Adding the ability to configure things.

Configuration is split into two separate layers. The first
are implementations of `Config`. These provide raw access
to the config options, and can be implemented any way that
people choose.

The second layer are app-specific views of the `Config`s
available. These allow all configuration options to be put
into one place, and easily accessed and reasoned about.

java/BUCK

@@ -1,4 +1,5 @@
 # BUILD FILE SYNTAX: SKYLARK
+
 export_file(
   name = 'changelog',
   out = "CHANGELOG",

java/server/src/org/openqa/selenium/grid/config/BUCK

@@ -0,0 +1,12 @@
+# BUILD FILE SYNTAX: SKYLARK
+
+java_library(
+    name = "config",
+    srcs = glob(["*.java"]),
+    deps = [
+        "//third_party/java/guava:guava",
+    ],
+    visibility = [
+        "//java/server/...",
+    ]
+)

java/server/src/org/openqa/selenium/grid/config/CompoundConfig.java

@@ -0,0 +1,44 @@
+// 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.config;
+
+import com.google.common.collect.ImmutableList;
+
+import java.util.List;
+import java.util.Optional;
+
+public class CompoundConfig implements Config {
+
+  private final List<Config> allConfigs;
+
+  public CompoundConfig(Config mostImportant, Config... othersInDescendingOrderOfImportance) {
+    this.allConfigs = ImmutableList.<Config>builder()
+        .add(mostImportant)
+        .add(othersInDescendingOrderOfImportance)
+        .build();
+  }
+
+  @Override
+  public Optional<String> get(String section, String option) {
+    return allConfigs.stream()
+        .map(config -> config.get(section, option))
+        .filter(Optional::isPresent)
+        .findFirst()
+        .orElse(Optional.empty());
+  }
+}

java/server/src/org/openqa/selenium/grid/config/ConcatenatingConfig.java

@@ -0,0 +1,45 @@
+// 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.config;
+
+import com.google.common.collect.ImmutableMap;
+
+import java.util.AbstractMap;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+
+public class ConcatenatingConfig implements Config {
+
+  private final Map<String, Object> values;
+
+  public ConcatenatingConfig(Map<?, ?> values) {
+    this.values = Objects.requireNonNull(values).entrySet().stream()
+        .peek(entry -> Objects.requireNonNull(entry.getKey(), "Key has not been set"))
+        .peek(entry -> Objects.requireNonNull(entry.getValue(), "Value has not been set"))
+        .map(entry -> new AbstractMap.SimpleImmutableEntry<>(
+            String.valueOf(entry.getKey()),
+            String.valueOf(entry.getValue())))
+        .collect(ImmutableMap.toImmutableMap(Map.Entry::getKey, Map.Entry::getValue));
+  }
+
+  @Override
+  public Optional<String> get(String section, String option) {
+    return Optional.ofNullable(values.get(section + "." + option)).map(String::valueOf);
+  }
+}

java/server/src/org/openqa/selenium/grid/config/Config.java

@@ -0,0 +1,33 @@
+// 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.config;
+
+import java.util.Optional;
+
+public interface Config {
+
+  Optional<String> get(String section, String option);
+
+  default Optional<Integer> getInt(String section, String option) {
+    return get(section, option).map(Integer::parseInt);
+  }
+
+  default Optional<Boolean> getBool(String section, String option) {
+    return get(section, option).map(Boolean::parseBoolean);
+  }
+}

java/server/src/org/openqa/selenium/grid/config/ConfigException.java

@@ -0,0 +1,25 @@
+// 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.config;
+
+public class ConfigException extends RuntimeException {
+
+  public ConfigException(String message) {
+    super(message);
+  }
+}

java/server/src/org/openqa/selenium/grid/config/EnvConfig.java

@@ -0,0 +1,28 @@
+// 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.config;
+
+import java.util.Optional;
+
+public class EnvConfig implements Config {
+
+  @Override
+  public Optional<String> get(String section, String option) {
+    return Optional.ofNullable(System.getenv().get(section + "." + option));
+  }
+}

java/server/src/org/openqa/selenium/grid/config/MapConfig.java

@@ -0,0 +1,41 @@
+// 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.config;
+
+import java.util.Map;
+import java.util.Optional;
+
+public class MapConfig implements Config {
+
+  private final Map<String, Object> raw;
+
+  public MapConfig(Map<String, Object> raw) {
+    this.raw = raw;
+  }
+
+  @Override
+  public Optional<String> get(String section, String option) {
+    Object rawSection = raw.get(section);
+    if (!(rawSection instanceof Map)) {
+      return Optional.empty();
+    }
+
+    Object value = ((Map<?, ?>) rawSection).get(option);
+    return value == null ? Optional.empty() : Optional.of(String.valueOf(value));
+  }
+}

