Github user aljoscha commented on a diff in the pull request:
https://github.com/apache/flink/pull/1984#discussion_r63493915
--- Diff:
flink-streaming-java/src/main/java/org/apache/flink/streaming/api/functions/source/FileSplitMonitoringFunction.java
---
@@ -0,0 +1,345 @@
+/*
+ * 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.api.functions.source;
+
+import org.apache.flink.annotation.Internal;
+import org.apache.flink.api.common.io.FileInputFormat;
+import org.apache.flink.api.java.tuple.Tuple2;
+import org.apache.flink.api.java.tuple.Tuple3;
+import org.apache.flink.configuration.Configuration;
+import org.apache.flink.core.fs.FileInputSplit;
+import org.apache.flink.core.fs.FileStatus;
+import org.apache.flink.core.fs.FileSystem;
+import org.apache.flink.core.fs.Path;
+import org.apache.flink.runtime.JobException;
+import org.apache.flink.streaming.api.checkpoint.Checkpointed;
+import org.apache.flink.util.Preconditions;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+import java.net.URI;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * This is the single (non-parallel) task which monitors a user-provided
path and assigns splits
+ * to downstream tasks for further reading and processing. Which splits
will be further processed
+ * depends on the user-provided {@link
FileSplitMonitoringFunction.WatchType}.
+ */
+@Internal
+public class FileSplitMonitoringFunction<OUT>
+ extends RichSourceFunction<FileInputSplit> implements
Checkpointed<Tuple3<List<Tuple2<Long, List<FileInputSplit>>>, Tuple2<Long,
List<FileInputSplit>>, Long>> {
+
+ private static final long serialVersionUID = 1L;
+
+ private static final Logger LOG =
LoggerFactory.getLogger(FileSplitMonitoringFunction.class);
+
+ /**
+ * Specifies when computation will be triggered.
+ */
+ public enum WatchType {
+ PROCESS_ONCE, // Processes the
current content of a file/path only ONCE, and stops monitoring.
+ REPROCESS_WITH_APPENDED // Reprocesses the whole file
when new data is appended.
+ }
+
+ /** The path to monitor. */
+ private final String path;
+
+ /** The default parallelism for the job, as this is going to be the
parallelism of the downstream readers. */
+ private final int readerParallelism;
+
+ /** The {@link FileInputFormat} to be read. */
+ private FileInputFormat<OUT> format;
+
+ /** How often to monitor the state of the directory for new data. */
+ private final long interval;
+
+ /** Which new data to process (see {@link WatchType}. */
+ private final WatchType watchType;
+
+ private List<Tuple2<Long, List<FileInputSplit>>>
splitsToFwdOrderedAscByModTime;
+
+ private Tuple2<Long, List<FileInputSplit>> currentSplitsToFwd;
+
+ private long globalModificationTime;
+
+ private FilePathFilter pathFilter;
+
+ private volatile boolean isRunning = true;
+
+ /**
+ * This is the {@link Configuration} to be used to initialize the input
format at the reader
+ * (see {@link #open(Configuration)}). In the codebase, whenever {@link
#open(Configuration)} is called,
+ * it is passed a new configuration, thus ignoring potential
user-specified parameters. Now, we pass a
+ * configuration object at the constructor, which is shipped to the
remote tasks.
+ * */
+ private Configuration configuration;
+
+ public FileSplitMonitoringFunction(
+ FileInputFormat<OUT> format, String path, Configuration
configuration,
+ WatchType watchType, int readerParallelism, long interval) {
+
+ this(format, path, configuration,
FilePathFilter.DefaultFilter.getInstance(), watchType, readerParallelism,
interval);
+ }
+
+ public FileSplitMonitoringFunction(
+ FileInputFormat<OUT> format, String path, Configuration
configuration,
+ FilePathFilter filter, WatchType watchType, int
readerParallelism, long interval) {
+
+ this.format = Preconditions.checkNotNull(format);
+ this.path = Preconditions.checkNotNull(path);
+ this.configuration = Preconditions.checkNotNull(configuration);
+
+ Preconditions.checkArgument(interval >= 100,
+ "The specified monitoring interval is smaller than the
minimum allowed one (100 ms).");
+ this.interval = interval;
+
+ this.watchType = watchType;
+
+ this.pathFilter = Preconditions.checkNotNull(filter);
+
+ this.readerParallelism = Math.max(readerParallelism, 1);
+ this.globalModificationTime = Long.MIN_VALUE;
+ }
+
+ @Override
+ @SuppressWarnings("unchecked")
+ public void open(Configuration parameters) throws Exception {
+ LOG.info("Opening File Monitoring Source.");
+
+ super.open(parameters);
+ format.configure(this.configuration);
+ }
+
+ @Override
+ public void run(SourceFunction.SourceContext<FileInputSplit> context)
throws Exception {
+ FileSystem fileSystem = FileSystem.get(new URI(path));
+
+ switch (watchType) {
+ case REPROCESS_WITH_APPENDED:
+ while (isRunning) {
+ monitorDirAndForwardSplits(fileSystem,
context);
+ Thread.sleep(interval);
+ }
+ isRunning = false;
+ break;
+ case PROCESS_ONCE:
+ monitorDirAndForwardSplits(fileSystem, context);
+ isRunning = false;
+ break;
+ default:
+ isRunning = false;
+ throw new RuntimeException("Unknown WatchType"
+ watchType);
+ }
+ }
+
+ public boolean isRunning() {
+ return this.isRunning;
+ }
+
+ private void monitorDirAndForwardSplits(FileSystem fs,
SourceContext<FileInputSplit> context) throws IOException, JobException {
+ final Object lock = context.getCheckpointLock();
+
+ // it may be non-null in the case of a recovery after a failure.
