Add resave command for all HistoryEntries

This pattern will mainly be used for data migrations, i.e. updating all
HistoryEntries' DomainTransactionRecords to the new schema.

TESTED=Ran in alpha, the underlying data dropped non-Objectify fields as
expected.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=168684356

java/google/registry/tools/server/ResaveAllHistoryEntriesAction.java

@@ -0,0 +1,84 @@
+// 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.tools.server;
+
+import static google.registry.model.ofy.ObjectifyService.ofy;
+import static google.registry.util.PipelineUtils.createJobPath;
+
+import com.google.appengine.tools.mapreduce.Mapper;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableSet;
+import com.googlecode.objectify.VoidWork;
+import google.registry.mapreduce.MapreduceRunner;
+import google.registry.mapreduce.inputs.EppResourceInputs;
+import google.registry.model.EppResource;
+import google.registry.model.reporting.HistoryEntry;
+import google.registry.request.Action;
+import google.registry.request.Response;
+import google.registry.request.auth.Auth;
+import javax.inject.Inject;
+
+/**
+ * A mapreduce that re-saves all {@link HistoryEntry} entities.
+ *
+ * <p>This is useful for completing data migrations on HistoryEntry fields.
+ *
+ * <p>Because there are no auth settings in the {@link Action} annotation, this command can only be
+ * run internally, or by pretending to be internal by setting the X-AppEngine-QueueName header,
+ * which only admin users can do.
+ */
+@Action(
+  path = "/_dr/task/resaveAllHistoryEntries",
+  auth = Auth.AUTH_INTERNAL_OR_ADMIN
+)
+public class ResaveAllHistoryEntriesAction implements Runnable {
+
+  @Inject MapreduceRunner mrRunner;
+  @Inject Response response;
+  @Inject ResaveAllHistoryEntriesAction() {}
+
+  @SuppressWarnings("unchecked")
+  @Override
+  public void run() {
+    response.sendJavaScriptRedirect(createJobPath(mrRunner
+        .setJobName("Re-save all HistoryEntry entities")
+        .setModuleName("tools")
+        .runMapOnly(
+            new ResaveAllHistoryEntriesActionMapper(),
+            ImmutableList.of(EppResourceInputs.createChildEntityInput(
+                ImmutableSet.<Class<? extends EppResource>>of(EppResource.class),
+                ImmutableSet.<Class<? extends HistoryEntry>>of(HistoryEntry.class))))));
+  }
+
+  /** Mapper to re-save all HistoryEntry entities. */
+  public static class ResaveAllHistoryEntriesActionMapper
+      extends Mapper<HistoryEntry, Void, Void> {
+
+    private static final long serialVersionUID = 123064872315192L;
+
+    @Override
+    public final void map(final HistoryEntry historyEntry) {
+      ofy().transact(new VoidWork() {
+        @Override
+        public void vrun() {
+          ofy().save().entity(ofy().load().entity(historyEntry).now()).now();
+        }});
+      getContext().incrementCounter(
+          String.format(
+              "HistoryEntries parented under %s re-saved", historyEntry.getParent().getKind()));
+    }
+  }
+}
+