[BEAM-143] add test for UnboundedSourceWrapper

runners/flink/runner/src/main/java/org/apache/beam/runners/flink/translation/wrappers/streaming/io/UnboundedSourceWrapper.java

@@ -17,6 +17,7 @@
  */
 package org.apache.beam.runners.flink.translation.wrappers.streaming.io;
 
+import com.fasterxml.jackson.databind.ObjectMapper;
 import com.google.cloud.dataflow.sdk.io.Read;
 import com.google.cloud.dataflow.sdk.io.UnboundedSource;
 import com.google.cloud.dataflow.sdk.options.PipelineOptions;
@@ -31,26 +32,36 @@
 import org.apache.flink.streaming.runtime.operators.Triggerable;
 import org.joda.time.Instant;
 
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+
 /**
- * A wrapper for Beam's unbounded sources. This class wraps around a source implementing the {@link com.google.cloud.dataflow.sdk.io.Read.Unbounded}
- * interface.
+ * A wrapper for Beam's unbounded sources. This class wraps around a source implementing the
+ * {@link com.google.cloud.dataflow.sdk.io.Read.Unbounded}  interface.
  *
- *</p>
- * For now we support non-parallel, not checkpointed sources.
+ * For now we only support non-parallel sources.
  * */
 public class UnboundedSourceWrapper<T> extends RichSourceFunction<WindowedValue<T>> implements Triggerable {
 
   private final String name;
-  private final UnboundedSource.UnboundedReader<T> reader;
+  private final UnboundedSource<T, ?> source;
 
   private StreamingRuntimeContext runtime = null;
   private StreamSource.ManualWatermarkContext<WindowedValue<T>> context = null;
 
   private volatile boolean isRunning = false;
 
-  public UnboundedSourceWrapper(PipelineOptions options, Read.Unbounded<T> transform) {
+  /** Serialized using custom Java serialization via Jackson */
+  private transient PipelineOptions pipelineOptions;
+
+  /** Instantiated during runtime **/
+  private transient UnboundedSource.UnboundedReader<T> reader;
+
+  public UnboundedSourceWrapper(PipelineOptions pipelineOptions, Read.Unbounded<T> transform) {
     this.name = transform.getName();
-    this.reader = transform.getSource().createReader(options, null);
+    this.pipelineOptions = pipelineOptions;
+    this.source = transform.getSource();
   }
 
   public String getName() {
@@ -67,40 +78,51 @@ WindowedValue<T> makeWindowedValue(T output, Instant timestamp) {
   @Override
   public void run(SourceContext<WindowedValue<T>> ctx) throws Exception {
     if (!(ctx instanceof StreamSource.ManualWatermarkContext)) {
-      throw new RuntimeException("We assume that all sources in Dataflow are EventTimeSourceFunction. " +
-          "Apparently " + this.name + " is not. Probably you should consider writing your own Wrapper for this source.");
+      throw new RuntimeException(
+          "We assume that all sources in Dataflow are EventTimeSourceFunction. " +
+              "Apparently " + this.name + " is not. " +
+              "Probably you should consider writing your own Wrapper for this source.");
     }
 
     context = (StreamSource.ManualWatermarkContext<WindowedValue<T>>) ctx;
     runtime = (StreamingRuntimeContext) getRuntimeContext();
 
-    this.isRunning = true;
+    isRunning = true;
+
+    reader = source.createReader(pipelineOptions, null);
+
     boolean inputAvailable = reader.start();
 
     setNextWatermarkTimer(this.runtime);
 
-    while (isRunning) {
-
-      while (!inputAvailable && isRunning) {
-        // wait a bit until we retry to pull more records
-        Thread.sleep(50);
-        inputAvailable = reader.advance();
-      }
 
-      if (inputAvailable) {
+    try {
 
-        // get it and its timestamp from the source
-        T item = reader.getCurrent();
-        Instant timestamp = reader.getCurrentTimestamp();
+      while (isRunning) {
 
