Correct array memory usage calculation for dictionary arrays

arrow/src/array/array.rs

@@ -197,11 +197,21 @@ pub trait Array: fmt::Debug + Send + Sync + JsonEqual {
         self.data_ref().null_count()
     }
 
-    /// Returns the total number of bytes of memory occupied by the buffers owned by this array.
-    fn get_buffer_memory_size(&self) -> usize;
+    /// Returns the total number of bytes of memory pointed to by this array.
+    /// The buffers store bytes in the Arrow memory format, and include the data as well as the validity map.
+    fn get_buffer_memory_size(&self) -> usize {
+        self.data_ref().get_buffer_memory_size()
+    }
 
     /// Returns the total number of bytes of memory occupied physically by this array.
-    fn get_array_memory_size(&self) -> usize;
+    /// This value will always be greater than returned by `get_buffer_memory_size()` and
+    /// includes the overhead of the data structures that contain the pointers to the various buffers.
+    fn get_array_memory_size(&self) -> usize {
+        // both data.get_array_memory_size and size_of_val(self) include ArrayData fields,
+        // to only count additional fields of this array substract size_of(ArrayData)
+        self.data_ref().get_array_memory_size() + std::mem::size_of_val(self)
+            - std::mem::size_of::<ArrayData>()
+    }
 
     /// returns two pointers that represent this array in the C Data Interface (FFI)
     fn to_raw(
@@ -575,6 +585,7 @@ where
 #[cfg(test)]
 mod tests {
     use super::*;
+
     #[test]
     fn test_empty_primitive() {
         let array = new_empty_array(&DataType::Int32);
@@ -661,4 +672,105 @@ mod tests {
             null_array.data().buffers()[0].len()
         );
     }
+
+    #[test]
+    fn test_memory_size_null() {
+        let null_arr = NullArray::new(32);
+
+        assert_eq!(0, null_arr.get_buffer_memory_size());
+        assert_eq!(
+            std::mem::size_of::<NullArray>(),
+            null_arr.get_array_memory_size()
+        );
+        assert_eq!(
+            std::mem::size_of::<NullArray>(),
+            std::mem::size_of::<ArrayData>(),
+        );
+    }
+
+    #[test]
+    fn test_memory_size_primitive() {
+        let arr = PrimitiveArray::<Int64Type>::from_iter_values(0..128);
+        let empty =
+            PrimitiveArray::<Int64Type>::from(ArrayData::new_empty(arr.data_type()));
+
+        // substract empty array to avoid magic numbers for the size of additional fields
+        assert_eq!(
+            arr.get_array_memory_size() - empty.get_array_memory_size(),
+            128 * std::mem::size_of::<i64>()
+        );
+    }
+
+    #[test]
+    fn test_memory_size_primitive_nullable() {
+        let arr: PrimitiveArray<Int64Type> = (0..128).map(Some).collect();
+        let empty_with_bitmap = PrimitiveArray::<Int64Type>::from(
+            ArrayData::builder(arr.data_type().clone())
+                .add_buffer(MutableBuffer::new(0).into())
+                .null_bit_buffer(MutableBuffer::new_null(0).into())
+                .build(),
+        );
+
+        // expected size is the size of the PrimitiveArray struct,
+        // which includes the optional validity buffer
+        // plus one buffer on the heap
+        assert_eq!(
+            std::mem::size_of::<PrimitiveArray<Int64Type>>()
+                + std::mem::size_of::<Buffer>(),
+            empty_with_bitmap.get_array_memory_size()
+        );
+
+        // substract empty array to avoid magic numbers for the size of additional fields
+        // the size of the validity bitmap is rounded up to 64 bytes
+        assert_eq!(
+            arr.get_array_memory_size() - empty_with_bitmap.get_array_memory_size(),
+            128 * std::mem::size_of::<i64>() + 64
+        );
+    }
+
+    #[test]
+    fn test_memory_size_dictionary() {
+        let values = PrimitiveArray::<Int64Type>::from_iter_values(0..16);
+        let keys = PrimitiveArray::<Int16Type>::from_iter_values(
+            (0..256).map(|i| (i % values.len()) as i16),
+        );
+
+        let dict_data = ArrayData::builder(DataType::Dictionary(
+            Box::new(keys.data_type().clone()),
+            Box::new(values.data_type().clone()),
+        ))
+        .len(keys.len())
+        .buffers(keys.data_ref().buffers().to_vec())
+        .child_data(vec![ArrayData::builder(DataType::Int64)
+            .len(values.len())
+            .buffers(values.data_ref().buffers().to_vec())
+            .build()])
+        .build();
+
+        let empty_data = ArrayData::new_empty(&DataType::Dictionary(
+            Box::new(DataType::Int16),
+            Box::new(DataType::Int64),
+        ));
+
+        let arr = DictionaryArray::<Int16Type>::from(dict_data);
+        let empty = DictionaryArray::<Int16Type>::from(empty_data);
+
+        let expected_keys_size = 256 * std::mem::size_of::<i16>();
+        assert_eq!(
+            arr.keys().get_array_memory_size() - empty.keys().get_array_memory_size(),
+            expected_keys_size
+        );
+
+        let expected_values_size = 16 * std::mem::size_of::<i64>();
+        assert_eq!(
+            arr.values().get_array_memory_size() - empty.values().get_array_memory_size(),
+            expected_values_size
+        );
+
+        let expected_size = expected_keys_size + expected_values_size;
+        assert_eq!(
+            arr.get_array_memory_size() - empty.get_array_memory_size(),
+            expected_size
+        );
+    }
 }

