{"action":"created","comment":{"url":"https://api.github.com/repos/caskdata/cdap/pulls/comments/57065801","id":57065801,"diff_hunk":"@@ -0,0 +1,134 @@\n+/*\n+ * Copyright © 2016 Cask Data, Inc.\n+ *\n+ * Licensed under the Apache License, Version 2.0 (the \"License\"); you may not\n+ * use this file except in compliance with the License. You may obtain a copy of\n+ * the License at\n+ *\n+ * http://www.apache.org/licenses/LICENSE-2.0\n+ *\n+ * Unless required by applicable law or agreed to in writing, software\n+ * distributed under the License is distributed on an \"AS IS\" BASIS, WITHOUT\n+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the\n+ * License for the specific language governing permissions and limitations under\n+ * the License.\n+ */\n+\n+package co.cask.cdap.etl.batch.mapreduce;\n+\n+import co.cask.cdap.api.dataset.lib.KeyValue;\n+import co.cask.cdap.api.mapreduce.MapReduceTaskContext;\n+import co.cask.cdap.api.metrics.Metrics;\n+import co.cask.cdap.etl.api.Aggregator;\n+import co.cask.cdap.etl.api.Emitter;\n+import co.cask.cdap.etl.api.Transformation;\n+import co.cask.cdap.etl.api.batch.BatchAggregator;\n+import co.cask.cdap.etl.api.batch.BatchRuntimeContext;\n+import co.cask.cdap.etl.batch.PipelinePluginInstantiator;\n+import co.cask.cdap.etl.batch.TransformExecutorFactory;\n+import co.cask.cdap.etl.batch.conversion.IdentityConversion;\n+import co.cask.cdap.etl.batch.conversion.WritableConversion;\n+import co.cask.cdap.etl.batch.conversion.WritableConversions;\n+import co.cask.cdap.etl.common.DatasetContextLookupProvider;\n+import com.google.common.base.Function;\n+import com.google.common.collect.Iterators;\n+import org.apache.hadoop.conf.Configuration;\n+import org.apache.hadoop.io.Writable;\n+import org.apache.hadoop.io.WritableComparable;\n+import org.apache.hadoop.mapreduce.Reducer;\n+\n+import java.util.HashMap;\n+import java.util.Iterator;\n+import java.util.Map;\n+import javax.annotation.Nullable;\n+\n+/**\n+ * Creates transform executors for mapreduce programs.\n+ *\n+ * @param <T> the type of input for the created transform executors\n+ */\n+public class ReducerTransformExecutorFactory<T> extends TransformExecutorFactory<T> {","path":"cdap-app-templates/cdap-etl/cdap-etl-batch/src/main/java/co/cask/cdap/etl/batch/mapreduce/ReducerTransformExecutorFactory.java","position":50,"original_position":50,"commit_id":"ca6522b373d22ca40838c71313f5bf7af9d94b76","original_commit_id":"ca6522b373d22ca40838c71313f5bf7af9d94b76","user":{"login":"albertshau","id":5215004,"avatar_url":"https://avatars.githubusercontent.com/u/5215004?v=3","gravatar_id":"","url":"https://api.github.com/users/albertshau","html_url":"https://github.com/albertshau","followers_url":"https://api.github.com/users/albertshau/followers","following_url":"https://api.github.com/users/albertshau/following{/other_user}","gists_url":"https://api.github.com/users/albertshau/gists{/gist_id}","starred_url":"https://api.github.com/users/albertshau/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/albertshau/subscriptions","organizations_url":"https://api.github.com/users/albertshau/orgs","repos_url":"https://api.github.com/users/albertshau/repos","events_url":"https://api.github.com/users/albertshau/events{/privacy}","received_events_url":"https://api.github.com/users/albertshau/received_events","type":"User","site_admin":false},"body":"should be able to. will take another pass to clean things up.","created_at":"2016-03-22T20:46:40Z","updated_at":"2016-03-22T20:46:40Z","html_url":"https://github.com/caskdata/cdap/pull/5341#discussion_r57065801","pull_request_url":"https://api.github.com/repos/caskdata/cdap/pulls/5341","_links":{"self":{"href":"https://api.github.com/repos/caskdata/cdap/pulls/comments/57065801"},"html":{"href":"https://github.com/caskdata/cdap/pull/5341#discussion_r57065801"},"pull_request":{"href":"https://api.github.com/repos/caskdata/cdap/pulls/5341"}}},"pull_request":{"url":"https://api.github.com/repos/caskdata/cdap/pulls/5341","id":63484056,"html_url":"https://github.com/caskdata/cdap/pull/5341","diff_url":"https://github.com/caskdata/cdap/pull/5341.diff","patch_url":"https://github.com/caskdata/cdap/pull/5341.patch","issue_url":"https://api.github.com/repos/caskdata/cdap/issues/5341","number":5341,"state":"open","locked":false,"title":"CDAP-5186 