[grid] decrement the connection per session counter on close #14842

java/src/org/openqa/selenium/grid/node/Node.java

@@ -101,6 +101,12 @@
  * by {@code sessionId}. This returns a boolean.</td>
  * </tr>
  * <tr>
+ * <td>DELETE</td>
+ * <td>/se/grid/node/connection/{sessionId}</td>
+ * <td>Notifies the node about closure of a websocket connection for the {@link Session}
+ * identified by {@code sessionId}.</td>
+ * </tr>
+ * <tr>
  * <td>POST</td>
  * <td>/se/grid/node/connection/{sessionId}</td>
  * <td>Allows the node to be ask about whether or not new websocket connections are allowed for the {@link Session}
@@ -173,6 +179,9 @@ protected Node(
             get("/se/grid/node/owner/{sessionId}")
                 .to(params -> new IsSessionOwner(this, sessionIdFrom(params)))
                 .with(spanDecorator("node.is_session_owner").andThen(requiresSecret)),
+            delete("/se/grid/node/connection/{sessionId}")
+                .to(params -> new ReleaseConnection(this, sessionIdFrom(params)))
+                .with(spanDecorator("node.is_session_owner").andThen(requiresSecret)),
             post("/se/grid/node/connection/{sessionId}")
                 .to(params -> new TryAcquireConnection(this, sessionIdFrom(params)))
                 .with(spanDecorator("node.is_session_owner").andThen(requiresSecret)),
@@ -250,6 +259,8 @@ public TemporaryFilesystem getDownloadsFilesystem(UUID uuid) throws IOException
 
   public abstract boolean tryAcquireConnection(SessionId id);
 
+  public abstract void releaseConnection(SessionId id);
+
   public abstract boolean isSupporting(Capabilities capabilities);
 
   public abstract NodeStatus getStatus();

java/src/org/openqa/selenium/grid/node/ProxyNodeWebsockets.java

@@ -237,7 +237,7 @@ private Consumer<Message> createWsEndPoint(
       WebSocket upstream =
           client.openSocket(
               new HttpRequest(GET, uri.toString()),
-              new ForwardingListener(downstream, sessionConsumer, sessionId));
+              new ForwardingListener(node, downstream, sessionConsumer, sessionId));
 
       return (msg) -> {
         try {
@@ -260,12 +260,17 @@ private Consumer<Message> createWsEndPoint(
   }
 
   private static class ForwardingListener implements WebSocket.Listener {
+    private final Node node;
     private final Consumer<Message> downstream;
     private final Consumer<SessionId> sessionConsumer;
     private final SessionId sessionId;
 
     public ForwardingListener(
-        Consumer<Message> downstream, Consumer<SessionId> sessionConsumer, SessionId sessionId) {
+        Node node,
+        Consumer<Message> downstream,
+        Consumer<SessionId> sessionConsumer,
+        SessionId sessionId) {
+      this.node = node;
       this.downstream = Objects.requireNonNull(downstream);
       this.sessionConsumer = Objects.requireNonNull(sessionConsumer);
       this.sessionId = Objects.requireNonNull(sessionId);
@@ -280,7 +285,7 @@ public void onBinary(byte[] data) {
     @Override
     public void onClose(int code, String reason) {
       downstream.accept(new CloseMessage(code, reason));
-      sessionConsumer.accept(sessionId);
+      node.releaseConnection(sessionId);
     }
 
     @Override

java/src/org/openqa/selenium/grid/node/ReleaseConnection.java

@@ -0,0 +1,43 @@
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+package org.openqa.selenium.grid.node;
+
+import java.io.UncheckedIOException;
+import org.openqa.selenium.internal.Require;
+import org.openqa.selenium.remote.SessionId;
+import org.openqa.selenium.remote.http.HttpHandler;
+import org.openqa.selenium.remote.http.HttpRequest;
+import org.openqa.selenium.remote.http.HttpResponse;
+
+class ReleaseConnection implements HttpHandler {
+
+  private final Node node;
+  private final SessionId id;
+
+  ReleaseConnection(Node node, SessionId id) {
+    this.node = Require.nonNull("Node", node);
+    this.id = Require.nonNull("Session id", id);
+  }
+
+  @Override
+  public HttpResponse execute(HttpRequest req) throws UncheckedIOException {
+    node.releaseConnection(id);
+
+    return new HttpResponse().setStatus(200);
+  }
+}

java/src/org/openqa/selenium/grid/node/TryAcquireConnection.java

@@ -19,8 +19,8 @@
 
 import static org.openqa.selenium.remote.http.Contents.asJson;
 
