bhalchandrap commented on a change in pull request #3736: URL: https://github.com/apache/hadoop/pull/3736#discussion_r805104237
########## File path: hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/common/SingleFilePerBlockCache.java ########## @@ -0,0 +1,328 @@ +/* + * 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.fs.common; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.io.File; +import java.io.IOException; +import java.nio.ByteBuffer; +import java.nio.channels.FileChannel; +import java.nio.channels.WritableByteChannel; +import java.nio.file.Files; +import java.nio.file.OpenOption; +import java.nio.file.Path; +import java.nio.file.StandardOpenOption; +import java.nio.file.attribute.FileAttribute; +import java.nio.file.attribute.PosixFilePermission; +import java.nio.file.attribute.PosixFilePermissions; +import java.util.ArrayList; +import java.util.Collections; +import java.util.EnumSet; +import java.util.List; +import java.util.Map; +import java.util.Set; +import java.util.concurrent.ConcurrentHashMap; + +/** + * Provides functionality necessary for caching blocks of data read from FileSystem. + * Each cache block is stored on the local disk as a separate file. + */ +public class SingleFilePerBlockCache implements BlockCache { + private static final Logger LOG = LoggerFactory.getLogger(SingleFilePerBlockCache.class); + + // Blocks stored in this cache. + private Map<Integer, Entry> blocks = new ConcurrentHashMap<>(); + + // Number of times a block was read from this cache. + // Used for determining cache utilization factor. + private int numGets = 0; + + private boolean closed; + + // Cache entry. + // Each block is stored as a separate file. + private static class Entry { + private final int blockNumber; + private final Path path; + private final int size; + private final long checksum; + + Entry(int blockNumber, Path path, int size, long checksum) { + this.blockNumber = blockNumber; + this.path = path; + this.size = size; + this.checksum = checksum; + } + + @Override + public String toString() { + return String.format( + "([%03d] %s: size = %d, checksum = %d)", + this.blockNumber, this.path, this.size, this.checksum); + } + } + + public SingleFilePerBlockCache() { + } + + /** + * Indicates whether the given block is in this cache. + */ + @Override + public boolean containsBlock(int blockNumber) { + return this.blocks.containsKey(blockNumber); + } + + /** + * Gets the blocks in this cache. + */ + @Override + public Iterable<Integer> blocks() { + return Collections.unmodifiableList(new ArrayList<Integer>(this.blocks.keySet())); + } + + /** + * Gets the number of blocks in this cache. + */ + @Override + public int size() { + return this.blocks.size(); + } + + /** + * Gets the block having the given {@code blockNumber}. + * + * @throws IllegalArgumentException if buffer is null. + */ + @Override + public void get(int blockNumber, ByteBuffer buffer) throws IOException { + if (this.closed) { + return; + } + + Validate.checkNotNull(buffer, "buffer"); + + Entry entry = this.getEntry(blockNumber); + buffer.clear(); + this.readFile(entry.path, buffer); + buffer.rewind(); + + validateEntry(entry, buffer); + } + + protected int readFile(Path path, ByteBuffer buffer) throws IOException { + int numBytesRead = 0; + int numBytes; + FileChannel channel = FileChannel.open(path, StandardOpenOption.READ); + while ((numBytes = channel.read(buffer)) > 0) { + numBytesRead += numBytes; + } + buffer.limit(buffer.position()); + channel.close(); + return numBytesRead; + } + + private Entry getEntry(int blockNumber) { + Validate.checkNotNegative(blockNumber, "blockNumber"); + + Entry entry = this.blocks.get(blockNumber); + if (entry == null) { + throw new IllegalStateException(String.format("block %d not found in cache", blockNumber)); + } + this.numGets++; + return entry; + } + + /** + * Puts the given block in this cache. + * + * @throws IllegalArgumentException if buffer is null. + * @throws IllegalArgumentException if buffer.limit() is zero or negative. + */ + @Override + public void put(int blockNumber, ByteBuffer buffer) throws IOException { + if (this.closed) { + return; + } + + Validate.checkNotNull(buffer, "buffer"); + + if (this.blocks.containsKey(blockNumber)) { + Entry entry = this.blocks.get(blockNumber); + validateEntry(entry, buffer); + return; + } + + Validate.checkPositiveInteger(buffer.limit(), "buffer.limit()"); + + Path blockFilePath = getCacheFilePath(); + long size = Files.size(blockFilePath); + if (size != 0) { + String message = + String.format("[%d] temp file already has data. %s (%d)", + blockNumber, blockFilePath, size); + throw new IllegalStateException(message); + } + + this.writeFile(blockFilePath, buffer); + long checksum = BufferData.getChecksum(buffer); + Entry entry = new Entry(blockNumber, blockFilePath, buffer.limit(), checksum); + this.blocks.put(blockNumber, entry); + } + + private static final Set<? extends OpenOption> CREATE_OPTIONS = + EnumSet.of(StandardOpenOption.WRITE, + StandardOpenOption.CREATE, + StandardOpenOption.TRUNCATE_EXISTING); + + protected void writeFile(Path path, ByteBuffer buffer) throws IOException { + buffer.rewind(); + WritableByteChannel writeChannel = Files.newByteChannel(path, CREATE_OPTIONS); + while (buffer.hasRemaining()) { + writeChannel.write(buffer); + } + writeChannel.close(); + } + + protected Path getCacheFilePath() throws IOException { + return getTempFilePath(); + } + + @Override + public void close() throws IOException { + if (this.closed) { + return; + } + + this.closed = true; + + LOG.info(this.getStats()); + int numFilesDeleted = 0; + + for (Entry entry : this.blocks.values()) { + try { + Files.deleteIfExists(entry.path); + numFilesDeleted++; + } catch (IOException e) { + // Ignore while closing so that we can delete as many cache files as possible. + } + } + + if (numFilesDeleted > 0) { + LOG.info("Deleted {} cache files", numFilesDeleted); + } + } + + @Override + public String toString() { + StringBuilder sb = new StringBuilder(); + sb.append("stats: "); + sb.append(getStats()); + sb.append(", blocks:["); + sb.append(this.getIntList(this.blocks())); + sb.append("]"); + return sb.toString(); + } + + private void validateEntry(Entry entry, ByteBuffer buffer) { + if (entry.size != buffer.limit()) { + String message = String.format( + "[%d] entry.size(%d) != buffer.limit(%d)", + entry.blockNumber, entry.size, buffer.limit()); + throw new IllegalStateException(message); + } + + long checksum = BufferData.getChecksum(buffer); + if (entry.checksum != checksum) { + String message = String.format( + "[%d] entry.checksum(%d) != buffer checksum(%d)", + entry.blockNumber, entry.checksum, checksum); + throw new IllegalStateException(message); + } + } + + private String getIntList(Iterable<Integer> nums) { + List<String> numList = new ArrayList<>(); + List<Integer> numbers = new ArrayList<Integer>(); + for (Integer n : nums) { + numbers.add(n); + } + Collections.sort(numbers); + + int index = 0; + while (index < numbers.size()) { Review comment: should be clear based on the function header I added. -- This is an automated message from the Apache Git Service. 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