support slice view data on writing ipc

arrow-ipc/src/writer.rs

@@ -580,7 +580,12 @@ fn append_variadic_buffer_counts(counts: &mut Vec<i64>, array: &ArrayData) {
         DataType::BinaryView | DataType::Utf8View => {
             // The spec documents the counts only includes the variadic buffers, not the view/null buffers.
             // https://arrow.apache.org/docs/format/Columnar.html#variadic-buffers
-            counts.push(array.buffers().len() as i64 - 1);
+            let views = array.buffers()[0].typed_data::<u128>();
+            if views.iter().any(|view| *view as u32 > 12) {
+                counts.push(array.buffers().len() as i64 - 1);
+            } else {
+                counts.push(0);
+            }
         }
         DataType::Dictionary(_, _) => {
             // Do nothing
@@ -1245,6 +1250,63 @@ fn get_list_array_buffers<O: OffsetSizeTrait>(data: &ArrayData) -> (Buffer, Arra
     (offsets, child_data)
 }
 
+fn update_buffer_index(value: &mut u128, new_buffer_index: u32) {
+    // keep length、prefix and offset，clear old buffer_index, see [`ByteView`] for detail.
+    let mask = !((0xFFFF_FFFFu128) << 64);
+    *value &= mask;
+
+    // move new buffer index to right position
+    let new_buffer_index = (new_buffer_index as u128) << 64;
+
+    // update value with new buffer index
+    *value |= new_buffer_index;
+}
+
+fn select_data_buffers(mut views_slice: Vec<u128>, data: &ArrayData) -> Vec<Buffer> {
+    let first_buffer = views_slice.iter().find(|view| (**view) as u32 > 12);
+    // all values shorter than 12 bytes.
+    if first_buffer.is_none() {
+        return vec![Buffer::from_vec(views_slice)];
+    }
+    let first_buffer_index = ((*first_buffer.unwrap()) >> 64) as u32 as usize;
+
+    let last_buffer = views_slice
+        .iter()
+        .rfind(|view| (**view) as u32 > 12)
+        .unwrap();
+    let last_buffer_index = ((*last_buffer) >> 64) as u32 as usize;
+
+    let data_buffers = &data.buffers()[1..];
+    let sliced_data_buffers = &data_buffers[first_buffer_index..last_buffer_index + 1];
+
+    // if first buffer index not 0, we need re-mapping view's buffer index to sliced data buffers
+    if first_buffer_index != 0 {
+        views_slice
+            .iter_mut()
+            .filter(|view| (**view) as u32 > 12)
+            .for_each(|view| {
+                // new buffer index = original buffer index - offset
+                let new_buffer_index = ((*view >> 64) as u32) - first_buffer_index as u32;
+                update_buffer_index(view, new_buffer_index);
+            });
+    }
+
+    let mut buffers = Vec::with_capacity(sliced_data_buffers.len() + 1);
+    buffers.push(views_slice.iter().copied().collect());
+    buffers.extend_from_slice(sliced_data_buffers);
+    buffers
+}
+
+fn get_byte_view_buffers(data: &ArrayData) -> Vec<Buffer> {
+    if data.is_empty() {
+        return Vec::with_capacity(0);
+    }
+
+    let views_slice = data.buffers()[0].typed_data::<u128>();
+    let views_slice = &views_slice[data.offset()..data.offset() + data.len()];
+    select_data_buffers(views_slice.to_vec(), data)
+}
+
 /// Write array data to a vector of bytes
 #[allow(clippy::too_many_arguments)]
 fn write_array_data(
@@ -1303,13 +1365,8 @@ fn write_array_data(
             )?;
         }
     } else if matches!(data_type, DataType::BinaryView | DataType::Utf8View) {
-        // Slicing the views buffer is safe and easy,
-        // but pruning unneeded data buffers is much more nuanced since it's complicated to prove that no views reference the pruned buffers
-        //
-        // Current implementation just serialize the raw arrays as given and not try to optimize anything.
-        // If users wants to "compact" the arrays prior to sending them over IPC,
-        // they should consider the gc API suggested in #5513
-        for buffer in array_data.buffers() {
+        let view_buffers = get_byte_view_buffers(array_data);
+        for buffer in view_buffers {
             offset = write_buffer(
                 buffer.as_slice(),
                 buffers,