && !user[:key].nil?
    @config.logger.error { "[LDClient] User and user key must be specified in all_flags_state" }
    return FeatureFlagsState.new(false)
  end

  begin
    features = @store.all(FEATURES)
  rescue => exn
    Util.log_exception(@config.logger, "Unable to read flags for all_flags_state", exn)
    return FeatureFlagsState.new(false)
  end

  state = FeatureFlagsState.new(true)
  client_only = options[:client_side_only] || false
  with_reasons = options[:with_reasons] || false
  details_only_if_tracked = options[:details_only_for_tracked_flags] || false
  features.each do |k, f|
    if client_only && !f[:clientSide]
      next
    end
    begin
      result = @evaluator.evaluate(f, user, @event_factory_default)
      state.add_flag(f, result.detail.value, result.detail.variation_index, with_reasons ? result.detail.reason : nil,
        details_only_if_tracked)
    rescue => exn
      Util.log_exception(@config.logger, "Error evaluating flag \"#{k}\" in all_flags_state", exn)
      state.add_flag(f, nil, nil, with_reasons ? EvaluationReason::error(EvaluationReason::ERROR_EXCEPTION) : nil,
        details_only_if_tracked)
    end
  end

  state
end
close() click to toggle source

Releases all network connections and other resources held by the client, making it no longer usable.

@return [void]

# File lib/ldclient-rb/ldclient.rb, line 374
def close
  @config.logger.info { "[LDClient] Closing LaunchDarkly client..." }
  @data_source.stop
  @event_processor.stop
  @store.stop
end
flush() click to toggle source

Tells the client that all pending analytics events should be delivered as soon as possible.

When the LaunchDarkly client generates analytics events (from {#variation}, {#variation_detail}, {#identify}, or {#track}), they are queued on a worker thread. The event thread normally sends all queued events to LaunchDarkly at regular intervals, controlled by the {Config#flush_interval} option. Calling `flush` triggers a send without waiting for the next interval.

Flushing is asynchronous, so this method will return before it is complete. However, if you call {#close}, events are guaranteed to be sent before that method returns.

# File lib/ldclient-rb/ldclient.rb, line 117
def flush
  @event_processor.flush
end
identify(user) click to toggle source

Registers the user. This method simply creates an analytics event containing the user properties, so that LaunchDarkly will know about that user if it does not already.

Calling {#variation} or {#variation_detail} also sends the user information to LaunchDarkly (if events are enabled), so you only need to use {#identify} if you want to identify the user without evaluating a flag.

Note that event delivery is asynchronous, so the event may not actually be sent until later; see {#flush}.

@param user [Hash] The user to register; this can have all the same user properties

described in {#variation}

@return [void]

# File lib/ldclient-rb/ldclient.rb, line 245
def identify(user)
  if !user || user[:key].nil?
    @config.logger.warn("Identify called with nil user or nil user key!")
    return
  end
  sanitize_user(user)
  @event_processor.add_event(@event_factory_default.new_identify_event(user))
end
initialized?() click to toggle source

Returns whether the client has been initialized and is ready to serve feature flag requests.

If this returns false, it means that the client did not succeed in connecting to LaunchDarkly within the time limit that you specified in the constructor. It could still succeed in connecting at a later time (on another thread), or it could have given up permanently (for instance, if your SDK key is invalid). In the meantime, any call to {#variation} or {#variation_detail} will behave as follows:

  1. It will check whether the feature store already contains data (that is, you

are using a database-backed store and it was populated by a previous run of this application). If so, it will use the last known feature flag data.

  1. Failing that, it will return the value that you specified for the `default`

parameter of {#variation} or {#variation_detail}.

@return [Boolean] true if the client has been initialized

# File lib/ldclient-rb/ldclient.rb, line 162
def initialized?
  @config.offline? || @config.use_ldd? || @data_source.initialized?
end
secure_mode_hash(user) click to toggle source

Creates a hash string that can be used by the JavaScript SDK to identify a user. For more information, see [Secure mode](docs.launchdarkly.com/docs/js-sdk-reference#section-secure-mode).

