// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at https://mozilla.org/MPL/2.0/.

//! The different metric types supported by the Glean SDK to handle data.

// Re-export of `glean` types we can re-use.
// That way a user only needs to depend on this crate, not on glean (and there can't be a
// version mismatch).
pub use glean::{
    traits, CommonMetricData, DistributionData, ErrorType, LabeledMetricData, Lifetime, MemoryUnit,
    RecordedEvent, TimeUnit, TimerId,
};

#[macro_use]
mod metric_getter;

mod boolean;
mod counter;
mod custom_distribution;
mod datetime;
mod denominator;
mod dual_labeled_counter;
mod dual_labeled_counter_sub;
mod event;
mod labeled;
mod labeled_boolean;
mod labeled_counter;
mod labeled_custom_distribution;
mod labeled_memory_distribution;
mod labeled_timing_distribution;
mod memory_distribution;
mod numerator;
mod object;
mod ping;
mod quantity;
mod rate;
pub(crate) mod string;
mod string_list;
mod text;
mod timespan;
mod timing_distribution;
mod url;
mod uuid;

pub use self::boolean::BooleanMetric;
pub use self::counter::CounterMetric;
pub use self::custom_distribution::{CustomDistributionMetric, LocalCustomDistribution};
pub use self::datetime::DatetimeMetric;
pub use self::denominator::DenominatorMetric;
pub use self::dual_labeled_counter::DualLabeledCounterMetric;
pub use self::dual_labeled_counter_sub::DualLabeledCounterSubMetric;
pub use self::event::{EventMetric, EventRecordingError, ExtraKeys, NoExtraKeys};
pub use self::labeled::LabeledMetric;
pub use self::labeled_boolean::LabeledBooleanMetric;
pub use self::labeled_counter::LabeledCounterMetric;
pub use self::labeled_custom_distribution::LabeledCustomDistributionMetric;
pub use self::labeled_memory_distribution::LabeledMemoryDistributionMetric;
pub use self::labeled_timing_distribution::LabeledTimingDistributionMetric;
pub use self::memory_distribution::{LocalMemoryDistribution, MemoryDistributionMetric};
pub use self::metric_getter::{
    BaseMetric, BaseMetricId, BaseMetricResult, LookupError, LookupResult, MetricId,
    MetricMetadata, MetricMetadataGetter, MetricMetadataGetterImpl, MetricNamer, SubMetricId,
};
pub use self::numerator::NumeratorMetric;
pub use self::object::{ObjectMetric, RuntimeObject};
pub use self::ping::Ping;
pub use self::quantity::QuantityMetric as LabeledQuantityMetric;
pub use self::quantity::QuantityMetric;
pub use self::rate::RateMetric;
pub use self::string::StringMetric;
pub use self::string::StringMetric as LabeledStringMetric;
pub use self::string_list::StringListMetric;
pub use self::text::TextMetric;
pub use self::timespan::TimespanMetric;
pub use self::timing_distribution::TimingDistributionMetric;
pub use self::url::UrlMetric;
pub use self::uuid::UuidMetric;

/// A metadata structure common to all Child metrics. Storing this data is not
/// necessary at all times, but many metrics require the ID for IPC
/// operations, and storing the name + category is necessary so that profiler
/// markers can be accurately recorded in child processes.
#[derive(Debug, Clone)]
pub struct ChildMetricMeta {
    pub id: BaseMetricId,
    pub name: String,
    pub category: String,
}

impl ChildMetricMeta {
    pub fn from_common_metric_data(id: BaseMetricId, meta: CommonMetricData) -> ChildMetricMeta {
        ChildMetricMeta {
            id,
            name: meta.name,
            category: meta.category,
        }
    }

    pub fn from_metric_identifier<'a, T>(id: BaseMetricId, inner: &'a T) -> ChildMetricMeta
    where
        T: glean::MetricIdentifier<'a>,
    {
        let (name, category, _) = inner.get_identifiers();
        ChildMetricMeta {
            id,
            name: name.into(),
            category: category.into(),
        }
    }

    pub fn from_name_category_pair<T, U>(id: BaseMetricId, name: T, category: U) -> ChildMetricMeta
    where
        T: Into<String>,
        U: Into<String>,
    {
        ChildMetricMeta {
            id,
            name: name.into(),
            category: category.into(),
        }
    }

    pub fn get_identifiers<'a>(&'a self) -> (&'a str, &'a str, Option<&'a str>) {
        (&self.category, &self.name, None)
    }
}

