ARROW-7935: [Java] Remove Netty dependency for BufferAllocator and ReferenceManager

java/memory/src/main/java/io/netty/buffer/PooledByteBufAllocatorL.java

@@ -26,6 +26,7 @@
 import org.apache.arrow.memory.OutOfMemoryException;
 import org.apache.arrow.memory.util.LargeMemoryUtil;
 
+import io.netty.util.internal.OutOfDirectMemoryError;
 import io.netty.util.internal.StringUtil;
 
 /**
@@ -56,9 +57,17 @@ public UnsafeDirectLittleEndian allocate(long size) {
     try {
       return allocator.directBuffer(LargeMemoryUtil.checkedCastToInt(size), Integer.MAX_VALUE);
     } catch (OutOfMemoryError e) {
-      throw new OutOfMemoryException("Failure allocating buffer.", e);
+      /*
+       * OutOfDirectMemoryError is thrown by Netty when we exceed the direct memory limit defined by
+       * -XX:MaxDirectMemorySize. OutOfMemoryError with "Direct buffer memory" message is thrown by
+       * java.nio.Bits when we exceed the direct memory limit. This should never be hit in practice
+       * as Netty is expected to throw an OutOfDirectMemoryError first.
+       */
+      if (e instanceof OutOfDirectMemoryError || "Direct buffer memory".equals(e.getMessage())) {
+        throw new OutOfMemoryException("Failure allocating buffer.", e);
+      }
+      throw e;
     }
-
   }
 
   public int getChunkSize() {

java/memory/src/main/java/org/apache/arrow/memory/ArrowByteBufAllocator.java

@@ -30,7 +30,10 @@
  * the signature and the fact that this Allocator returns ExpandableByteBufs which enable
  * otherwise non-expandable
  * ArrowBufs to be expandable.
+ *
+ * @deprecated This class may be removed in a future release.
  */
+@Deprecated
 public class ArrowByteBufAllocator extends AbstractByteBufAllocator {
 
   private static final int DEFAULT_BUFFER_SIZE = 4096;

java/memory/src/main/java/org/apache/arrow/memory/BaseAllocator.java

@@ -33,7 +33,6 @@
 import org.immutables.value.Value;
 
 import io.netty.buffer.ArrowBuf;
-import io.netty.util.internal.OutOfDirectMemoryError;
 
 /**
  * A base-class that implements all functionality of {@linkplain BufferAllocator}s.
@@ -319,22 +318,12 @@ public ArrowBuf buffer(final long initialRequestSize, BufferManager manager) {
       listener.onAllocation(actualRequestSize);
       return buffer;
     } catch (OutOfMemoryError e) {
-      /*
-       * OutOfDirectMemoryError is thrown by Netty when we exceed the direct memory limit defined by
-       * -XX:MaxDirectMemorySize. OutOfMemoryError with "Direct buffer memory" message is thrown by
-       * java.nio.Bits when we exceed the direct memory limit. This should never be hit in practice
-       * as Netty is expected to throw an OutOfDirectMemoryError first.
-       */
-      if (e instanceof OutOfDirectMemoryError || "Direct buffer memory".equals(e.getMessage())) {
-        throw new OutOfMemoryException(e);
-      }
       throw e;
     } finally {
       if (!success) {
         releaseBytes(actualRequestSize);
       }
     }
-
   }
 
   /**

java/memory/src/main/java/org/apache/arrow/memory/BufferAllocator.java

@@ -56,7 +56,10 @@ public interface BufferAllocator extends AutoCloseable {
    * Returns the allocator this allocator falls back to when it needs more memory.
    *
    * @return the underlying allocator used by this allocator
+   *
+   * @deprecated This method may be removed in a future release.
    */
+  @Deprecated
   ByteBufAllocator getAsByteBufAllocator();
 
   /**

java/memory/src/main/java/org/apache/arrow/memory/BufferLedger.java

@@ -526,7 +526,7 @@ void print(StringBuilder sb, int indent, BaseAllocator.Verbosity verbosity) {
   /**
    * Returns the underlying {@link UnsafeDirectLittleEndian} instance used by this BufferLedger.
    *
-   * @deprecated Use #unwrap(UnsafeDirectLittleEndian.class) instead.
+   * @deprecated This method may be removed in a future release.
    */
   @Deprecated
   public UnsafeDirectLittleEndian getUnderlying() {
@@ -554,6 +554,7 @@ public <T> T unwrap(Class<T> clazz) {
       return clazz.cast(allocationManager);
     }
 
+    // TODO: remove this in a future release.
     if (clazz == UnsafeDirectLittleEndian.class) {
       Preconditions.checkState(allocationManager instanceof NettyAllocationManager,
           "Underlying memory was not allocated by Netty");