HADOOP-17038 Support disabling buffered reads in ABFS positional reads. (#2646)

- Contributed by @anoopsjohn

hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/AzureBlobFileSystem.java

@@ -30,9 +30,12 @@
 import java.util.Hashtable;
 import java.util.List;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.EnumSet;
 import java.util.Map;
+import java.util.Optional;
 import java.util.concurrent.Callable;
+import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
@@ -73,6 +76,8 @@
 import org.apache.hadoop.fs.azurebfs.contracts.services.AzureServiceErrorCode;
 import org.apache.hadoop.fs.azurebfs.security.AbfsDelegationTokenManager;
 import org.apache.hadoop.fs.azurebfs.services.AbfsCounters;
+import org.apache.hadoop.fs.impl.AbstractFSBuilderImpl;
+import org.apache.hadoop.fs.impl.OpenFileParameters;
 import org.apache.hadoop.fs.permission.AclEntry;
 import org.apache.hadoop.fs.permission.AclStatus;
 import org.apache.hadoop.fs.permission.FsAction;
@@ -82,6 +87,7 @@
 import org.apache.hadoop.security.token.Token;
 import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.util.functional.RemoteIterators;
+import org.apache.hadoop.util.LambdaUtils;
 import org.apache.hadoop.util.Progressable;
 
 import static org.apache.hadoop.fs.azurebfs.AbfsStatistic.*;
@@ -176,11 +182,18 @@ public URI getUri() {
   @Override
   public FSDataInputStream open(final Path path, final int bufferSize) throws IOException {
     LOG.debug("AzureBlobFileSystem.open path: {} bufferSize: {}", path, bufferSize);
+    // bufferSize is unused.
+    return open(path, Optional.empty());
+  }
+
+  private FSDataInputStream open(final Path path,
+      final Optional<Configuration> options) throws IOException {
     statIncrement(CALL_OPEN);
     Path qualifiedPath = makeQualified(path);
 
     try {
-      InputStream inputStream = abfsStore.openFileForRead(qualifiedPath, statistics);
+      InputStream inputStream = abfsStore.openFileForRead(qualifiedPath,
+          options, statistics);
       return new FSDataInputStream(inputStream);
     } catch(AzureBlobFileSystemException ex) {
       checkException(path, ex);
@@ -188,6 +201,19 @@ public FSDataInputStream open(final Path path, final int bufferSize) throws IOEx
     }
   }
 
+  @Override
+  protected CompletableFuture<FSDataInputStream> openFileWithOptions(
+      final Path path, final OpenFileParameters parameters) throws IOException {
+    LOG.debug("AzureBlobFileSystem.openFileWithOptions path: {}", path);
+    AbstractFSBuilderImpl.rejectUnknownMandatoryKeys(
+        parameters.getMandatoryKeys(),
+        Collections.emptySet(),
+        "for " + path);
+    return LambdaUtils.eval(
+        new CompletableFuture<>(), () ->
+            open(path, Optional.of(parameters.getOptions())));
+  }
+
   @Override
   public FSDataOutputStream create(final Path f, final FsPermission permission, final boolean overwrite, final int bufferSize,
       final short replication, final long blockSize, final Progressable progress) throws IOException {

hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/AzureBlobFileSystemStore.java

@@ -46,6 +46,7 @@
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 
 import org.apache.hadoop.thirdparty.com.google.common.annotations.VisibleForTesting;
@@ -125,6 +126,7 @@
 import static org.apache.hadoop.fs.azurebfs.constants.AbfsHttpConstants.SINGLE_WHITE_SPACE;
 import static org.apache.hadoop.fs.azurebfs.constants.AbfsHttpConstants.TOKEN_VERSION;
 import static org.apache.hadoop.fs.azurebfs.constants.ConfigurationKeys.AZURE_ABFS_ENDPOINT;
+import static org.apache.hadoop.fs.azurebfs.constants.ConfigurationKeys.FS_AZURE_BUFFERED_PREAD_DISABLE;
 import static org.apache.hadoop.fs.azurebfs.constants.ConfigurationKeys.FS_AZURE_IDENTITY_TRANSFORM_CLASS;
 
 /**
@@ -606,7 +608,15 @@ public void createDirectory(final Path path, final FsPermission permission, fina
     }
   }
 
