[arrow] branch master updated: ARROW-4489: [Rust] PrimitiveArray.value_slice performs bounds checking when it should not

[ks...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

kszucs pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/arrow.git


The following commit(s) were added to refs/heads/master by this push:
     new 133d402  ARROW-4489: [Rust] PrimitiveArray.value_slice performs bounds checking when it should not
133d402 is described below

commit 133d4022bb7bd2df665a46f19fa40324ef1c5911
Author: Paddy Horan <pa...@hotmail.com>
AuthorDate: Mon Feb 11 11:22:15 2019 +0100

    ARROW-4489: [Rust] PrimitiveArray.value_slice performs bounds checking when it should not
    
    If you run the following test it will fail:
    ```rust
        #[test]
        fn test_value_slice() {
            let arr = Int32Array::from(vec![2, 3, 4]);
            let _slice = arr.value_slice(0, 4);
        }
    ```
    When working with SIMD I plan to rely on the fact that we have buffers padded to a multiple of 64 bytes.  This makes the implementation easier to maintain and more efficient.  However, it involves reading and writing to the padded region.
    
    Author: Paddy Horan <pa...@hotmail.com>
    
    Closes #3569 from paddyhoran/value_slice_fix and squashes the following commits:
    
    5f93b76b <Paddy Horan> Added test for no bounds checking.
    5340a01f <Paddy Horan> Removed bounds checking on `value_slice`
---
 rust/arrow/src/array.rs | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/rust/arrow/src/array.rs b/rust/arrow/src/array.rs
index 127edb9..c887ab7 100644
--- a/rust/arrow/src/array.rs
+++ b/rust/arrow/src/array.rs
@@ -236,8 +236,10 @@ impl<T: ArrowNumericType> PrimitiveArray<T> {
     ///
     /// Note this doesn't do any bound checking, for performance reason.
     pub fn value_slice(&self, offset: usize, len: usize) -> &[T::Native] {
-        let raw = unsafe { std::slice::from_raw_parts(self.raw_values(), self.len()) };
-        &raw[offset..offset + len]
+        let raw = unsafe {
+            std::slice::from_raw_parts(self.raw_values().offset(offset as isize), len)
+        };
+        &raw[..]
     }
 
     // Returns a new primitive array builder
@@ -754,6 +756,12 @@ mod tests {
     }
 
     #[test]
+    fn test_value_slice_no_bounds_check() {
+        let arr = Int32Array::from(vec![2, 3, 4]);
+        let _slice = arr.value_slice(0, 4);
+    }
+
+    #[test]
     fn test_primitive_array_builder() {
         // Test building an primitive array with ArrayData builder and offset
         let buf = Buffer::from(&[0, 1, 2, 3, 4].to_byte_slice());