Support timed edge polling and synchronous loading

ConsoleAppExample/Program.cs

@@ -17,13 +17,23 @@ static void Main(string[] args)
  MainApp().Wait();
  }
 
- async static Task MainApp()
+ static async Task MainApp()
  {
  Console.WriteLine("Hello World!");
 
- var config = new EdgeFeatureHubConfig("http://localhost:8064",
- "default/b63faed0-1a66-48a6-8679-e362d1d33d7d/QgoWPhyDisWwHY5heuVzXbB41xqXwB*fL7QfLvLTb6OA00Cx8t1");
- config.Init();
+ FeatureLogging.TraceLogger += (sender, s) => Console.WriteLine(s); 
+ FeatureLogging.ErrorLogger += (sender, s) => Console.WriteLine(s); 
+ FeatureLogging.DebugLogger += (sender, s) => Console.WriteLine(s); 
+ FeatureLogging.InfoLogger += (sender, s) => Console.WriteLine(s);
+
+ // var serverEvalKey = "d8cdd2f2-6003-4136-ad99-ee05730dfd97/YPSbDzRdrepVoTHUSm0IU8Da0hjJmZYxBG03jCEK";
+ // var clientEvalKey = "d8cdd2f2-6003-4136-ad99-ee05730dfd97/gC3QHHb6mFQfNSerIItsCUUGZJL8aK*YyIiRr6cn5i5vN7eGtRA"; 
+ // var config = new EdgeFeatureHubConfig("http://localhost:8903",
+ // serverEvalKey).UsePolling(10); // every 10 seconds
+ var config = new EdgeFeatureHubConfig(); // use environment variables
+ Console.WriteLine("Waiting for state to arrive");
+ await config.Init();
+ Console.WriteLine($"State should have arrived {config.Repository.Readyness}");
 
  Console.WriteLine($"Server evaluated {config.ServerEvaluation}");
 

FeatureHubSDK/ClientContext.cs

@@ -226,7 +226,16 @@ public ServerEvalFeatureContext(IFeatureRepositoryContext repository, IFeatureHu
  _weCreatedSources = false;
  }
 
- public override IFeature this[string name] => _repository.GetFeature(name);
+ public override IFeature this[string name]
+ {
+ get
+ {
+ // we tell edge to poll if it hasn't already, it also lets the timeout go do an update in the background
+ _currentEdgeService?.Poll();
+
+ return _repository.GetFeature(name);
+ }
+ }
 
  public override async Task<IClientContext> Build()
  {
@@ -278,7 +287,16 @@ public class ClientEvalFeatureContext : BaseClientContext
  _weCreatedSources = false;
  }
 
- public override IFeature this[string name] => _repository.GetFeature(name).WithContext(this);
+ public override IFeature this[string name]
+ {
+ get
+ {
+ // we tell edge to poll if it hasn't already, it also lets the timeout go do an update in the background
+ _edgeService?.Poll();
+
+ return _repository.GetFeature(name).WithContext(this);
+ }
+ }
 
 #pragma warning disable 1998
  public override async Task<IClientContext> Build()

FeatureHubSDK/EdgeFeatureHubConfig.cs

@@ -2,6 +2,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Threading.Tasks;
 
 namespace FeatureHubSDK
 {
@@ -18,14 +19,30 @@ public class FeatureHubConfig
  public interface IFeatureHubConfig
  {
 
+ /// <summary>
+ /// This is the fully constructed EventSource url
+ /// </summary>
  string Url { get; }
+ /// <summary>
+ /// this is the URL of the GET edit service
+ /// </summary>
+ string EdgeUrl { get; }
+ List<string> SdkKeys { get; }
+
  bool ServerEvaluation { get; }
 
+ /// <summary>
+ /// Tells the client to use Polling. Can also be assumed if FEATUREHUB_POLL_TIMEOUT env var is set
+ /// </summary>
+ /// <param name="timeout"></param>
+ /// <returns></returns>
+ IFeatureHubConfig UsePolling(int timeout = 360);
+
  /*
  * Initialise the configuration. This will kick off the event source to connect and attempt to start
  * pushing data into the FeatureHub repository for use in contexts.
  */
- void Init();
+ Task Init();
 