@param user [Hash] the user properties @return [String] a hash string

# File lib/ldclient-rb/ldclient.rb, line 140
def secure_mode_hash(user)
  OpenSSL::HMAC.hexdigest("sha256", @sdk_key, user[:key].to_s)
end
toggle?(key, user, default = false) click to toggle source

@param key [String] the feature flag key @param user [Hash] the user properties @param default [Boolean] (false) the value to use if the flag cannot be evaluated @return [Boolean] the flag value @deprecated Use {#variation} instead.

# File lib/ldclient-rb/ldclient.rb, line 128
def toggle?(key, user, default = false)
  @config.logger.warn { "[LDClient] toggle? is deprecated. Use variation instead" }
  variation(key, user, default)
end
track(event_name, user, data = nil, metric_value = nil) click to toggle source

Tracks that a user performed an event. This method creates a “custom” analytics event containing the specified event name (key), user properties, and optional data.

Note that event delivery is asynchronous, so the event may not actually be sent until later; see {#flush}.

As of this version’s release date, the LaunchDarkly service does not support the `metricValue` parameter. As a result, specifying `metricValue` will not yet produce any different behavior from omitting it. Refer to the [SDK reference guide](docs.launchdarkly.com/docs/ruby-sdk-reference#section-track) for the latest status.

@param event_name [String] The name of the event @param user [Hash] The user to register; this can have all the same user properties

described in {#variation}

@param data [Hash] An optional hash containing any additional data associated with the event @param metric_value [Number] A numeric value used by the LaunchDarkly experimentation

feature in numeric custom metrics. Can be omitted if this event is used by only
non-numeric metrics. This field will also be returned as part of the custom event
for Data Export.

@return [void]

# File lib/ldclient-rb/ldclient.rb, line 276
def track(event_name, user, data = nil, metric_value = nil)
  if !user || user[:key].nil?
    @config.logger.warn("Track called with nil user or nil user key!")
    return
  end
  sanitize_user(user)
  @event_processor.add_event(@event_factory_default.new_custom_event(event_name, user, data, metric_value))
end
variation(key, user, default) click to toggle source

Determines the variation of a feature flag to present to a user.

At a minimum, the user hash should contain a `:key`, which should be the unique identifier for your user (or, for an anonymous user, a session identifier or cookie).

Other supported user attributes include IP address, country code, and an arbitrary hash of custom attributes. For more about the supported user properties and how they work in LaunchDarkly, see [Targeting users](docs.launchdarkly.com/docs/targeting-users).

The optional `:privateAttributeNames` user property allows you to specify a list of attribute names that should not be sent back to LaunchDarkly. [Private attributes](docs.launchdarkly.com/docs/private-user-attributes) can also be configured globally in {Config}.

@example Basic user hash

{key: "my-user-id"}

@example More complete user hash

{key: "my-user-id", ip: "127.0.0.1", country: "US", custom: {customer_rank: 1000}}

@example User with a private attribute

{key: "my-user-id", email: "email@example.com", privateAttributeNames: ["email"]}

@param key [String] the unique feature key for the feature flag, as shown

on the LaunchDarkly dashboard

@param user [Hash] a hash containing parameters for the end user requesting the flag @param default the default value of the flag; this is used if there is an error

condition making it impossible to find or evaluate the flag

@return the variation to show the user, or the default value if there's an an error

# File lib/ldclient-rb/ldclient.rb, line 199
def variation(key, user, default)
  evaluate_internal(key, user, default, @event_factory_default).value
end
variation_detail(key, user, default) click to toggle source

Determines the variation of a feature flag for a user, like {#variation}, but also provides additional information about how this value was calculated.

The return value of `variation_detail` is an {EvaluationDetail} object, which has three properties: the result value, the positional index of this value in the flag's list of variations, and an object describing the main reason why this value was selected. See {EvaluationDetail} for more on these properties.

Calling `variation_detail` instead of `variation` also causes the “reason” data to be included in analytics events, if you are capturing detailed event data for this flag.

