org.openqa.selenium.grid.server.EventBusOptions Maven / Gradle / Ivy

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//
//   http://www.apache.org/licenses/LICENSE-2.0
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package org.openqa.selenium.grid.server;

import org.openqa.selenium.events.EventBus;
import org.openqa.selenium.grid.config.Config;

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Objects;
import java.util.logging.Logger;

public class EventBusOptions {

  private static final Logger LOG = Logger.getLogger(EventBus.class.getName());
  private static final String DEFAULT_CLASS = "org.openqa.selenium.events.zeromq.ZeroMqEventBus";

  private final Config config;
  private EventBus bus;

  public EventBusOptions(Config config) {
    this.config = Objects.requireNonNull(config, "Config must be set.");
  }

  public EventBus getEventBus() {
    if (bus == null) {
      synchronized (this) {
        if (bus == null) {
          bus = createBus();
        }
      }
    }

    return bus;
  }

  private EventBus createBus() {
    String clazzName = config.get("events", "implementation").orElse(DEFAULT_CLASS);
    LOG.info("Creating event bus: " + clazzName);
    try {
      Class busClazz = Class.forName(clazzName);
      Method create = busClazz.getMethod("create", Config.class);

      if (!Modifier.isStatic(create.getModifiers())) {
        throw new IllegalArgumentException(String.format(
            "Event bus class %s's `create(Config)` method must be static", clazzName));
      }

      if (!EventBus.class.isAssignableFrom(create.getReturnType())) {
        throw new IllegalArgumentException(String.format(
            "Event bus class %s's `create(Config)` method must return an EventBus", clazzName));
      }

      return (EventBus) create.invoke(null, config);
    } catch (NoSuchMethodException e) {
      throw new IllegalArgumentException(String.format(
          "Event bus class %s must have a static `create(Config)` method", clazzName));
    } catch (ReflectiveOperationException e) {
      throw new IllegalArgumentException("Unable to find event bus class: " + clazzName, e);
    }
  }
}