HDFS-3246: pRead equivalent for direct read path

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/ByteBufferPositionedReadable.java

@@ -0,0 +1,66 @@
+/**
+ * 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;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
+/**
+ * Implementers of this interface provide a positioned read API that writes to a
+ * {@link ByteBuffer} rather than a {@code byte[]}.
+ *
+ * @see PositionedReadable
+ * @see ByteBufferReadable
+ */
+@InterfaceAudience.Public
+@InterfaceStability.Evolving
+public interface ByteBufferPositionedReadable {
+  /**
+   * Reads up to {@code buf.remaining()} bytes into buf from a given position
+   * in the file and returns the number of bytes read. Callers should use
+   * {@code buf.limit(...)} to control the size of the desired read and
+   * {@code buf.position(...)} to control the offset into the buffer the data
+   * should be written to.
+   * <p>
+   * After a successful call, {@code buf.position()} will be advanced by the
+   * number of bytes read and {@code buf.limit()} will be unchanged.
+   * <p>
+   * In the case of an exception, the state of the buffer (the contents of the
+   * buffer, the {@code buf.position()}, the {@code buf.limit()}, etc.) is
+   * undefined, and callers should be prepared to recover from this
+   * eventuality.
+   * <p>
+   * Callers should use {@link StreamCapabilities#hasCapability(String)} with
+   * {@link StreamCapabilities#PREADBYTEBUFFER} to check if the underlying
+   * stream supports this interface, otherwise they might get a
+   * {@link UnsupportedOperationException}.
+   * <p>
+   * Implementations should treat 0-length requests as legitimate, and must not
+   * signal an error upon their receipt.
+   *
+   * @param position position within file
+   * @param buf the ByteBuffer to receive the results of the read operation.
+   * @return the number of bytes read, possibly zero, or -1 if reached
+   *         end-of-stream
+   * @throws IOException if there is some error performing the read
+   */
+  int read(long position, ByteBuffer buf) throws IOException;
+}

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/ByteBufferReadable.java

@@ -19,6 +19,7 @@
 
 import java.io.IOException;
 import java.nio.ByteBuffer;
+
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.classification.InterfaceStability;
 
@@ -33,16 +34,18 @@ public interface ByteBufferReadable {
    * Reads up to buf.remaining() bytes into buf. Callers should use
    * buf.limit(..) to control the size of the desired read.
    * <p>
-   * After a successful call, buf.position() will be advanced by the number 
-   * of bytes read and buf.limit() should be unchanged.
+   * After a successful call, {@code buf.position()} will be advanced by the
+   * number of bytes read and {@code buf.limit()} will be unchanged.
    * <p>
-   * In the case of an exception, the values of buf.position() and buf.limit()
-   * are undefined, and callers should be prepared to recover from this
+   * In the case of an exception, the state of the buffer (the contents of the
+   * buffer, the {@code buf.position()}, the {@code buf.limit()}, etc.) is
+   * undefined, and callers should be prepared to recover from this
    * eventuality.
    * <p>
-   * Many implementations will throw {@link UnsupportedOperationException}, so
-   * callers that are not confident in support for this method from the
-   * underlying filesystem should be prepared to handle that exception.
+   * Callers should use {@link StreamCapabilities#hasCapability(String)} with
+   * {@link StreamCapabilities#READBYTEBUFFER} to check if the underlying
+   * stream supports this interface, otherwise they might get a
+   * {@link UnsupportedOperationException}.
    * <p>
    * Implementations should treat 0-length requests as legitimate, and must not
    * signal an error upon their receipt.

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FSDataInputStream.java

@@ -39,7 +39,8 @@
 public class FSDataInputStream extends DataInputStream
     implements Seekable, PositionedReadable, 
       ByteBufferReadable, HasFileDescriptor, CanSetDropBehind, CanSetReadahead,
-      HasEnhancedByteBufferAccess, CanUnbuffer, StreamCapabilities {
+      HasEnhancedByteBufferAccess, CanUnbuffer, StreamCapabilities,
+      ByteBufferPositionedReadable {
   /**
    * Map ByteBuffers that we have handed out to readers to ByteBufferPool 
    * objects
@@ -148,7 +149,8 @@ public int read(ByteBuffer buf) throws IOException {
       return ((ByteBufferReadable)in).read(buf);
     }
 
-    throw new UnsupportedOperationException("Byte-buffer read unsupported by input stream");
+    throw new UnsupportedOperationException("Byte-buffer read unsupported " +
+            "by input stream");
   }
 
   @Override
@@ -247,4 +249,13 @@ public boolean hasCapability(String capability) {
   public String toString() {
     return super.toString() + ": " + in;
   }
+
+  @Override
+  public int read(long position, ByteBuffer buf) throws IOException {
+    if (in instanceof ByteBufferPositionedReadable) {
+      return ((ByteBufferPositionedReadable) in).read(position, buf);
+    }
+    throw new UnsupportedOperationException("Byte-buffer pread unsupported " +
+        "by input stream");
+  }
 }