For more information, see the reference guide on [Evaluation reasons](docs.launchdarkly.com/v2.0/docs/evaluation-reasons).

@param key [String] the unique feature key for the feature flag, as shown

on the LaunchDarkly dashboard

@param user [Hash] a hash containing parameters for the end user requesting the flag @param default the default value of the flag; this is used if there is an error

condition making it impossible to find or evaluate the flag

@return [EvaluationDetail] an object describing the result

# File lib/ldclient-rb/ldclient.rb, line 226
def variation_detail(key, user, default)
  evaluate_internal(key, user, default, @event_factory_with_reasons)
end

Private Instance Methods

create_default_data_source(sdk_key, config, diagnostic_accumulator) click to toggle source
# File lib/ldclient-rb/ldclient.rb, line 383
def create_default_data_source(sdk_key, config, diagnostic_accumulator)
  if config.offline?
    return NullUpdateProcessor.new
  end
  raise ArgumentError, "sdk_key must not be nil" if sdk_key.nil?  # see LDClient constructor comment on sdk_key
  if config.stream?
    StreamProcessor.new(sdk_key, config, diagnostic_accumulator)
  else
    config.logger.info { "Disabling streaming API" }
    config.logger.warn { "You should only disable the streaming API if instructed to do so by LaunchDarkly support" }
    requestor = Requestor.new(sdk_key, config)
    PollingProcessor.new(config, requestor)
  end
end
evaluate_internal(key, user, default, event_factory) click to toggle source

@return [EvaluationDetail]

# File lib/ldclient-rb/ldclient.rb, line 399
def evaluate_internal(key, user, default, event_factory)
  if @config.offline?
    return Evaluator.error_result(EvaluationReason::ERROR_CLIENT_NOT_READY, default)
  end

  unless user
    @config.logger.error { "[LDClient] Must specify user" }
    detail = Evaluator.error_result(EvaluationReason::ERROR_USER_NOT_SPECIFIED, default)
    return detail
  end

  if user[:key].nil?
    @config.logger.warn { "[LDClient] Variation called with nil user key; returning default value" }
    detail = Evaluator.error_result(EvaluationReason::ERROR_USER_NOT_SPECIFIED, default)
    return detail
  end

  if !initialized?
    if @store.initialized?
      @config.logger.warn { "[LDClient] Client has not finished initializing; using last known values from feature store" }
    else
      @config.logger.error { "[LDClient] Client has not finished initializing; feature store unavailable, returning default value" }
      detail = Evaluator.error_result(EvaluationReason::ERROR_CLIENT_NOT_READY, default)
      @event_processor.add_event(event_factory.new_unknown_flag_event(key, user, default, detail.reason))
      return  detail
    end
  end

  feature = @store.get(FEATURES, key)

  if feature.nil?
    @config.logger.info { "[LDClient] Unknown feature flag \"#{key}\". Returning default value" }
    detail = Evaluator.error_result(EvaluationReason::ERROR_FLAG_NOT_FOUND, default)
    @event_processor.add_event(event_factory.new_unknown_flag_event(key, user, default, detail.reason))
    return detail
  end

  begin
    res = @evaluator.evaluate(feature, user, event_factory)
    if !res.events.nil?
      res.events.each do |event|
        @event_processor.add_event(event)
      end
    end
    detail = res.detail
    if detail.default_value?
      detail = EvaluationDetail.new(default, nil, detail.reason)
    end
    @event_processor.add_event(event_factory.new_eval_event(feature, user, detail, default))
    return detail
  rescue => exn
    Util.log_exception(@config.logger, "Error evaluating feature flag \"#{key}\"", exn)
    detail = Evaluator.error_result(EvaluationReason::ERROR_EXCEPTION, default)
    @event_processor.add_event(event_factory.new_default_event(feature, user, default, detail.reason))
    return detail
  end
end
sanitize_user(user) click to toggle source
# File lib/ldclient-rb/ldclient.rb, line 457
def sanitize_user(user)
  if user[:key]
    user[:key] = user[:key].to_s
  end
end