Java client connection state part 1 (#24166)

src/SignalR/clients/java/signalr/src/main/java/com/microsoft/signalr/HubConnection.java

@@ -66,6 +66,7 @@ public class HubConnection implements AutoCloseable {
     private final int negotiateVersion = 1;
     private final Logger logger = LoggerFactory.getLogger(HubConnection.class);
     private ScheduledExecutorService handshakeTimeout = null;
+    private Completable start;
 
     /**
      * Sets the server timeout interval for the connection.
@@ -341,10 +342,18 @@ public class HubConnection implements AutoCloseable {
      * @return A Completable that completes when the connection has been established.
      */
     public Completable start() {
+        CompletableSubject localStart = CompletableSubject.create();
+
+        hubConnectionStateLock.lock();
+        try {
             if (hubConnectionState != HubConnectionState.DISCONNECTED) {
-            return Completable.complete();
+                logger.debug("The connection is in the '{}' state. Waiting for in-progress start to complete or completing this start immediately.", hubConnectionState);
+                return start;
             }
 
+            hubConnectionState = HubConnectionState.CONNECTING;
+            start = localStart;
+
             handshakeResponseSubject = CompletableSubject.create();
             handshakeReceived = false;
             CompletableSubject tokenCompletable = CompletableSubject.create();
@@ -370,8 +379,6 @@ public class HubConnection implements AutoCloseable {
                 negotiate = tokenCompletable.andThen(Single.defer(() -> Single.just(new NegotiateResponse(baseUrl))));
             }
 
-        CompletableSubject start = CompletableSubject.create();
-
             negotiate.flatMapCompletable(negotiateResponse -> {
                 logger.debug("Starting HubConnection.");
                 if (transport == null) {
@@ -415,9 +422,19 @@ public class HubConnection implements AutoCloseable {
                     }));
                 }));
             // subscribe makes this a "hot" completable so this runs immediately
-        }).subscribeWith(start);
+            }).subscribe(() -> {
+                localStart.onComplete();
+            }, error -> {
+                hubConnectionStateLock.lock();
+                hubConnectionState = HubConnectionState.DISCONNECTED;
+                hubConnectionStateLock.unlock();
+                localStart.onError(error);
+            });
+        } finally {
+            hubConnectionStateLock.unlock();
+        }
 
-        return start;
+        return localStart;
     }
 
     private void activatePingTimer() {
@@ -445,8 +462,8 @@ public class HubConnection implements AutoCloseable {
     }
 
     private Single<NegotiateResponse> startNegotiate(String url, int negotiateAttempts) {
-        if (hubConnectionState != HubConnectionState.DISCONNECTED) {
+        if (hubConnectionState != HubConnectionState.CONNECTING) {
-            return Single.just(null);
+            throw new RuntimeException("HubConnection trying to negotiate when not in the CONNECTING state.");
         }
 
         return handleNegotiate(url).flatMap(response -> {

src/SignalR/clients/java/signalr/src/main/java/com/microsoft/signalr/HubConnectionState.java

@@ -9,4 +9,5 @@ package com.microsoft.signalr;
 public enum HubConnectionState {
     CONNECTED,
     DISCONNECTED,
+    CONNECTING,
 }

src/SignalR/clients/java/signalr/src/test/java/com/microsoft/signalr/HubConnectionTest.java

@@ -24,6 +24,7 @@ import io.reactivex.Completable;
 import io.reactivex.Observable;
 import io.reactivex.Single;
 import io.reactivex.disposables.Disposable;
+import io.reactivex.schedulers.Schedulers;
 import io.reactivex.subjects.CompletableSubject;
 import io.reactivex.subjects.PublishSubject;
 import io.reactivex.subjects.ReplaySubject;
@@ -2577,9 +2578,10 @@ class HubConnectionTest {
             value.getAndUpdate((val) -> val + 1);
         });
 
+        SingleSubject<ByteBuffer> handshakeMessageTask = mockTransport.getNextSentMessage();
         // On start we're going to receive the handshake response and also an invocation in the same payload.
         hubConnection.start();
-        mockTransport.getStartTask().timeout(1, TimeUnit.SECONDS).blockingAwait();
+        ByteBuffer sentMessage = handshakeMessageTask.timeout(1, TimeUnit.SECONDS).blockingGet();
         String expectedSentMessage  = "{\"protocol\":\"json\",\"version\":1}" + RECORD_SEPARATOR;
         assertEquals(expectedSentMessage, TestUtils.byteBufferToString(mockTransport.getSentMessages()[0]));
 