-        // write it to the output collector
-        synchronized (ctx.getCheckpointLock()) {
-          context.collectWithTimestamp(makeWindowedValue(item, timestamp), timestamp.getMillis());
+        if (!inputAvailable && isRunning) {
+          // wait a bit until we retry to pull more records
+          Thread.sleep(50);
+          inputAvailable = reader.advance();
         }
 
-        inputAvailable = reader.advance();
+        if (inputAvailable) {
+
+          // get it and its timestamp from the source
+          T item = reader.getCurrent();
+          Instant timestamp = reader.getCurrentTimestamp();
+
+          // write it to the output collector
+          synchronized (ctx.getCheckpointLock()) {
+            context.collectWithTimestamp(makeWindowedValue(item, timestamp), timestamp.getMillis());
+          }
+
+          inputAvailable = reader.advance();
+        }
       }
 
+    } finally {
+      reader.close();
     }
   }
 
@@ -131,4 +153,19 @@ private void setNextWatermarkTimer(StreamingRuntimeContext runtime) {
   private long getTimeToNextWaternark(long watermarkInterval) {
     return System.currentTimeMillis() + watermarkInterval;
   }
+
+
+  // Special serialization of the PipelineOptions necessary to instantiate the reader.
+  private void writeObject(ObjectOutputStream out) throws IOException, ClassNotFoundException {
+    out.defaultWriteObject();
+    ObjectMapper mapper = new ObjectMapper();
+    mapper.writeValue(out, pipelineOptions);
+  }
+
+  // Special deserialization of the PipelineOptions necessary to instantiate the reader.
+  private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
+    in.defaultReadObject();
+    ObjectMapper mapper = new ObjectMapper();
+    pipelineOptions = mapper.readValue(in, PipelineOptions.class);
+  }
 }