// We only access the methods here when we're building with Gecko, as that's
// when we have access to the profiler. We don't need alternative (i.e.
// non-gecko) implementations, as any imports from this sub-module are also
// gated with the same #[cfg(feature...)]
#[cfg(feature = "with_gecko")]
pub(crate) mod profiler_utils {
    use std::marker::PhantomData;

    use chrono::{DateTime, FixedOffset, Local};

    use crate::private::{MetricMetadataGetter, MetricNamer};

    use super::max_string_byte_length;
    pub(crate) use super::truncate_string_for_marker;

    // Declare the telemetry profiling category as a constant here.
    // This lets us avoid re-importing gecko_profiler ... within metric files,
    // which keeps the importing a bit cleaner, and reduces profiler intrusion.
    #[allow(non_upper_case_globals)]
    pub const TelemetryProfilerCategory: gecko_profiler::ProfilingCategoryPair =
        gecko_profiler::ProfilingCategoryPair::Telemetry(None);

    pub(crate) fn local_now_with_offset() -> DateTime<FixedOffset> {
        // See https://bugzilla.mozilla.org/show_bug.cgi?id=1611770.
        //
        // It's not clear if this bug on Windows still exist with the latest versions of
        // the `time` crate. Removed the workaround.
        let now: DateTime<Local> = Local::now();
        now.with_timezone(now.offset())
    }

    /// Try to convert a glean::Datetime into a chrono::DateTime Returns none if
    /// the glean::Datetime offset is not a valid timezone We would prefer to
    /// use .into or similar, but we need to wait until this is implemented in
    /// the Glean SDK. See Bug 1925313 for more details.
    #[allow(deprecated)] // use of deprecated chrono functions.
    pub(crate) fn glean_to_chrono_datetime(
        gdt: &glean::Datetime,
    ) -> Option<chrono::LocalResult<chrono::DateTime<chrono::FixedOffset>>> {
        use chrono::{FixedOffset, TimeZone};
        let tz = FixedOffset::east_opt(gdt.offset_seconds);
        if tz.is_none() {
            return None;
        }

        Some(
            FixedOffset::east(gdt.offset_seconds)
                .ymd_opt(gdt.year, gdt.month, gdt.day)
                .and_hms_nano_opt(gdt.hour, gdt.minute, gdt.second, gdt.nanosecond),
        )
    }

    // Truncate a vector down to a maximum size.
    // We want to avoid storing large vectors of values in the profiler buffer,
    // so this helper method allows markers to explicitly limit the size of
    // vectors of values that might originate from Glean
    pub(crate) fn truncate_vector_for_marker<T>(vec: &Vec<T>) -> Vec<T>
    where
        T: Clone,
    {
        const MAX_VECTOR_LENGTH: usize = 1024;
        if vec.len() > MAX_VECTOR_LENGTH {
            vec[0..MAX_VECTOR_LENGTH - 1].to_vec()
        } else {
            vec.clone()
        }
    }

