mustafaiman commented on a change in pull request #791: HIVE-21924 URL: https://github.com/apache/hive/pull/791#discussion_r331627809
########## File path: ql/src/java/org/apache/hadoop/hive/ql/io/SkippingTextInputFormat.java ########## @@ -0,0 +1,212 @@ +/* + * 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 org.apache.hadoop.hive.ql.io; + +import org.apache.hadoop.fs.FSDataInputStream; +import org.apache.hadoop.fs.FileSystem; +import org.apache.hadoop.fs.Path; +import org.apache.hadoop.mapred.FileSplit; +import org.apache.hadoop.mapred.JobConf; +import org.apache.hadoop.mapred.TextInputFormat; + +import java.io.IOException; +import java.util.ArrayDeque; +import java.util.Map; +import java.util.Queue; +import java.util.concurrent.ConcurrentHashMap; + +/** + * SkippingInputFormat is a header/footer aware input format. It truncates + * splits identified by TextInputFormat. Header and footers are removed + * from the splits. + */ +public class SkippingTextInputFormat extends TextInputFormat { + + private final Map<Path, Long> startIndexMap = new ConcurrentHashMap<Path, Long>(); + private final Map<Path, Long> endIndexMap = new ConcurrentHashMap<Path, Long>(); + private JobConf conf; + private int headerCount; + private int footerCount; + + @Override + public void configure(JobConf conf) { + this.conf = conf; + super.configure(conf); + } + + public void configure(JobConf conf, int headerCount, int footerCount) { + configure(conf); + this.headerCount = headerCount; + this.footerCount = footerCount; + } + + @Override + protected FileSplit makeSplit(Path file, long start, long length, String[] hosts) { + return makeSplitInternal(file, start, length, hosts, null); + } + + @Override + protected FileSplit makeSplit(Path file, long start, long length, String[] hosts, String[] inMemoryHosts) { + return makeSplitInternal(file, start, length, hosts, inMemoryHosts); + } + + private FileSplit makeSplitInternal(Path file, long start, long length, String[] hosts, String[] inMemoryHosts) { + long cachedStart; + long cachedEnd; + try { + cachedStart = getCachedStartIndex(file); + cachedEnd = getCachedEndIndex(file); + } catch (IOException e) { + LOG.warn("Could not detect header/footer", e); + return new NullRowsInputFormat.DummyInputSplit(file); + } + if (cachedStart > start + length) { + return new NullRowsInputFormat.DummyInputSplit(file); + } + if (cachedStart > start) { + length = length - (cachedStart - start); + start = cachedStart; + } + if (cachedEnd < start) { + return new NullRowsInputFormat.DummyInputSplit(file); + } + if (cachedEnd < start + length) { + length = cachedEnd - start; + } + if (inMemoryHosts == null) { + return super.makeSplit(file, start, length, hosts); + } else { + return super.makeSplit(file, start, length, hosts, inMemoryHosts); + } + } + + private long getCachedStartIndex(Path path) throws IOException { + if (headerCount == 0) { + return 0; + } + Long startIndexForFile = startIndexMap.get(path); + if (startIndexForFile == null) { + FileSystem fileSystem; + FSDataInputStream fis = null; + fileSystem = path.getFileSystem(conf); + try { + fis = fileSystem.open(path); + for (int j = 0; j < headerCount; j++) { + if (fis.readLine() == null) { + startIndexMap.put(path, Long.MAX_VALUE); + return Long.MAX_VALUE; + } + } + // back 1 byte because readers skip the entire first row if split start is not 0 + startIndexForFile = fis.getPos() - 1; + } finally { + if (fis != null) { + fis.close(); + } + } + startIndexMap.put(path, startIndexForFile); + } + return startIndexForFile; + } + + private long getCachedEndIndex(Path path) throws IOException { + Long endIndexForFile = endIndexMap.get(path); + if (endIndexForFile == null) { + final long bufferSectionSize = 5 * 1024; + FileSystem fileSystem = path.getFileSystem(conf); + long endOfFile = fileSystem.getFileStatus(path).getLen(); + if (footerCount == 0) { + endIndexForFile = endOfFile; + } else { + long bufferSectionEnd = endOfFile; + long bufferSectionStart = Math.max(0, bufferSectionEnd - bufferSectionSize); Review comment: I dont think it adds any value. You would not expect such small input in production that buffersectionstart is actually before the actual startIndex of the split. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
