Add mapreduce for RDE hosts import

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=136766682

java/google/registry/rde/RdeHostReader.java

@@ -0,0 +1,107 @@
+// Copyright 2016 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.rde;
+
+import com.google.appengine.tools.cloudstorage.GcsFilename;
+import com.google.appengine.tools.cloudstorage.GcsService;
+import com.google.appengine.tools.cloudstorage.GcsServiceFactory;
+import com.google.appengine.tools.cloudstorage.RetryParams;
+import com.google.appengine.tools.mapreduce.InputReader;
+import google.registry.config.ConfigModule;
+import google.registry.gcs.GcsUtils;
+import google.registry.model.host.HostResource;
+import google.registry.util.FormattingLogger;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.Serializable;
+import java.util.NoSuchElementException;
+import javax.annotation.concurrent.NotThreadSafe;
+
+/** Mapreduce {@link InputReader} for reading hosts from escrow files */
+@NotThreadSafe
+public class RdeHostReader extends InputReader<HostResource> implements Serializable {
+
+  private static final long serialVersionUID = 3037264959150412846L;
+
+  private static final FormattingLogger logger = FormattingLogger.getLoggerForCallerClass();
+  private static final GcsService GCS_SERVICE =
+      GcsServiceFactory.createGcsService(RetryParams.getDefaultInstance());
+
+  final String importBucketName;
+  final String importFileName;
+  final int offset;
+  final int maxResults;
+
+  private int count = 0;
+
+  transient RdeParser parser;
+
+  /**
+   * Creates a new instance of {@link RdeParser}
+   */
+  private RdeParser newParser() {
+    GcsUtils utils = new GcsUtils(GCS_SERVICE, ConfigModule.provideGcsBufferSize());
+    GcsFilename filename = new GcsFilename(importBucketName, importFileName);
+    InputStream xmlInput = utils.openInputStream(filename);
+    try {
+      RdeParser parser = new RdeParser(xmlInput);
+      // skip the file offset and count
+      // if count is greater than 0, the reader has been rehydrated after doing some work.
+      // skip any already processed records.
+      parser.skipHosts(offset + count);
+      return parser;
+    } catch (Exception e) {
+      logger.severefmt(e, "Error opening rde file %s/%s", importBucketName, importFileName);
+      throw new RuntimeException(e);
+    }
+  }
+
+  public RdeHostReader(
+      String importBucketName,
+      String importFileName,
+      int offset,
+      int maxResults) {
+    this.importBucketName = importBucketName;
+    this.importFileName = importFileName;
+    this.offset = offset;
+    this.maxResults = maxResults;
+  }
+
+  @Override
+  public HostResource next() throws IOException {
+    if (count < maxResults) {
+      if (parser == null) {
+        parser = newParser();
+        if (parser.isAtHost()) {
+          count++;
+          return XjcToHostResourceConverter.convert(parser.getHost());
+        }
+      }
+      if (parser.nextHost()) {
+        count++;
+        return XjcToHostResourceConverter.convert(parser.getHost());
+      }
+    }
+    throw new NoSuchElementException();
+  }
+
+  @Override
+  public void endSlice() throws IOException {
+    super.endSlice();
+    if (parser != null) {
+      parser.close();
+    }
+  }
+}