    // Given an ID, look up the metric referred to by said ID, get the
    // metadata associated with it (category, name, label), and stream that
    // information (with the JSONWriter) into the profiler buffer.
    pub(crate) fn stream_identifiers_by_id<MetricT: MetricMetadataGetter + MetricNamer>(
        id: &super::MetricId,
        json_writer: &mut gecko_profiler::JSONWriter,
    ) {
        match MetricT::get_metric_metadata_by_id(id) {
            Ok((metadata, mlabel)) => {
                // Write the category, as that will always be contained
                // (correctly) within the metadata that we extract from
                // within the metric.
                json_writer.unique_string_property("cat", &metadata.category);
                // Getting the name and label of a metric is non trivial. We
                // have three different (potential) sources of label, one of
                // which requires us to split the name to get it, so do some
                // case by case analysis to try and get a coherent
                // name/label.
                match metadata.label.or(mlabel) {
                    // If either the label we get from the metric, or the
                    // label we got while retrieveing the metric, is valid,
                    // use them directly.
                    Some(label) => {
                        // If the label comes from a dual_labeled_counter,
                        // it is prefixed and delimited with a record separator
                        // which we should adapt for display.
                        let label = label.strip_prefix('\x1E').unwrap_or(&label);
                        let label = label.replace('\x1E', ", ");
                        json_writer.unique_string_property("id", &metadata.name);
                        json_writer.unique_string_property("label", &label);
                    }
                    // Otherwise, assume that the label must be part of the
                    // name, and try and split it.
                    None => match metadata.name.split_once("/") {
                        Some((name, label)) => {
                            json_writer.unique_string_property("id", &name);
                            json_writer.unique_string_property("label", &label);
                        }
                        None => {
                            json_writer.unique_string_property("id", &metadata.name);
                        }
                    },
                }
            }
            Err(e) => {
                let error_string = format!("Error looking up {:?}: {:?}", id, e);
                json_writer.unique_string_property("id", &error_string);
            }
        }
    }

    // Generic marker structs:

    #[derive(serde::Serialize, serde::Deserialize, Debug)]
    pub(crate) struct StringLikeMetricMarker<MetricT> {
        id: super::MetricId,
        val: String,
        _phantom: PhantomData<MetricT>,
    }

    impl<MetricT> StringLikeMetricMarker<MetricT> {
        pub fn new(id: super::MetricId, val: &String) -> StringLikeMetricMarker<MetricT> {
            StringLikeMetricMarker::<MetricT> {
                id: id,
                val: truncate_string_for_marker(val.clone()),
                _phantom: PhantomData,
            }
        }

        pub fn new_owned(id: super::MetricId, val: String) -> StringLikeMetricMarker<MetricT> {
            StringLikeMetricMarker::<MetricT> {
                id: id,
                val: truncate_string_for_marker(val),
                _phantom: PhantomData,
            }
        }
    }

    impl<MetricT: MetricMetadataGetter + MetricNamer> gecko_profiler::ProfilerMarker
        for StringLikeMetricMarker<MetricT>
    {
        fn marker_type_name() -> &'static str {
            "StringLikeMetric"
        }

        fn marker_type_display() -> gecko_profiler::MarkerSchema {
            use gecko_profiler::schema::*;
            let mut schema = MarkerSchema::new(&[Location::MarkerChart, Location::MarkerTable]);
            schema.set_tooltip_label(
                "{marker.data.cat}.{marker.data.id} {marker.data.label} {marker.data.val}",
            );
            schema.set_table_label("{marker.name} - {marker.data.cat}.{marker.data.id} {marker.data.label}: {marker.data.val}");
            schema.add_key_label_format("cat", "Category", Format::UniqueString);
            schema.add_key_label_format("id", "Metric", Format::UniqueString);
            schema.add_key_label_format("label", "Label", Format::UniqueString);
            schema.add_key_label_format("val", "Value", Format::String);
            schema
        }

        fn stream_json_marker_data(&self, json_writer: &mut gecko_profiler::JSONWriter) {
            crate::private::profiler_utils::stream_identifiers_by_id::<MetricT>(
                &self.id.into(),
                json_writer,
            );

            debug_assert!(self.val.len() <= max_string_byte_length());
            json_writer.string_property("val", self.val.as_str());
        }
    }

    #[derive(serde::Serialize, serde::Deserialize, Debug)]
    pub(crate) struct IntLikeMetricMarker<MetricT, T>
    where
        T: Into<i64>,
    {
        id: super::MetricId,
        label: Option<String>,
        val: T,
        _phantom: PhantomData<MetricT>,
    }

    impl<MetricT, T> IntLikeMetricMarker<MetricT, T>
    where
        T: Into<i64>,
    {
        pub fn new(
            id: super::MetricId,
            label: Option<String>,
            val: T,
        ) -> IntLikeMetricMarker<MetricT, T> {
            IntLikeMetricMarker {
                id,
                label,
                val,
                _phantom: PhantomData,
            }
        }
    }

