ARROW-16674: [Java] C data interface: Reading as nioBuffer from imported buffer causes error (apache#13249)

zhztheplayer · web-flow · commit fac08404aa70 · 2022-09-14T11:49:15.000+02:00
Lead-authored-by: Hongze Zhang &lt;hongze.zhang@intel.com&gt;
Co-authored-by: Hongze Zhang &lt;mailtozhz@126.com&gt;
Signed-off-by: Antoine Pitrou &lt;antoine@python.org&gt;
diff --git a/java/c/src/main/java/org/apache/arrow/c/ArrayImporter.java b/java/c/src/main/java/org/apache/arrow/c/ArrayImporter.java
@@ -141,9 +141,10 @@ private List<ArrowBuf> importBuffers(ArrowArray.Snapshot snapshot) {
     for (long bufferPtr : buffers) {
       ArrowBuf buffer = null;
       if (bufferPtr != NULL) {
-        // TODO(roee88): an API for getting the size for each buffer is not yet
-        // available
-        buffer = new ArrowBuf(referenceManager, null, Integer.MAX_VALUE, bufferPtr);
+        // See ARROW-17720: [Java] C data interface: Add API to compute imported buffer size
+        int capacity = Integer.MAX_VALUE;
+        buffer = new ArrowBuf(referenceManager, null, capacity, bufferPtr);
+        buffer.writerIndex(capacity);
       }
       result.add(buffer);
     }
diff --git a/java/c/src/test/java/org/apache/arrow/c/RoundtripTest.java b/java/c/src/test/java/org/apache/arrow/c/RoundtripTest.java
@@ -23,6 +23,7 @@
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -715,6 +716,22 @@ public void testSchema() {
     }
   }
 
+  @Test
+  public void testImportedBufferAsNioBuffer() {
+    IntVector imported;
+    try (final IntVector vector = new IntVector("v", allocator)) {
+      setVector(vector, 1, 2, 3, null);
+      imported = (IntVector) vectorRoundtrip(vector);
+    }
+    ArrowBuf dataBuffer = imported.getDataBuffer();
+    ByteBuffer nioBuffer = dataBuffer.nioBuffer().asReadOnlyBuffer();
+    nioBuffer.order(ByteOrder.nativeOrder());
+    assertEquals(1, nioBuffer.getInt(0));
+    assertEquals(2, nioBuffer.getInt(1 << 2));
+    assertEquals(3, nioBuffer.getInt(2 << 2));
+    imported.close();
+  }
+
   @Test
   public void testImportReleasedArray() {
     // Consumer allocates empty structures
diff --git a/java/memory/memory-core/src/main/java/org/apache/arrow/memory/ArrowBuf.java b/java/memory/memory-core/src/main/java/org/apache/arrow/memory/ArrowBuf.java
@@ -74,23 +74,23 @@ public final class ArrowBuf implements AutoCloseable {
   private long writerIndex;
   private final HistoricalLog historicalLog = BaseAllocator.DEBUG ?
           new HistoricalLog(BaseAllocator.DEBUG_LOG_LENGTH, "ArrowBuf[%d]", id) : null;
-  private volatile long length;
+  private volatile long capacity;
 
   /**
    * Constructs a new ArrowBuf.
    *
    * @param referenceManager The memory manager to track memory usage and reference count of this buffer
-   * @param length The  byte length of this buffer
+   * @param capacity The capacity in bytes of this buffer
    */
   public ArrowBuf(
       final ReferenceManager referenceManager,
       final BufferManager bufferManager,
-      final long length,
+      final long capacity,
       final long memoryAddress) {
     this.referenceManager = referenceManager;
     this.bufferManager = bufferManager;
     this.addr = memoryAddress;
-    this.length = length;
+    this.capacity = capacity;
     this.readerIndex = 0;
     this.writerIndex = 0;
     if (BaseAllocator.DEBUG) {
@@ -136,7 +136,7 @@ public ReferenceManager getReferenceManager() {
   }
 
   public long capacity() {
-    return length;
+    return capacity;
   }
 
   /**
@@ -146,14 +146,14 @@ public long capacity() {
    */
   public synchronized ArrowBuf capacity(long newCapacity) {
 
-    if (newCapacity == length) {
+    if (newCapacity == capacity) {
       return this;
     }
 
     Preconditions.checkArgument(newCapacity >= 0);
 
-    if (newCapacity < length) {
-      length = newCapacity;
+    if (newCapacity < capacity) {
+      capacity = newCapacity;
       return this;
     }
 
@@ -195,8 +195,8 @@ public ArrowBuf slice() {
    */
   public ArrowBuf slice(long index, long length) {
 
-    Preconditions.checkPositionIndex(index, this.length);
-    Preconditions.checkPositionIndex(index + length, this.length);
+    Preconditions.checkPositionIndex(index, this.capacity);
+    Preconditions.checkPositionIndex(index + length, this.capacity);
 
     /*
      * Re the behavior of reference counting, see http://netty.io/wiki/reference-counted-objects
@@ -235,7 +235,7 @@ public long memoryAddress() {
 
   @Override
   public String toString() {
-    return String.format("ArrowBuf[%d], address:%d, length:%d", id, memoryAddress(), length);
+    return String.format("ArrowBuf[%d], address:%d, capacity:%d", id, memoryAddress(), capacity);
   }
 
   @Override

Original file line number	Diff line number	Diff line change
`@@ -141,9 +141,10 @@ private List<ArrowBuf> importBuffers(ArrowArray.Snapshot snapshot) {`
`141`	`141`	`for (long bufferPtr : buffers) {`
`142`	`142`	`ArrowBuf buffer = null;`
`143`	`143`	`if (bufferPtr != NULL) {`
`144`		`- // TODO(roee88): an API for getting the size for each buffer is not yet`
`145`		`- // available`
`146`		`- buffer = new ArrowBuf(referenceManager, null, Integer.MAX_VALUE, bufferPtr);`
	`144`	`+ // See ARROW-17720: [Java] C data interface: Add API to compute imported buffer size`
	`145`	`+ int capacity = Integer.MAX_VALUE;`
	`146`	`+ buffer = new ArrowBuf(referenceManager, null, capacity, bufferPtr);`
	`147`	`+ buffer.writerIndex(capacity);`
`147`	`148`	`}`
`148`	`149`	`result.add(buffer);`
`149`	`150`	`}`