Github user zentol commented on a diff in the pull request:
https://github.com/apache/flink/pull/1929#discussion_r60932233
--- Diff:
flink-streaming-java/src/main/java/org/apache/flink/streaming/api/functions/source/FileSplitMonitoringFunction.java
---
@@ -0,0 +1,259 @@
+/*
+ * 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.api.common.io.FileInputFormat;
+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.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.HashSet;
+import java.util.List;
+import java.util.Set;
+
+/**
+ * This is the single (non-parallel) task, that monitors a user-procided
path, and assigns splits
+ * to downstream tasks for further reading and processing, depending on
the user-provided {@link FileSplitMonitoringFunction.WatchType}.
+ *
+ * This method keeps track of which splits have already being processed by
which task, and at which point
+ * in the file we are currently processing, at the granularity of the
split. In addition, it keeps track
+ * of the last modification time for each file, so that it can detect new
data.
+ */
+public class FileSplitMonitoringFunction<OUT>
+ extends RichSourceFunction<FileInputSplit> {
+
+ private static final long serialVersionUID = 1L;
+
+ private static final Logger LOG =
LoggerFactory.getLogger(FileSplitMonitoringFunction.class);
+
+ /**
+ * Specifies when computation will be triggered. This can be currently
done in 3 ways.
+ * <li/>{@code ONLY_NEW_FILES} which implies that only new files will
be processed.
+ * <li/>{@code REPROCESS_WITH_APPENDED} which reprocesses the whole
file, as soon as new data is appended to it.
+ */
+ public enum WatchType {
+ 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 long globalModificationTime;
+
+ private FilePathFilter pathFilter;
+
+ private volatile boolean isRunning = true;
+
+ public FileSplitMonitoringFunction(
+ FileInputFormat<OUT> format, String path,
+ WatchType watchType, int readerParallelism, long interval) {
+
+ this(format, path, FilePathFilter.DefaultFilter.getInstance(),
watchType, readerParallelism, interval);
+ }
+
+ public FileSplitMonitoringFunction(
+ FileInputFormat<OUT> format, String path, FilePathFilter filter,
+ WatchType watchType, int readerParallelism, long interval) {
+
+ this.format = Preconditions.checkNotNull(format);
+ this.path = Preconditions.checkNotNull(path);
+
+ 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 {
+ super.open(parameters);
+ format.configure(parameters);
+ }
+
+ /**
+ * Creates the input splits for the path to be assigned to the
downstream tasks.
+ * Those are going to read their contents for further processing.
+ */
+ private FileInputSplit[] createInputSplits() throws JobException {
+ FileInputSplit[] inputSplits;
+ try {
+ inputSplits =
format.createInputSplits(readerParallelism);
+ } catch (Throwable t) {
+ throw new JobException("Creating the input splits
caused an error: " + t.getMessage(), t);
+ }
+ return inputSplits;
+ }
+
+ @Override
+ public void run(SourceFunction.SourceContext<FileInputSplit> context)
throws Exception {
+ FileSystem fileSystem = FileSystem.get(new URI(path));
+ while (isRunning) {
+ monitor(fileSystem, context);
+ Thread.sleep(interval);
+ }
+ }
+
+ private void monitor(FileSystem fs, SourceContext<FileInputSplit>
context) throws IOException, JobException {
+ List<FileStatus> files = listEligibleFiles(fs);
+ for (FileInputSplit split : getInputSplitsToForward(files)) {
+ processSplit(split, context);
+ }
+ }
+
+ private void processSplit(FileInputSplit split,
SourceContext<FileInputSplit> context) {
+ if (watchType == WatchType.REPROCESS_WITH_APPENDED) {
+ context.collect(split);
+ } else {
+ throw new RuntimeException("Unknown WatchType" +
watchType);
+ }
+ }
+
+ private Set<FileInputSplit> getInputSplitsToForward(List<FileStatus>
files) throws JobException {
+ if(files.isEmpty()) {
+ return new HashSet<>();
+ }
+
+ FileInputSplit[] inputSplits = createInputSplits();
+
+ Set<FileInputSplit> splitsToForward = new HashSet<>();
+ for (FileInputSplit split: inputSplits) {
+ for(FileStatus file: files) {
+ if (file.getPath().equals(split.getPath())) {
+ splitsToForward.add(split);
+ break;
+ }
+ }
+ }
+ return splitsToForward;
+ }
+
+ /**
+ * Returns the files that have data to be processed. This method
returns the
+ * Paths to the aforementioned files. It is up to the {@link
#processSplit(FileInputSplit, SourceContext)}
+ * method to decide which parts of the file to be processed, and
forward them downstream.
+ */
+ private List<FileStatus> listEligibleFiles(FileSystem fileSystem)
throws IOException {
+ List<FileStatus> files = new ArrayList<>();
+
+ FileStatus[] statuses = fileSystem.listStatus(new Path(path));
+ long maxModificationTime = Long.MIN_VALUE;
+ if (statuses == null) {
+ LOG.warn("Path does not exist: {}", path);
+ } else {
+ // handle the new files
+ for (FileStatus status : statuses) {
+ Path filePath = status.getPath();
+ long modificationTime =
status.getModificationTime();
+ if (!shouldIgnore(filePath, modificationTime)) {
+ files.add(status);
+ if(modificationTime >
maxModificationTime) {
--- End diff --
missing space after if
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