perf: Improve Bitmap construction performance

crates/polars-arrow/src/bitmap/bitmap_ops.rs

@@ -5,38 +5,33 @@ use super::Bitmap;
 use crate::bitmap::MutableBitmap;
 use crate::trusted_len::TrustedLen;
 
-/// Creates a [Vec<u8>] from an [`Iterator`] of [`BitChunk`].
-/// # Safety
-/// The iterator must be [`TrustedLen`].
-pub unsafe fn from_chunk_iter_unchecked<T: BitChunk, I: Iterator<Item = T>>(
-    iterator: I,
-) -> Vec<u8> {
-    let (_, upper) = iterator.size_hint();
-    let upper = upper.expect("try_from_trusted_len_iter requires an upper limit");
-    let len = upper * std::mem::size_of::<T>();
-
-    let mut buffer = Vec::with_capacity(len);
-
-    let mut dst = buffer.as_mut_ptr();
-    for item in iterator {
-        let bytes = item.to_ne_bytes();
-        for i in 0..std::mem::size_of::<T>() {
-            std::ptr::write(dst, bytes[i]);
-            dst = dst.add(1);
-        }
-    }
-    assert_eq!(
-        dst.offset_from(buffer.as_ptr()) as usize,
-        len,
-        "Trusted iterator length was not accurately reported"
-    );
-    buffer.set_len(len);
-    buffer
+#[inline(always)]
+pub(crate) fn push_bitchunk<T: BitChunk>(buffer: &mut Vec<u8>, value: T) {
+    buffer.extend(value.to_ne_bytes())
 }
 
 /// Creates a [`Vec<u8>`] from a [`TrustedLen`] of [`BitChunk`].
 pub fn chunk_iter_to_vec<T: BitChunk, I: TrustedLen<Item = T>>(iter: I) -> Vec<u8> {
-    unsafe { from_chunk_iter_unchecked(iter) }
+    let cap = iter.size_hint().0 * std::mem::size_of::<T>();
+    let mut buffer = Vec::with_capacity(cap);
+    for v in iter {
+        push_bitchunk(&mut buffer, v)
+    }
+    buffer
+}
+
+fn chunk_iter_to_vec_and_remainder<T: BitChunk, I: TrustedLen<Item = T>>(
+    iter: I,
+    remainder: T,
+) -> Vec<u8> {
+    let cap = (iter.size_hint().0 + 1) * std::mem::size_of::<T>();
+    let mut buffer = Vec::with_capacity(cap);
+    for v in iter {
+        push_bitchunk(&mut buffer, v)
+    }
+    push_bitchunk(&mut buffer, remainder);
+    debug_assert_eq!(buffer.len(), cap);
+    buffer
 }
 
 /// Apply a bitwise operation `op` to four inputs and return the result as a [`Bitmap`].
@@ -62,9 +57,8 @@ where
         .zip(a3_chunks)
         .zip(a4_chunks)
         .map(|(((a1, a2), a3), a4)| op(a1, a2, a3, a4));
-    let buffer =
-        chunk_iter_to_vec(chunks.chain(std::iter::once(op(rem_a1, rem_a2, rem_a3, rem_a4))));
 
+    let buffer = chunk_iter_to_vec_and_remainder(chunks, op(rem_a1, rem_a2, rem_a3, rem_a4));
     let length = a1.len();
 
     Bitmap::from_u8_vec(buffer, length)
@@ -90,8 +84,7 @@ where
         .zip(a3_chunks)
         .map(|((a1, a2), a3)| op(a1, a2, a3));
 
-    let buffer = chunk_iter_to_vec(chunks.chain(std::iter::once(op(rem_a1, rem_a2, rem_a3))));
-
+    let buffer = chunk_iter_to_vec_and_remainder(chunks, op(rem_a1, rem_a2, rem_a3));
     let length = a1.len();
 
     Bitmap::from_u8_vec(buffer, length)
@@ -112,8 +105,7 @@ where
         .zip(rhs_chunks)
         .map(|(left, right)| op(left, right));
 
-    let buffer = chunk_iter_to_vec(chunks.chain(std::iter::once(op(rem_lhs, rem_rhs))));
-
+    let buffer = chunk_iter_to_vec_and_remainder(chunks, op(rem_lhs, rem_rhs));
     let length = lhs.len();
 
     Bitmap::from_u8_vec(buffer, length)
@@ -125,10 +117,7 @@ where
     F: Fn(u64) -> u64,
 {
     let rem = op(iter.remainder());
-
-    let iterator = iter.map(op).chain(std::iter::once(rem));
-
-    let buffer = chunk_iter_to_vec(iterator);
+    let buffer = chunk_iter_to_vec_and_remainder(iter.map(op), rem);
 
