feat: Use last modified headers (#108)

* Use last modified headers

* Update tests and WASM

* Update min ruby version

* Update Matrix to use ruby 3.1 as min.

* update signature

* Still save if last modified header is empty and no config is saved

* ci-testing

* Setup try/catch for parsing headers

* Make sure valid date format for header

.github/workflows/unit-tests.yaml

@@ -15,12 +15,12 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        ruby-version: [ '3.0', '3.0.4', '3.1.0', '3.2.0' ]
+        ruby-version: [ '3.1.0', '3.2.0', '3.3.0' ]
 
     steps:
       - uses: actions/checkout@v4
       - name: Set up Ruby
-        uses: ruby/setup-ruby@v1
+        uses: ruby/setup-ruby@v1.187.0
         with:
           ruby-version: ${{ matrix.ruby-version }}
           bundler-cache: true # runs 'bundle install' and caches installed gems automatically

Gemfile

@@ -1,7 +1,7 @@
 source 'https://rubygems.org'
 
 gemspec
-gem 'sorbet-runtime'
+gem 'sorbet-runtime', '0.5.11481'
 gem 'oj'
 gem 'wasmtime'
 gem 'concurrent-ruby'

devcycle-ruby-server-sdk.gemspec

@@ -21,12 +21,12 @@ Gem::Specification.new do |s|
   s.summary     = "DevCycle Bucketing API Ruby Gem"
   s.description = "DevCycle Ruby Server SDK, for interacting with feature flags created with the DevCycle platform."
   s.license     = "MIT"
-  s.required_ruby_version = ">= 2.4"
+  s.required_ruby_version = ">= 3.1"
 
   s.add_runtime_dependency 'typhoeus', '~> 1.0', '>= 1.0.1'
-  s.add_runtime_dependency 'wasmtime', '13.0.0'
+  s.add_runtime_dependency 'wasmtime', '20.0.2'
   s.add_runtime_dependency 'concurrent-ruby', '~> 1.2.0'
-  s.add_runtime_dependency 'sorbet-runtime', '~> 0.5'
+  s.add_runtime_dependency 'sorbet-runtime', '>= 0.5.11481'
   s.add_runtime_dependency 'oj', '~> 3.0'
   s.add_runtime_dependency 'google-protobuf', '~> 3.22'
 

lib/devcycle-ruby-server-sdk/api/client.rb

@@ -158,13 +158,13 @@ def variable_value(user, key, default, opts = {})
     end
 
     # Get variable by key for user data
-    # @param user [User]
+    # @param user [DevCycle::User]
     # @param key [String] Variable key
     # @param default Default value for variable if none is retrieved
     # @param [Hash] opts the optional parameters
     # @return [Variable]
     def variable(user, key, default, opts = {})
-      if !user.is_a?(DevCycle::User)
+      unless user.is_a?(DevCycle::User)
         fail ArgumentError, "user param must be an instance of DevCycle::User!"
       end
 

lib/devcycle-ruby-server-sdk/localbucketing/config_manager.rb

@@ -4,6 +4,7 @@
 require 'concurrent-ruby'
 require 'typhoeus'
 require 'json'
+require 'time'
 
 module DevCycle
   class ConfigManager
@@ -19,13 +20,14 @@ def initialize(sdkKey, local_bucketing, wait_for_init)
       @local_bucketing = local_bucketing
       @sdkKey = sdkKey
       @config_e_tag = ""
+      @config_last_modified = ""
       @logger = local_bucketing.options.logger
       @polling_enabled = true
       @max_config_retries = 2
 
       @config_poller = Concurrent::TimerTask.new({
-          execution_interval: @local_bucketing.options.config_polling_interval_ms.fdiv(1000)
-        }) do |task|
+                                                   execution_interval: @local_bucketing.options.config_polling_interval_ms.fdiv(1000)
+                                                 }) do |task|
         fetch_config
       end
 
@@ -53,22 +55,43 @@ def fetch_config
           Accept: "application/json",
         })
 
+      begin
+        Date.parse(@config_last_modified)
+        if @config_last_modified != ""
+          req.options[:headers]["If-Modified-Since"] = Time.httpdate(@config_last_modified)
+        end
+      rescue
+      end
+
+
       if @config_e_tag != ""
         req.options[:headers]['If-None-Match'] = @config_e_tag
       end
 
