Make the SlotSelector an argument of the Distributor

This also provides the indirection needed to get this from the
`DistributorOptions`.

java/server/src/org/openqa/selenium/grid/commands/BUILD.bazel

@@ -25,6 +25,7 @@ java_library(
         "//java/server/src/org/openqa/selenium/grid/distributor",
         "//java/server/src/org/openqa/selenium/grid/distributor/config",
         "//java/server/src/org/openqa/selenium/grid/distributor/local",
+        "//java/server/src/org/openqa/selenium/grid/distributor/selector",
         "//java/server/src/org/openqa/selenium/grid/graphql",
         "//java/server/src/org/openqa/selenium/grid/log",
         "//java/server/src/org/openqa/selenium/grid/node",

java/server/src/org/openqa/selenium/grid/commands/Hub.java

@@ -28,6 +28,7 @@
 import org.openqa.selenium.grid.distributor.Distributor;
 import org.openqa.selenium.grid.distributor.config.DistributorOptions;
 import org.openqa.selenium.grid.distributor.local.LocalDistributor;
+import org.openqa.selenium.grid.distributor.selector.DefaultSlotSelector;
 import org.openqa.selenium.grid.graphql.GraphqlHandler;
 import org.openqa.selenium.grid.log.LoggingOptions;
 import org.openqa.selenium.grid.router.ProxyCdpIntoGrid;
@@ -156,6 +157,7 @@ protected Handlers createHandlers(Config config) {
       clientFactory,
       sessions,
       queue,
+      distributorOptions.getSlotSelector(),
       secret,
       distributorOptions.getHealthCheckInterval());
     handler.addHandler(distributor);

java/server/src/org/openqa/selenium/grid/commands/Standalone.java

@@ -154,6 +154,7 @@ protected Handlers createHandlers(Config config) {
       clientFactory,
       sessions,
       queue,
+      distributorOptions.getSlotSelector(),
       registrationSecret,
       distributorOptions.getHealthCheckInterval());
     combinedHandler.addHandler(distributor);

java/server/src/org/openqa/selenium/grid/distributor/config/BUILD.bazel

@@ -11,6 +11,7 @@ java_library(
         "//java:auto-service",
         "//java/server/src/org/openqa/selenium/grid/config",
         "//java/server/src/org/openqa/selenium/grid/distributor",
+        "//java/server/src/org/openqa/selenium/grid/distributor/selector",
         artifact("com.beust:jcommander"),
     ],
 )

java/server/src/org/openqa/selenium/grid/distributor/config/DistributorFlags.java

@@ -21,6 +21,7 @@
 import static org.openqa.selenium.grid.config.StandardGridRoles.DISTRIBUTOR_ROLE;
 import static org.openqa.selenium.grid.distributor.config.DistributorOptions.DEFAULT_DISTRIBUTOR_IMPLEMENTATION;
 import static org.openqa.selenium.grid.distributor.config.DistributorOptions.DEFAULT_HEALTHCHECK_INTERVAL;
+import static org.openqa.selenium.grid.distributor.config.DistributorOptions.DEFAULT_SLOT_SELECTOR_IMPLEMENTATION;
 import static org.openqa.selenium.grid.distributor.config.DistributorOptions.DISTRIBUTOR_SECTION;
 
 import com.google.auto.service.AutoService;
@@ -64,6 +65,10 @@ public class DistributorFlags implements HasRoles {
     example = DEFAULT_DISTRIBUTOR_IMPLEMENTATION)
   private String implementation = DEFAULT_DISTRIBUTOR_IMPLEMENTATION;
 
+  @Parameter(names = {"--slot-selector"}, description = "Full classname of non-default slot selector implementation")
+  @ConfigValue(section = DISTRIBUTOR_SECTION, name = "slot-selector", example = DEFAULT_SLOT_SELECTOR_IMPLEMENTATION)
+  private String slotSelector = DEFAULT_SLOT_SELECTOR_IMPLEMENTATION;
+
   @Parameter(
     names = {"--healthcheck-interval"},
     description = "How often, in seconds, will the health check run for all Nodes." +

java/server/src/org/openqa/selenium/grid/distributor/config/DistributorOptions.java