     Bitmap::from_u8_vec(buffer, length)
 }

crates/polars-arrow/src/compute/utils.rs

@@ -1,9 +1,10 @@
+use std::borrow::Borrow;
 use std::ops::{BitAnd, BitOr};
 
 use polars_error::{polars_ensure, PolarsResult};
 
 use crate::array::Array;
-use crate::bitmap::{and_not, ternary, Bitmap};
+use crate::bitmap::{and_not, push_bitchunk, ternary, Bitmap};
 
 pub fn combine_validities_and3(
     opt1: Option<&Bitmap>,
@@ -49,6 +50,63 @@ pub fn combine_validities_and_not(
     }
 }
 
+pub fn combine_validities_and_many<B: Borrow<Bitmap>>(bitmaps: &[Option<B>]) -> Option<Bitmap> {
+    let mut bitmaps = bitmaps
+        .iter()
+        .flatten()
+        .map(|b| b.borrow())
+        .collect::<Vec<_>>();
+
+    match bitmaps.len() {
+        0 => None,
+        1 => bitmaps.pop().cloned(),
+        2 => combine_validities_and(bitmaps.pop(), bitmaps.pop()),
+        3 => combine_validities_and3(bitmaps.pop(), bitmaps.pop(), bitmaps.pop()),
+        _ => {
+            let mut iterators = bitmaps
+                .iter()
+                .map(|v| v.fast_iter_u64())
+                .collect::<Vec<_>>();
+            let mut buffer = Vec::with_capacity(iterators.first().unwrap().size_hint().0 + 2);
+
+            'rows: loop {
+                // All ones so as identity for & operation
+                let mut out = u64::MAX;
+                for iter in iterators.iter_mut() {
+                    if let Some(v) = iter.next() {
+                        out &= v
+                    } else {
+                        break 'rows;
+                    }
+                }
+                push_bitchunk(&mut buffer, out);
+            }
+
+            // All ones so as identity for & operation
+            let mut out = [u64::MAX, u64::MAX];
+            let mut len = 0;
+            for iter in iterators.into_iter() {
+                let (rem, rem_len) = iter.remainder();
+                len = rem_len;
+
+                for (out, rem) in out.iter_mut().zip(rem) {
+                    *out &= rem;
+                }
+            }
+            push_bitchunk(&mut buffer, out[0]);
+            if len > 64 {
+                push_bitchunk(&mut buffer, out[1]);
+            }
+            let bitmap = Bitmap::from_u8_vec(buffer, bitmaps[0].len());
+            if bitmap.unset_bits() == bitmap.len() {
+                None
+            } else {
+                Some(bitmap)
+            }
+        },
+    }
+}
+
 // Errors iff the two arrays have a different length.
 #[inline]
 pub fn check_same_len(lhs: &dyn Array, rhs: &dyn Array) -> PolarsResult<()> {

crates/polars-arrow/src/types/native.rs

@@ -38,7 +38,8 @@ pub trait NativeType:
         + std::ops::IndexMut<usize, Output = u8>
         + for<'a> TryFrom<&'a [u8]>
         + std::fmt::Debug
-        + Default;
+        + Default
+        + IntoIterator<Item = u8>;
 
     /// To bytes in little endian
     fn to_le_bytes(&self) -> Self::Bytes;

crates/polars-core/src/chunked_array/ops/sort/arg_sort_multiple.rs

@@ -1,4 +1,4 @@
-use arrow::compute::utils::combine_validities_and;
+use arrow::compute::utils::combine_validities_and_many;
 use compare_inner::NullOrderCmp;
 use polars_row::{convert_columns, EncodingField, RowsEncoded};
 use polars_utils::iter::EnumerateIdxTrait;
@@ -121,7 +121,7 @@ pub fn encode_rows_vertical_par_unordered_broadcast_nulls(
             .collect::<Vec<_>>();
         let rows = _get_rows_encoded_unordered(&sliced)?;
 
-        let validity = sliced
+        let validities = sliced
             .iter()
             .flat_map(|s| {
                 let s = s.rechunk();
@@ -131,7 +131,9 @@ pub fn encode_rows_vertical_par_unordered_broadcast_nulls(
                     .into_iter()
                     .map(|arr| arr.validity().cloned())
             })
-            .fold(None, |l, r| combine_validities_and(l.as_ref(), r.as_ref()));
+            .collect::<Vec<_>>();
+
+        let validity = combine_validities_and_many(&validities);
         Ok(rows.into_array().with_validity_typed(validity))
     });
     let chunks = POOL.install(|| chunks.collect::<PolarsResult<Vec<_>>>());

crates/polars-ops/src/frame/join/mod.rs

@@ -45,8 +45,6 @@ use polars_utils::hashing::BytesHash;
 use rayon::prelude::*;
 
 use super::IntoDf;
-const LHS_NAME: &str = "POLARS_K_L";
-const RHS_NAME: &str = "POLARS_K_R";
 
 pub trait DataFrameJoinOps: IntoDf {
     /// Generic join method. Can be used to join on multiple columns.
@@ -260,12 +258,8 @@ pub trait DataFrameJoinOps: IntoDf {
             };
         }
 
