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https://issues.apache.org/jira/browse/APEXMALHAR-2008?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15190284#comment-15190284
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ASF GitHub Bot commented on APEXMALHAR-2008:
--------------------------------------------
Github user ishark commented on a diff in the pull request:
https://github.com/apache/incubator-apex-malhar/pull/207#discussion_r55778161
--- Diff:
library/src/main/java/com/datatorrent/lib/io/fs/HDFSFileSplitter.java ---
@@ -0,0 +1,184 @@
+/**
+ * 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.File;
+import java.io.IOException;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import javax.validation.constraints.NotNull;
+
+import org.apache.hadoop.fs.FileStatus;
+import org.apache.hadoop.fs.Path;
+
+import com.datatorrent.api.Context.OperatorContext;
+import com.datatorrent.lib.io.block.BlockMetadata.FileBlockMetadata;
+
+/**
+ * HDFSFileSplitter extends {@link FileSplitterInput} to,
+ * 1. Add relative path to file metadata.
+ * 2. Ignore HDFS temp files (files with extensions _COPYING_).
+ * 3. Set sequencial read option on readers.
+ */
+public class HDFSFileSplitter extends FileSplitterInput
+{
+ private boolean sequencialFileRead;
+
+ public HDFSFileSplitter()
+ {
+ super();
+ super.setScanner(new HDFSScanner());
+ }
+
+ @Override
+ protected FileMetadata createFileMetadata(FileInfo fileInfo)
+ {
+ return new HDFSFileMetaData(fileInfo.getFilePath());
+ }
+
+ @Override
+ protected HDFSFileMetaData buildFileMetadata(FileInfo fileInfo) throws
IOException
+ {
+ FileMetadata metadata = super.buildFileMetadata(fileInfo);
+ HDFSFileMetaData hdfsFileMetaData = (HDFSFileMetaData)metadata;
+
+ Path path = new Path(fileInfo.getFilePath());
+ FileStatus status = getFileStatus(path);
+ if (fileInfo.getDirectoryPath() == null) { // Direct filename is given
as input.
+ hdfsFileMetaData.setRelativePath(status.getPath().getName());
+ } else {
+ String relativePath = getRelativePathWithFolderName(fileInfo);
+ hdfsFileMetaData.setRelativePath(relativePath);
+ }
+ return hdfsFileMetaData;
+ }
+
+ /*
+ * As folder name was given to input for copy, prefix folder name to the
sub items to copy.
+ */
+ private String getRelativePathWithFolderName(FileInfo fileInfo)
+ {
+ String parentDir = new Path(fileInfo.getDirectoryPath()).getName();
+ return parentDir + File.separator + fileInfo.getRelativeFilePath();
+ }
+
+ @Override
+ protected FileBlockMetadata createBlockMetadata(FileMetadata
fileMetadata)
+ {
+ FileBlockMetadata blockMetadta = new
FileBlockMetadata(fileMetadata.getFilePath());
+ blockMetadta.setReadBlockInSequence(sequencialFileRead);
+ return blockMetadta;
+ }
+
+ public boolean isSequencialFileRead()
+ {
+ return sequencialFileRead;
+ }
+
+ public void setSequencialFileRead(boolean sequencialFileRead)
+ {
+ this.sequencialFileRead = sequencialFileRead;
+ }
+
+ /**
+ * HDFSScanner extends {@link TimeBasedDirectoryScanner} to ignore HDFS
temporary files
+ * and files containing unsupported characters.
+ */
+ public static class HDFSScanner extends TimeBasedDirectoryScanner
+ {
+ protected static final String HDFS_TEMP_FILE = ".*._COPYING_";
+ protected static final String UNSUPPORTED_CHARACTOR = ":";
+ private transient Pattern ignoreRegex;
--- End diff --
One way to handle this could be to expose ignoreRegex as a property for
module, with default being _COPYING_. Could be useful ignore other file
extensions as well. It can be also be part of superclass if it applies to other
type of file readers.
> Create hdfs file input module
> ------------------------------
>
> Key: APEXMALHAR-2008
> URL: https://issues.apache.org/jira/browse/APEXMALHAR-2008
> Project: Apache Apex Malhar
> Issue Type: Task
> Reporter: Priyanka Gugale
> Assignee: Priyanka Gugale
> Priority: Minor
> Original Estimate: 72h
> Remaining Estimate: 72h
>
> To read HDFS files in parallel using Apex we normally use FileSplitter and
> FileReader module. It would be a good idea to combine those operators as a
> unit in module. Having a module will give us readily usable set of operators
> to read HDFS files.
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