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/StreamCapabilities.java

@@ -65,6 +65,12 @@ public interface StreamCapabilities {
    */
   String READBYTEBUFFER = "in:readbytebuffer";
 
+  /**
+   * Stream read(long, ByteBuffer) capability implemented by
+   * {@link ByteBufferPositionedReadable#read(long, java.nio.ByteBuffer)}.
+   */
+  String PREADBYTEBUFFER = "in:preadbytebuffer";
+
   /**
    * Capabilities that a stream can support and be queried for.
    */

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/crypto/CryptoStreamsTestBase.java

@@ -26,6 +26,7 @@
 import java.util.EnumSet;
 import java.util.Random;
 
+import org.apache.hadoop.fs.ByteBufferPositionedReadable;
 import org.apache.hadoop.fs.ByteBufferReadable;
 import org.apache.hadoop.fs.CanUnbuffer;
 import org.apache.hadoop.fs.FSDataOutputStream;
@@ -129,6 +130,32 @@ private void preadCheck(PositionedReadable in) throws Exception {
     Assert.assertArrayEquals(result, expectedData);
   }
 
+  private int byteBufferPreadAll(ByteBufferPositionedReadable in,
+                                 ByteBuffer buf) throws IOException {
+    int n = 0;
+    int total = 0;
+    while (n != -1) {
+      total += n;
+      if (!buf.hasRemaining()) {
+        break;
+      }
+      n = in.read(total, buf);
+    }
+
+    return total;
+  }
+
+  private void byteBufferPreadCheck(ByteBufferPositionedReadable in)
+          throws Exception {
+    ByteBuffer result = ByteBuffer.allocate(dataLen);
+    int n = byteBufferPreadAll(in, result);
+
+    Assert.assertEquals(dataLen, n);
+    ByteBuffer expectedData = ByteBuffer.allocate(n);
+    expectedData.put(data, 0, n);
+    Assert.assertArrayEquals(result.array(), expectedData.array());
+  }
+
   protected OutputStream getOutputStream(int bufferSize) throws IOException {
     return getOutputStream(bufferSize, key, iv);
   }
@@ -288,20 +315,36 @@ private int readAll(InputStream in, long pos, byte[] b, int off, int len)
 
     return total;
   }
+
+  private int readAll(InputStream in, long pos, ByteBuffer buf)
+      throws IOException {
+    int n = 0;
+    int total = 0;
+    while (n != -1) {
+      total += n;
+      if (!buf.hasRemaining()) {
+        break;
+      }
+      n = ((ByteBufferPositionedReadable) in).read(pos + total, buf);
+    }
+
+    return total;
+  }
 
   /** Test positioned read. */
   @Test(timeout=120000)
   public void testPositionedRead() throws Exception {
-    OutputStream out = getOutputStream(defaultBufferSize);
-    writeData(out);
+    try (OutputStream out = getOutputStream(defaultBufferSize)) {
+      writeData(out);
+    }
 
-    InputStream in = getInputStream(defaultBufferSize);
-    // Pos: 1/3 dataLen
-    positionedReadCheck(in , dataLen / 3);
+    try (InputStream in = getInputStream(defaultBufferSize)) {
+      // Pos: 1/3 dataLen
+      positionedReadCheck(in, dataLen / 3);
 
-    // Pos: 1/2 dataLen
-    positionedReadCheck(in, dataLen / 2);
-    in.close();
+      // Pos: 1/2 dataLen
+      positionedReadCheck(in, dataLen / 2);
+    }
   }
 
   private void positionedReadCheck(InputStream in, int pos) throws Exception {
@@ -315,6 +358,35 @@ private void positionedReadCheck(InputStream in, int pos) throws Exception {
     System.arraycopy(data, pos, expectedData, 0, n);
     Assert.assertArrayEquals(readData, expectedData);
   }
+
+  /** Test positioned read with ByteBuffers. */
+  @Test(timeout=120000)
+  public void testPositionedReadWithByteBuffer() throws Exception {
+    try (OutputStream out = getOutputStream(defaultBufferSize)) {
+      writeData(out);
+    }
+
+    try (InputStream in = getInputStream(defaultBufferSize)) {
+      // Pos: 1/3 dataLen
+      positionedReadCheckWithByteBuffer(in, dataLen / 3);
+
+      // Pos: 1/2 dataLen
+      positionedReadCheckWithByteBuffer(in, dataLen / 2);
+    }
+  }
+
+  private void positionedReadCheckWithByteBuffer(InputStream in, int pos)
+          throws Exception {
+    ByteBuffer result = ByteBuffer.allocate(dataLen);
+    int n = readAll(in, pos, result);
+
+    Assert.assertEquals(dataLen, n + pos);
+    byte[] readData = new byte[n];
+    System.arraycopy(result.array(), 0, readData, 0, n);
+    byte[] expectedData = new byte[n];
+    System.arraycopy(data, pos, expectedData, 0, n);
+    Assert.assertArrayEquals(readData, expectedData);
+  }
 
