Java tutorial
/* * 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.streaming.connectors.fs.bucketing; import org.apache.commons.lang3.time.StopWatch; import org.apache.flink.api.common.ExecutionConfig; import org.apache.flink.api.common.state.ListState; import org.apache.flink.api.common.state.OperatorStateStore; import org.apache.flink.api.common.typeinfo.TypeInformation; import org.apache.flink.api.java.typeutils.InputTypeConfigurable; import org.apache.flink.configuration.Configuration; import org.apache.flink.runtime.fs.hdfs.HadoopFileSystem; import org.apache.flink.runtime.state.CheckpointListener; import org.apache.flink.runtime.state.FunctionInitializationContext; import org.apache.flink.runtime.state.FunctionSnapshotContext; import org.apache.flink.streaming.api.checkpoint.CheckpointedFunction; import org.apache.flink.streaming.api.checkpoint.CheckpointedRestoring; import org.apache.flink.streaming.api.functions.sink.RichSinkFunction; import org.apache.flink.streaming.api.operators.StreamingRuntimeContext; import org.apache.flink.streaming.connectors.fs.Clock; import org.apache.flink.streaming.connectors.fs.RollingSink; import org.apache.flink.streaming.connectors.fs.SequenceFileWriter; import org.apache.flink.streaming.connectors.fs.StringWriter; import org.apache.flink.streaming.connectors.fs.Writer; import org.apache.flink.streaming.runtime.tasks.ProcessingTimeCallback; import org.apache.flink.streaming.runtime.tasks.ProcessingTimeService; import org.apache.flink.util.Preconditions; import org.apache.hadoop.fs.FSDataOutputStream; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; import org.apache.hadoop.hdfs.DistributedFileSystem; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import java.io.IOException; import java.io.Serializable; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Set; import java.util.UUID; import java.util.Iterator; /** * Sink that emits its input elements to {@link FileSystem} files within * buckets. This is integrated with the checkpointing mechanism to provide exactly once semantics. * * <p> * When creating the sink a {@code basePath} must be specified. The base directory contains * one directory for every bucket. The bucket directories themselves contain several part files, * one for each parallel subtask of the sink. These part files contain the actual output data. * * <p> * The sink uses a {@link Bucketer} to determine in which bucket directory each element should * be written to inside the base directory. The {@code Bucketer} can, for example, use time or * a property of the element to determine the bucket directory. The default {@code Bucketer} is a * {@link DateTimeBucketer} which will create one new bucket every hour. You can specify * a custom {@code Bucketer} using {@link #setBucketer(Bucketer)}. For example, use the * {@link BasePathBucketer} if you don't want to have buckets but still want to write part-files * in a fault-tolerant way. * * <p> * The filenames of the part files contain the part prefix, the parallel subtask index of the sink * and a rolling counter. For example the file {@code "part-1-17"} contains the data from * {@code subtask 1} of the sink and is the {@code 17th} bucket created by that subtask. Per default * the part prefix is {@code "part"} but this can be configured using {@link #setPartPrefix(String)}. * When a part file becomes bigger than the user-specified batch size the current part file is closed, * the part counter is increased and a new part file is created. The batch size defaults to {@code 384MB}, * this can be configured using {@link #setBatchSize(long)}. * * <p> * In some scenarios, the open buckets are required to change based on time. In these cases, the sink * needs to determine when a bucket has become inactive, in order to flush and close the part file. * To support this there are two configurable settings: * <ol> * <li>the frequency to check for inactive buckets, configured by {@link #setInactiveBucketCheckInterval(long)}, * and</li> * <li>the minimum amount of time a bucket has to not receive any data before it is considered inactive, * configured by {@link #setInactiveBucketThreshold(long)}</li> * </ol> * Both of these parameters default to {@code 60,000 ms}, or {@code 1 min}. * * <p> * Part files can be in one of three states: {@code in-progress}, {@code pending} or {@code finished}. * The reason for this is how the sink works together with the checkpointing mechanism to provide exactly-once * semantics and fault-tolerance. The part file that is currently being written to is {@code in-progress}. Once * a part file is closed for writing it becomes {@code pending}. When a checkpoint is successful the currently * pending files will be moved to {@code finished}. * * <p> * If case of a failure, and in order to guarantee exactly-once semantics, the