-  public AbfsInputStream openFileForRead(final Path path, final FileSystem.Statistics statistics)
+  public AbfsInputStream openFileForRead(final Path path,
+      final FileSystem.Statistics statistics)
+      throws AzureBlobFileSystemException {
+    return openFileForRead(path, Optional.empty(), statistics);
+  }
+
+  public AbfsInputStream openFileForRead(final Path path,
+      final Optional<Configuration> options,
+      final FileSystem.Statistics statistics)
       throws AzureBlobFileSystemException {
     try (AbfsPerfInfo perfInfo = startTracking("openFileForRead", "getPathStatus")) {
       LOG.debug("openFileForRead filesystem: {} path: {}",
@@ -635,12 +645,16 @@ public AbfsInputStream openFileForRead(final Path path, final FileSystem.Statist
       // Add statistics for InputStream
       return new AbfsInputStream(client, statistics,
               relativePath, contentLength,
-              populateAbfsInputStreamContext(),
+              populateAbfsInputStreamContext(options),
               eTag);
     }
   }
 
-  private AbfsInputStreamContext populateAbfsInputStreamContext() {
+  private AbfsInputStreamContext populateAbfsInputStreamContext(
+      Optional<Configuration> options) {
+    boolean bufferedPreadDisabled = options
+        .map(c -> c.getBoolean(FS_AZURE_BUFFERED_PREAD_DISABLE, false))
+        .orElse(false);
     return new AbfsInputStreamContext(abfsConfiguration.getSasTokenRenewPeriodForStreamsInSeconds())
             .withReadBufferSize(abfsConfiguration.getReadBufferSize())
             .withReadAheadQueueDepth(abfsConfiguration.getReadAheadQueueDepth())
@@ -651,6 +665,7 @@ private AbfsInputStreamContext populateAbfsInputStreamContext() {
             .withShouldReadBufferSizeAlways(
                 abfsConfiguration.shouldReadBufferSizeAlways())
             .withReadAheadBlockSize(abfsConfiguration.getReadAheadBlockSize())
+            .withBufferedPreadDisabled(bufferedPreadDisabled)
             .build();
   }
 

hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/constants/ConfigurationKeys.java

@@ -20,6 +20,7 @@
 
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.fs.FileSystem;
 
 /**
  * Responsible to keep all the Azure Blob File System configurations keys in Hadoop configuration file.
@@ -181,6 +182,12 @@ public static String accountProperty(String property, String account) {
   public static final String FS_AZURE_LOCAL_USER_SP_MAPPING_FILE_PATH = "fs.azure.identity.transformer.local.service.principal.mapping.file.path";
   /** Key for Local Group to Service Group file location. */
   public static final String FS_AZURE_LOCAL_GROUP_SG_MAPPING_FILE_PATH = "fs.azure.identity.transformer.local.service.group.mapping.file.path";
-
+  /**
+   * Optional config to enable a lock free pread which will bypass buffer in AbfsInputStream.
+   * This is not a config which can be set at cluster level. It can be used as
+   * an option on FutureDataInputStreamBuilder.
+   * @see FileSystem#openFile(org.apache.hadoop.fs.Path)
+   */
+  public static final String FS_AZURE_BUFFERED_PREAD_DISABLE = "fs.azure.buffered.pread.disable";
   private ConfigurationKeys() {}
 }

hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/services/AbfsInputStream.java

@@ -70,6 +70,14 @@ public class AbfsInputStream extends FSInputStream implements CanUnbuffer,
   private final boolean tolerateOobAppends; // whether tolerate Oob Appends
   private final boolean readAheadEnabled; // whether enable readAhead;
   private final boolean alwaysReadBufferSize;
+  /*
+   * By default the pread API will do a seek + read as in FSInputStream.
+   * The read data will be kept in a buffer. When bufferedPreadDisabled is true,
+   * the pread API will read only the specified amount of data from the given
+   * offset and the buffer will not come into use at all.
+   * @see #read(long, byte[], int, int)
+   */
+  private final boolean bufferedPreadDisabled;
 
   private boolean firstRead = true;
   // SAS tokens can be re-used until they expire
@@ -117,6 +125,8 @@ public AbfsInputStream(
     this.readAheadEnabled = true;
     this.alwaysReadBufferSize
         = abfsInputStreamContext.shouldReadBufferSizeAlways();
+    this.bufferedPreadDisabled = abfsInputStreamContext
+        .isBufferedPreadDisabled();
     this.cachedSasToken = new CachedSASToken(
         abfsInputStreamContext.getSasTokenRenewPeriodForStreamsInSeconds());
     this.streamStatistics = abfsInputStreamContext.getStreamStatistics();
@@ -135,6 +145,41 @@ public String getPath() {
     return path;
   }
 