    impl<MetricT: MetricMetadataGetter + MetricNamer, T> gecko_profiler::ProfilerMarker
        for IntLikeMetricMarker<MetricT, T>
    where
        T: serde::Serialize + serde::de::DeserializeOwned + Into<i64> + Copy,
    {
        fn marker_type_name() -> &'static str {
            "IntLikeMetric"
        }

        fn marker_type_display() -> gecko_profiler::MarkerSchema {
            use gecko_profiler::schema::*;
            let mut schema = MarkerSchema::new(&[Location::MarkerChart, Location::MarkerTable]);
            schema.set_tooltip_label(
                "{marker.data.cat}.{marker.data.id} {marker.data.label} {marker.data.val}",
            );
            schema.set_table_label(
                "{marker.name} - {marker.data.cat}.{marker.data.id} {marker.data.label}: {marker.data.val}",
            );
            schema.add_key_label_format("cat", "Category", Format::UniqueString);
            schema.add_key_label_format("id", "Metric", Format::UniqueString);
            schema.add_key_label_format("label", "Label", Format::UniqueString);
            schema.add_key_label_format("val", "Value", Format::Integer);

            schema
        }

        fn stream_json_marker_data(&self, json_writer: &mut gecko_profiler::JSONWriter) {
            crate::private::profiler_utils::stream_identifiers_by_id::<MetricT>(
                &self.id.into(),
                json_writer,
            );

            json_writer.int_property("val", self.val.clone().into());
        }
    }

    // This might seem like overkill for discerning between a single element and
    // a vector of elements. However, from the perspective of the profiler buffer
    // this is quite reasonable, as it has a lower memory overhead. Doing the maths
    // (and assuming a 64-bit system, so usize = 8 bytes):
    // Enum: i64 value (8-bytes), enum discernment byte = 9 bytes,
    // Vector: i64 values (at least 8 bytes), usize length, usize capacity, data
    //     pointer = 32 bytes
    #[derive(serde::Serialize, serde::Deserialize, Debug)]
    pub(crate) enum DistributionValues<T> {
        Sample(T),
        Samples(Vec<T>),
    }

    #[derive(serde::Serialize, serde::Deserialize, Debug)]
    pub(crate) struct DistributionMetricMarker<MetricT, T> {
        id: super::MetricId,
        label: Option<String>,
        value: DistributionValues<T>,
        _phantom: PhantomData<MetricT>,
    }

    impl<MetricT, T> DistributionMetricMarker<MetricT, T> {
        pub fn new(
            id: super::MetricId,
            label: Option<String>,
            value: DistributionValues<T>,
        ) -> DistributionMetricMarker<MetricT, T> {
            DistributionMetricMarker {
                id,
                label,
                value,
                _phantom: PhantomData,
            }
        }
    }

    impl<MetricT: MetricMetadataGetter + MetricNamer, T> gecko_profiler::ProfilerMarker
        for DistributionMetricMarker<MetricT, T>
    where
        T: serde::Serialize + serde::de::DeserializeOwned + Copy + std::fmt::Display,
    {
        fn marker_type_name() -> &'static str {
            "DistMetric"
        }

        fn marker_type_display() -> gecko_profiler::MarkerSchema {
            use gecko_profiler::schema::*;
            let mut schema = MarkerSchema::new(&[Location::MarkerChart, Location::MarkerTable]);
            schema.set_tooltip_label(
                "{marker.data.cat}.{marker.data.id} {marker.data.label} {marker.data.sample}",
            );
            schema.set_table_label(
                "{marker.name} - {marker.data.cat}.{marker.data.id} {marker.data.label}: {marker.data.sample}{marker.data.samples}",
            );
            schema.set_chart_label("{marker.data.cat}.{marker.data.id}");
            schema.add_key_label_format("cat", "Category", Format::UniqueString);
            schema.add_key_label_format("id", "Metric", Format::UniqueString);
            schema.add_key_label_format("label", "Label", Format::UniqueString);
            schema.add_key_label_format("sample", "Sample", Format::String);
            schema.add_key_label_format("samples", "Samples", Format::String);
            schema
        }