       @max_config_retries.times do
-        @logger.debug("Requesting new config from #{get_config_url}, current etag: #{@config_e_tag}")
+        @logger.debug("Requesting new config from #{get_config_url}, current etag: #{@config_e_tag}, last modified: #{@config_last_modified}")
         resp = req.run
         @logger.debug("Config request complete, status: #{resp.code}")
         case resp.code
         when 304
-          @logger.debug("Config not modified, using cache, etag: #{@config_e_tag}")
+          @logger.debug("Config not modified, using cache, etag: #{@config_e_tag}, last modified: #{@config_last_modified}")
           break
         when 200
-          @logger.debug("New config received, etag: #{resp.headers['Etag']}")
-          set_config(resp.body, resp.headers['Etag'])
-          @logger.debug("New config stored, etag: #{@config_e_tag}")
+          @logger.debug("New config received, etag: #{resp.headers['Etag']} LM:#{resp.headers['Last-Modified']}")
+          lm_header = resp.headers['Last-Modified']
+          begin
+            lm_timestamp = Time.rfc2822(lm_header)
+            current_lm = Time.rfc2822(@config_last_modified)
+            if lm_timestamp == "" && @config_last_modified == "" || (current_lm.utc < lm_timestamp.utc)
+              set_config(resp.body, resp.headers['Etag'], lm_header)
+              @logger.debug("New config stored, etag: #{@config_e_tag}, last modified: #{lm_header}")
+            else
+              @logger.warn("Config response was an older config than currently stored config.")
+            end
+          rescue
+            @logger.warn("Failed to parse last modified header, setting config.")
+            set_config(resp.body, resp.headers['Etag'], lm_header)
+          end
           break
         when 403
           stop_polling
@@ -91,13 +114,14 @@ def fetch_config
       nil
     end
 
-    def set_config(config, etag)
+    def set_config(config, etag, lastmodified)
       if !JSON.parse(config).is_a?(Hash)
         raise("Invalid JSON body parsed from Config Response")
       end
 
       @local_bucketing.store_config(config)
       @config_e_tag = etag
+      @config_last_modified = lastmodified
       @local_bucketing.has_config = true
     end
 

lib/devcycle-ruby-server-sdk/localbucketing/event_queue.rb

@@ -1,6 +1,8 @@
 require 'typhoeus'
 require 'sorbet-runtime'
 require 'concurrent-ruby'
+require 'securerandom'
+
 
 module DevCycle
   class EventQueue
@@ -9,6 +11,7 @@ class EventQueue
     sig { params(sdkKey: String, options: EventQueueOptions, local_bucketing: LocalBucketing).void }
     def initialize(sdkKey, options, local_bucketing)
       @sdkKey = sdkKey
+      @client_uuid = SecureRandom.uuid
       @events_api_uri = options.events_api_uri
       @logger = options.logger
       @event_flush_interval_ms = options.event_flush_interval_ms
@@ -22,7 +25,7 @@ def initialize(sdkKey, options, local_bucketing)
       @flush_timer_task.execute
       @flush_mutex = Mutex.new
       @local_bucketing = local_bucketing
-      @local_bucketing.init_event_queue(options)
+      @local_bucketing.init_event_queue(@client_uuid, options)
     end
 
     def close

lib/devcycle-ruby-server-sdk/localbucketing/local_bucketing.rb

@@ -32,6 +32,7 @@ class LocalBucketing
                                          .inherit_stderr
                                          .set_argv(ARGV)
                                          .set_env(ENV)
+                                         .build
     @@store = Wasmtime::Store.new(@@engine, wasi_ctx: @@wasi_ctx)
     @@linker = Wasmtime::Linker.new(@@engine, wasi: true)
 
@@ -245,13 +246,14 @@ def store_config(config)
       end
     end
 
-    sig { params(options: EventQueueOptions).returns(NilClass) }
-    def init_event_queue(options)
+    sig { params(client_uuid: String, options: EventQueueOptions).returns(NilClass) }
+    def init_event_queue(client_uuid, options)
       @wasm_mutex.synchronize do
         options_json = Oj.dump(options)
+        client_uuid_addr = malloc_asc_string(client_uuid)
         options_addr = malloc_asc_string(options_json)
         @@stack_tracer = @@stack_tracer_raise
-        @@instance.invoke("initEventQueue", @sdkKeyAddr, options_addr)
+        @@instance.invoke("initEventQueue", @sdkKeyAddr, client_uuid_addr, options_addr)
       end
     end
 

lib/devcycle-ruby-server-sdk/localbucketing/update_wasm.sh

@@ -0,0 +1,5 @@
+#!/bin/bash
+BUCKETING_LIB_VERSION="1.24.2"
+WAT_DOWNLOAD=0
+rm bucketing-lib.release.wasm
+wget "https://unpkg.com/@devcycle/bucketing-assembly-script@$BUCKETING_LIB_VERSION/build/bucketing-lib.release.wasm"

spec/api/devcycle_api_spec.rb

@@ -93,7 +93,7 @@
     it 'should work' do
       result = @api_instance.all_variables(@user)
 
-      expect(result.length).to eq 1
+      expect(result.length).to eq 5
     end
   end