+  @Override
+  public int read(long position, byte[] buffer, int offset, int length)
+      throws IOException {
+    // When bufferedPreadDisabled = true, this API does not use any shared buffer,
+    // cursor position etc. So this is implemented as NOT synchronized. HBase
+    // kind of random reads on a shared file input stream will greatly get
+    // benefited by such implementation.
+    // Strict close check at the begin of the API only not for the entire flow.
+    synchronized (this) {
+      if (closed) {
+        throw new IOException(FSExceptionMessages.STREAM_IS_CLOSED);
+      }
+    }
+    LOG.debug("pread requested offset = {} len = {} bufferedPreadDisabled = {}",
+        offset, length, bufferedPreadDisabled);
+    if (!bufferedPreadDisabled) {
+      return super.read(position, buffer, offset, length);
+    }
+    validatePositionedReadArgs(position, buffer, offset, length);
+    if (length == 0) {
+      return 0;
+    }
+    if (streamStatistics != null) {
+      streamStatistics.readOperationStarted();
+    }
+    int bytesRead = readRemote(position, buffer, offset, length);
+    if (statistics != null) {
+      statistics.incrementBytesRead(bytesRead);
+    }
+    if (streamStatistics != null) {
+      streamStatistics.bytesRead(bytesRead);
+    }
+    return bytesRead;
+  }
+
   @Override
   public int read() throws IOException {
     byte[] b = new byte[1];

hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azurebfs/services/AbfsInputStreamContext.java

@@ -44,6 +44,8 @@ public class AbfsInputStreamContext extends AbfsStreamContext {
 
   private boolean optimizeFooterRead;
 
+  private boolean bufferedPreadDisabled;
+
   public AbfsInputStreamContext(final long sasTokenRenewPeriodForStreamsInSeconds) {
     super(sasTokenRenewPeriodForStreamsInSeconds);
   }
@@ -97,6 +99,12 @@ public AbfsInputStreamContext withReadAheadBlockSize(
     return this;
   }
 
+  public AbfsInputStreamContext withBufferedPreadDisabled(
+      final boolean bufferedPreadDisabled) {
+    this.bufferedPreadDisabled = bufferedPreadDisabled;
+    return this;
+  }
+
   public AbfsInputStreamContext build() {
     if (readBufferSize > readAheadBlockSize) {
       LOG.debug(
@@ -142,4 +150,7 @@ public int getReadAheadBlockSize() {
     return readAheadBlockSize;
   }
 
+  public boolean isBufferedPreadDisabled() {
+    return bufferedPreadDisabled;
+  }
 }

hadoop-tools/hadoop-azure/src/site/markdown/abfs.md

@@ -812,6 +812,16 @@ aheads. Specify the value in bytes. The value should be between 16384 to
 104857600 both inclusive (16 KB to 100 MB). The default value will be
 4194304 (4 MB).
 
+`fs.azure.buffered.pread.disable`: By default the positional read API will do a
+seek and read on input stream. This read will fill the buffer cache in
+AbfsInputStream and update the cursor positions. If this optimization is true
+it will skip usage of buffer and do a lock free REST call for reading from blob.
+This optimization is very much helpful for HBase kind of short random read over
+a shared AbfsInputStream instance.
+Note: This is not a config which can be set at cluster level. It can be used as
+an option on FutureDataInputStreamBuilder.
+See FileSystem#openFile(Path path)
+
 To run under limited memory situations configure the following. Especially
 when there are too many writes from the same process. 
 

hadoop-tools/hadoop-azure/src/test/java/org/apache/hadoop/fs/azurebfs/services/ITestAbfsPositionedRead.java