        fn stream_json_marker_data(&self, json_writer: &mut gecko_profiler::JSONWriter) {
            crate::private::profiler_utils::stream_identifiers_by_id::<MetricT>(
                &self.id.into(),
                json_writer,
            );

            match &self.value {
                DistributionValues::Sample(s) => {
                    let s = format!("{}", s);
                    json_writer.string_property("sample", s.as_str());
                }
                DistributionValues::Samples(s) => {
                    let s = format!(
                        "[{}]",
                        s.iter()
                            .map(|v| v.to_string())
                            .collect::<Vec<_>>()
                            .join(",")
                    );
                    json_writer.string_property("samples", s.as_str());
                }
            };
        }
    }

    #[derive(serde::Serialize, serde::Deserialize, Debug)]
    pub(crate) struct BooleanMetricMarker<MetricT> {
        id: super::MetricId,
        label: Option<String>,
        val: bool,
        _phantom: PhantomData<MetricT>,
    }

    impl<MetricT> BooleanMetricMarker<MetricT> {
        pub fn new(
            id: super::MetricId,
            label: Option<String>,
            val: bool,
        ) -> BooleanMetricMarker<MetricT> {
            BooleanMetricMarker {
                id,
                label,
                val,
                _phantom: PhantomData,
            }
        }
    }

    impl<MetricT: MetricMetadataGetter + MetricNamer> gecko_profiler::ProfilerMarker
        for BooleanMetricMarker<MetricT>
    {
        fn marker_type_name() -> &'static str {
            "BooleanMetric"
        }

        fn marker_type_display() -> gecko_profiler::MarkerSchema {
            use gecko_profiler::schema::*;
            let mut schema = MarkerSchema::new(&[Location::MarkerChart, Location::MarkerTable]);
            schema.set_tooltip_label("{marker.data.cat}.{marker.data.id} {marker.data.val}");
            schema.set_table_label(
                "{marker.name} - {marker.data.cat}.{marker.data.id}: {marker.data.val}",
            );
            schema.add_key_label_format("cat", "Category", Format::UniqueString);
            schema.add_key_label_format("id", "Metric", Format::UniqueString);
            schema.add_key_label_format("label", "Label", Format::UniqueString);
            schema.add_key_label_format("val", "Value", Format::String);
            schema
        }

        fn stream_json_marker_data(&self, json_writer: &mut gecko_profiler::JSONWriter) {
            crate::private::profiler_utils::stream_identifiers_by_id::<MetricT>(
                &self.id.into(),
                json_writer,
            );

            json_writer.bool_property("val", self.val);
        }
    }
    #[derive(serde::Serialize, serde::Deserialize, Debug)]
    pub(crate) struct PingMarker {
        name: String,
        reason: Option<String>,
    }

    impl PingMarker {
        pub(crate) fn new_for_submit(name: String, reason: Option<String>) -> Self {
            PingMarker { name, reason }
        }
    }

    impl gecko_profiler::ProfilerMarker for PingMarker {
        fn marker_type_name() -> &'static str {
            "GleanPing"
        }

        fn marker_type_display() -> gecko_profiler::MarkerSchema {
            use gecko_profiler::schema::*;
            let mut schema = MarkerSchema::new(&[Location::MarkerChart, Location::MarkerTable]);
            schema.set_tooltip_label("{marker.data.id} {marker.data.reason}");
            schema.set_table_label("{marker.data.id} {marker.data.reason}");
            schema.add_key_label_format("id", "Ping name", Format::UniqueString);
            schema.add_key_label_format("reason", "Submission reason", Format::String);
            schema
        }

        fn stream_json_marker_data(&self, json_writer: &mut gecko_profiler::JSONWriter) {
            json_writer.unique_string_property("id", self.name.as_str());

            if let Some(reason) = &self.reason {
                json_writer.string_property("reason", reason);
            };
        }
    }
}

// These two methods, and the constant function, "live" within profiler_utils,
// but as we need them available for testing, when we might not have gecko
// available, we use a different set of cfg features to enable them in both
// cases. Note that we re-export the main truncation method within
// `profiler_utils` to correct the namespace.
#[cfg(any(feature = "with_gecko", test))]
pub(crate) fn truncate_string_for_marker(input: String) -> String {
    truncate_string_for_marker_to_length(input, max_string_byte_length())
}