@@ -20,6 +20,7 @@
 import org.openqa.selenium.grid.config.Config;
 import org.openqa.selenium.grid.config.ConfigException;
 import org.openqa.selenium.grid.distributor.Distributor;
+import org.openqa.selenium.grid.distributor.selector.SlotSelector;
 
 import java.net.URI;
 import java.net.URISyntaxException;
@@ -31,6 +32,8 @@ public class DistributorOptions {
   static final String DISTRIBUTOR_SECTION = "distributor";
   static final String DEFAULT_DISTRIBUTOR_IMPLEMENTATION =
     "org.openqa.selenium.grid.distributor.local.LocalDistributor";
+  static final String DEFAULT_SLOT_SELECTOR_IMPLEMENTATION =
+    "org.openqa.selenium.grid.distributor.selector.DefaultSlotSelector";
 
   public static final int DEFAULT_HEALTHCHECK_INTERVAL = 300;
 
@@ -92,4 +95,12 @@ public Distributor getDistributor() {
       Distributor.class,
       DEFAULT_DISTRIBUTOR_IMPLEMENTATION);
   }
+
+  public SlotSelector getSlotSelector() {
+    return config.getClass(
+      DISTRIBUTOR_SECTION,
+      "slot-selector",
+      SlotSelector.class,
+      DEFAULT_SLOT_SELECTOR_IMPLEMENTATION);
+  }
 }

java/server/src/org/openqa/selenium/grid/distributor/local/LocalDistributor.java

@@ -45,6 +45,7 @@
 import org.openqa.selenium.grid.distributor.Distributor;
 import org.openqa.selenium.grid.distributor.config.DistributorOptions;
 import org.openqa.selenium.grid.distributor.selector.DefaultSlotSelector;
+import org.openqa.selenium.grid.distributor.selector.SlotSelector;
 import org.openqa.selenium.grid.log.LoggingOptions;
 import org.openqa.selenium.grid.node.HealthCheck;
 import org.openqa.selenium.grid.node.Node;
@@ -119,9 +120,10 @@ public LocalDistributor(
     HttpClient.Factory clientFactory,
     SessionMap sessions,
     NewSessionQueue sessionQueue,
+    SlotSelector slotSelector,
     Secret registrationSecret,
     Duration healthcheckInterval) {
-    super(tracer, clientFactory, new DefaultSlotSelector(), sessions, registrationSecret);
+    super(tracer, clientFactory, slotSelector, sessions, registrationSecret);
     this.tracer = Require.nonNull("Tracer", tracer);
     this.bus = Require.nonNull("Event bus", bus);
     this.clientFactory = Require.nonNull("HTTP client factory", clientFactory);
@@ -175,6 +177,7 @@ public static Distributor create(Config config) {
       clientFactory,
       sessions,
       sessionQueue,
+      distributorOptions.getSlotSelector(),
       secretOptions.getRegistrationSecret(),
       distributorOptions.getHealthCheckInterval());
   }

java/server/src/org/openqa/selenium/grid/distributor/selector/BUILD.bazel

@@ -10,6 +10,7 @@ java_library(
     ],
     deps = [
         "//java/client/src/org/openqa/selenium:core",
+        "//java/server/src/org/openqa/selenium/grid/config",
         "//java/server/src/org/openqa/selenium/grid/data",
         artifact("com.google.guava:guava"),
     ],

java/server/src/org/openqa/selenium/grid/distributor/selector/DefaultSlotSelector.java

@@ -19,6 +19,7 @@
 
 import com.google.common.annotations.VisibleForTesting;
 import org.openqa.selenium.Capabilities;
+import org.openqa.selenium.grid.config.Config;
 import org.openqa.selenium.grid.data.NodeStatus;
 import org.openqa.selenium.grid.data.Slot;
 import org.openqa.selenium.grid.data.SlotId;
@@ -65,4 +66,7 @@ long getNumberOfSupportedBrowsers(NodeStatus nodeStatus) {
       .count();
   }
 
+  public static SlotSelector create(Config config) {
+    return new DefaultSlotSelector();
+  }
 }

