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
173
174
175
176
177
178
179

use fdb::range::RangeOptions;

use crate::scan::ScanLimiter;

/// Build [`ScanProperties`] with custom [`RangeOptions`] and
/// [`ScanLimiter`].
///
/// Methods can be chained. Value of [`ScanProperties`] is constructed
/// by calling [`build`] method.
///
/// [`build`]: ScanPropertiesBuilder::build
#[derive(Debug)]
pub struct ScanPropertiesBuilder {
    range_options: RangeOptions,
    scan_limiter: ScanLimiter,
}

impl ScanPropertiesBuilder {
    /// Returns a new builder.
    pub fn new() -> ScanPropertiesBuilder {
        ScanPropertiesBuilder {
            range_options: RangeOptions::default(),
            scan_limiter: ScanLimiter::new(None, None, None),
        }
    }

    /// Set [`RangeOptions`] using a closure.
    ///
    /// # Safety
    ///
    /// There is **no way** in the [`RangeOptions`] API to set a limit
    /// of `0`. *Infact* if you set the limit to `0`, you are
    /// indicating that you want [unlimited] rows, which almost always
    /// is not the behavior that you want.
    ///
    /// [unlimited]: fdb::range::KEYVALUE_LIMIT_UNLIMITED
    pub unsafe fn set_range_options<F>(&mut self, f: F) -> &mut ScanPropertiesBuilder
    where
        F: FnOnce(&mut RangeOptions),
    {
        f(&mut self.range_options);
        self
    }

    /// Set [`ScanLimiter`].
    pub fn set_scan_limiter(&mut self, scan_limiter: ScanLimiter) -> &mut ScanPropertiesBuilder {
        self.scan_limiter = scan_limiter;
        self
    }

    /// Create the configured [`ScanProperties`].
    pub fn build(self) -> ScanProperties {
        let ScanPropertiesBuilder {
            range_options,
            scan_limiter,
        } = self;

        ScanProperties {
            range_options,
            scan_limiter,
        }
    }
}

impl Default for ScanPropertiesBuilder {
    fn default() -> ScanPropertiesBuilder {
        ScanPropertiesBuilder::new()
    }
}

/// Properties that pertain to a scan. It consists of [`RangeOptions`]
/// and a [`ScanLimiter`].

// Note: Unlike Java RecordLayer, we do not have
//       `ScanProperties.FORWARD_SCAN` or
//       `ScanProperties.FORWARD_SCAN` as that is taken care of
//       `reverse` option in `RangeOptions`. We also do not have Java
//       class `ExecuteProperties` as concerns covered by it is taken
//       care of by `RangeOptions` and `ScanLimiter`.
//
//       In addition there is no unit test for this type as
//       `scan_properties_builder_build` takes care of exercising the
//       API.
//
//       Also, see comment mentioned for type `KeyValueCursorBuilder`
//       regarding `PartialEq` and unit testing.
#[cfg(not(test))]
#[derive(Debug, Clone)]
pub struct ScanProperties {
    range_options: RangeOptions,
    scan_limiter: ScanLimiter,
}

/// We need to derive `PartialEq` for testing.
#[cfg(test)]
#[derive(Debug, Clone, PartialEq)]
pub struct ScanProperties {
    range_options: RangeOptions,
    scan_limiter: ScanLimiter,
}

impl ScanProperties {
    /// Get reference to [`RangeOptions`] used by the scan.
    pub fn get_range_options_ref(&self) -> &RangeOptions {
        &self.range_options
    }

    /// Get reference to [`ScanLimiter`] used by the scan.
    pub fn get_scan_limiter_ref(&self) -> &ScanLimiter {
        &self.scan_limiter
    }

    pub(crate) fn into_parts(self) -> (RangeOptions, ScanLimiter) {
        let ScanProperties {
            range_options,
            scan_limiter,
        } = self;
        (range_options, scan_limiter)
    }
}

#[cfg(test)]
mod tests {
    use fdb::range::StreamingMode;

    use crate::scan::{ByteScanLimiter, KeyValueScanLimiter, ScanLimiter};

    use super::ScanPropertiesBuilder;

    #[test]
    fn builder_build() {
        // Smoke test on the API usage
        let scan_properties = {
            let mut builder = ScanPropertiesBuilder::new();
            unsafe {
                builder.set_range_options(|r| {
                    r.set_limit(100);
                    r.set_reverse(true);
                })
            }
            .set_scan_limiter(ScanLimiter::new(
                Some(KeyValueScanLimiter::tracking()),
                Some(ByteScanLimiter::tracking()),
                None,
            ));
            builder.build()
        };

        assert!(scan_properties.get_range_options_ref().get_reverse());
        assert_eq!(scan_properties.get_range_options_ref().get_limit(), 100);
        assert_eq!(
            scan_properties.get_range_options_ref().get_mode(),
            StreamingMode::Iterator
        );

        // Safety: Safe to unwrap because we are setting `Some` value
        //         above.
        assert_eq!(
            scan_properties
                .get_scan_limiter_ref()
                .get_keyvalue_scan_limiter_ref()
                .unwrap()
                .get_limit(),
            usize::MAX
        );
        assert_eq!(
            scan_properties
                .get_scan_limiter_ref()
                .get_byte_scan_limiter_ref()
                .unwrap()
                .get_limit(),
            usize::MAX
        );
        assert!(scan_properties
            .get_scan_limiter_ref()
            .get_time_scan_limiter_ref()
            .is_none());
    }
}