runners/flink/runner/src/test/java/org/apache/beam/runners/flink/streaming/UnboundedSourceITCase.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.beam.runners.flink.streaming;
+
+import com.google.cloud.dataflow.sdk.Pipeline;
+import com.google.cloud.dataflow.sdk.coders.BigEndianIntegerCoder;
+import com.google.cloud.dataflow.sdk.coders.Coder;
+import com.google.cloud.dataflow.sdk.io.Read;
+import com.google.cloud.dataflow.sdk.io.TextIO;
+import com.google.cloud.dataflow.sdk.io.UnboundedSource;
+import com.google.cloud.dataflow.sdk.options.PipelineOptions;
+import com.google.cloud.dataflow.sdk.transforms.DoFn;
+import com.google.cloud.dataflow.sdk.transforms.ParDo;
+import com.google.cloud.dataflow.sdk.transforms.windowing.AfterPane;
+import com.google.cloud.dataflow.sdk.transforms.windowing.BoundedWindow;
+import com.google.cloud.dataflow.sdk.transforms.windowing.GlobalWindow;
+import com.google.cloud.dataflow.sdk.transforms.windowing.GlobalWindows;
+import com.google.cloud.dataflow.sdk.transforms.windowing.PaneInfo;
+import com.google.cloud.dataflow.sdk.transforms.windowing.Window;
+import com.google.cloud.dataflow.sdk.util.WindowedValue;
+import com.google.cloud.dataflow.sdk.values.PCollection;
+import com.google.common.base.Joiner;
+import org.apache.beam.runners.flink.FlinkTestPipeline;
+import org.apache.flink.streaming.util.StreamingProgramTestBase;
+import org.joda.time.Instant;
+import org.junit.internal.ArrayComparisonFailure;
+
+import javax.annotation.Nullable;
+import java.io.IOException;
+import java.util.List;
+import java.util.NoSuchElementException;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+
+
+public class UnboundedSourceITCase extends StreamingProgramTestBase {
+
+  protected static String resultPath;
+
+  public UnboundedSourceITCase() {
+  }
+
+  static final String[] EXPECTED_RESULT = new String[]{
+      "1", "2", "3", "4", "5", "6", "7", "8", "9"};
+
+  @Override
+  protected void preSubmit() throws Exception {
+    resultPath = getTempDirPath("result");
+  }
+
+  @Override
+  protected void postSubmit() throws Exception {
+    compareResultsByLinesInMemory(Joiner.on('\n').join(EXPECTED_RESULT), resultPath);
+  }
+
+  @Override
+  protected void testProgram() throws Exception {
+    runProgram(resultPath);
+  }
+
+  private static void runProgram(String resultPath) {
+
+    Pipeline p = FlinkTestPipeline.createForStreaming();
+
+    PCollection<String> result = p
+        .apply(Read.from(new RangeReadSource(1, 10)))
+        .apply(Window.<Integer>into(new GlobalWindows())
+            .triggering(AfterPane.elementCountAtLeast(10))
+            .discardingFiredPanes())
+        .apply(ParDo.of(new DoFn<Integer, String>() {
+          @Override
+          public void processElement(ProcessContext c) throws Exception {
+            c.output(c.element().toString());
+          }
+        }));
+
+    result.apply(TextIO.Write.to(resultPath));
+
+    try {
+      p.run();
+    } catch(Exception e) {
+      assertEquals("The source terminates as expected.", e.getCause().getCause().getMessage());
+    }
+  }
+
+
+  private static class RangeReadSource extends UnboundedSource<Integer, UnboundedSource.CheckpointMark> {
+
+    final int from;
+    final int to;
+
+    RangeReadSource(int from, int to) {
+      this.from = from;
+      this.to = to;
+    }
+
+
+    @Override
+    public List<? extends UnboundedSource<Integer, CheckpointMark>> generateInitialSplits(
+        int desiredNumSplits, PipelineOptions options) throws Exception {
+      return null;
+    }
+
+    @Override
+    public UnboundedReader<Integer> createReader(PipelineOptions options, @Nullable CheckpointMark checkpointMark) {
+      return new RangeReadReader(options);
+    }
+
+    @Nullable
+    @Override
+    public Coder<CheckpointMark> getCheckpointMarkCoder() {
+      return null;
+    }
+
+    @Override
+    public void validate() {
+    }
+
+    @Override
+    public Coder<Integer> getDefaultOutputCoder() {
+      return BigEndianIntegerCoder.of();
+    }
+
+    private class RangeReadReader extends UnboundedReader<Integer> {
+
+      private int current;
+
+      public RangeReadReader(PipelineOptions options) {
+        assertNotNull(options);
+        current = from;
+      }
+
+      @Override
+      public boolean start() throws IOException {
+        return true;
+      }
+
+      @Override
+      public boolean advance() throws IOException {
+        current++;
+        if (current >= to) {
+          try {
+            compareResultsByLinesInMemory(Joiner.on('\n').join(EXPECTED_RESULT), resultPath);
+            throw new IOException("The source terminates as expected.");
+          } catch (IOException e) {
+            // pass on the exception to terminate the source
+            throw e;
+          } catch (Throwable t) {
+            // expected here from the file check
+          }
+        }
+        return current < to;
+      }
+
+      @Override
+      public Integer getCurrent() throws NoSuchElementException {
+        return current;
+      }
+
+      @Override
+      public Instant getCurrentTimestamp() throws NoSuchElementException {
+        return Instant.now();
+      }
+
+      @Override
+      public void close() throws IOException {
+      }
+
+      @Override
+      public Instant getWatermark() {
+        return Instant.now();
+      }
+
+      @Override
+      public CheckpointMark getCheckpointMark() {
+        return null;
+      }
+
+      @Override
+      public UnboundedSource<Integer, ?> getCurrentSource() {
+        return RangeReadSource.this;
+      }
+    }
+  }
+}
+
+