sink should roll back to the state it * had when that last successful checkpoint occurred. To this end, when restoring, the restored files in {@code pending} * state are transferred into the {@code finished} state while any {@code in-progress} files are rolled back, so that * they do not contain data that arrived after the checkpoint from which we restore. If the {@code FileSystem} supports * the {@code truncate()} method this will be used to reset the file back to its previous state. If not, a special * file with the same name as the part file and the suffix {@code ".valid-length"} will be created that contains the * length up to which the file contains valid data. When reading the file, it must be ensured that it is only read up * to that point. The prefixes and suffixes for the different file states and valid-length files can be configured * using the adequate setter method, e.g. {@link #setPendingSuffix(String)}. * * <p> * <b>NOTE:</b> * <ol> * <li> * If checkpointing is not enabled the pending files will never be moved to the finished state. In that case, * the pending suffix/prefix can be set to {@code ""} to make the sink work in a non-fault-tolerant way but * still provide output without prefixes and suffixes. * </li> * <li> * The part files are written using an instance of {@link Writer}. By default, a * {@link StringWriter} is used, which writes the result of {@code toString()} for * every element, separated by newlines. You can configure the writer using the * {@link #setWriter(Writer)}. For example, {@link SequenceFileWriter} * can be used to write Hadoop {@code SequenceFiles}. * </li> * </ol> * * <p> * Example: * <pre>{@code * new BucketingSink<Tuple2<IntWritable, Text>>(outPath) * .setWriter(new SequenceFileWriter<IntWritable, Text>()) * .setBucketer(new DateTimeBucketer("yyyy-MM-dd--HHmm") * }</pre> * * This will create a sink that writes to {@code SequenceFiles} and rolls every minute. * * @see DateTimeBucketer * @see StringWriter * @see SequenceFileWriter * * @param <T> Type of the elements emitted by this sink */ public class BucketingSink<T> extends RichSinkFunction<T> implements InputTypeConfigurable, CheckpointedFunction, CheckpointListener, CheckpointedRestoring<RollingSink.BucketState>, ProcessingTimeCallback { private static final long serialVersionUID = 1L; private static Logger LOG = LoggerFactory.getLogger(BucketingSink.class); // -------------------------------------------------------------------------------------------- // User configuration values // -------------------------------------------------------------------------------------------- // These are initialized with some defaults but are meant to be changeable by the user /** * The default maximum size of part files (currently {@code 384 MB}). */ private final long DEFAULT_BATCH_SIZE = 1024L * 1024L * 384L; /** * The default time between checks for inactive buckets. By default, {60 sec}. */ private final long DEFAULT_INACTIVE_BUCKET_CHECK_INTERVAL_MS = 60 * 1000L; /** * The default threshold (in {@code ms}) for marking a bucket as inactive and * closing its part files. By default, {60 sec}. */ private final long DEFAULT_INACTIVE_BUCKET_THRESHOLD_MS = 60 * 1000L; /** * The suffix for {@code in-progress} part files. These are files we are * currently writing to, but which were not yet confirmed by a checkpoint. */ private final String DEFAULT_IN_PROGRESS_SUFFIX = ".in-progress"; /** * The prefix for {@code in-progress} part files. These are files we are * currently writing to, but which were not yet confirmed by a checkpoint. */ private final String DEFAULT_IN_PROGRESS_PREFIX = "_"; /** * The suffix for {@code pending} part files. These are closed files that we are * not currently writing to (inactive or reached {@link #batchSize}), but which * were not yet confirmed by a checkpoint. */ private final String DEFAULT_PENDING_SUFFIX = ".pending"; /** * The prefix for {@code pending} part files. These are closed files that we are * not currently writing to (inactive or reached {@link #batchSize}), but which * were not yet confirmed by a checkpoint. */ private final String DEFAULT_PENDING_PREFIX = "_"; /** * When {@code truncate()} is not supported by the used {@link FileSystem}, we create * a file along the part file with this suffix that contains the length up to which * the part file is valid. */ private final String DEFAULT_VALID_SUFFIX = ".valid-length"; /** * When {@code truncate()} is not supported by the used {@link FileSystem}, we create * a file along the part file with this preffix that contains the length up to which * the part file is valid. */ private final String DEFAULT_VALID_PREFIX = "_"; /** * The default prefix for part files. */ private final String DEFAULT_PART_REFIX = "part"; /** * The default timeout for asynchronous operations such