@@ -0,0 +1,233 @@
+/**
+ * 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.hadoop.fs.azurebfs.services;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.concurrent.ExecutionException;
+
+import org.junit.Rule;
+import org.junit.rules.TestName;
+import org.junit.Test;
+
+import org.apache.hadoop.fs.FSDataInputStream;
+import org.apache.hadoop.fs.FutureDataInputStreamBuilder;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.fs.azurebfs.AbstractAbfsIntegrationTest;
+import org.apache.hadoop.fs.azurebfs.constants.ConfigurationKeys;
+import org.apache.hadoop.fs.contract.ContractTestUtils;
+import org.apache.hadoop.fs.statistics.IOStatistics;
+import org.apache.hadoop.fs.statistics.StreamStatisticNames;
+import org.assertj.core.api.Assertions;
+
+public class ITestAbfsPositionedRead extends AbstractAbfsIntegrationTest {
+
+  private static final int TEST_FILE_DATA_SIZE = 100;
+
+  @Rule
+  public TestName methodName = new TestName();
+
+  public ITestAbfsPositionedRead() throws Exception {
+  }
+
+  @Test
+  public void testPositionedRead() throws IOException {
+    describe("Testing positioned reads in AbfsInputStream");
+    Path dest = path(methodName.getMethodName());
+
+    byte[] data = ContractTestUtils.dataset(TEST_FILE_DATA_SIZE, 'a', 'z');
+    ContractTestUtils.writeDataset(getFileSystem(), dest, data, data.length,
+        TEST_FILE_DATA_SIZE, true);
+    int bytesToRead = 10;
+    try (FSDataInputStream inputStream = getFileSystem().open(dest)) {
+      assertTrue(
+          "unexpected stream type "
+              + inputStream.getWrappedStream().getClass().getSimpleName(),
+          inputStream.getWrappedStream() instanceof AbfsInputStream);
+      byte[] readBuffer = new byte[bytesToRead];
+      int readPos = 0;
+      Assertions
+          .assertThat(inputStream.read(readPos, readBuffer, 0, bytesToRead))
+          .describedAs(
+              "AbfsInputStream pread did not read the correct number of bytes")
+          .isEqualTo(bytesToRead);
+      Assertions.assertThat(readBuffer)
+          .describedAs("AbfsInputStream pread did not read correct data")
+          .containsExactly(
+              Arrays.copyOfRange(data, readPos, readPos + bytesToRead));
+      // Read only 10 bytes from offset 0. But by default it will do the seek
+      // and read where the entire 100 bytes get read into the
+      // AbfsInputStream buffer.
+      Assertions
+          .assertThat(Arrays.copyOfRange(
+              ((AbfsInputStream) inputStream.getWrappedStream()).getBuffer(), 0,
+              TEST_FILE_DATA_SIZE))
+          .describedAs(
+              "AbfsInputStream pread did not read more data into its buffer")
+          .containsExactly(data);
+      // Check statistics
+      assertStatistics(inputStream.getIOStatistics(), bytesToRead, 1, 1,
+          TEST_FILE_DATA_SIZE);
+
+      readPos = 50;
+      Assertions
+          .assertThat(inputStream.read(readPos, readBuffer, 0, bytesToRead))
+          .describedAs(
+              "AbfsInputStream pread did not read the correct number of bytes")
+          .isEqualTo(bytesToRead);
+      Assertions.assertThat(readBuffer)
+          .describedAs("AbfsInputStream pread did not read correct data")
+          .containsExactly(
+              Arrays.copyOfRange(data, readPos, readPos + bytesToRead));
+      // Check statistics
+      assertStatistics(inputStream.getIOStatistics(), 2 * bytesToRead, 2, 1,
+          TEST_FILE_DATA_SIZE);
+      // Did positioned read from pos 0 and then 50 but the stream pos should
+      // remain at 0.
+      Assertions.assertThat(inputStream.getPos())
+          .describedAs("AbfsInputStream positioned reads moved stream position")
+          .isEqualTo(0);
+    }
+  }
+
+  private void assertStatistics(IOStatistics ioStatistics,
+      long expectedBytesRead, long expectedReadOps, long expectedRemoteReadOps,
+      long expectedRemoteReadBytes) {
+    Assertions
+        .assertThat(ioStatistics.counters()
+            .get(StreamStatisticNames.STREAM_READ_BYTES).longValue())
+        .describedAs("Mismatch in bytesRead statistics")
+        .isEqualTo(expectedBytesRead);
+    Assertions
+        .assertThat(ioStatistics.counters()
+            .get(StreamStatisticNames.STREAM_READ_OPERATIONS).longValue())
+        .describedAs("Mismatch in readOps statistics")
+        .isEqualTo(expectedReadOps);
+    Assertions
+        .assertThat(ioStatistics.counters()
+            .get(StreamStatisticNames.REMOTE_READ_OP).longValue())
+        .describedAs("Mismatch in remoteReadOps statistics")
+        .isEqualTo(expectedRemoteReadOps);
+    Assertions
+        .assertThat(ioStatistics.counters()
+            .get(StreamStatisticNames.REMOTE_BYTES_READ).longValue())
+        .describedAs("Mismatch in remoteReadBytes statistics")