-        let lhs_keys = prepare_keys_multiple(&selected_left, args.join_nulls)?
-            .into_series()
-            .with_name(LHS_NAME);
-        let rhs_keys = prepare_keys_multiple(&selected_right, args.join_nulls)?
-            .into_series()
-            .with_name(RHS_NAME);
+        let lhs_keys = prepare_keys_multiple(&selected_left, args.join_nulls)?.into_series();
+        let rhs_keys = prepare_keys_multiple(&selected_right, args.join_nulls)?.into_series();
         let names_right = selected_right.iter().map(|s| s.name()).collect::<Vec<_>>();
 
         // Multiple keys.

crates/polars-ops/src/series/ops/fused.rs

@@ -1,5 +1,5 @@
 use arrow::array::PrimitiveArray;
-use arrow::compute::utils::combine_validities_and;
+use arrow::compute::utils::combine_validities_and3;
 use polars_core::prelude::*;
 use polars_core::utils::align_chunks_ternary;
 use polars_core::with_match_physical_numeric_polars_type;
@@ -11,10 +11,7 @@ fn fma_arr<T: NumericNative>(
     c: &PrimitiveArray<T>,
 ) -> PrimitiveArray<T> {
     assert_eq!(a.len(), b.len());
-    let validity = combine_validities_and(
-        combine_validities_and(a.validity(), b.validity()).as_ref(),
-        c.validity(),
-    );
+    let validity = combine_validities_and3(a.validity(), b.validity(), c.validity());
     let a = a.values().as_slice();
     let b = b.values().as_slice();
     let c = c.values().as_slice();
@@ -65,10 +62,7 @@ fn fsm_arr<T: NumericNative>(
     c: &PrimitiveArray<T>,
 ) -> PrimitiveArray<T> {
     assert_eq!(a.len(), b.len());
-    let validity = combine_validities_and(
-        combine_validities_and(a.validity(), b.validity()).as_ref(),
-        c.validity(),
-    );
+    let validity = combine_validities_and3(a.validity(), b.validity(), c.validity());
     let a = a.values().as_slice();
     let b = b.values().as_slice();
     let c = c.values().as_slice();
@@ -118,10 +112,7 @@ fn fms_arr<T: NumericNative>(
     c: &PrimitiveArray<T>,
 ) -> PrimitiveArray<T> {
     assert_eq!(a.len(), b.len());
-    let validity = combine_validities_and(
-        combine_validities_and(a.validity(), b.validity()).as_ref(),
-        c.validity(),
-    );
+    let validity = combine_validities_and3(a.validity(), b.validity(), c.validity());
     let a = a.values().as_slice();
     let b = b.values().as_slice();
     let c = c.values().as_slice();

crates/polars-pipe/src/executors/sinks/joins/row_values.rs

@@ -1,7 +1,7 @@
 use std::sync::Arc;
 
 use arrow::array::{ArrayRef, BinaryArray, StaticArray};
-use arrow::compute::utils::combine_validities_and;
+use arrow::compute::utils::combine_validities_and_many;
 use polars_core::error::PolarsResult;
 use polars_row::RowsEncoded;
 
@@ -80,11 +80,12 @@ impl RowValues {
         Ok(if join_nulls {
             array
         } else {
-            let validity = self
+            let validities = self
                 .join_columns_material
                 .iter()
-                .map(|arr| arr.validity().cloned())
-                .fold(None, |l, r| combine_validities_and(l.as_ref(), r.as_ref()));
+                .map(|arr| arr.validity())
+                .collect::<Vec<_>>();
+            let validity = combine_validities_and_many(&validities);
             array.with_validity_typed(validity)
         })
     }

py-polars/tests/unit/operations/test_join.py

@@ -835,3 +835,25 @@ def test_join_list_non_numeric() -> None:
         "lists": [["a", "b", "c"], ["a", "c", "b"], ["a", "c", "d"]],
         "count": [1, 2, 1],
     }
+
+
+@pytest.mark.slow()
+def test_join_4_columns_with_validity() -> None:
+    # join on 4 columns so we trigger combine validities
+    # use 138 as that is 2 u64 and a remainder
+    a = pl.DataFrame(
+        {"a": [None if a % 6 == 0 else a for a in range(138)]}
+    ).with_columns(
+        b=pl.col("a"),
+        c=pl.col("a"),
+        d=pl.col("a"),
+    )
+
+    assert a.join(a, on=["a", "b", "c", "d"], how="inner", join_nulls=True).shape == (
+        644,
+        4,
+    )
+    assert a.join(a, on=["a", "b", "c", "d"], how="inner", join_nulls=False).shape == (
+        115,
+        4,
+    )