implement aggregator plugin type","user":{"login":"albertshau","id":5215004,"avatar_url":"https://avatars.githubusercontent.com/u/5215004?v=3","gravatar_id":"","url":"https://api.github.com/users/albertshau","html_url":"https://github.com/albertshau","followers_url":"https://api.github.com/users/albertshau/followers","following_url":"https://api.github.com/users/albertshau/following{/other_user}","gists_url":"https://api.github.com/users/albertshau/gists{/gist_id}","starred_url":"https://api.github.com/users/albertshau/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/albertshau/subscriptions","organizations_url":"https://api.github.com/users/albertshau/orgs","repos_url":"https://api.github.com/users/albertshau/repos","events_url":"https://api.github.com/users/albertshau/events{/privacy}","received_events_url":"https://api.github.com/users/albertshau/received_events","type":"User","site_admin":false},"body":"Implementing the aggregator plugin type for mapreduce engine.\r\nEach aggregator translates to a reduce step in a mapreduce job.\r\nThe group by method is called in the mapper in order to decide\r\nwhat to reduce on. The aggregate method is called first thing in\r\nthe reducer.\r\n\r\nMoved most of the logic formerly in ETLMapper into TransformRunner\r\nso that it can be re-used in the new added ETLReducer. Also moved\r\nOutputWriter classes that were internal to ETLMapReduce out of the\r\nclass so that they can be re-used in the TransformRunner.","created_at":"2016-03-20T01:30:56Z","updated_at":"2016-03-22T20:46:40Z","closed_at":null,"merged_at":null,"merge_commit_sha":"6354ef2be997538d6b3de3c705ea96c3ce411edc","assignee":null,"milestone":null,"commits_url":"https://api.github.com/repos/caskdata/cdap/pulls/5341/commits","review_comments_url":"https://api.github.com/repos/caskdata/cdap/pulls/5341/comments","review_comment_url":"https://api.github.com/repos/caskdata/cdap/pulls/comments{/number}","comments_url":"https://api.github.com/repos/caskdata/cdap/issues/5341/comments","statuses_url":"https://api.github.com/repos/caskdata/cdap/statuses/ca6522b373d22ca40838c71313f5bf7af9d94b76","head":{"label":"caskdata:feature/CDAP-5146-aggregator-implementation","ref":"feature/CDAP-5146-aggregator-implementation","sha":"ca6522b373d22ca40838c71313f5bf7af9d94b76","user":{"login":"caskdata","id":8123023,"avatar_url":"https://avatars.githubusercontent.com/u/8123023?v=3","gravatar_id":"","url":"https://api.github.com/users/caskdata","html_url":"https://github.com/caskdata","followers_url":"https://api.github.com/users/caskdata/followers","following_url":"https://api.github.com/users/caskdata/following{/other_user}","gists_url":"https://api.github.com/users/caskdata/gists{/gist_id}","starred_url":"https://api.github.com/users/caskdata/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/caskdata/subscriptions","organizations_url":"https://api.github.com/users/caskdata/orgs","repos_url":"https://api.github.com/users/caskdata/repos","events_url":"https://api.github.com/users/caskdata/events{/privacy}","received_events_url":"https://api.github.com/users/caskdata/received_events","type":"Organization","site_admin":false},"repo":{"id":22542759,"name":"cdap","full_name":"caskdata/cdap","owner":{"login":"caskdata","id":8123023,"avatar_url":"https://avatars.githubusercontent.com/u/8123023?v=3","gravatar_id":"","url":"https://api.github.com/users/caskdata","html_url":"https://github.com/caskdata","followers_url":"https://api.github.com/users/caskdata/followers","following_url":"https://api.github.com/users/caskdata/following{/other_user}","gists_url":"https://api.github.com/users/caskdata/gists{/gist_id}","starred_url":"https://api.github.com/users/caskdata/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/caskdata/subscriptions","organizations_url":"https://api.github.com/users/caskdata/orgs","repos_url":"https://api.github.com/users/caskdata/repos","events_url":"https://api.github.com/users/caskdata/events{/privacy}","received_events_url":"https://api.github.com/users/caskdata/received_events","type":"Organization","site_admin":false},"private":false,"html_url":"https://github.com/caskdata/cdap","description":"Cask 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