1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102

// 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.

use crate::bit_iterator::BitSliceIterator;
use crate::contains_nulls;
use arrow_buffer::bit_util::get_bit;
use std::mem::size_of;

use crate::data::ArrayData;

use super::utils::equal_len;

pub(crate) const NULL_SLICES_SELECTIVITY_THRESHOLD: f64 = 0.4;

pub(super) fn primitive_equal<T>(
    lhs: &ArrayData,
    rhs: &ArrayData,
    lhs_start: usize,
    rhs_start: usize,
    len: usize,
) -> bool {
    let byte_width = size_of::<T>();
    let lhs_values = &lhs.buffers()[0].as_slice()[lhs.offset() * byte_width..];
    let rhs_values = &rhs.buffers()[0].as_slice()[rhs.offset() * byte_width..];

    // Only checking one null mask here because by the time the control flow reaches
    // this point, the equality of the two masks would have already been verified.
    if !contains_nulls(lhs.null_buffer(), lhs_start + lhs.offset(), len) {
        // without nulls, we just need to compare slices
        equal_len(
            lhs_values,
            rhs_values,
            lhs_start * byte_width,
            rhs_start * byte_width,
            len * byte_width,
        )
    } else {
        let selectivity_frac = lhs.null_count() as f64 / lhs.len() as f64;

        if selectivity_frac >= NULL_SLICES_SELECTIVITY_THRESHOLD {
            // get a ref of the null buffer bytes, to use in testing for nullness
            let lhs_null_bytes = lhs.null_buffer().as_ref().unwrap().as_slice();
            let rhs_null_bytes = rhs.null_buffer().as_ref().unwrap().as_slice();
            // with nulls, we need to compare item by item whenever it is not null
            (0..len).all(|i| {
                let lhs_pos = lhs_start + i;
                let rhs_pos = rhs_start + i;
                let lhs_is_null = !get_bit(lhs_null_bytes, lhs_pos + lhs.offset());
                let rhs_is_null = !get_bit(rhs_null_bytes, rhs_pos + rhs.offset());

                lhs_is_null
                    || (lhs_is_null == rhs_is_null)
                        && equal_len(
                            lhs_values,
                            rhs_values,
                            lhs_pos * byte_width,
                            rhs_pos * byte_width,
                            byte_width, // 1 * byte_width since we are comparing a single entry
                        )
            })
        } else {
            let lhs_slices_iter = BitSliceIterator::new(
                lhs.null_buffer().as_ref().unwrap(),
                lhs_start + lhs.offset(),
                len,
            );
            let rhs_slices_iter = BitSliceIterator::new(
                rhs.null_buffer().as_ref().unwrap(),
                rhs_start + rhs.offset(),
                len,
            );

            lhs_slices_iter.zip(rhs_slices_iter).all(
                |((l_start, l_end), (r_start, r_end))| {
                    l_start == r_start
                        && l_end == r_end
                        && equal_len(
                            lhs_values,
                            rhs_values,
                            (lhs_start + l_start) * byte_width,
                            (rhs_start + r_start) * byte_width,
                            (l_end - l_start) * byte_width,
                        )
                },
            )
        }
    }
}