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

@@ -39,6 +39,7 @@
 import org.openqa.selenium.grid.data.SlotId;
 import org.openqa.selenium.grid.distributor.local.LocalDistributor;
 import org.openqa.selenium.grid.distributor.remote.RemoteDistributor;
+import org.openqa.selenium.grid.distributor.selector.DefaultSlotSelector;
 import org.openqa.selenium.grid.node.CapabilityResponseEncoder;
 import org.openqa.selenium.grid.node.HealthCheck;
 import org.openqa.selenium.grid.node.Node;
@@ -117,6 +118,7 @@ public void setUpDistributor() throws MalformedURLException {
       clientFactory,
       sessions,
       queue,
+      new DefaultSlotSelector(),
       registrationSecret,
       Duration.ofMinutes(5));
 

java/server/test/org/openqa/selenium/grid/distributor/BUILD.bazel

@@ -22,6 +22,7 @@ java_test_suite(
         "//java/server/src/org/openqa/selenium/grid/distributor",
         "//java/server/src/org/openqa/selenium/grid/distributor/local",
         "//java/server/src/org/openqa/selenium/grid/distributor/remote",
+        "//java/server/src/org/openqa/selenium/grid/distributor/selector",
         "//java/server/src/org/openqa/selenium/grid/node",
         "//java/server/src/org/openqa/selenium/grid/node/local",
         "//java/server/src/org/openqa/selenium/grid/security",

java/server/test/org/openqa/selenium/grid/distributor/DistributorTest.java

@@ -43,6 +43,7 @@
 import org.openqa.selenium.grid.data.Slot;
 import org.openqa.selenium.grid.distributor.local.LocalDistributor;
 import org.openqa.selenium.grid.distributor.remote.RemoteDistributor;
+import org.openqa.selenium.grid.distributor.selector.DefaultSlotSelector;
 import org.openqa.selenium.grid.node.HealthCheck;
 import org.openqa.selenium.grid.node.Node;
 import org.openqa.selenium.grid.node.local.LocalNode;
@@ -132,6 +133,7 @@ public void setUp() throws URISyntaxException {
       HttpClient.Factory.createDefault(),
       sessions,
       queue,
+      new DefaultSlotSelector(),
       registrationSecret,
       Duration.ofMinutes(5));
     stereotype = new ImmutableCapabilities("browserName", "cheese");
@@ -167,6 +169,7 @@ public void shouldStartHeartBeatOnNodeRegistration() {
       new PassthroughHttpClient.Factory(node),
       sessions,
       queue,
+      new DefaultSlotSelector(),
       registrationSecret,
       Duration.ofMinutes(5));
     distributor.add(node);
@@ -213,6 +216,7 @@ public void shouldBeAbleToAddANodeAndCreateASession() {
       new PassthroughHttpClient.Factory(node),
       sessions,
       queue,
+      new DefaultSlotSelector(),
       registrationSecret,
       Duration.ofMinutes(5));
     distributor.add(node);
@@ -251,6 +255,7 @@ public void creatingASessionAddsItToTheSessionMap() {
       new PassthroughHttpClient.Factory(node),
       sessions,
       queue,
+      new DefaultSlotSelector(),
       registrationSecret,
       Duration.ofMinutes(5));
     distributor.add(node);
@@ -290,6 +295,7 @@ public void shouldBeAbleToRemoveANode() throws MalformedURLException {
       new PassthroughHttpClient.Factory(node),
       sessions,
       queue,
+      new DefaultSlotSelector(),
       registrationSecret,
       Duration.ofMinutes(5));
     Distributor distributor = new RemoteDistributor(
@@ -326,6 +332,7 @@ public void testDrainingNodeDoesNotAcceptNewSessions() {
       new PassthroughHttpClient.Factory(node),
       sessions,
       queue,
+      new DefaultSlotSelector(),
       registrationSecret,
       Duration.ofMinutes(5));
     distributor.add(node);
@@ -361,6 +368,7 @@ public void testDrainedNodeShutsDownOnceEmpty() throws InterruptedException {
       new PassthroughHttpClient.Factory(node),
       sessions,
       queue,
+      new DefaultSlotSelector(),
       registrationSecret,
       Duration.ofMinutes(5));
     distributor.add(node);
@@ -403,6 +411,7 @@ public void drainedNodeDoesNotShutDownIfNotEmpty() throws InterruptedException {
       new PassthroughHttpClient.Factory(node),
       sessions,
       queue,
+      new DefaultSlotSelector(),
       registrationSecret,
       Duration.ofMinutes(5));
     distributor.add(node);
@@ -448,6 +457,7 @@ public void drainedNodeShutsDownAfterSessionsFinish() throws InterruptedExceptio
       new PassthroughHttpClient.Factory(node),
       sessions,
       queue,
+      new DefaultSlotSelector(),
       registrationSecret,
       Duration.ofMinutes(5));
     distributor.add(node);
@@ -518,6 +528,7 @@ public void theMostLightlyLoadedNodeIsSelectedFirst() {
       new PassthroughHttpClient.Factory(handler),
       sessions,
       queue,
+      new DefaultSlotSelector(),
       registrationSecret,
       Duration.ofMinutes(5))
       .add(heavy)
@@ -556,6 +567,7 @@ public void shouldUseLastSessionCreatedTimeAsTieBreaker() {
       new PassthroughHttpClient.Factory(handler),
       sessions,
       queue,
+      new DefaultSlotSelector(),
       registrationSecret,
       Duration.ofMinutes(5))
       .add(leastRecent);
@@ -645,6 +657,7 @@ public void shouldIncludeHostsThatAreUpInHostList() {
       new PassthroughHttpClient.Factory(handler),
       sessions,
       queue,
+      new DefaultSlotSelector(),
       registrationSecret,
       Duration.ofMinutes(5));
     handler.addHandler(distributor);
@@ -682,6 +695,7 @@ public void shouldNotScheduleAJobIfAllSlotsAreBeingUsed() {
       new PassthroughHttpClient.Factory(node),
       sessions,
       queue,
+      new DefaultSlotSelector(),
       registrationSecret,
       Duration.ofMinutes(5));
 
