test: add criterion benchmark for spark_map_sort

Covers int and string keys at three map sizes (4, 16, 64 entries per map)
with a fixed batch of 8192 maps.

Author: andygrove

native/spark-expr/Cargo.toml

@@ -112,3 +112,7 @@ harness = false
 [[bench]]
 name = "cast_non_int_numeric_timestamp"
 harness = false
+
+[[bench]]
+name = "map_sort"
+harness = false

native/spark-expr/benches/map_sort.rs

@@ -0,0 +1,107 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+//! Benchmarks for spark_map_sort.
+
+use arrow::array::builder::{Int32Builder, MapBuilder, StringBuilder};
+use arrow::array::{ArrayRef, MapArray, MapFieldNames};
+use criterion::{criterion_group, criterion_main, BenchmarkId, Criterion};
+use datafusion::physical_plan::ColumnarValue;
+use datafusion_comet_spark_expr::spark_map_sort;
+use std::hint::black_box;
+use std::sync::Arc;
+
+const BATCH_SIZE: usize = 8192;
+
+fn map_field_names() -> MapFieldNames {
+    MapFieldNames {
+        entry: "entries".into(),
+        key: "key".into(),
+        value: "value".into(),
+    }
+}
+
+/// Build a MapArray with `BATCH_SIZE` rows where each map has `entries_per_map` entries.
+/// Keys are integers in reverse order so every map needs a real sort.
+fn build_int_key_map(entries_per_map: usize) -> MapArray {
+    let mut builder = MapBuilder::new(
+        Some(map_field_names()),
+        Int32Builder::new(),
+        Int32Builder::new(),
+    );
+    for row in 0..BATCH_SIZE {
+        for entry_idx in 0..entries_per_map {
+            // Reverse order so input is unsorted; vary across rows so different maps differ.
+            let key = (entries_per_map - entry_idx) as i32 + (row % 7) as i32;
+            let value = entry_idx as i32;
+            builder.keys().append_value(key);
+            builder.values().append_value(value);
+        }
+        builder.append(true).unwrap();
+    }
+    builder.finish()
+}
+
+/// Same shape as `build_int_key_map` but with string keys.
+fn build_string_key_map(entries_per_map: usize) -> MapArray {
+    let mut builder = MapBuilder::new(
+        Some(map_field_names()),
+        StringBuilder::new(),
+        Int32Builder::new(),
+    );
+    for row in 0..BATCH_SIZE {
+        for entry_idx in 0..entries_per_map {
+            let key = format!("key_{:04}", entries_per_map - entry_idx + (row % 7));
+            let value = entry_idx as i32;
+            builder.keys().append_value(&key);
+            builder.values().append_value(value);
+        }
+        builder.append(true).unwrap();
+    }
+    builder.finish()
+}
+
+fn bench_map_sort(c: &mut Criterion) {
+    let mut group = c.benchmark_group("spark_map_sort");
+
+    for entries in [4usize, 16, 64] {
+        let int_map: ArrayRef = Arc::new(build_int_key_map(entries));
+        group.bench_with_input(
+            BenchmarkId::new("int_keys", entries),
+            &int_map,
+            |b, array| {
+                let args = vec![ColumnarValue::Array(Arc::clone(array))];
+                b.iter(|| black_box(spark_map_sort(black_box(&args)).unwrap()));
+            },
+        );
+
+        let string_map: ArrayRef = Arc::new(build_string_key_map(entries));
+        group.bench_with_input(
+            BenchmarkId::new("string_keys", entries),
+            &string_map,
+            |b, array| {
+                let args = vec![ColumnarValue::Array(Arc::clone(array))];
+                b.iter(|| black_box(spark_map_sort(black_box(&args)).unwrap()));
+            },
+        );
+    }
+
+    group.finish();
+}
+
+criterion_group!(benches, bench_map_sort);
+criterion_main!(benches);

native/spark-expr/src/lib.rs

@@ -58,6 +58,7 @@ pub use bloom_filter::{BloomFilterAgg, BloomFilterMightContain};
 mod conditional_funcs;
 mod conversion_funcs;
 mod map_funcs;
+pub use map_funcs::spark_map_sort;
 mod math_funcs;
 mod nondetermenistic_funcs;