arrow/src/array/array_binary.rs

@@ -17,7 +17,6 @@
 
 use std::convert::{From, TryInto};
 use std::fmt;
-use std::mem;
 use std::{any::Any, iter::FromIterator};
 
 use super::{
@@ -199,16 +198,6 @@ impl<OffsetSize: BinaryOffsetSizeTrait> Array for GenericBinaryArray<OffsetSize>
     fn data(&self) -> &ArrayData {
         &self.data
     }
-
-    /// Returns the total number of bytes of memory occupied by the buffers owned by this [$name].
-    fn get_buffer_memory_size(&self) -> usize {
-        self.data.get_buffer_memory_size()
-    }
-
-    /// Returns the total number of bytes of memory occupied physically by this [$name].
-    fn get_array_memory_size(&self) -> usize {
-        self.data.get_array_memory_size() + mem::size_of_val(self)
-    }
 }
 
 impl<OffsetSize: BinaryOffsetSizeTrait> From<ArrayData>
@@ -600,16 +589,6 @@ impl Array for FixedSizeBinaryArray {
     fn data(&self) -> &ArrayData {
         &self.data
     }
-
-    /// Returns the total number of bytes of memory occupied by the buffers owned by this [FixedSizeBinaryArray].
-    fn get_buffer_memory_size(&self) -> usize {
-        self.data.get_buffer_memory_size()
-    }
-
-    /// Returns the total number of bytes of memory occupied physically by this [FixedSizeBinaryArray].
-    fn get_array_memory_size(&self) -> usize {
-        self.data.get_array_memory_size() + mem::size_of_val(self)
-    }
 }
 
 /// A type of `DecimalArray` whose elements are binaries.
@@ -780,16 +759,6 @@ impl Array for DecimalArray {
     fn data(&self) -> &ArrayData {
         &self.data
     }
-
-    /// Returns the total number of bytes of memory occupied by the buffers owned by this [DecimalArray].
-    fn get_buffer_memory_size(&self) -> usize {
-        self.data.get_buffer_memory_size()
-    }
-
-    /// Returns the total number of bytes of memory occupied physically by this [DecimalArray].
-    fn get_array_memory_size(&self) -> usize {
-        self.data.get_array_memory_size() + mem::size_of_val(self)
-    }
 }
 
 #[cfg(test)]

arrow/src/array/array_boolean.rs

@@ -18,7 +18,6 @@
 use std::borrow::Borrow;
 use std::convert::From;
 use std::iter::{FromIterator, IntoIterator};
-use std::mem;
 use std::{any::Any, fmt};
 
 use super::*;
@@ -114,16 +113,6 @@ impl Array for BooleanArray {
     fn data(&self) -> &ArrayData {
         &self.data
     }
-
-    /// Returns the total number of bytes of memory occupied by the buffers owned by this [BooleanArray].
-    fn get_buffer_memory_size(&self) -> usize {
-        self.data.get_buffer_memory_size()
-    }
-
-    /// Returns the total number of bytes of memory occupied physically by this [BooleanArray].
-    fn get_array_memory_size(&self) -> usize {
-        self.data.get_array_memory_size() + mem::size_of_val(self)
-    }
 }
 
 impl From<Vec<bool>> for BooleanArray {

arrow/src/array/array_dictionary.rs

@@ -18,7 +18,6 @@
 use std::any::Any;
 use std::fmt;
 use std::iter::IntoIterator;
-use std::mem;
 use std::{convert::From, iter::FromIterator};
 
 use super::{
@@ -209,18 +208,6 @@ impl<T: ArrowPrimitiveType> Array for DictionaryArray<T> {
     fn data(&self) -> &ArrayData {
         &self.data
     }
-
-    fn get_buffer_memory_size(&self) -> usize {
-        // Since both `keys` and `values` derive (are references from) `data`, we only need to account for `data`.
-        self.data.get_buffer_memory_size()
-    }
-
-    fn get_array_memory_size(&self) -> usize {
-        self.data.get_array_memory_size()
-            + self.keys.get_array_memory_size()
-            + self.values.get_array_memory_size()
-            + mem::size_of_val(self)
-    }
 }
 
 impl<T: ArrowPrimitiveType> fmt::Debug for DictionaryArray<T> {

arrow/src/array/array_list.rs

@@ -17,7 +17,6 @@
 
 use std::any::Any;
 use std::fmt;
-use std::mem;
 
 use num::Num;
 