#[cfg(any(feature = "with_gecko", test))]
const fn max_string_byte_length() -> usize {
    1024
}

#[cfg(any(feature = "with_gecko", test))]
#[inline]
fn truncate_string_for_marker_to_length(mut input: String, byte_length: usize) -> String {
    // Truncating an arbitrary string in Rust is not not exactly easy, as
    // Strings are UTF-8 encoded. The "built-in" String::truncate, however,
    // operates on bytes, and panics if the truncation crosses a character
    // boundary.
    // To avoid this, we need to find the first unicode char boundary that
    // is less than the size that we're looking for. Note that we're
    // interested in how many *bytes* the string takes up (when we add it
    // to a marker), so we truncate to `MAX_STRING_BYTE_LENGTH` bytes, or
    // (by walking the truncation point back) to a number of bytes that
    // still represents valid UTF-8.
    // Note, this truncation may not provide a valid json result, and
    // truncation acts on glyphs, not graphemes, so the resulting text
    // may not render exactly the same as before it was truncated.

    // Copied from src/core/num/mod.rs
    // Check if a given byte is a utf8 character boundary
    #[inline]
    const fn is_utf8_char_boundary(b: u8) -> bool {
        // This is bit magic equivalent to: b < 128 || b >= 192
        (b as i8) >= -0x40
    }

    // Check if our truncation point is a char boundary. If it isn't, move
    // it "back" along the string until it is.
    // Note, this is an almost direct port of the rust standard library
    // function `str::floor_char_boundary`. We re-produce it as this API is
    // not yet stable, and we make some small changes (such as modifying
    // the input in-place) that are more convenient for this method.
    if byte_length < input.len() {
        let lower_bound = byte_length.saturating_sub(3);

        let new_byte_length = input.as_bytes()[lower_bound..=byte_length]
            .iter()
            .rposition(|b| is_utf8_char_boundary(*b));

        // SAFETY: we know that the character boundary will be within four bytes
        let truncation_point = unsafe { lower_bound + new_byte_length.unwrap_unchecked() };
        input.truncate(truncation_point)
    }
    input
}

pub trait TestGetNumErrors {
    /// **Exported for test purposes.**
    ///
    /// Gets the number of recorded errors for the given metric and error type.
    ///
    /// # Arguments
    ///
    /// * `error` - The type of error
    ///
    /// # Returns
    ///
    /// The number of errors reported.
    fn test_get_num_recorded_errors(&self, error_type: glean::ErrorType) -> i32;
}

#[cfg(test)]
mod truncation_tests {
    use crate::private::truncate_string_for_marker;
    use crate::private::truncate_string_for_marker_to_length;

    // Testing is heavily inspired/copied from the existing tests for the
    // standard library function `floor_char_boundary`.
    // See: https://github.com/rust-lang/rust/blob/bca5fdebe0e539d123f33df5f2149d5976392e76/library/alloc/tests/str.rs#L2363

    // Check a series of truncation points (i.e. string lengths), and assert
    // that they all produce the same trunctated string from the input.
    fn check_many(s: &str, arg: impl IntoIterator<Item = usize>, truncated: &str) {
        for len in arg {
            assert_eq!(
                truncate_string_for_marker_to_length(s.to_string(), len),
                truncated,
                "truncate_string_for_marker_to_length({:?}, {:?}) != {:?}",
                len,
                s,
                truncated
            );
        }
    }

    #[test]
    fn truncate_1byte_chars() {
        check_many("jp", [0], "");
        check_many("jp", [1], "j");
        check_many("jp", 2..4, "jp");
    }

    #[test]
    fn truncate_2byte_chars() {
        check_many("ĵƥ", 0..2, "");
        check_many("ĵƥ", 2..4, "ĵ");
        check_many("ĵƥ", 4..6, "ĵƥ");
    }

    #[test]
    fn truncate_3byte_chars() {
        check_many("日本", 0..3, "");
        check_many("日本", 3..6, "日");
        check_many("日本", 6..8, "日本");
    }

