enhancement: Generate OptimizelyConfig object on API Call instead of SDK initialization (#296)

## Summary
`OptimizelyConfig` object is generated when SDK is being initialized. This operation is heavy and blocks the SDK from initializing quickly. This object is only used when users explicitly access it using `get_optimizely_config` API call. This PR moves the creation of this object from SDK initialization to the actual API call.

## Test plan
- Manually tested thoroughly
- All unit tests pass
- All FSC tests pass

## Issues
fixes #295

Author: zashraf1985

lib/optimizely/config_manager/http_project_config_manager.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 #
-#    Copyright 2019-2020, Optimizely and contributors
+#    Copyright 2019-2020, 2022, Optimizely and contributors
 #
 #    Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -33,7 +33,7 @@ module Optimizely
   class HTTPProjectConfigManager < ProjectConfigManager
     # Config manager that polls for the datafile and updated ProjectConfig based on an update interval.
 
-    attr_reader :stopped, :optimizely_config
+    attr_reader :stopped
 
     # Initialize config manager. One of sdk_key or url has to be set to be able to use.
     #
@@ -80,8 +80,8 @@ def initialize(
       @last_modified = nil
       @skip_json_validation = skip_json_validation
       @notification_center = notification_center.is_a?(Optimizely::NotificationCenter) ? notification_center : NotificationCenter.new(@logger, @error_handler)
+      @optimizely_config = nil
       @config = datafile.nil? ? nil : DatafileProjectConfig.create(datafile, @logger, @error_handler, @skip_json_validation)
-      @optimizely_config = @config.nil? ? nil : OptimizelyConfig.new(@config).config
       @mutex = Mutex.new
       @resource = ConditionVariable.new
       @async_scheduler = AsyncScheduler.new(method(:fetch_datafile_config), @polling_interval, auto_update, @logger)
@@ -140,6 +140,12 @@ def config
       @config
     end
 
+    def optimizely_config
+      @optimizely_config = OptimizelyConfig.new(@config).config if @optimizely_config.nil?
+
+      @optimizely_config
+    end
+
     private
 
     def fetch_datafile_config
@@ -209,7 +215,9 @@ def set_config(config)
       end
 
       @config = config
-      @optimizely_config = OptimizelyConfig.new(config).config
+
+      # clearing old optimizely config so that a fresh one is generated on the next api call.
+      @optimizely_config = nil
 
       @notification_center.send_notifications(NotificationCenter::NOTIFICATION_TYPES[:OPTIMIZELY_CONFIG_UPDATE])
 

lib/optimizely/config_manager/static_project_config_manager.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 #
-#    Copyright 2019-2020, Optimizely and contributors
+#    Copyright 2019-2020, 2022, Optimizely and contributors
 #
 #    Licensed under the Apache License, Version 2.0 (the "License");
 #    you may not use this file except in compliance with the License.
@@ -23,7 +23,7 @@
 module Optimizely
   class StaticProjectConfigManager < ProjectConfigManager
     # Implementation of ProjectConfigManager interface.
-    attr_reader :config, :optimizely_config
+    attr_reader :config
 
     def initialize(datafile, logger, error_handler, skip_json_validation)
       # Looks up and sets datafile and config based on response body.
@@ -40,8 +40,13 @@ def initialize(datafile, logger, error_handler, skip_json_validation)
         error_handler,
         skip_json_validation
       )
+      @optimizely_config = nil
+    end
+
+    def optimizely_config
+      @optimizely_config = OptimizelyConfig.new(@config).config if @optimizely_config.nil?
 
-      @optimizely_config = @config.nil? ? nil : OptimizelyConfig.new(@config).config
+      @optimizely_config
     end
   end
 end