as recoverLease and truncate (in {@code ms}). */ private final long DEFAULT_ASYNC_TIMEOUT_MS = 60 * 1000; /** * The base {@code Path} that stores all bucket directories. */ private final String basePath; /** * The {@code Bucketer} that is used to determine the path of bucket directories. */ private Bucketer<T> bucketer; /** * We have a template and call duplicate() for each parallel writer in open() to get the actual * writer that is used for the part files. */ private Writer<T> writerTemplate; private long batchSize = DEFAULT_BATCH_SIZE; private long inactiveBucketCheckInterval = DEFAULT_INACTIVE_BUCKET_CHECK_INTERVAL_MS; private long inactiveBucketThreshold = DEFAULT_INACTIVE_BUCKET_THRESHOLD_MS; // These are the actually configured prefixes/suffixes private String inProgressSuffix = DEFAULT_IN_PROGRESS_SUFFIX; private String inProgressPrefix = DEFAULT_IN_PROGRESS_PREFIX; private String pendingSuffix = DEFAULT_PENDING_SUFFIX; private String pendingPrefix = DEFAULT_PENDING_PREFIX; private String validLengthSuffix = DEFAULT_VALID_SUFFIX; private String validLengthPrefix = DEFAULT_VALID_PREFIX; private String partPrefix = DEFAULT_PART_REFIX; /** * The timeout for asynchronous operations such as recoverLease and truncate (in {@code ms}). */ private long asyncTimeout = DEFAULT_ASYNC_TIMEOUT_MS; // -------------------------------------------------------------------------------------------- // Internal fields (not configurable by user) // -------------------------------------------------------------------------------------------- /** * We use reflection to get the .truncate() method, this is only available starting with Hadoop 2.7 */ private transient Method refTruncate; /** * The state object that is handled by Flink from snapshot/restore. This contains state for * every open bucket: the current in-progress part file path, its valid length and the pending part files. */ private transient State<T> state; private transient ListState<State<T>> restoredBucketStates; /** * User-defined FileSystem parameters */ private Configuration fsConfig; /** * The FileSystem reference. */ private transient FileSystem fs; private transient Clock clock; private transient ProcessingTimeService processingTimeService; /** * Creates a new {@code BucketingSink} that writes files to the given base directory. * * <p> * This uses a{@link DateTimeBucketer} as {@link Bucketer} and a {@link StringWriter} has writer. * The maximum bucket size is set to 384 MB. * * @param basePath The directory to which to write the bucket files. */ public BucketingSink(String basePath) { this.basePath = basePath; this.bucketer = new DateTimeBucketer<>(); this.writerTemplate = new StringWriter<>(); } /** * Specify a custom {@code Configuration} that will be used when creating * the {@link FileSystem} for writing. */ public BucketingSink<T> setFSConfig(Configuration config) { this.fsConfig = new Configuration(); fsConfig.addAll(config); return this; } /** * Specify a custom {@code Configuration} that will be used when creating * the {@link FileSystem} for writing. */ public BucketingSink<T> setFSConfig(org.apache.hadoop.conf.Configuration config) { this.fsConfig = new Configuration(); for (Map.Entry<String, String> entry : config) { fsConfig.setString(entry.getKey(), entry.getValue()); } return this; } @Override @SuppressWarnings("unchecked") public void setInputType(TypeInformation<?> type, ExecutionConfig executionConfig) { if (this.writerTemplate instanceof InputTypeConfigurable) { ((InputTypeConfigurable) writerTemplate).setInputType(type, executionConfig); } } @Override public void initializeState(FunctionInitializationContext context) throws Exception { Preconditions.checkArgument(this.restoredBucketStates == null, "The operator has already been initialized."); try { initFileSystem(); } catch (IOException e) { LOG.error("Error while creating FileSystem when initializing the state of the BucketingSink.", e); throw new RuntimeException( "Error while creating FileSystem when initializing the state of the BucketingSink.", e); } if (this.refTruncate == null) { this.refTruncate = reflectTruncate(fs); } OperatorStateStore stateStore = context.getOperatorStateStore(); restoredBucketStates = stateStore.getSerializableListState("bucket-states"); int subtaskIndex = getRuntimeContext().getIndexOfThisSubtask(); if (context.isRestored()) { LOG.info("Restoring state for the {} (taskIdx={}).", getClass().getSimpleName(), subtaskIndex); for (State<T> recoveredState : restoredBucketStates.get()) { handleRestoredBucketState(recoveredState); if (LOG.isDebugEnabled()) { LOG.debug("{} idx {} restored {}", getClass().getSimpleName(), subtaskIndex, recoveredState); } } } else { LOG.info("No state to restore for the {} (taskIdx={}).", getClass().getSimpleName(), subtaskIndex); } } @Override public void open(Configuration