@@ -261,16 +260,6 @@ impl<OffsetSize: 'static + OffsetSizeTrait> Array for GenericListArray<OffsetSiz
     fn data(&self) -> &ArrayData {
         &self.data
     }
-
-    /// Returns the total number of bytes of memory occupied by the buffers owned by this [ListArray].
-    fn get_buffer_memory_size(&self) -> usize {
-        self.data.get_buffer_memory_size()
-    }
-
-    /// Returns the total number of bytes of memory occupied physically by this [ListArray].
-    fn get_array_memory_size(&self) -> usize {
-        self.data.get_array_memory_size() + mem::size_of_val(self)
-    }
 }
 
 impl<OffsetSize: OffsetSizeTrait> fmt::Debug for GenericListArray<OffsetSize> {
@@ -444,18 +433,6 @@ impl Array for FixedSizeListArray {
     fn data(&self) -> &ArrayData {
         &self.data
     }
-
-    /// Returns the total number of bytes of memory occupied by the buffers owned by this [FixedSizeListArray].
-    fn get_buffer_memory_size(&self) -> usize {
-        self.data.get_buffer_memory_size() + self.values().get_buffer_memory_size()
-    }
-
-    /// Returns the total number of bytes of memory occupied physically by this [FixedSizeListArray].
-    fn get_array_memory_size(&self) -> usize {
-        self.data.get_array_memory_size()
-            + self.values().get_array_memory_size()
-            + mem::size_of_val(self)
-    }
 }
 
 impl fmt::Debug for FixedSizeListArray {

arrow/src/array/array_primitive.rs

@@ -150,16 +150,6 @@ impl<T: ArrowPrimitiveType> Array for PrimitiveArray<T> {
     fn data(&self) -> &ArrayData {
         &self.data
     }
-
-    /// Returns the total number of bytes of memory occupied by the buffers owned by this [PrimitiveArray].
-    fn get_buffer_memory_size(&self) -> usize {
-        self.data.get_buffer_memory_size()
-    }
-
-    /// Returns the total number of bytes of memory occupied physically by this [PrimitiveArray].
-    fn get_array_memory_size(&self) -> usize {
-        self.data.get_array_memory_size() + mem::size_of::<RawPtrBox<T::Native>>()
-    }
 }
 
 fn as_datetime<T: ArrowPrimitiveType>(v: i64) -> Option<NaiveDateTime> {
@@ -508,9 +498,6 @@ mod tests {
             assert!(arr.is_valid(i));
             assert_eq!(i as i32, arr.value(i));
         }
-
-        assert_eq!(64, arr.get_buffer_memory_size());
-        assert_eq!(136, arr.get_array_memory_size());
     }
 
     #[test]
@@ -530,9 +517,6 @@ mod tests {
                 assert!(!arr.is_valid(i));
             }
         }
-
-        assert_eq!(128, arr.get_buffer_memory_size());
-        assert_eq!(216, arr.get_array_memory_size());
     }
 
     #[test]

arrow/src/array/array_string.rs

@@ -17,7 +17,6 @@
 
 use std::convert::From;
 use std::fmt;
-use std::mem;
 use std::{any::Any, iter::FromIterator};
 
 use super::{
@@ -286,16 +285,6 @@ impl<OffsetSize: StringOffsetSizeTrait> Array for GenericStringArray<OffsetSize>
     fn data(&self) -> &ArrayData {
         &self.data
     }
-
-    /// Returns the total number of bytes of memory occupied by the buffers owned by this [$name].
-    fn get_buffer_memory_size(&self) -> usize {
-        self.data.get_buffer_memory_size()
-    }
-
-    /// Returns the total number of bytes of memory occupied physically by this [$name].
-    fn get_array_memory_size(&self) -> usize {
-        self.data.get_array_memory_size() + mem::size_of_val(self)
-    }
 }
 
 impl<OffsetSize: StringOffsetSizeTrait> From<ArrayData>

arrow/src/array/array_struct.rs

@@ -19,7 +19,6 @@ use std::any::Any;
 use std::convert::{From, TryFrom};
 use std::fmt;
 use std::iter::IntoIterator;
-use std::mem;
 
 use super::{make_array, Array, ArrayData, ArrayRef};
 use crate::datatypes::DataType;
@@ -178,16 +177,6 @@ impl Array for StructArray {
     fn len(&self) -> usize {
         self.data_ref().len()
     }
-
-    /// Returns the total number of bytes of memory occupied by the buffers owned by this [StructArray].
-    fn get_buffer_memory_size(&self) -> usize {
-        self.data.get_buffer_memory_size()
-    }
-
-    /// Returns the total number of bytes of memory occupied physically by this [StructArray].
-    fn get_array_memory_size(&self) -> usize {
-        self.data.get_array_memory_size() + mem::size_of_val(self)
-    }
 }
 
 impl From<Vec<(Field, ArrayRef)>> for StructArray {