aasha commented on a change in pull request #1225: URL: https://github.com/apache/hive/pull/1225#discussion_r454943283
########## File path: ql/src/java/org/apache/hadoop/hive/ql/exec/repl/util/FileList.java ########## @@ -0,0 +1,181 @@ +/* + * 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.exec.repl.util; + +import com.google.common.annotations.VisibleForTesting; +import org.apache.hadoop.fs.FileSystem; +import org.apache.hadoop.fs.Path; +import org.apache.hadoop.hive.conf.HiveConf; +import org.apache.hadoop.hive.ql.parse.SemanticException; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.io.BufferedReader; +import java.io.IOException; +import java.io.InputStreamReader; +import java.util.Iterator; +import java.util.NoSuchElementException; +import java.util.concurrent.LinkedBlockingQueue; + + +/** + * A file backed list of Strings which is in-memory till the threshold. + */ +public class FileList implements AutoCloseable, Iterator<String> { + private static final Logger LOG = LoggerFactory.getLogger(FileList.class); + private static int fileListStreamerID = 0; + private static final String FILE_LIST_STREAMER_PREFIX = "file-list-streamer-"; + + private LinkedBlockingQueue<String> cache; + private volatile boolean thresholdHit = false; + private int thresholdPoint; + private float thresholdFactor = 0.9f; + private Path backingFile; + private FileListStreamer fileListStreamer; + private String nextElement; + private boolean noMoreElement; + private HiveConf conf; + private BufferedReader backingFileReader; + + + public FileList(Path backingFile, int cacheSize, HiveConf conf) throws IOException { + this.backingFile = backingFile; + if (cacheSize > 0) { + // Cache size must be > 0 for this list to be used for the write operation. + this.cache = new LinkedBlockingQueue<>(cacheSize); + fileListStreamer = new FileListStreamer(cache, backingFile, conf); + LOG.debug("File list backed by {} can be used for write operation.", backingFile); + } else { + thresholdHit = true; + } + this.conf = conf; + thresholdPoint = getThreshold(cacheSize); + } + + /** + * Only add operation is safe for concurrent operations. + */ + public void add(String entry) throws SemanticException { + if (thresholdHit && !fileListStreamer.isAlive()) { + throw new SemanticException("List is not getting saved anymore to file " + backingFile.toString()); + } + try { + cache.put(entry); + } catch (InterruptedException e) { + throw new SemanticException(e); + } + if (!thresholdHit && cache.size() >= thresholdPoint) { + initStoreToFile(cache.size()); + } + } + + @Override + public boolean hasNext() { + if (!thresholdHit) { + return (cache != null && !cache.isEmpty()); + } + if (nextElement != null) { + return true; + } + if (noMoreElement) { + return false; + } + nextElement = readNextLine(); + if (nextElement == null) { + noMoreElement = true; + } + return !noMoreElement; + } + + @Override + public String next() { + if (!hasNext()) { + throw new NoSuchElementException("No more element in the list backed by " + backingFile); + } + String retVal = nextElement; + nextElement = null; + return thresholdHit ? retVal : cache.poll(); + } + + private synchronized void initStoreToFile(int cacheSize) { + if (!thresholdHit) { + fileListStreamer.setName(getNextID()); + fileListStreamer.setDaemon(true); + fileListStreamer.start(); + thresholdHit = true; + LOG.info("Started streaming the list elements to file: {}, cache size {}", backingFile, cacheSize); + } + } + + private String readNextLine() { + String nextElement = null; + try { + if (backingFileReader == null) { + FileSystem fs = FileSystem.get(backingFile.toUri(), conf); + if (fs.exists(backingFile)) { + backingFileReader = new BufferedReader(new InputStreamReader(fs.open(backingFile))); + } + } + nextElement = (backingFileReader == null) ? null : backingFileReader.readLine(); + } catch (IOException e) { + LOG.error("Unable to read list from backing file " + backingFile, e); + } + return nextElement; + } + + @Override + public void close() throws IOException { + if (thresholdHit && fileListStreamer != null) { + fileListStreamer.close(); + } + if (backingFileReader != null) { + backingFileReader.close(); + } + LOG.info("Completed close for File List backed by:{}, thresholdHit:{} ", backingFile, thresholdHit); + } + + private static String getNextID() { + if (Integer.MAX_VALUE == fileListStreamerID) { + //reset the counter + fileListStreamerID = 0; + } + fileListStreamerID++; + return FILE_LIST_STREAMER_PREFIX + fileListStreamerID; + } + + public int getThreshold(int cacheSize) { + boolean copyAtLoad = conf.getBoolVar(HiveConf.ConfVars.REPL_DATA_COPY_LAZY); + return copyAtLoad ? 0 : (int)(cacheSize * thresholdFactor); + } + + @VisibleForTesting + public boolean isStreamingToFile() { Review comment: If you mark it as public it becomes accesible. So its not protected by @VisibleForTesting anymore ---------------------------------------------------------------- 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: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: gitbox-unsubscr...@hive.apache.org For additional commands, e-mail: gitbox-h...@hive.apache.org