  IFeatureRepositoryContext Repository { get; set; }
  IEdgeService EdgeService { get; set; }
@@ -55,15 +72,24 @@ public class EdgeFeatureHubConfig : IFeatureHubConfig
  {
  private readonly string _url;
  private readonly bool _serverEvaluation;
+ private readonly string _edgeUrl;
+ private readonly List<string> _sdkKeys = new List<string>();
 
  public EdgeFeatureHubConfig(string edgeUrl, string sdkKey)
  {
- _serverEvaluation = sdkKey != null && !sdkKey.Contains("*"); // two part keys are server evaluated
+ if (edgeUrl == null || sdkKey == null)
+ {
+ throw new FeatureHubKeyInvalidException($"The edge url or sdk key are null.");
+ }
+
+ _serverEvaluation = !sdkKey.Contains("*"); // two part keys are server evaluated
 
  if (!sdkKey.Contains("/"))
  {
  throw new FeatureHubKeyInvalidException($"The SDK key `{sdkKey}` is invalid");
  }
+
+ _sdkKeys.Add(sdkKey);
 
  if (edgeUrl.EndsWith("/"))
  {
@@ -75,12 +101,26 @@ public EdgeFeatureHubConfig(string edgeUrl, string sdkKey)
  edgeUrl = edgeUrl.Substring(0, edgeUrl.Length - "/features".Length);
  }
 
+ _edgeUrl = edgeUrl; // the API client automatically adds the /features, etc on
+
  _url = edgeUrl + "/features/" + sdkKey;
  }
 
- public void Init()
+ /// <summary>
+ /// Use this constructor if you set the environment variables.
+ /// </summary>
+ public EdgeFeatureHubConfig() : this(Environment.GetEnvironmentVariable("FEATUREHUB_EDGE_URL"),
+ Environment.GetEnvironmentVariable("FEATUREHUB_API_KEY"))
+ {
+
+ } 
+
+ public string EdgeUrl => _edgeUrl;
+ public List<string> SdkKeys => _sdkKeys;
+
+ public async Task Init()
  {
- EdgeService.Poll();
+ await EdgeService.Poll();
  }
 
  public bool ServerEvaluation => _serverEvaluation;
@@ -93,7 +133,16 @@ public IEdgeService EdgeService
  {
  if (_edgeService == null)
  {
- _edgeService = FeatureHubConfig.defaultEdgeProvider(this.Repository, this);
+ var pollTimeoutDefault = Environment.GetEnvironmentVariable("FEATUREHUB_POLL_TIMEOUT");
+ if (pollTimeoutDefault != null)
+ {
+ _edgeService = new EdgeClientPoll(Repository, this,
+ int.Parse(pollTimeoutDefault));
+ }
+ else
+ {
+ _edgeService = FeatureHubConfig.defaultEdgeProvider(this.Repository, this); 
+ }
  }
 
  return _edgeService;
@@ -104,6 +153,12 @@ public IEdgeService EdgeService
  }
  }
 
+ public IFeatureHubConfig UsePolling(int timeout = 360)
+ {
+ _edgeService = new EdgeClientPoll(Repository, this, timeout);
+ return this;
+ }
+
  private IFeatureRepositoryContext _repository;
 
  public IFeatureRepositoryContext Repository
@@ -132,7 +187,14 @@ public IClientContext NewContext(IFeatureRepositoryContext repository = null, Ed
 
  if (edgeServiceSource == null)
  {
- edgeServiceSource = (repo, config) => FeatureHubConfig.defaultEdgeProvider(repo, config);
+ if (_edgeService != null)
+ {
+ edgeServiceSource = (repo, config) => _edgeService;
+ }
+ else 
+ {
+ edgeServiceSource = (repo, config) => FeatureHubConfig.defaultEdgeProvider(repo, config);
+ }
  }
 
  if (_serverEvaluation)

FeatureHubSDK/EventServiceListener.cs

@@ -14,34 +14,36 @@ public interface IEdgeService
 
  bool IsRequiresReplacementOnHeaderChange { get; }
  void Close();
- void Poll();
+ Task Poll();
  }
 
  public static class FeatureLogging
  {
  // Attach event handler to receive Trace level logs
- public static EventHandler<String> TraceLogger;
+ public static EventHandler<string> TraceLogger = (sender, args) => { };
  // Attach event handler to receive Debug level logs
- public static EventHandler<String> DebugLogger;
+ public static EventHandler<string> DebugLogger = (sender, args) => { };
  // Attach event handler to receive Info level logs
- public static EventHandler<String> InfoLogger;
+ public static EventHandler<string> InfoLogger = (sender, args) => { };
+ // Attach event handler to receive Warn level logs
+ public static EventHandler<string> WarnLogger = (sender, args) => { };
  // Attach event handler to receive Error level logs
- public static EventHandler<String> ErrorLogger;
+ public static EventHandler<string> ErrorLogger = (sender, args) => { };
  }
 
  class ConfigData
  {
  [JsonProperty("edge.stale")]
- public Boolean stale { get; set; }
+ public Boolean Stale { get; set; }
  }
 
