arrow 8.0.0

Rust implementation of Apache Arrow
Documentation 
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
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172

// 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::{
    array::ArrayData,
    array::{data::count_nulls, OffsetSizeTrait},
    buffer::Buffer,
    util::bit_util::get_bit,
};

use super::{equal_range, utils::child_logical_null_buffer};

fn lengths_equal<T: OffsetSizeTrait>(lhs: &[T], rhs: &[T]) -> bool {
    // invariant from `base_equal`
    debug_assert_eq!(lhs.len(), rhs.len());

    if lhs.is_empty() {
        return true;
    }

    if lhs[0] == T::zero() && rhs[0] == T::zero() {
        return lhs == rhs;
    };

    // The expensive case, e.g.
    // [0, 2, 4, 6, 9] == [4, 6, 8, 10, 13]
    lhs.windows(2)
        .zip(rhs.windows(2))
        .all(|(lhs_offsets, rhs_offsets)| {
            // length of left == length of right
            (lhs_offsets[1] - lhs_offsets[0]) == (rhs_offsets[1] - rhs_offsets[0])
        })
}

#[allow(clippy::too_many_arguments)]
#[inline]
fn offset_value_equal<T: OffsetSizeTrait>(
    lhs_values: &ArrayData,
    rhs_values: &ArrayData,
    lhs_nulls: Option<&Buffer>,
    rhs_nulls: Option<&Buffer>,
    lhs_offsets: &[T],
    rhs_offsets: &[T],
    lhs_pos: usize,
    rhs_pos: usize,
    len: usize,
) -> bool {
    let lhs_start = lhs_offsets[lhs_pos].to_usize().unwrap();
    let rhs_start = rhs_offsets[rhs_pos].to_usize().unwrap();
    let lhs_len = lhs_offsets[lhs_pos + len] - lhs_offsets[lhs_pos];
    let rhs_len = rhs_offsets[rhs_pos + len] - rhs_offsets[rhs_pos];

    lhs_len == rhs_len
        && equal_range(
            lhs_values,
            rhs_values,
            lhs_nulls,
            rhs_nulls,
            lhs_start,
            rhs_start,
            lhs_len.to_usize().unwrap(),
        )
}

pub(super) fn list_equal<T: OffsetSizeTrait>(
    lhs: &ArrayData,
    rhs: &ArrayData,
    lhs_nulls: Option<&Buffer>,
    rhs_nulls: Option<&Buffer>,
    lhs_start: usize,
    rhs_start: usize,
    len: usize,
) -> bool {
    let lhs_offsets = lhs.buffer::<T>(0);
    let rhs_offsets = rhs.buffer::<T>(0);

    // There is an edge-case where a n-length list that has 0 children, results in panics.
    // For example; an array with offsets [0, 0, 0, 0, 0] has 4 slots, but will have
    // no valid children.
    // Under logical equality, the child null bitmap will be an empty buffer, as there are
    // no child values. This causes panics when trying to count set bits.
    //
    // We caught this by chance from an accidental test-case, but due to the nature of this
    // crash only occuring on list equality checks, we are adding a check here, instead of
    // on the buffer/bitmap utilities, as a length check would incur a penalty for almost all
    // other use-cases.
    //
    // The solution is to check the number of child values from offsets, and return `true` if
    // they = 0. Empty arrays are equal, so this is correct.
    //
    // It's unlikely that one would create a n-length list array with no values, where n > 0,
    // however, one is more likely to slice into a list array and get a region that has 0
    // child values.
    // The test that triggered this behaviour had [4, 4] as a slice of 1 value slot.
    let lhs_child_length = lhs_offsets.get(len).unwrap().to_usize().unwrap()
        - lhs_offsets.first().unwrap().to_usize().unwrap();
    let rhs_child_length = rhs_offsets.get(len).unwrap().to_usize().unwrap()
        - rhs_offsets.first().unwrap().to_usize().unwrap();

    if lhs_child_length == 0 && lhs_child_length == rhs_child_length {
        return true;
    }

    let lhs_values = &lhs.child_data()[0];
    let rhs_values = &rhs.child_data()[0];

    let lhs_null_count = count_nulls(lhs_nulls, lhs_start, len);
    let rhs_null_count = count_nulls(rhs_nulls, rhs_start, len);

    // compute the child logical bitmap
    let child_lhs_nulls =
        child_logical_null_buffer(lhs, lhs_nulls, lhs.child_data().get(0).unwrap());
    let child_rhs_nulls =
        child_logical_null_buffer(rhs, rhs_nulls, rhs.child_data().get(0).unwrap());

    if lhs_null_count == 0 && rhs_null_count == 0 {
        lengths_equal(
            &lhs_offsets[lhs_start..lhs_start + len],
            &rhs_offsets[rhs_start..rhs_start + len],
        ) && equal_range(
            lhs_values,
            rhs_values,
            child_lhs_nulls.as_ref(),
            child_rhs_nulls.as_ref(),
            lhs_offsets[lhs_start].to_usize().unwrap(),
            rhs_offsets[rhs_start].to_usize().unwrap(),
            (lhs_offsets[lhs_start + len] - lhs_offsets[lhs_start])
                .to_usize()
                .unwrap(),
        )
    } else {
        // get a ref of the parent null buffer bytes, to use in testing for nullness
        let lhs_null_bytes = lhs_nulls.unwrap().as_slice();
        let rhs_null_bytes = rhs_nulls.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)
                    && offset_value_equal::<T>(
                        lhs_values,
                        rhs_values,
                        child_lhs_nulls.as_ref(),
                        child_rhs_nulls.as_ref(),
                        lhs_offsets,
                        rhs_offsets,
                        lhs_pos,
                        rhs_pos,
                        1,
                    )
        })
    }
}