feat: add assignment and exposure events tracking options

lib/amplitude-experiment.rb

@@ -6,6 +6,7 @@
 require 'experiment/variant'
 require 'experiment/factory'
 require 'experiment/remote/client'
+require 'experiment/remote/fetch_options'
 require 'experiment/local/client'
 require 'experiment/local/config'
 require 'experiment/local/assignment/assignment'

lib/experiment/remote/client.rb

@@ -30,7 +30,7 @@ def initialize(api_key, config = nil)
     # @param [User] user
     # @return [Hash] Variants Hash
     def fetch(user)
-      AmplitudeExperiment.filter_default_variants(fetch_internal(user))
+      AmplitudeExperiment.filter_default_variants(fetch_internal(user, nil))
     rescue StandardError => e
       @logger.error("[Experiment] Failed to fetch variants: #{e.message}")
       {}
@@ -41,9 +41,10 @@ def fetch(user)
     # This method will automatically retry if configured (default). This function differs from fetch as it will
     # return a default variant object if the flag was evaluated but the user was not assigned (i.e. off).
     # @param [User] user
+    # @param [FetchOptions] fetch_options
     # @return [Hash] Variants Hash
-    def fetch_v2(user)
-      fetch_internal(user)
+    def fetch_v2(user, fetch_options = nil)
+      fetch_internal(user, fetch_options)
     rescue StandardError => e
       @logger.error("[Experiment] Failed to fetch variants: #{e.message}")
       {}
@@ -56,7 +57,7 @@ def fetch_v2(user)
     # @yield [User, Hash] callback block takes user object and variants hash
     def fetch_async(user, &callback)
       Thread.new do
-        variants = fetch_internal(user)
+        variants = AmplitudeExperiment.filter_default_variants(fetch_internal(user, nil))
         yield(user, variants) unless callback.nil?
         variants
       rescue StandardError => e
@@ -72,10 +73,10 @@ def fetch_async(user, &callback)
     # This method will automatically retry if configured (default).
     # @param [User] user
     # @yield [User, Hash] callback block takes user object and variants hash
-    def fetch_async_v2(user, &callback)
+    def fetch_async_v2(user, fetch_options = nil, &callback)
       Thread.new do
-        variants = fetch_internal(user)
-        yield(user, filter_default_variants(variants)) unless callback.nil?
+        variants = fetch_internal(user, fetch_options)
+        yield(user, variants) unless callback.nil?
         variants
       rescue StandardError => e
         @logger.error("[Experiment] Failed to fetch variants: #{e.message}")
@@ -87,14 +88,15 @@ def fetch_async_v2(user, &callback)
     private
 
     # @param [User] user
-    def fetch_internal(user)
+    # @param [FetchOptions] fetch_options
+    def fetch_internal(user, fetch_options)
       @logger.debug("[Experiment] Fetching variants for user: #{user.as_json}")
-      do_fetch(user, @config.connect_timeout_millis, @config.fetch_timeout_millis)
+      do_fetch(user, fetch_options, @config.connect_timeout_millis, @config.fetch_timeout_millis)
     rescue StandardError => e
       @logger.error("[Experiment] Fetch failed: #{e.message}")
       if should_retry_fetch?(e)
         begin
-          retry_fetch(user)
+          retry_fetch(user, fetch_options)
         rescue StandardError => err
           @logger.error("[Experiment] Retry Fetch failed: #{err.message}")
         end
@@ -103,7 +105,8 @@ def fetch_internal(user)
     end
 
     # @param [User] user
-    def retry_fetch(user)
+    # @param [FetchOptions] fetch_options
+    def retry_fetch(user, fetch_options)
       return {} if @config.fetch_retries.zero?
 
       @logger.debug('[Experiment] Retrying fetch')
@@ -112,7 +115,7 @@ def retry_fetch(user)
       @config.fetch_retries.times do
         sleep(delay_millis.to_f / 1000.0)
         begin
-          return do_fetch(user, @config.connect_timeout_millis, @config.fetch_retry_timeout_millis)
+          return do_fetch(user, fetch_options, @config.connect_timeout_millis, @config.fetch_retry_timeout_millis)
         rescue StandardError => e
           @logger.error("[Experiment] Retry failed: #{e.message}")
           err = e
@@ -123,15 +126,24 @@ def retry_fetch(user)
     end
 