parameters) throws Exception { super.open(parameters); state = new State<>(); processingTimeService = ((StreamingRuntimeContext) getRuntimeContext()).getProcessingTimeService(); long currentProcessingTime = processingTimeService.getCurrentProcessingTime(); processingTimeService.registerTimer(currentProcessingTime + inactiveBucketCheckInterval, this); this.clock = new Clock() { @Override public long currentTimeMillis() { return processingTimeService.getCurrentProcessingTime(); } }; } /** * Create a file system with the user-defined {@code HDFS} configuration. * @throws IOException */ private void initFileSystem() throws IOException { if (fs != null) { return; } org.apache.hadoop.conf.Configuration hadoopConf = HadoopFileSystem.getHadoopConfiguration(); if (fsConfig != null) { String disableCacheName = String.format("fs.%s.impl.disable.cache", new Path(basePath).toUri().getScheme()); hadoopConf.setBoolean(disableCacheName, true); for (String key : fsConfig.keySet()) { hadoopConf.set(key, fsConfig.getString(key, null)); } } fs = new Path(basePath).getFileSystem(hadoopConf); } @Override public void close() throws Exception { for (Map.Entry<String, BucketState<T>> entry : state.bucketStates.entrySet()) { closeCurrentPartFile(entry.getValue()); } } @Override public void invoke(T value) throws Exception { Path bucketPath = bucketer.getBucketPath(clock, new Path(basePath), value); long currentProcessingTime = processingTimeService.getCurrentProcessingTime(); BucketState<T> bucketState = state.getBucketState(bucketPath); if (bucketState == null) { bucketState = new BucketState<>(currentProcessingTime); state.addBucketState(bucketPath, bucketState); } if (shouldRoll(bucketState)) { openNewPartFile(bucketPath, bucketState); } bucketState.writer.write(value); bucketState.lastWrittenToTime = currentProcessingTime; } /** * Returns {@code true} if the current {@code part-file} should be closed and a new should be created. * This happens if: * <ol> * <li>no file is created yet for the task to write to, or</li> * <li>the current file has reached the maximum bucket size.</li> * </ol> */ private boolean shouldRoll(BucketState<T> bucketState) throws IOException { boolean shouldRoll = false; int subtaskIndex = getRuntimeContext().getIndexOfThisSubtask(); if (!bucketState.isWriterOpen) { shouldRoll = true; LOG.debug("BucketingSink {} starting new bucket.", subtaskIndex); } else { long writePosition = bucketState.writer.getPos(); if (writePosition > batchSize) { shouldRoll = true; LOG.debug("BucketingSink {} starting new bucket because file position {} is above batch size {}.", subtaskIndex, writePosition, batchSize); } } return shouldRoll; } @Override public void onProcessingTime(long timestamp) throws Exception { long currentProcessingTime = processingTimeService.getCurrentProcessingTime(); checkForInactiveBuckets(currentProcessingTime); processingTimeService.registerTimer(currentProcessingTime + inactiveBucketCheckInterval, this); } /** * Checks for inactive buckets, and closes them. Buckets are considered inactive if they have not been * written to for a period greater than {@code inactiveBucketThreshold} ms. This enables in-progress * files to be moved to the pending state and be finalised on the next checkpoint. */ private void checkForInactiveBuckets(long currentProcessingTime) throws Exception { synchronized (state.bucketStates) { for (Map.Entry<String, BucketState<T>> entry : state.bucketStates.entrySet()) { if (entry.getValue().lastWrittenToTime < currentProcessingTime - inactiveBucketThreshold) { LOG.debug("BucketingSink {} closing bucket due to inactivity of over {} ms.", getRuntimeContext().getIndexOfThisSubtask(), inactiveBucketThreshold); closeCurrentPartFile(entry.getValue()); } } } } /** * Closes the current part file and opens a new one with a new bucket path, as returned by the * {@link Bucketer}. If the bucket is not new, then this will create a new file with the same path * as its predecessor, but with an increased rolling counter (see {@link BucketingSink}. */ private void openNewPartFile(Path bucketPath, BucketState<T> bucketState) throws Exception { closeCurrentPartFile(bucketState); if (!fs.exists(bucketPath)) { try { if (fs.mkdirs(bucketPath)) { LOG.debug("Created new bucket directory: {}", bucketPath); } } catch (IOException e) { throw new RuntimeException("Could not create new bucket path.", e); } } // The following loop tries different partCounter values in ascending order until it reaches the minimum // that is not yet used. This works since there is only one parallel subtask that tries names with this // subtask id. Otherwise we would run into concurrency issues here. This is aligned with the way we now // clean the base directory in case of rescaling. int subtaskIndex = getRuntimeContext().getIndexOfThisSubtask(); Path