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https://issues.apache.org/jira/browse/FLINK-3889?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15286304#comment-15286304
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ASF GitHub Bot commented on FLINK-3889:
---------------------------------------
Github user aljoscha commented on a diff in the pull request:
https://github.com/apache/flink/pull/1984#discussion_r63492862
--- 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;
--- End diff --
I think this should also go into the synchronized block, so that forwarding
and changing the state is atomic.
> Make File Monitoring Function checkpointable.
> ---------------------------------------------
>
> Key: FLINK-3889
> URL: https://issues.apache.org/jira/browse/FLINK-3889
> Project: Flink
> Issue Type: Sub-task
> Components: Streaming
> Reporter: Kostas Kloudas
> Assignee: Kostas Kloudas
>
> This is essentially the combination of FLINK-3808 and FLINK-3717.
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