     # @param [User] user
+    # @param [FetchOptions] fetch_options
     # @param [Integer] connect_timeout_millis
     # @param [Integer] fetch_timeout_millis
-    def do_fetch(user, connect_timeout_millis, fetch_timeout_millis)
+    def do_fetch(user, fetch_options, connect_timeout_millis, fetch_timeout_millis)
       start_time = Time.now
       user_context = add_context(user)
       headers = {
         'Authorization' => "Api-Key #{@api_key}",
         'Content-Type' => 'application/json;charset=utf-8'
       }
+      unless fetch_options.nil?
+        unless fetch_options.tracks_assignment.nil?
+          headers['X-Amp-Exp-Track'] = fetch_options.tracks_assignment ? 'track' : 'no-track'
+        end
+        unless fetch_options.tracks_exposure.nil?
+          headers['X-Amp-Exp-Exposure-Track'] = fetch_options.tracks_exposure ? 'track' : 'no-track'
+        end
+      end
       connect_timeout = connect_timeout_millis.to_f / 1000 if (connect_timeout_millis.to_f / 1000) > 0
       read_timeout = fetch_timeout_millis.to_f / 1000 if (fetch_timeout_millis.to_f / 1000) > 0
       http = PersistentHttpClient.get(@uri, { open_timeout: connect_timeout, read_timeout: read_timeout }, @api_key)

lib/experiment/remote/fetch_options.rb

@@ -0,0 +1,17 @@
+module AmplitudeExperiment
+  # Fetch options
+  class FetchOptions
+    # Whether to track assignment events.
+    # @return [Boolean, nil] the value of tracks_assignment
+    attr_accessor :tracks_assignment
+
+    # Whether to track exposure events.
+    # @return [Boolean, nil] the value of tracks_exposure
+    attr_accessor :tracks_exposure
+
+    def initialize(tracks_assignment: nil, tracks_exposure: nil)
+      @tracks_assignment = tracks_assignment
+      @tracks_exposure = tracks_exposure
+    end
+  end
+end

spec/experiment/remote/client_spec.rb

@@ -93,10 +93,13 @@ def self.test_fetch_async_shared(response, test_user, variant_name, debug, expec
           stub_request(:post, server_url)
             .to_return(status: 200, body: response)
           client = RemoteEvaluationClient.new(api_key, RemoteEvaluationConfig.new(debug: debug))
+          callback_called = false
           variants = client.fetch_async(test_user) do |user, block_variants|
             expect(user).to equal(test_user)
             expect(block_variants.fetch(variant_name)).to eq(expected_variant)
+            callback_called = true
           end
+          sleep 1 until callback_called
           expect(variants.key?(variant_name)).to be_truthy
           expect(variants.fetch(variant_name)).to eq(expected_variant)
         end
@@ -175,6 +178,54 @@ def self.test_fetch_async_shared(response, test_user, variant_name, debug, expec
         expect { variants = client.fetch_v2(test_user) }.to output(/Retrying fetch/).to_stdout_from_any_process
         expect(variants).to eq({})
       end
+
+      it 'fetch v2 with fetch options' do
+        stub_request(:post, server_url)
+          .to_return(status: 200, body: response_with_key)
+        test_user = User.new(user_id: 'test_user')
+        client = RemoteEvaluationClient.new(api_key)
+
+        WebMock.reset!
+        fetch_options = FetchOptions.new(tracks_assignment: true, tracks_exposure: true)
+        variants = client.fetch_v2(test_user, fetch_options)
+        expect(variants.key?(variant_name)).to be_truthy
+        expect(variants.fetch(variant_name)).to eq(Variant.new(key: 'on', payload: 'payload', value: 'on'))
+
+        expect(a_request(:post, server_url).with(headers: { 'X-Amp-Exp-Track' => 'track', 'X-Amp-Exp-Exposure-Track' => 'track' })).to have_been_made.once
+
+        WebMock.reset!
+        fetch_options = FetchOptions.new(tracks_assignment: false, tracks_exposure: false)
+        client.fetch_v2(test_user, fetch_options)
+        expect(a_request(:post, server_url).with(headers: { 'X-Amp-Exp-Track' => 'no-track', 'X-Amp-Exp-Exposure-Track' => 'no-track' })).to have_been_made.once
+
+        WebMock.reset!
+        last_request = nil
+        WebMock.after_request { |request_signature, _response| last_request = request_signature }
+        fetch_options = FetchOptions.new
+        client.fetch_v2(test_user, fetch_options)
+        expect(a_request(:post, server_url)).to have_been_made.once
+        expect(last_request.headers.key?('X-Amp-Exp-Track')).to be_falsy
+        expect(last_request.headers.key?('X-Amp-Exp-Exposure-Track')).to be_falsy
+      end
+    end
+
+    describe '#fetch_async_v2' do
+      it 'fetch async v2 with fetch options' do
+        stub_request(:post, server_url)
+          .to_return(status: 200, body: response_with_key)
+        test_user = User.new(user_id: 'test_user')
+        fetch_options = FetchOptions.new(tracks_assignment: true, tracks_exposure: true)
+        client = RemoteEvaluationClient.new(api_key, RemoteEvaluationConfig.new(debug: true))
+        callback_called = false
+        client.fetch_async_v2(test_user, fetch_options) do |user, block_variants|
+          expect(user).to equal(test_user)
+          expect(block_variants.key?(variant_name)).to be_truthy
+          expect(block_variants.fetch(variant_name)).to eq(Variant.new(key: 'on', payload: 'payload'))
+          expect(a_request(:post, server_url).with(headers: { 'X-Amp-Exp-Track' => 'track', 'X-Amp-Exp-Exposure-Track' => 'track' })).to have_been_made.once
+          callback_called = true
+        end
+        sleep 1 until callback_called
+      end
     end
   end
 end