partPath = new Path(bucketPath, partPrefix + "-" + subtaskIndex + "-" + bucketState.partCounter); while (fs.exists(partPath) || fs.exists(getPendingPathFor(partPath)) || fs.exists(getInProgressPathFor(partPath))) { bucketState.partCounter++; partPath = new Path(bucketPath, partPrefix + "-" + subtaskIndex + "-" + bucketState.partCounter); } // increase, so we don't have to check for this name next time bucketState.partCounter++; LOG.debug("Next part path is {}", partPath.toString()); bucketState.currentFile = partPath.toString(); Path inProgressPath = getInProgressPathFor(partPath); if (bucketState.writer == null) { bucketState.writer = writerTemplate.duplicate(); } bucketState.writer.open(fs, inProgressPath); bucketState.isWriterOpen = true; } /** * Closes the current part file and moves it from the in-progress state to the pending state. */ private void closeCurrentPartFile(BucketState<T> bucketState) throws Exception { if (bucketState.isWriterOpen) { bucketState.writer.close(); bucketState.isWriterOpen = false; } if (bucketState.currentFile != null) { Path currentPartPath = new Path(bucketState.currentFile); Path inProgressPath = getInProgressPathFor(currentPartPath); Path pendingPath = getPendingPathFor(currentPartPath); fs.rename(inProgressPath, pendingPath); LOG.debug("Moving in-progress bucket {} to pending file {}", inProgressPath, pendingPath); bucketState.pendingFiles.add(currentPartPath.toString()); bucketState.currentFile = null; } } /** * Gets the truncate() call using reflection. * <p> * <b>NOTE:</b> This code comes from Flume. */ private Method reflectTruncate(FileSystem fs) { Method m = null; if (fs != null) { Class<?> fsClass = fs.getClass(); try { m = fsClass.getMethod("truncate", Path.class, long.class); } catch (NoSuchMethodException ex) { LOG.debug( "Truncate not found. Will write a file with suffix '{}' " + " and prefix '{}' to specify how many bytes in a bucket are valid.", validLengthSuffix, validLengthPrefix); return null; } // verify that truncate actually works FSDataOutputStream outputStream; Path testPath = new Path(UUID.randomUUID().toString()); try { outputStream = fs.create(testPath); outputStream.writeUTF("hello"); outputStream.close(); } catch (IOException e) { LOG.error("Could not create file for checking if truncate works.", e); throw new RuntimeException("Could not create file for checking if truncate works.", e); } try { m.invoke(fs, testPath, 2); } catch (IllegalAccessException | InvocationTargetException e) { LOG.debug("Truncate is not supported.", e); m = null; } try { fs.delete(testPath, false); } catch (IOException e) { LOG.error("Could not delete truncate test file.", e); throw new RuntimeException("Could not delete truncate test file.", e); } } return m; } private Path getPendingPathFor(Path path) { return new Path(path.getParent(), pendingPrefix + path.getName()).suffix(pendingSuffix); } private Path getInProgressPathFor(Path path) { return new Path(path.getParent(), inProgressPrefix + path.getName()).suffix(inProgressSuffix); } private Path getValidLengthPathFor(Path path) { return new Path(path.getParent(), validLengthPrefix + path.getName()).suffix(validLengthSuffix); } @Override public void notifyCheckpointComplete(long checkpointId) throws Exception { synchronized (state.bucketStates) { Iterator<Map.Entry<String, BucketState<T>>> bucketStatesIt = state.bucketStates.entrySet().iterator(); while (bucketStatesIt.hasNext()) { BucketState<T> bucketState = bucketStatesIt.next().getValue(); synchronized (bucketState.pendingFilesPerCheckpoint) { Iterator<Map.Entry<Long, List<String>>> pendingCheckpointsIt = bucketState.pendingFilesPerCheckpoint .entrySet().iterator(); while (pendingCheckpointsIt.hasNext()) { Map.Entry<Long, List<String>> entry = pendingCheckpointsIt.next(); Long pastCheckpointId = entry.getKey(); List<String> pendingPaths = entry.getValue(); if (pastCheckpointId <= checkpointId) { LOG.debug("Moving pending files to final location for checkpoint {}", pastCheckpointId); for (String filename : pendingPaths) { Path finalPath = new Path(filename); Path pendingPath = getPendingPathFor(finalPath); fs.rename(pendingPath, finalPath); LOG.debug( "Moving pending file {} to final location having completed checkpoint {}.", pendingPath, pastCheckpointId); } pendingCheckpointsIt.remove(); } } if (!bucketState.isWriterOpen && bucketState.pendingFiles.isEmpty() && bucketState.pendingFilesPerCheckpoint.isEmpty()) { // We've dealt with all the pending files and the writer for this bucket is not currently open. // Therefore this bucket is currently inactive and we can remove it from our state. bucketStatesIt.remove(); } } } } } @Override public void snapshotState(FunctionSnapshotContext context) throws Exception { Preconditions.checkNotNull(restoredBucketStates, "The operator has not been properly