ddsketch/canonical/mapping/
mod.rs

1//! Index mapping.
2
3use datadog_protos::sketches::{index_mapping::Interpolation, IndexMapping as ProtoIndexMapping};
4
5use super::error::ProtoConversionError;
6
7mod fixed;
8pub use self::fixed::FixedLogarithmicMapping;
9
10mod logarithmic;
11pub use self::logarithmic::LogarithmicMapping;
12
13/// Maps values to bin indices and vice versa.
14///
15/// The mapping defines the relationship between floating-point values and integer bin indices, determining the relative
16/// accuracy of the sketch.
17pub trait IndexMapping: Clone + Send + Sync {
18    /// Returns the index of the bin for the given positive value.
19    ///
20    /// The value must be positive. For negative values, use the index of the absolute value and store in the negative
21    /// store.
22    fn index(&self, value: f64) -> i32;
23
24    /// Returns the representative value for the given index.
25    ///
26    /// This is typically the geometric mean of the bin's lower and upper bounds.
27    fn value(&self, index: i32) -> f64;
28
29    /// Returns the lower bound of the bin at the given index.
30    fn lower_bound(&self, index: i32) -> f64;
31
32    /// Returns the relative accuracy of this mapping.
33    ///
34    /// The relative accuracy is the maximum relative error guaranteed for any quantile query.
35    fn relative_accuracy(&self) -> f64;
36
37    /// Returns the minimum positive value that can be indexed.
38    fn min_indexable_value(&self) -> f64;
39
40    /// Returns the maximum positive value that can be indexed.
41    fn max_indexable_value(&self) -> f64;
42
43    /// Returns the gamma value (base of the logarithm) for this mapping.
44    fn gamma(&self) -> f64;
45
46    /// Returns the index offset used by this mapping.
47    ///
48    /// The index offset shifts all bin indices by a constant value.
49    fn index_offset(&self) -> f64;
50
51    /// Returns the interpolation mode used by this mapping.
52    ///
53    /// The interpolation mode determines how the logarithm is approximated.
54    fn interpolation(&self) -> Interpolation;
55
56    /// Validates that a protobuf `IndexMapping` is compatible with this mapping.
57    ///
58    /// # Errors
59    ///
60    /// If the given protobuf mapping parameters do not match this mapping's configuration, an error describing the
61    /// mismatch is returned.
62    fn validate_proto_mapping(&self, proto: &ProtoIndexMapping) -> Result<(), ProtoConversionError>;
63
64    /// Converts this mapping to a protobuf `IndexMapping`.
65    fn to_proto(&self) -> ProtoIndexMapping;
66}
ddsketch/canonical/mapping/mod.rs

ddsketch/canonical/mapping/
mod.rs
