zoltar9264 commented on code in PR #20152: URL: https://github.com/apache/flink/pull/20152#discussion_r938431052
########## flink-dstl/flink-dstl-dfs/src/main/java/org/apache/flink/changelog/fs/ChangelogStreamHandleReaderWithCache.java: ########## @@ -0,0 +1,203 @@ +/* + * 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.flink.changelog.fs; + +import org.apache.flink.configuration.Configuration; +import org.apache.flink.configuration.ConfigurationUtils; +import org.apache.flink.core.fs.FSDataInputStream; +import org.apache.flink.core.fs.Path; +import org.apache.flink.core.fs.RefCountedFile; +import org.apache.flink.runtime.state.StreamStateHandle; +import org.apache.flink.runtime.state.filesystem.FileStateHandle; +import org.apache.flink.util.ExceptionUtils; +import org.apache.flink.util.IOUtils; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.io.BufferedInputStream; +import java.io.DataInputStream; +import java.io.File; +import java.io.FileInputStream; +import java.io.FileOutputStream; +import java.io.IOException; +import java.nio.file.Files; +import java.util.Arrays; +import java.util.Iterator; +import java.util.Random; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.ScheduledExecutorService; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicInteger; + +import static org.apache.flink.changelog.fs.ChangelogStreamWrapper.wrap; +import static org.apache.flink.changelog.fs.ChangelogStreamWrapper.wrapAndSeek; +import static org.apache.flink.changelog.fs.FsStateChangelogOptions.CACHE_IDLE_TIMEOUT; + +/** StateChangeIterator with local cache. */ +class ChangelogStreamHandleReaderWithCache implements ChangelogStreamHandleReader { + private static final Logger LOG = + LoggerFactory.getLogger(ChangelogStreamHandleReaderWithCache.class); + + private static final String CACHE_FILE_SUB_DIR = "dstl-cache-file"; + private static final String CACHE_FILE_PREFIX = "dstl"; + + // reference count == 1 means only cache component reference the cache file + private static final int NO_USING_REF_COUNT = 1; + + private final File[] cacheDirectories; + private final AtomicInteger next; + + private final ConcurrentHashMap<Path, RefCountedFile> cache = new ConcurrentHashMap<>(); + private final ScheduledExecutorService cacheCleanScheduler; + private final long cacheIdleMillis; + + ChangelogStreamHandleReaderWithCache(Configuration config) { + this.cacheDirectories = + Arrays.stream(ConfigurationUtils.parseTempDirectories(config)) + .map(path -> new File(path, CACHE_FILE_SUB_DIR)) + .toArray(File[]::new); + this.next = new AtomicInteger(new Random().nextInt(this.cacheDirectories.length)); + + this.cacheCleanScheduler = + SchedulerFactory.create(1, "ChangelogCacheFileCleanScheduler", LOG); + this.cacheIdleMillis = config.get(CACHE_IDLE_TIMEOUT).toMillis(); + } + + @Override + public DataInputStream openAndSeek(StreamStateHandle handle, Long offset) throws IOException { + if (!canBeCached(handle)) { + return wrapAndSeek(handle.openInputStream(), offset); + } + + final FileStateHandle fileHandle = (FileStateHandle) handle; + final RefCountedFile refCountedFile = getRefCountedFile(fileHandle); + + FileInputStream fin = openAndSeek(refCountedFile, offset); + + return wrapStream(fileHandle.getFilePath(), fin); + } + + private boolean canBeCached(StreamStateHandle handle) throws IOException { + if (handle instanceof FileStateHandle) { + FileStateHandle fileHandle = (FileStateHandle) handle; + return fileHandle.getFilePath().getFileSystem().isDistributedFS(); + } else { + return false; + } + } + + private RefCountedFile getRefCountedFile(FileStateHandle fileHandle) { + return cache.compute( + fileHandle.getFilePath(), + (key, oldValue) -> { + if (oldValue == null) { + oldValue = downloadToCacheFile(fileHandle); + } + oldValue.retain(); + return oldValue; + }); + } + + private RefCountedFile downloadToCacheFile(FileStateHandle fileHandle) { + RefCountedFile refCountedFile = null; + + try (FSDataInputStream inputStream = fileHandle.openInputStream()) { + File directory = cacheDirectories[next.getAndIncrement() % cacheDirectories.length]; + File file = File.createTempFile(CACHE_FILE_PREFIX, null, directory); + + IOUtils.copyBytes(wrap(inputStream), new FileOutputStream(file)); + LOG.debug( + "download and decompress dstl file : {} to cache file : {}", + fileHandle.getFilePath(), + refCountedFile.getFile().getPath()); + + refCountedFile = new RefCountedFile(file); + } catch (IOException e) { + ExceptionUtils.rethrow(e); + } + + return refCountedFile; + } + + private FileInputStream openAndSeek(RefCountedFile refCountedFile, long offset) + throws IOException { + FileInputStream fin = new FileInputStream(refCountedFile.getFile()); + if (offset != 0) { + LOG.debug("seek to {}", offset); + fin.getChannel().position(offset); + } + return fin; + } + + private DataInputStream wrapStream(Path dfsPath, FileInputStream fin) { + return new DataInputStream(new BufferedInputStream(fin)) { + @Override + public void close() throws IOException { + try { + super.close(); + } finally { + cache.computeIfPresent( + dfsPath, + (key, value) -> { + value.release(); + if (value.getReferenceCounter() == NO_USING_REF_COUNT) { + cacheCleanScheduler.schedule( + () -> cleanCacheFile(dfsPath), + cacheIdleMillis, + TimeUnit.MILLISECONDS); + } + return value; + }); + } + } + }; + } + + private void cleanCacheFile(Path dfsPath) { + cache.computeIfPresent( + dfsPath, + (key, value) -> { + if (value.getReferenceCounter() == NO_USING_REF_COUNT) { + LOG.debug("clean cached file : {}", value.getFile().getPath()); + value.release(); + return null; Review Comment: Yes, may be we should add some annotations ? -- This is an automated message from the Apache Git Service. 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