initialized."); restoredBucketStates.clear(); synchronized (state.bucketStates) { int subtaskIdx = getRuntimeContext().getIndexOfThisSubtask(); for (Map.Entry<String, BucketState<T>> bucketStateEntry : state.bucketStates.entrySet()) { BucketState<T> bucketState = bucketStateEntry.getValue(); if (bucketState.isWriterOpen) { bucketState.currentFileValidLength = bucketState.writer.flush(); } synchronized (bucketState.pendingFilesPerCheckpoint) { bucketState.pendingFilesPerCheckpoint.put(context.getCheckpointId(), bucketState.pendingFiles); } bucketState.pendingFiles = new ArrayList<>(); } restoredBucketStates.add(state); if (LOG.isDebugEnabled()) { LOG.debug("{} idx {} checkpointed {}.", getClass().getSimpleName(), subtaskIdx, state); } } } private void handleRestoredBucketState(State<T> restoredState) { Preconditions.checkNotNull(restoredState); for (BucketState<T> bucketState : restoredState.bucketStates.values()) { // we can clean all the pending files since they were renamed to // final files after this checkpoint was successful // (we re-start from the last **successful** checkpoint) bucketState.pendingFiles.clear(); handlePendingInProgressFile(bucketState.currentFile, bucketState.currentFileValidLength); // Now that we've restored the bucket to a valid state, reset the current file info bucketState.currentFile = null; bucketState.currentFileValidLength = -1; bucketState.isWriterOpen = false; handlePendingFilesForPreviousCheckpoints(bucketState.pendingFilesPerCheckpoint); synchronized (bucketState.pendingFilesPerCheckpoint) { bucketState.pendingFilesPerCheckpoint.clear(); } } } private void handleRestoredRollingSinkState(RollingSink.BucketState restoredState) { restoredState.pendingFiles.clear(); handlePendingInProgressFile(restoredState.currentFile, restoredState.currentFileValidLength); // Now that we've restored the bucket to a valid state, reset the current file info restoredState.currentFile = null; restoredState.currentFileValidLength = -1; handlePendingFilesForPreviousCheckpoints(restoredState.pendingFilesPerCheckpoint); synchronized (restoredState.pendingFilesPerCheckpoint) { restoredState.pendingFilesPerCheckpoint.clear(); } } private void handlePendingInProgressFile(String file, long validLength) { if (file != null) { // We were writing to a file when the last checkpoint occurred. This file can either // be still in-progress or became a pending file at some point after the checkpoint. // Either way, we have to truncate it back to a valid state (or write a .valid-length // file that specifies up to which length it is valid) and rename it to the final name // before starting a new bucket file. Path partPath = new Path(file); try { Path partPendingPath = getPendingPathFor(partPath); Path partInProgressPath = getInProgressPathFor(partPath); if (fs.exists(partPendingPath)) { LOG.debug( "In-progress file {} has been moved to pending after checkpoint, moving to final location.", partPath); // has been moved to pending in the mean time, rename to final location fs.rename(partPendingPath, partPath); } else if (fs.exists(partInProgressPath)) { LOG.debug("In-progress file {} is still in-progress, moving to final location.", partPath); // it was still in progress, rename to final path fs.rename(partInProgressPath, partPath); } else if (fs.exists(partPath)) { LOG.debug("In-Progress file {} was already moved to final location {}.", file, partPath); } else { LOG.debug( "In-Progress file {} was neither moved to pending nor is still in progress. Possibly, " + "it was moved to final location by a previous snapshot restore", file); } // We use reflection to get the .truncate() method, this // is only available starting with Hadoop 2.7 if (this.refTruncate == null) { this.refTruncate = reflectTruncate(fs); } // truncate it or write a ".valid-length" file to specify up to which point it is valid if (refTruncate != null) { LOG.debug("Truncating {} to valid length {}", partPath, validLength); // some-one else might still hold the lease from a previous try, we are // recovering, after all ... if (fs instanceof DistributedFileSystem) { DistributedFileSystem dfs = (DistributedFileSystem) fs; LOG.debug("Trying to recover file lease {}", partPath); dfs.recoverLease(partPath); boolean isclosed = dfs.isFileClosed(partPath); StopWatch sw = new StopWatch(); sw.start(); while (!isclosed) { if (sw.getTime() > asyncTimeout) { break; } try { Thread.sleep(500); } catch (InterruptedException e1) { // ignore it } isclosed = dfs.isFileClosed(partPath); } } Boolean truncated = (Boolean) refTruncate.invoke(fs, partPath, validLength); if (!truncated) { LOG.debug("Truncate did not immediately complete for {}, waiting...", partPath); // we must wait for the asynchronous truncate operation to complete StopWatch sw = new StopWatch(); sw.start(); long newLen = fs.getFileStatus(partPath).getLen(); while (newLen != validLength) { if (sw.getTime() > asyncTimeout) { break; } try { Thread.sleep(500); } catch (InterruptedException e1) { // ignore it } newLen = fs.getFileStatus(partPath).getLen(); } if (newLen != validLength) { throw new RuntimeException("Truncate did not truncate to right length. Should be " + validLength + " is " + newLen + "."); } } } else { LOG.debug("Writing valid-length file for {} to specify valid length {}", partPath, validLength); Path validLengthFilePath = getValidLengthPathFor(partPath); if (!fs.exists(validLengthFilePath) && fs.exists(partPath)) { FSDataOutputStream lengthFileOut = fs.create(validLengthFilePath); lengthFileOut.writeUTF(Long.toString(validLength)); lengthFileOut.close(); } } } catch (IOException e) { LOG.error("Error while restoring BucketingSink state.", e); throw new RuntimeException("Error while restoring BucketingSink state.", e); } catch (InvocationTargetException | IllegalAccessException e) { LOG.error("Could not invoke truncate.", e); throw new RuntimeException("Could not invoke truncate.", e); } } } private void handlePendingFilesForPreviousCheckpoints(Map<Long, List<String>> pendingFilesPerCheckpoint) { // Move files that are confirmed by a checkpoint but did not get moved to final location // because the checkpoint notification did not happen before a failure LOG.debug("Moving pending files to final location on restore."); Set<Long> pastCheckpointIds = pendingFilesPerCheckpoint.keySet(); for (Long pastCheckpointId : pastCheckpointIds) { // All the pending files are buckets that have been completed but are waiting to be renamed // to their final name for (String filename : pendingFilesPerCheckpoint.get(pastCheckpointId)) { Path finalPath = new Path(filename); Path pendingPath = getPendingPathFor(finalPath); try { if (fs.exists(pendingPath)) { LOG.debug( "Restoring BucketingSink State: Moving pending file {} to final location after complete checkpoint {}.", pendingPath, pastCheckpointId); fs.rename(pendingPath, finalPath); } } catch (IOException e) { LOG.error( "Restoring BucketingSink State: Error while renaming pending file {} to final path {}: {}", pendingPath, finalPath, e); throw new RuntimeException( "Error while renaming pending file " + pendingPath + " to final path " + finalPath, e); } } } } // -------------------------------------------------------------------------------------------- // Backwards compatibility with Flink 1.1 // -------------------------------------------------------------------------------------------- @Override public void restoreState(RollingSink.BucketState state) throws Exception { LOG.info("{} (taskIdx={}) restored bucket state from the RollingSink an older Flink version: {}", getClass().getSimpleName(), getRuntimeContext().getIndexOfThisSubtask(), state); try { initFileSystem(); } catch (IOException e) { LOG.error("Error while creating FileSystem when restoring the state of the BucketingSink.", e); throw new RuntimeException( "Error while creating FileSystem when restoring the state of the BucketingSink.", e); } handleRestoredRollingSinkState(state); } // -------------------------------------------------------------------------------------------- // Setters for User configuration values // -------------------------------------------------------------------------------------------- /** * Sets the maximum bucket size in bytes. * * <p> * When a bucket part file becomes larger than this size a new bucket part file is started and * the old one is closed. The name of the bucket files depends on the {@link Bucketer}. * * @param batchSize The bucket part file size in bytes. */ public BucketingSink<T> setBatchSize(long batchSize) { this.batchSize = batchSize; return this; } /** * Sets the default time between checks for inactive buckets. * * @param interval The timeout, in milliseconds. */ public BucketingSink<T> setInactiveBucketCheckInterval(long interval) { this.inactiveBucketCheckInterval = interval; return this; } /** * Sets the default threshold for marking a bucket as inactive and closing its part files. * Buckets which haven't been written to for at least this period of time become inactive. * * @param threshold The timeout, in milliseconds. */ public BucketingSink<T> setInactiveBucketThreshold(long threshold) { this.inactiveBucketThreshold = threshold; return this; } /** * Sets the {@link Bucketer} to use for determining the bucket files to write to. * * @param bucketer The bucketer to use. */ public BucketingSink<T> setBucketer(Bucketer<T> bucketer) { this.bucketer = bucketer; return this; } /** * Sets the {@link Writer} to be used for writing the incoming elements to bucket files. * * @param writer The {@code Writer} to use. */ public BucketingSink<T> setWriter(Writer<T> writer) { this.writerTemplate = writer; return this; } /** * Sets