@@ -2647,7 +2649,7 @@ class HubConnectionTest {
     }
 
     @Test
-    public void callingStartOnStartedHubConnectionNoOps()  {
+    public void callingStartOnStartedHubConnectionNoops()  {
         HubConnection hubConnection = TestUtils.createHubConnection("http://example.com");
         hubConnection.start().timeout(1, TimeUnit.SECONDS).blockingAwait();
         assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
@@ -2655,7 +2657,35 @@ class HubConnectionTest {
         hubConnection.start().timeout(1, TimeUnit.SECONDS).blockingAwait();
         assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
 
-        hubConnection.stop();
+        hubConnection.stop().timeout(1, TimeUnit.SECONDS).blockingAwait();
+        assertEquals(HubConnectionState.DISCONNECTED, hubConnection.getConnectionState());
+    }
+
+    @Test
+    public void callingStartOnStartingHubConnectionWaitsForOriginalStart()  {
+        CompletableSubject startedAccessToken = CompletableSubject.create();
+        CompletableSubject continueAccessToken = CompletableSubject.create();
+        HubConnection hubConnection = HubConnectionBuilder.create("http://example.com")
+                .withTransportImplementation(new MockTransport(true))
+                .withHttpClient(new TestHttpClient())
+                .withAccessTokenProvider(Single.defer(() -> {
+                    startedAccessToken.onComplete();
+                    continueAccessToken.timeout(1, TimeUnit.SECONDS).blockingAwait();
+                    return Single.just("test");
+                }).subscribeOn(Schedulers.newThread()))
+                .shouldSkipNegotiate(true)
+                .build();
+        Completable start = hubConnection.start();
+        startedAccessToken.timeout(1, TimeUnit.SECONDS).blockingAwait();
+        assertEquals(HubConnectionState.CONNECTING, hubConnection.getConnectionState());
+
+        Completable start2 = hubConnection.start();
+        continueAccessToken.onComplete();
+        start.timeout(1, TimeUnit.SECONDS).blockingAwait();
+        start2.timeout(1, TimeUnit.SECONDS).blockingAwait();
+        assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
+
+        hubConnection.stop().timeout(1, TimeUnit.SECONDS).blockingAwait();
         assertEquals(HubConnectionState.DISCONNECTED, hubConnection.getConnectionState());
     }
 
@@ -3595,9 +3625,6 @@ class HubConnectionTest {
         assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
         hubConnection.stop().blockingAwait();
         assertEquals("ExampleValue", beforeRedirectHeader.get());
-
-        hubConnection.start().timeout(1, TimeUnit.SECONDS).blockingAwait();
-        assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
         assertEquals("Bearer redirectToken", afterRedirectHeader.get());
 
         // Making sure you can do this after restarting the HubConnection.
@@ -3605,9 +3632,6 @@ class HubConnectionTest {
         assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
         hubConnection.stop().blockingAwait();
         assertEquals("ExampleValue", beforeRedirectHeader.get());
-
-        hubConnection.start().timeout(1, TimeUnit.SECONDS).blockingAwait();
-        assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
         assertEquals("Bearer redirectToken", afterRedirectHeader.get());
     }
 
@@ -3699,7 +3723,7 @@ class HubConnectionTest {
     }
 
     @Test
-    public void hubConnectionCloseCallsStop() throws Exception {
+    public void hubConnectionCloseCallsStop() {
         MockTransport mockTransport = new MockTransport();
         TestHttpClient client = new TestHttpClient()
                 .on("POST", "http://example.com/negotiate?negotiateVersion=1", (req) -> Single.just(new HttpResponse(200, "", TestUtils.stringToByteBuffer("{\"url\":\"http://testexample.com/\"}"))))

src/SignalR/clients/java/signalr/src/test/java/com/microsoft/signalr/sample/Chat.java

@@ -8,7 +8,6 @@ import java.util.Scanner;
 import com.microsoft.signalr.HubConnection;
 import com.microsoft.signalr.HubConnectionBuilder;
 
-
 public class Chat {
     public static void main(final String[] args) throws Exception {
         System.out.println("Enter the URL of the SignalR Chat you want to join");
@@ -33,7 +32,7 @@ public class Chat {
             while (!message.equals("leave")) {
                 // Scans the next token of the input as an int.
                 message = reader.nextLine();
-                hubConnection.send("Send", message);
+                hubConnection.send("Send", "Java", message);
             }
 
             hubConnection.stop().blockingAwait();