metriken-exposition 0.16.0

use std::collections::HashMap;
use std::time::{Duration, SystemTime};

#[cfg(feature = "msgpack")]
use rmp_serde::encode::Error as SerializeMsgpackError;
#[cfg(feature = "json")]
use serde_json::Error as JsonError;

#[derive(Clone, Debug)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct Counter {
    pub name: String,
    pub value: u64,
    pub metadata: HashMap<String, String>,
}

#[derive(Clone, Debug)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct Gauge {
    pub name: String,
    pub value: i64,
    pub metadata: HashMap<String, String>,
}

#[derive(Clone, Debug)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct Histogram {
    pub name: String,
    pub value: histogram::Histogram,
    pub metadata: HashMap<String, String>,
}

/// Contains a snapshot of metric readings.
#[derive(Clone, Debug)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct SnapshotV1 {
    pub systemtime: SystemTime,

    #[cfg_attr(feature = "serde", serde(default))]
    pub metadata: HashMap<String, String>,

    pub counters: Vec<Counter>,
    pub gauges: Vec<Gauge>,
    pub histograms: Vec<Histogram>,
}

/// Contains a snapshot of metric readings.
#[derive(Clone, Debug)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
pub struct SnapshotV2 {
    pub systemtime: SystemTime,
    pub duration: Duration,

    #[cfg_attr(feature = "serde", serde(default))]
    pub metadata: HashMap<String, String>,

    pub counters: Vec<Counter>,
    pub gauges: Vec<Gauge>,
    pub histograms: Vec<Histogram>,
}

#[derive(Clone, Debug)]
#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
#[cfg_attr(feature = "serde", serde(untagged))]
pub enum Snapshot {
    V1(SnapshotV1),
    V2(SnapshotV2),
}

#[cfg(feature = "parquet")]
pub(crate) struct HashedSnapshot {
    pub(crate) ts: u64,
    pub(crate) duration: Option<u64>,
    pub(crate) counters: HashMap<String, Counter>,
    pub(crate) gauges: HashMap<String, Gauge>,
    pub(crate) histograms: HashMap<String, Histogram>,
}

impl Snapshot {
    pub fn systemtime(&self) -> SystemTime {
        match self {
            Snapshot::V1(s) => s.systemtime,
            Snapshot::V2(s) => s.systemtime,
        }
    }

    pub fn duration(&self) -> Option<Duration> {
        match self {
            Snapshot::V1(_) => None,
            Snapshot::V2(s) => Some(s.duration),
        }
    }

    pub fn metadata(&mut self) -> HashMap<String, String> {
        match self {
            Snapshot::V1(s) => std::mem::take(&mut s.metadata),
            Snapshot::V2(s) => std::mem::take(&mut s.metadata),
        }
    }

    pub fn counters(&mut self) -> Vec<Counter> {
        match self {
            Snapshot::V1(s) => std::mem::take(&mut s.counters),
            Snapshot::V2(s) => std::mem::take(&mut s.counters),
        }
    }

    pub fn gauges(&mut self) -> Vec<Gauge> {
        match self {
            Snapshot::V1(s) => std::mem::take(&mut s.gauges),
            Snapshot::V2(s) => std::mem::take(&mut s.gauges),
        }
    }

    pub fn histograms(&mut self) -> Vec<Histogram> {
        match self {
            Snapshot::V1(s) => std::mem::take(&mut s.histograms),
            Snapshot::V2(s) => std::mem::take(&mut s.histograms),
        }
    }

    #[cfg(feature = "json")]
    pub fn to_json<T>(val: &T) -> Result<Vec<u8>, JsonError>
    where
        T: serde::Serialize + ?Sized,
    {
        let mut res = serde_json::to_vec(val)?;
        res.push(b'\n');
        Ok(res)
    }

    #[cfg(feature = "msgpack")]
    pub fn to_msgpack<T>(val: &T) -> Result<Vec<u8>, SerializeMsgpackError>
    where
        T: serde::Serialize + ?Sized,
    {
        rmp_serde::encode::to_vec(val)
    }
}

#[cfg(feature = "parquet")]
impl From<Snapshot> for HashedSnapshot {
    fn from(mut snapshot: Snapshot) -> Self {
        let ts: u64 = snapshot
            .systemtime()
            .duration_since(SystemTime::UNIX_EPOCH)
            .expect("System Clock is earlier than 1970; needs reset")
            .as_nanos() as u64;

        let duration: Option<u64> = snapshot.duration().map(|x| x.as_nanos() as u64);

        let counters: HashMap<String, Counter> =
            HashMap::from_iter(snapshot.counters().into_iter().map(|v| (v.name.clone(), v)));
        let gauges: HashMap<String, Gauge> =
            HashMap::from_iter(snapshot.gauges().into_iter().map(|v| (v.name.clone(), v)));
        let histograms: HashMap<String, Histogram> = HashMap::from_iter(
            snapshot
                .histograms()
                .into_iter()
                .map(|v| (v.name.clone(), v)),
        );

        Self {
            ts,
            duration,
            counters,
            gauges,
            histograms,
        }
    }
}