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From GitBox <...@apache.org>
Subject [GitHub] [flink] Ryantaocer commented on a change in pull request #8290: [FLINK-12070] [network] Implement new bounded blocking subpartitions
Date Mon, 06 May 2019 03:21:52 GMT
Ryantaocer commented on a change in pull request #8290: [FLINK-12070] [network] Implement new
bounded blocking subpartitions
URL: https://github.com/apache/flink/pull/8290#discussion_r281054990
 
 

 ##########
 File path: flink-runtime/src/main/java/org/apache/flink/runtime/io/network/partition/BoundedBlockingSubpartition.java
 ##########
 @@ -0,0 +1,416 @@
+/*
+ * 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.runtime.io.network.partition;
+
+import org.apache.flink.annotation.VisibleForTesting;
+import org.apache.flink.runtime.io.network.api.EndOfPartitionEvent;
+import org.apache.flink.runtime.io.network.api.serialization.EventSerializer;
+import org.apache.flink.runtime.io.network.buffer.Buffer;
+import org.apache.flink.runtime.io.network.buffer.BufferConsumer;
+import org.apache.flink.runtime.io.network.partition.BoundedBlockingSubpartitionMemory.Writer;
+import org.apache.flink.util.FlinkRuntimeException;
+import org.apache.flink.util.IOUtils;
+
+import org.apache.flink.shaded.netty4.io.netty.util.internal.PlatformDependent;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.GuardedBy;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+import java.nio.channels.FileChannel.MapMode;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardOpenOption;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import static org.apache.flink.util.Preconditions.checkArgument;
+import static org.apache.flink.util.Preconditions.checkState;
+
+/**
+ * An implementation of the ResultSubpartition for a bounded result transferred
+ * in a blocking manner: The result is first produced, then consumed.
+ * The result can be consumed possibly multiple times.
+ *
+ * <p>The implementation creates a temporary memory mapped file and writes all buffers
to that
+ * memory and serves the result from that memory. The kernel backs the mapped memory region
+ * with physical memory and file space incrementally as new pages are filled.
+ */
+class BoundedBlockingSubpartition extends ResultSubpartition {
+
+	/** This lock guards the creation of readers and disposal of the memory mapped file. */
+	private final Object lock = new Object();
+
+	/** The current buffer, may be filled further over time. */
+	@Nullable
+	private BufferConsumer currentBuffer;
+
+	/** The memory that we store the data in, via a memory mapped file. */
+	private final MemoryMappedBuffers memory;
+
+	/** All created and not yet released readers. */
+	@GuardedBy("lock")
+	private final Set<BoundedBlockingSubpartitionReader> readers;
+
+	/** Counter for the number of data buffers (not events!) written. */
+	private int numDataBuffersWritten;
+
+	/** The counter for the number of data buffers and events. */
+	private int numBuffersAndEventsWritten;
+
+	/** Flag indicating whether the writing has finished and this is now available for read.
*/
+	private boolean isFinished;
+
+	/** Flag indicating whether the subpartition has been released. */
+	private boolean isReleased;
+
+	/**
+	 * Common constructor.
+	 */
+	public BoundedBlockingSubpartition(
+			int index,
+			ResultPartition parent,
+			Path filePath) throws IOException {
+		this(index, parent, filePath, Integer.MAX_VALUE);
+	}
+
+	/**
+	 * Constructor for testing. By default regions are rolled over at 2GB (max size of direct
buffers
+	 * in Java). This constructor allows tests to pass in a smaller threshold to test rolling
over
+	 * without having to actually produce more than 2GB during testing.
+	 */
+	@VisibleForTesting
+	BoundedBlockingSubpartition(
+			int index,
+			ResultPartition parent,
+			Path filePath,
+			int maxMMapRegionSize) throws IOException {
+
+		super(index, parent);
+
+		final FileChannel fc = FileChannel.open(filePath,
+				StandardOpenOption.READ, StandardOpenOption.WRITE, StandardOpenOption.CREATE_NEW);
+
+		this.memory = new MemoryMappedBuffers(filePath, fc, maxMMapRegionSize);
+		this.readers = new HashSet<>();
+	}
+
+	// ------------------------------------------------------------------------
+
+	/**
+	 * Checks if writing is finished.
+	 * Readers cannot be created until writing is finished, and no further writes can happen
after that.
+	 */
+	public boolean isFinished() {
+		return isFinished;
+	}
+
+	@Override
+	public boolean isReleased() {
+		return isReleased;
+	}
+
+	@Override
+	public boolean add(BufferConsumer bufferConsumer) throws IOException {
+		if (isFinished()) {
+			bufferConsumer.close();
+			return false;
+		}
+
+		flushCurrentBuffer();
 
 Review comment:
   Should catch `IOException` from `flushCurrentBuffer` just like `flush()`?

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