+        .isEqualTo(expectedRemoteReadBytes);
+  }
+
+  @Test
+  public void testPositionedReadWithBufferedReadDisabled() throws IOException {
+    describe("Testing positioned reads in AbfsInputStream with BufferedReadDisabled");
+    Path dest = path(methodName.getMethodName());
+    byte[] data = ContractTestUtils.dataset(TEST_FILE_DATA_SIZE, 'a', 'z');
+    ContractTestUtils.writeDataset(getFileSystem(), dest, data, data.length,
+        TEST_FILE_DATA_SIZE, true);
+    FutureDataInputStreamBuilder builder = getFileSystem().openFile(dest);
+    builder.opt(ConfigurationKeys.FS_AZURE_BUFFERED_PREAD_DISABLE, true);
+    FSDataInputStream inputStream = null;
+    try {
+      inputStream = builder.build().get();
+    } catch (IllegalArgumentException | UnsupportedOperationException
+        | InterruptedException | ExecutionException e) {
+      throw new IOException(
+          "Exception opening " + dest + " with FutureDataInputStreamBuilder",
+          e);
+    }
+    assertNotNull("Null InputStream over " + dest, inputStream);
+    int bytesToRead = 10;
+    try {
+      AbfsInputStream abfsIs = (AbfsInputStream) inputStream.getWrappedStream();
+      byte[] readBuffer = new byte[bytesToRead];
+      int readPos = 10;
+      Assertions
+          .assertThat(inputStream.read(readPos, readBuffer, 0, bytesToRead))
+          .describedAs(
+              "AbfsInputStream pread did not read the correct number of bytes")
+          .isEqualTo(bytesToRead);
+      Assertions.assertThat(readBuffer)
+          .describedAs("AbfsInputStream pread did not read correct data")
+          .containsExactly(
+              Arrays.copyOfRange(data, readPos, readPos + bytesToRead));
+      // Read only 10 bytes from offset 10. This time, as buffered pread is
+      // disabled, it will only read the exact bytes as requested and no data
+      // will get read into the AbfsInputStream#buffer. Infact the buffer won't
+      // even get initialized.
+      assertNull("AbfsInputStream pread caused the internal buffer creation",
+          abfsIs.getBuffer());
+      // Check statistics
+      assertStatistics(inputStream.getIOStatistics(), bytesToRead, 1, 1,
+          bytesToRead);
+      readPos = 40;
+      Assertions
+          .assertThat(inputStream.read(readPos, readBuffer, 0, bytesToRead))
+          .describedAs(
+              "AbfsInputStream pread did not read the correct number of bytes")
+          .isEqualTo(bytesToRead);
+      Assertions.assertThat(readBuffer)
+          .describedAs("AbfsInputStream pread did not read correct data")
+          .containsExactly(
+              Arrays.copyOfRange(data, readPos, readPos + bytesToRead));
+      assertStatistics(inputStream.getIOStatistics(), 2 * bytesToRead, 2, 2,
+          2 * bytesToRead);
+      // Now make a seek and read so that internal buffer gets created
+      inputStream.seek(0);
+      Assertions.assertThat(inputStream.read(readBuffer)).describedAs(
+          "AbfsInputStream seek+read did not read the correct number of bytes")
+          .isEqualTo(bytesToRead);
+      // This read would have fetched all 100 bytes into internal buffer.
+      Assertions
+          .assertThat(Arrays.copyOfRange(
+              ((AbfsInputStream) inputStream.getWrappedStream()).getBuffer(), 0,
+              TEST_FILE_DATA_SIZE))
+          .describedAs(
+              "AbfsInputStream seek+read did not read more data into its buffer")
+          .containsExactly(data);
+      assertStatistics(inputStream.getIOStatistics(), 3 * bytesToRead, 3, 3,
+          TEST_FILE_DATA_SIZE + 2 * bytesToRead);
+      resetBuffer(abfsIs.getBuffer());
+      // Now again do pos read and make sure not any extra data being fetched.
+      readPos = 0;
+      Assertions
+          .assertThat(inputStream.read(readPos, readBuffer, 0, bytesToRead))
+          .describedAs(
+              "AbfsInputStream pread did not read the correct number of bytes")
+          .isEqualTo(bytesToRead);
+      Assertions.assertThat(readBuffer)
+          .describedAs("AbfsInputStream pread did not read correct data")
+          .containsExactly(
+              Arrays.copyOfRange(data, readPos, readPos + bytesToRead));
+      Assertions
+          .assertThat(Arrays.copyOfRange(
+              ((AbfsInputStream) inputStream.getWrappedStream()).getBuffer(), 0,
+              TEST_FILE_DATA_SIZE))
+          .describedAs(
+              "AbfsInputStream pread read more data into its buffer than expected")
+          .doesNotContain(data);
+      assertStatistics(inputStream.getIOStatistics(), 4 * bytesToRead, 4, 4,
+          TEST_FILE_DATA_SIZE + 3 * bytesToRead);
+    } finally {
+      inputStream.close();
+    }
+  }
+
+  private void resetBuffer(byte[] buf) {
+    for (int i = 0; i < buf.length; i++) {
+      buf[i] = (byte) 0;
+    }
+  }
+}