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https://issues.apache.org/jira/browse/APEXMALHAR-2013?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15203831#comment-15203831
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ASF GitHub Bot commented on APEXMALHAR-2013:
--------------------------------------------
Github user yogidevendra commented on a diff in the pull request:
https://github.com/apache/incubator-apex-malhar/pull/216#discussion_r56786779
--- Diff:
library/src/main/java/com/datatorrent/lib/io/fs/HDFSFileMerger.java ---
@@ -0,0 +1,218 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you 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 com.datatorrent.lib.io.fs;
+
+import java.io.IOException;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.apache.hadoop.fs.FileStatus;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+
+import com.google.common.annotations.VisibleForTesting;
+
+import com.datatorrent.api.Context.OperatorContext;
+import com.datatorrent.lib.io.fs.Synchronizer.OutputFileMetadata;
+
+/**
+ * HDFS file merger extends file merger to optimize for HDFS file copy
usecase.
+ * This uses fast merge from HDFS if destination filesystem is same as
+ * application filesystem.
+ */
+public class HDFSFileMerger extends FileMerger
+{
+ /**
+ * Fast merge is possible if append is allowed for output file system.
+ */
+ private transient boolean fastMergeActive;
--- End diff --
Because fastMergeActive is quick check.
FastMergeDecisionMaker.isFastMergePossible is expensive check. We do second
check only if quick check is passed.
> HDFS output module for file copy
> --------------------------------
>
> Key: APEXMALHAR-2013
> URL: https://issues.apache.org/jira/browse/APEXMALHAR-2013
> Project: Apache Apex Malhar
> Issue Type: Task
> Reporter: Yogi Devendra
> Assignee: Yogi Devendra
>
> To write files to HDFS using block-by-block approach.
> Main use-case being to copy the files. Thus, original sequence of blocks has
> to be maintained.
> To achieve this goal, this module would use information emitted by HDFS
> input module (APEXMALHAR-2008) viz. FileMetaData, BlockMetaData, BlockData.
>
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