ARROW-7514_make_getvalueoffset_obsolete

Make BinaryArray.GetValueOffset obsolete

Author: Takashi Hashida

csharp/src/Apache.Arrow/Arrays/BinaryArray.cs

@@ -171,6 +171,7 @@ public BinaryArray(IArrowType dataType, int length,
         public ReadOnlySpan<byte> Values => ValueBuffer.Span.CastTo<byte>();
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        [Obsolete]
         public int GetValueOffset(int index)
         {
             if (index < 0 || index > Length)
@@ -193,10 +194,12 @@ public int GetValueLength(int index)
 
         public ReadOnlySpan<byte> GetBytes(int index)
         {
-            var offset = GetValueOffset(index);
-            var length = GetValueLength(index);
+            if (index < 0 || index >= Length)
+            {
+                throw new ArgumentOutOfRangeException(nameof(index));
+            }
 
-            return ValueBuffer.Span.Slice(offset, length);
+            return ValueBuffer.Span.Slice(ValueOffsets[index], GetValueLength(index));
         }
 
     }

csharp/test/Apache.Arrow.Tests/ArrowArrayTests.cs

@@ -46,6 +46,12 @@ public void ThrowsWhenGetValueAndOffsetIndexOutOfBounds()
             Assert.Equal(2, array.GetValueOffset(2));
             Assert.Throws<ArgumentOutOfRangeException>(() => array.GetValueOffset(3));
 
+            Assert.Throws<IndexOutOfRangeException>(() => array.ValueOffsets[-1]);
+            Assert.Equal(0, array.ValueOffsets[0]);
+            Assert.Equal(1, array.ValueOffsets[1]);
+            Assert.Equal(2, array.ValueOffsets[2]);
+            Assert.Throws<IndexOutOfRangeException>(() => array.ValueOffsets[3]);
+
         }
 
         [Fact]