    #[test]
    fn truncate_4byte_chars() {
        check_many("🇯🇵", 0..4, "");
        check_many("🇯🇵", 4..8, "🇯");
        check_many("🇯🇵", 8..10, "🇯🇵");
    }

    // Check a single string against it's expected truncated outcome
    fn check_one(s: String, truncated: String) {
        assert_eq!(
            truncate_string_for_marker(s.clone()),
            truncated,
            "truncate_string_for_marker({:?}) != {:?}",
            s,
            truncated
        );
    }

    #[test]
    fn full_truncation() {
        // Keep the values in this up to date with MAX_STRING_BYTE_LENGTH

        // For each of these tests, we use a padding value to get near to 1024
        // bytes, then add on a variety of further characters that push us up
        // to or over the limit. We then check that we correctly truncated to
        // the correct character or grapheme.
        let pad = |reps: usize| -> String { "-".repeat(reps) };

        // Note: len(jpjpj) = 5
        check_one(pad(1020) + "jpjpj", pad(1020) + "jpjp");

        // Note: len(ĵƥ) = 4
        check_one(pad(1020) + "ĵƥ", pad(1020) + "ĵƥ");
        check_one(pad(1021) + "ĵƥ", pad(1021) + "ĵ");

        // Note: len(日本) = 6
        check_one(pad(1018) + "日本", pad(1018) + "日本");
        check_one(pad(1020) + "日本", pad(1020) + "日");
        check_one(pad(1022) + "日本", pad(1022));

        // Note: len(🇯🇵) = 8, len(🇯) = 4
        check_one(pad(1016) + "🇯🇵", pad(1016) + "🇯🇵");
        check_one(pad(1017) + "🇯🇵", pad(1017) + "🇯");
        check_one(pad(1021) + "🇯🇵", pad(1021) + "");
    }
}

macro_rules! impl_malloc_size_of_metric {
    ($($ty:ident),+ $(,)?) => {
        $(
            impl malloc_size_of::MallocSizeOf for $ty {
                fn size_of(&self, ops: &mut malloc_size_of::MallocSizeOfOps) -> usize {
                    match self {
                        $ty::Child { .. } => 0,
                        $ty::Parent { inner, .. } => inner.size_of(ops),
                    }
                }
            }
        )+
    };
}

impl_malloc_size_of_metric!(
    CounterMetric,
    CustomDistributionMetric,
    DatetimeMetric,
    DenominatorMetric,
    MemoryDistributionMetric,
    NumeratorMetric,
    RateMetric,
    StringMetric,
    StringListMetric,
    TextMetric,
    TimespanMetric,
    TimingDistributionMetric,
    UrlMetric,
    UuidMetric,
);

impl malloc_size_of::MallocSizeOf for BooleanMetric {
    fn size_of(&self, ops: &mut malloc_size_of::MallocSizeOfOps) -> usize {
        match self {
            BooleanMetric::Child(_) | BooleanMetric::UnorderedChild(_) => 0,
            BooleanMetric::Parent { inner, .. } => inner.size_of(ops),
        }
    }
}

impl malloc_size_of::MallocSizeOf for QuantityMetric {
    fn size_of(&self, ops: &mut malloc_size_of::MallocSizeOfOps) -> usize {
        match self {
            QuantityMetric::Child(_) | QuantityMetric::UnorderedChild(_) => 0,
            QuantityMetric::Parent { inner, .. } => inner.size_of(ops),
        }
    }
}

impl<K> malloc_size_of::MallocSizeOf for EventMetric<K> {
    fn size_of(&self, ops: &mut malloc_size_of::MallocSizeOfOps) -> usize {
        match self {
            EventMetric::Child(_c) => 0,
            EventMetric::Parent { inner, .. } => inner.size_of(ops),
        }
    }
}
impl<K> malloc_size_of::MallocSizeOf for ObjectMetric<K> {
    fn size_of(&self, ops: &mut malloc_size_of::MallocSizeOfOps) -> usize {
        match self {
            ObjectMetric::Child => 0,
            ObjectMetric::Parent { inner, .. } => inner.size_of(ops),
        }
    }
}