@@ -719,6 +733,7 @@ public void shouldReleaseSlotOnceSessionEnds() {
       new PassthroughHttpClient.Factory(node),
       sessions,
       queue,
+      new DefaultSlotSelector(),
       registrationSecret,
       Duration.ofMinutes(5));
     distributor.add(node);
@@ -770,6 +785,7 @@ public void shouldNotStartASessionIfTheCapabilitiesAreNotSupported() {
       new PassthroughHttpClient.Factory(handler),
       sessions,
       queue,
+      new DefaultSlotSelector(),
       registrationSecret,
       Duration.ofMinutes(5));
     handler.addHandler(distributor);
@@ -807,6 +823,7 @@ public void attemptingToStartASessionWhichFailsMarksAsTheSlotAsAvailable() {
       new PassthroughHttpClient.Factory(node),
       sessions,
       queue,
+      new DefaultSlotSelector(),
       registrationSecret,
       Duration.ofMinutes(5));
     distributor.add(node);
@@ -849,6 +866,7 @@ public void shouldReturnNodesThatWereDownToPoolOfNodesOnceTheyMarkTheirHealthChe
       new PassthroughHttpClient.Factory(handler),
       sessions,
       queue,
+      new DefaultSlotSelector(),
       registrationSecret,
       Duration.ofMinutes(5));
     handler.addHandler(distributor);
@@ -910,6 +928,7 @@ public void shouldPrioritizeHostsWithTheMostSlotsAvailableForASessionType() {
       new PassthroughHttpClient.Factory(handler),
       sessions,
       queue,
+      new DefaultSlotSelector(),
       registrationSecret,
       Duration.ofMinutes(5));
     handler.addHandler(distributor);

java/server/test/org/openqa/selenium/grid/distributor/local/BUILD.bazel

@@ -17,6 +17,7 @@ java_test_suite(
         "//java/server/src/org/openqa/selenium/grid/data",
         "//java/server/src/org/openqa/selenium/grid/distributor",
         "//java/server/src/org/openqa/selenium/grid/distributor/local",
+        "//java/server/src/org/openqa/selenium/grid/distributor/selector",
         "//java/server/src/org/openqa/selenium/grid/node",
         "//java/server/src/org/openqa/selenium/grid/node/local",
         "//java/server/src/org/openqa/selenium/grid/security",

java/server/test/org/openqa/selenium/grid/distributor/local/GridModelTest.java

@@ -21,6 +21,7 @@
 import org.openqa.selenium.events.EventBus;
 import org.openqa.selenium.events.local.GuavaEventBus;
 import org.openqa.selenium.grid.distributor.Distributor;
+import org.openqa.selenium.grid.distributor.selector.DefaultSlotSelector;
 import org.openqa.selenium.grid.security.Secret;
 import org.openqa.selenium.grid.sessionmap.SessionMap;
 import org.openqa.selenium.grid.sessionmap.local.LocalSessionMap;
@@ -51,6 +52,7 @@ public class GridModelTest {
     clientFactory,
     sessions,
     queue,
+    new DefaultSlotSelector(),
     secret,
     Duration.ofMinutes(5));