java/server/src/org/openqa/selenium/grid/server/BUCK

@@ -9,7 +9,9 @@ java_library(
     deps = [
         "//java/client/src/org/openqa/selenium/remote:remote",
         "//java/server/src/org/openqa/selenium/injector:injector",
+        "//java/server/src/org/openqa/selenium/grid/config:config",
         "//java/server/src/org/openqa/selenium/grid/web:web",
+        "//third_party/java/beust:jcommander",
         "//third_party/java/guava:guava",
         "//third_party/java/jetty:jetty",
     ],

java/server/src/org/openqa/selenium/grid/server/BaseServer.java

@@ -35,6 +35,7 @@
 import org.seleniumhq.jetty9.server.ServerConnector;
 import org.seleniumhq.jetty9.servlet.ServletContextHandler;
 import org.seleniumhq.jetty9.servlet.ServletHolder;
+import org.seleniumhq.jetty9.util.thread.QueuedThreadPool;
 
 import java.net.URL;
 import java.util.LinkedHashMap;
@@ -54,13 +55,10 @@ public class BaseServer implements Server<BaseServer> {
   private final Injector injector;
   private URL url;
 
-  public BaseServer() {
-    this(0);
-  }
-
-  public BaseServer(int port) {
-    this.port = port;
-    this.server = new org.seleniumhq.jetty9.server.Server();
+  public BaseServer(BaseServerOptions options) {
+    this.port = options.getPort();
+    this.server = new org.seleniumhq.jetty9.server.Server(
+        new QueuedThreadPool(options.getMaxServerThreads()));
 
     // Insertion order may matter
     this.handlers = new LinkedHashMap<>();

java/server/src/org/openqa/selenium/grid/server/BaseServerOptions.java

@@ -0,0 +1,52 @@
+// 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.server;
+
+import org.openqa.selenium.grid.config.Config;
+import org.openqa.selenium.grid.config.ConfigException;
+
+public class BaseServerOptions {
+
+  private final Config config;
+
+  public BaseServerOptions(Config config) {
+    this.config = config;
+  }
+
+  public int getPort() {
+    int port = config.getInt("server", "port")
+        .orElse(0);
+
+    if (port < 0) {
+      throw new ConfigException("Port cannot be less than 0: " + port);
+    }
+
+    return port;
+  }
+
+  public int getMaxServerThreads() {
+    int count = config.getInt("server", "max-threads")
+        .orElse(Runtime.getRuntime().availableProcessors() * 3);
+
+    if (count < 0) {
+      throw new ConfigException("Maximum number of server threads cannot be less than 0: " + count);
+    }
+
+    return count;
+  }
+}

java/server/src/org/openqa/selenium/grid/server/CommonConfig.java

@@ -0,0 +1,50 @@
+// 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.server;
+
+import com.beust.jcommander.Parameter;
+
+import org.openqa.selenium.grid.config.Config;
+
+import java.util.Optional;
+
+public class CommonConfig implements Config {
+
+  @Parameter(description = "Port to listen on", names = {"-p", "--port"})
+  private int port = 0;
+
+  @Parameter(description = "Maximum number of listener threads", names = "--max-threads")
+  private int maxThreads = Runtime.getRuntime().availableProcessors() * 3;
+
+  @Override
+  public Optional<String> get(String section, String option) {
+    switch (section) {
+      case "server":
+        switch (option) {
+          case "max-threads":
+            return Optional.of(String.valueOf(maxThreads));
+
+          case "port":
+            return Optional.of(String.valueOf(port));
+        }
+        break;
+    }
+
+    return Optional.empty();
+  }
+}

java/server/test/org/openqa/selenium/grid/config/BUCK

@@ -0,0 +1,14 @@
+# BUILD FILE SYNTAX: SKYLARK
+
+java_test(
+    name = "config",
+    srcs = glob(["*.java"]),
+    labels = [
+        "small",
+    ],
+    deps = [
+        "//java/server/src/org/openqa/selenium/grid/config:config",
+        "//third_party/java/guava:guava",
+        "//third_party/java/junit:junit",
+    ],
+)