  public class EventServiceListener : IEdgeService
  {
  private EventSource _eventSource;
  private readonly IFeatureHubConfig _featureHost;
  private readonly IFeatureRepositoryContext _repository;
- private string _xFeatureHubHeader = null;
- private bool _closed = false;
+ private string _xFeatureHubHeader;
+ private bool _closed;
 
  public EventServiceListener(IFeatureRepositoryContext repository, IFeatureHubConfig config)
  {
@@ -66,21 +68,8 @@ public async Task ContextChange(string newHeader)
  if (_eventSource == null || _eventSource.ReadyState == ReadyState.Open || _eventSource.ReadyState == ReadyState.Connecting)
  {
  _eventSource?.Close();
-
- var promise = new TaskCompletionSource<Readyness>();
-
- EventHandler<Readyness> handler = (sender, r) =>
- {
- promise.TrySetResult(r);
- };
-
- _repository.ReadynessHandler += handler;
-
- Init();
-
- await promise.Task;
-
- _repository.ReadynessHandler -= handler;
+ _eventSource = null;
+ await Poll();
  }
  }
  }
@@ -89,6 +78,9 @@ public async Task ContextChange(string newHeader)
  Init();
  }
  }
+
+
+
 
  public bool ClientEvaluation => !_featureHost.ServerEvaluation;
 
@@ -117,8 +109,8 @@ public void Init()
  if (_closed) return;
 
  var config = new Configuration(uri: new UriBuilder(_featureHost.Url).Uri,
- backoffResetThreshold: TimeSpan.FromSeconds(int.Parse(DefaultEnvConfig("FEATUREHUB_BACKOFF_RETRY_LIMIT", "100"))),
- delayRetryDuration: TimeSpan.FromSeconds(int.Parse(DefaultEnvConfig("FEATUREHUB_DELAY_RETRY_MS", "10000"))),
+ backoffResetThreshold: TimeSpan.FromMinutes(int.Parse(DefaultEnvConfig("FEATUREHUB_BACKOFF_RESET_THRESHOLD", "1"))),
+ delayRetryDuration: TimeSpan.FromMilliseconds(int.Parse(DefaultEnvConfig("FEATUREHUB_DELAY_RETRY_MS", "10000"))),
  requestHeaders: _featureHost.ServerEvaluation ? BuildContextHeader() : null);
 
  if (FeatureLogging.InfoLogger != null)
@@ -129,26 +121,15 @@ public void Init()
  _eventSource = new EventSource(config);
  _eventSource.Error += (sender, ex) =>
  {
- if (ex.Exception is EventSourceServiceUnsuccessfulResponseException result)
- {
- if (result.StatusCode != 503)
- {
- _repository.Notify(SSEResultState.Failure, null);
- FeatureLogging.ErrorLogger(this, "Server issued a failure, stopping.");
- _closed = true;
- _eventSource.Close();
- }
- }
+ if (!(ex.Exception is EventSourceServiceUnsuccessfulResponseException result)) return;
+ if (result.StatusCode == 503) return;
+ 
+ _repository.Notify(SSEResultState.Failure, null);
+ FeatureLogging.ErrorLogger(this, "Server issued a failure, stopping.");
+ _closed = true;
+ _eventSource.Close();
  };
-
- // if (FeatureLogging.DebugLogger != null)
- // {
- // _eventSource.Closed += (sender, args) =>
- // {
- // FeatureLogging.DebugLogger(this, "source closed");
- // };
- // }
-
+
  _eventSource.MessageReceived += (sender, args) =>
  {
  SSEResultState? state;
@@ -185,7 +166,7 @@ public void Init()
  if (args.Message.Data != null)
  {
  var configData = JsonConvert.DeserializeObject<ConfigData>(args.Message.Data);
- if (configData.stale)
+ if (configData.Stale)
  {
  if (FeatureLogging.ErrorLogger != null)
  {
@@ -204,9 +185,7 @@ public void Init()
  }
 
  if (FeatureLogging.TraceLogger != null)
- {
- FeatureLogging.TraceLogger(this , $"featurehub: The state was {state} with value {args.Message.Data}");
- }
+ FeatureLogging.TraceLogger(this, $"featurehub: The state was {state} with value {args.Message.Data}");
 
  if (state == null) return;
 
@@ -234,11 +213,24 @@ public void Close()
  _eventSource.Close();
  }
 
- public void Poll()
+ public async Task Poll()
  {
  if (_eventSource == null)
  {
+ var promise = new TaskCompletionSource<Readyness>();
+
+ EventHandler<Readyness> handler = (sender, r) =>
+ {
+ promise.TrySetResult(r);
+ };
+
+ _repository.ReadynessHandler += handler;
+
  Init();
+
+ await promise.Task;
+
+ _repository.ReadynessHandler -= handler;
  }
  }
  }