-import com.google.common.collect.ImmutableMap;
 import java.io.UncheckedIOException;
+import java.util.Map;
 import org.openqa.selenium.internal.Require;
 import org.openqa.selenium.remote.SessionId;
 import org.openqa.selenium.remote.http.HttpHandler;
@@ -39,7 +39,6 @@ class TryAcquireConnection implements HttpHandler {
 
   @Override
   public HttpResponse execute(HttpRequest req) throws UncheckedIOException {
-    return new HttpResponse()
-        .setContent(asJson(ImmutableMap.of("value", node.tryAcquireConnection(id))));
+    return new HttpResponse().setContent(asJson(Map.of("value", node.tryAcquireConnection(id))));
   }
 }

java/src/org/openqa/selenium/grid/node/config/NodeFlags.java

@@ -81,8 +81,8 @@ public class NodeFlags implements HasRoles {
   @Parameter(
       names = {"--connection-limit-per-session"},
       description =
-          "Let X be the maximum number of websocket connections per session.This will ensure one"
-              + " session is not able to exhaust the connection limit of the host")
+          "Let X be the maximum number of concurrent websocket connections per session. This will"
+              + " ensure one session is not able to exhaust the connection limit of the host")
   @ConfigValue(section = NODE_SECTION, name = "connection-limit-per-session", example = "8")
   public int connectionLimitPerSession = DEFAULT_CONNECTION_LIMIT;
 

java/src/org/openqa/selenium/grid/node/k8s/OneShotNode.java

@@ -365,7 +365,24 @@ public boolean isSessionOwner(SessionId id) {
 
   @Override
   public boolean tryAcquireConnection(SessionId id) {
-    return sessionId.equals(id) && connectionLimitPerSession > connectionCounter.getAndIncrement();
+    if (!sessionId.equals(id)) {
+      return false;
+    }
+
+    if (connectionLimitPerSession > connectionCounter.getAndIncrement()) {
+      return true;
+    }
+
+    // ensure a rejected connection will not be counted
+    connectionCounter.getAndDecrement();
+    return false;
+  }
+
+  @Override
+  public void releaseConnection(SessionId id) {
+    if (sessionId.equals(id)) {
+      connectionCounter.getAndDecrement();
+    }
   }
 
   @Override

java/src/org/openqa/selenium/grid/node/local/LocalNode.java

@@ -623,7 +623,31 @@ public boolean tryAcquireConnection(SessionId id) throws NoSuchSessionException
 
     AtomicLong counter = slot.getConnectionCounter();
 
-    return connectionLimitPerSession > counter.getAndIncrement();
+    if (connectionLimitPerSession > counter.getAndIncrement()) {
+      return true;
+    }
+
+    // ensure a rejected connection will not be counted
+    counter.getAndDecrement();
+    return false;
+  }
+
+  @Override
+  public void releaseConnection(SessionId id) {
+    SessionSlot slot = currentSessions.getIfPresent(id);
+
+    if (slot == null) {
+      return;
+    }
+
+    if (connectionLimitPerSession == -1) {
+      // no limit
+      return;
+    }
+
+    AtomicLong counter = slot.getConnectionCounter();
+
+    counter.decrementAndGet();
   }
 
   @Override

java/src/org/openqa/selenium/grid/node/remote/RemoteNode.java

@@ -196,6 +196,18 @@ public boolean tryAcquireConnection(SessionId id) {
     return Boolean.TRUE.equals(Values.get(res, Boolean.class));
   }
 