   /** Test read fully */
   @Test(timeout=120000)
@@ -505,12 +577,40 @@ private void byteBufferReadCheck(InputStream in, ByteBuffer buf,
     System.arraycopy(data, 0, expectedData, 0, n);
     Assert.assertArrayEquals(readData, expectedData);
   }
+
+  private void byteBufferPreadCheck(InputStream in, ByteBuffer buf,
+      int bufPos) throws Exception {
+    // Test reading from position 0
+    buf.position(bufPos);
+    int n = ((ByteBufferPositionedReadable) in).read(0, buf);
+    Assert.assertEquals(bufPos + n, buf.position());
+    byte[] readData = new byte[n];
+    buf.rewind();
+    buf.position(bufPos);
+    buf.get(readData);
+    byte[] expectedData = new byte[n];
+    System.arraycopy(data, 0, expectedData, 0, n);
+    Assert.assertArrayEquals(readData, expectedData);
+
+    // Test reading from half way through the data
+    buf.position(bufPos);
+    n = ((ByteBufferPositionedReadable) in).read(dataLen / 2, buf);
+    Assert.assertEquals(bufPos + n, buf.position());
+    readData = new byte[n];
+    buf.rewind();
+    buf.position(bufPos);
+    buf.get(readData);
+    expectedData = new byte[n];
+    System.arraycopy(data, dataLen / 2, expectedData, 0, n);
+    Assert.assertArrayEquals(readData, expectedData);
+  }
 
   /** Test byte buffer read with different buffer size. */
   @Test(timeout=120000)
   public void testByteBufferRead() throws Exception {
-    OutputStream out = getOutputStream(defaultBufferSize);
-    writeData(out);
+    try (OutputStream out = getOutputStream(defaultBufferSize)) {
+      writeData(out);
+    }
 
     // Default buffer size, initial buffer position is 0
     InputStream in = getInputStream(defaultBufferSize);
@@ -560,6 +660,53 @@ public void testByteBufferRead() throws Exception {
     byteBufferReadCheck(in, buf, 11);
     in.close();
   }
+
+  /** Test byte buffer pread with different buffer size. */
+  @Test(timeout=120000)
+  public void testByteBufferPread() throws Exception {
+    try (OutputStream out = getOutputStream(defaultBufferSize)) {
+      writeData(out);
+    }
+
+    try (InputStream defaultBuf = getInputStream(defaultBufferSize);
+         InputStream smallBuf = getInputStream(smallBufferSize)) {
+
+      ByteBuffer buf = ByteBuffer.allocate(dataLen + 100);
+
+      // Default buffer size, initial buffer position is 0
+      byteBufferPreadCheck(defaultBuf, buf, 0);
+
+      // Default buffer size, initial buffer position is not 0
+      buf.clear();
+      byteBufferPreadCheck(defaultBuf, buf, 11);
+
+      // Small buffer size, initial buffer position is 0
+      buf.clear();
+      byteBufferPreadCheck(smallBuf, buf, 0);
+
+      // Small buffer size, initial buffer position is not 0
+      buf.clear();
+      byteBufferPreadCheck(smallBuf, buf, 11);
+
+      // Test with direct ByteBuffer
+      buf = ByteBuffer.allocateDirect(dataLen + 100);
+
+      // Direct buffer, default buffer size, initial buffer position is 0
+      byteBufferPreadCheck(defaultBuf, buf, 0);
+
+      // Direct buffer, default buffer size, initial buffer position is not 0
+      buf.clear();
+      byteBufferPreadCheck(defaultBuf, buf, 11);
+
+      // Direct buffer, small buffer size, initial buffer position is 0
+      buf.clear();
+      byteBufferPreadCheck(smallBuf, buf, 0);
+
+      // Direct buffer, small buffer size, initial buffer position is not 0
+      buf.clear();
+      byteBufferPreadCheck(smallBuf, buf, 11);
+    }
+  }
 
   @Test(timeout=120000)
   public void testCombinedOp() throws Exception {
@@ -797,5 +944,23 @@ public void testUnbuffer() throws Exception {
         // The close will be called when exiting this try-with-resource block
       }
     }
+
+    // Test ByteBuffer pread
+    try (InputStream in = getInputStream(smallBufferSize)) {
+      if (in instanceof ByteBufferPositionedReadable) {
+        ByteBufferPositionedReadable bbpin = (ByteBufferPositionedReadable) in;
+
+        // Test unbuffer after pread
+        byteBufferPreadCheck(bbpin);
+        ((CanUnbuffer) in).unbuffer();
+
+        // Test pread again after unbuffer
+        byteBufferPreadCheck(bbpin);
+
+        // Test close after unbuffer
+        ((CanUnbuffer) in).unbuffer();
+        // The close will be called when exiting this try-with-resource block
+      }
+    }
   }
 }