+ if (currentSplitsToFwd != null) {
+ synchronized (lock) {
+ forwardSplits(currentSplitsToFwd, context);
+ }
+ }
+ currentSplitsToFwd = null;
+
+ // it may be non-null in the case of a recovery after a failure.
+ if (splitsToFwdOrderedAscByModTime == null) {
+ splitsToFwdOrderedAscByModTime =
getInputSplitSortedOnModTime(fs);
+ }
+
+ Iterator<Tuple2<Long, List<FileInputSplit>>> it =
+ splitsToFwdOrderedAscByModTime.iterator();
+
+ while (it.hasNext()) {
+ synchronized (lock) {
+ currentSplitsToFwd = it.next();
+ it.remove();
+ forwardSplits(currentSplitsToFwd, context);
+ }
+ }
+
+ // set them to null to distinguish from a restore.
+ splitsToFwdOrderedAscByModTime = null;
+ currentSplitsToFwd = null;
+ }
+
+ private void forwardSplits(Tuple2<Long, List<FileInputSplit>>
splitsToFwd, SourceContext<FileInputSplit> context) {
+ currentSplitsToFwd = splitsToFwd;
+ Long modTime = currentSplitsToFwd.f0;
+ List<FileInputSplit> splits = currentSplitsToFwd.f1;
+
+ Iterator<FileInputSplit> it = splits.iterator();
+ while (it.hasNext()) {
+ FileInputSplit split = it.next();
+ processSplit(split, context);
+ it.remove();
+ }
+
+ // update the global modification time
+ if (modTime >= globalModificationTime) {
+ globalModificationTime = modTime;
+ }
+ }
+
+ private void processSplit(FileInputSplit split,
SourceContext<FileInputSplit> context) {
+ LOG.info("Forwarding split: " + split);
+ context.collect(split);
+ }
+
+ private List<Tuple2<Long, List<FileInputSplit>>>
getInputSplitSortedOnModTime(FileSystem fileSystem) throws IOException {
+ List<FileStatus> eligibleFiles = listEligibleFiles(fileSystem);
+ if (eligibleFiles.isEmpty()) {
+ return new ArrayList<>();
+ }
+
+ Map<Long, List<FileInputSplit>> splitsToForward =
getInputSplits(eligibleFiles);
+ List<Tuple2<Long, List<FileInputSplit>>> sortedSplitsToForward
= new ArrayList<>();
+
+ for (Map.Entry<Long, List<FileInputSplit>> entry :
splitsToForward.entrySet()) {
+ sortedSplitsToForward.add(new Tuple2<>(entry.getKey(),
entry.getValue()));
+ }
+
+ Collections.sort(sortedSplitsToForward, new
Comparator<Tuple2<Long, List<FileInputSplit>>>() {
+ @Override
+ public int compare(Tuple2<Long, List<FileInputSplit>>
o1, Tuple2<Long, List<FileInputSplit>> o2) {
+ return (int) (o1.f0 - o2.f0);
+ }
+ });
+
+ return sortedSplitsToForward;
+ }
+
+ /**
+ * Creates the input splits for the path to be assigned to the
downstream tasks.
--- End diff --
The `files` parameter should be called `eligibleFiles`, right? Also the
comment seems to indicate that files in the list are not used while they are
the ones that are actually used.
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at infrastruct...@apache.org or file a JIRA ticket
with INFRA.
---