+  @Override
+  public void releaseConnection(SessionId id) {
+    Require.nonNull("Session ID", id);
+
+    HttpRequest req = new HttpRequest(DELETE, "/se/grid/node/connection/" + id);
+    HttpTracing.inject(tracer, tracer.getCurrentContext(), req);
+
+    HttpResponse res = client.with(addSecret).execute(req);
+
+    Values.get(res, Void.class);
+  }
+
   @Override
   public Session getSession(SessionId id) throws NoSuchSessionException {
     Require.nonNull("Session ID", id);

java/test/org/openqa/selenium/grid/distributor/AddingNodesTest.java

@@ -450,6 +450,9 @@ public boolean tryAcquireConnection(SessionId id) {
       return false;
     }
 
+    @Override
+    public void releaseConnection(SessionId id) {}
+
     @Override
     public boolean isSupporting(Capabilities capabilities) {
       return Objects.equals("cake", capabilities.getCapability("cheese"));

java/test/org/openqa/selenium/grid/router/DistributedTest.java

@@ -30,8 +30,12 @@
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import org.openqa.selenium.Capabilities;
+import org.openqa.selenium.HasCapabilities;
 import org.openqa.selenium.SessionNotCreatedException;
 import org.openqa.selenium.WebDriver;
+import org.openqa.selenium.bidi.BiDi;
+import org.openqa.selenium.bidi.BiDiProvider;
 import org.openqa.selenium.grid.config.MapConfig;
 import org.openqa.selenium.grid.config.MemoizedConfig;
 import org.openqa.selenium.grid.config.TomlConfig;
@@ -43,6 +47,7 @@
 import org.openqa.selenium.netty.server.NettyServer;
 import org.openqa.selenium.remote.RemoteWebDriver;
 import org.openqa.selenium.remote.http.ClientConfig;
+import org.openqa.selenium.remote.http.ConnectionFailedException;
 import org.openqa.selenium.remote.http.Contents;
 import org.openqa.selenium.remote.http.HttpClient;
 import org.openqa.selenium.remote.http.HttpMethod;
@@ -76,7 +81,9 @@ public void setupServers() {
                         + "\n"
                         + "override-max-sessions = true"
                         + "\n"
-                        + "max-sessions = 2")));
+                        + "max-sessions = 2"
+                        + "\n"
+                        + "connection-limit-per-session = 3")));
     tearDowns.add(deployment);
 
     server = deployment.getServer();
@@ -192,4 +199,46 @@ void clientTimeoutDoesNotLeakARunningBrowser() throws Exception {
       Safely.safelyCall(healthy::quit);
     }
   }
+
+  @Test
+  void connectionLimitIsRespected() throws Exception {
+    assertThat(server.isStarted()).isTrue();
+
+    // don't use the RemoteWebDriver.builder here, using it does create an unknown number of
+    // connections
+    WebDriver driver = new RemoteWebDriver(server.getUrl(), browser.getCapabilities());
+
+    try {
+      Capabilities caps = ((HasCapabilities) driver).getCapabilities();
+      BiDiProvider biDiProvider = new BiDiProvider();
+
+      BiDi cnn1 = biDiProvider.getImplementation(caps, null).getBiDi();
+      BiDi cnn2 = biDiProvider.getImplementation(caps, null).getBiDi();
+      BiDi cnn3 = biDiProvider.getImplementation(caps, null).getBiDi();
+
+      Assertions.assertThrows(
+          ConnectionFailedException.class,
+          () -> biDiProvider.getImplementation(caps, null).getBiDi());
+      cnn1.close();
+      BiDi cnn4 = biDiProvider.getImplementation(caps, null).getBiDi();
+
+      Assertions.assertThrows(
+          ConnectionFailedException.class,
+          () -> biDiProvider.getImplementation(caps, null).getBiDi());
+      cnn2.close();
+      cnn3.close();
+      BiDi cnn5 = biDiProvider.getImplementation(caps, null).getBiDi();
+      BiDi cnn6 = biDiProvider.getImplementation(caps, null).getBiDi();
+
+      Assertions.assertThrows(
+          ConnectionFailedException.class,
+          () -> biDiProvider.getImplementation(caps, null).getBiDi());
+
+      cnn4.close();
+      cnn5.close();
+      cnn6.close();
+    } finally {
+      Safely.safelyCall(driver::quit);
+    }
+  }
 }