the suffix of in-progress part files. The default is {@code "in-progress"}. */ public BucketingSink<T> setInProgressSuffix(String inProgressSuffix) { this.inProgressSuffix = inProgressSuffix; return this; } /** * Sets the prefix of in-progress part files. The default is {@code "_"}. */ public BucketingSink<T> setInProgressPrefix(String inProgressPrefix) { this.inProgressPrefix = inProgressPrefix; return this; } /** * Sets the suffix of pending part files. The default is {@code ".pending"}. */ public BucketingSink<T> setPendingSuffix(String pendingSuffix) { this.pendingSuffix = pendingSuffix; return this; } /** * Sets the prefix of pending part files. The default is {@code "_"}. */ public BucketingSink<T> setPendingPrefix(String pendingPrefix) { this.pendingPrefix = pendingPrefix; return this; } /** * Sets the suffix of valid-length files. The default is {@code ".valid-length"}. */ public BucketingSink<T> setValidLengthSuffix(String validLengthSuffix) { this.validLengthSuffix = validLengthSuffix; return this; } /** * Sets the prefix of valid-length files. The default is {@code "_"}. */ public BucketingSink<T> setValidLengthPrefix(String validLengthPrefix) { this.validLengthPrefix = validLengthPrefix; return this; } /** * Sets the prefix of part files. The default is {@code "part"}. */ public BucketingSink<T> setPartPrefix(String partPrefix) { this.partPrefix = partPrefix; return this; } /** * Disable cleanup of leftover in-progress/pending files when the sink is opened. * * <p> * This should only be disabled if using the sink without checkpoints, to not remove * the files already in the directory. * * @deprecated This option is deprecated and remains only for backwards compatibility. * We do not clean up lingering files anymore. */ @Deprecated public BucketingSink<T> disableCleanupOnOpen() { return this; } /** * Sets the default timeout for asynchronous operations such as recoverLease and truncate. * * @param timeout The timeout, in milliseconds. */ public BucketingSink<T> setAsyncTimeout(long timeout) { this.asyncTimeout = timeout; return this; } // -------------------------------------------------------------------------------------------- // Internal Classes // -------------------------------------------------------------------------------------------- /** * This is used during snapshot/restore to keep track of in-progress buckets. * For each bucket, we maintain a state. */ static final class State<T> implements Serializable { private static final long serialVersionUID = 1L; /** * For every bucket directory (key), we maintain a bucket state (value). */ final Map<String, BucketState<T>> bucketStates = new HashMap<>(); void addBucketState(Path bucketPath, BucketState<T> state) { synchronized (bucketStates) { bucketStates.put(bucketPath.toString(), state); } } BucketState<T> getBucketState(Path bucketPath) { synchronized (bucketStates) { return bucketStates.get(bucketPath.toString()); } } @Override public String toString() { return bucketStates.toString(); } } /** * This is used for keeping track of the current in-progress buckets and files that we mark * for moving from pending to final location after we get a checkpoint-complete notification. */ static final class BucketState<T> implements Serializable { private static final long serialVersionUID = 1L; /** * The file that was in-progress when the last checkpoint occurred. */ String currentFile; /** * The valid length of the in-progress file at the time of the last checkpoint. */ long currentFileValidLength = -1; /** * The time this bucket was last written to. */ long lastWrittenToTime; /** * Pending files that accumulated since the last checkpoint. */ List<String> pendingFiles = new ArrayList<>(); /** * When doing a checkpoint we move the pending files since the last checkpoint to this map * with the id of the checkpoint. When we get the checkpoint-complete notification we move * pending files of completed checkpoints to their final location. */ final Map<Long, List<String>> pendingFilesPerCheckpoint = new HashMap<>(); /** * For counting the part files inside a bucket directory. Part files follow the pattern * {@code "{part-prefix}-{subtask}-{count}"}. When creating new part files we increase the counter. */ private transient int partCounter; /** * Tracks if the writer is currently opened or closed. */ private transient boolean isWriterOpen; /** * The actual writer that we user for writing the part files. */ private transient Writer<T> writer; @Override public String toString() { return "In-progress=" + currentFile + " validLength=" + currentFileValidLength + " pendingForNextCheckpoint=" + pendingFiles + " pendingForPrevCheckpoints=" + pendingFilesPerCheckpoint + " lastModified@" + lastWrittenToTime; } BucketState(long lastWrittenToTime) { this.lastWrittenToTime = lastWrittenToTime; } } }