Add tool to check if other requests are still running

This is needed for the Lock.java enhancement where a lock will be implicitly
released if the request owning it dies.

No matter which solution we want for refactoring the Lock itself, we will need this class.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=167600314

java/google/registry/util/RequestStatusChecker.java

@@ -0,0 +1,34 @@
+// Copyright 2017 The Nomulus Authors. All Rights Reserved.
+//
+// Licensed 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 google.registry.util;
+
+import java.io.Serializable;
+
+/** Used to query whether requests are still running. */
+public interface RequestStatusChecker extends Serializable {
+
+  /**
+   * Returns the unique log identifier of the current request.
+   *
+   * <p>Multiple calls must return the same value during the same Request.
+   */
+  public String getLogId();
+
+  /**
+   * Returns true if the given request is currently running.
+   */
+  public boolean isRunning(String requestLogId);
+}
+