substrate_prometheus_endpoint/
sourced.rs

1// This file is part of Substrate.
2
3// Copyright (C) Parity Technologies (UK) Ltd.
4// SPDX-License-Identifier: Apache-2.0
5
6// Licensed under the Apache License, Version 2.0 (the "License");
7// you may not use this file except in compliance with the License.
8// You may obtain a copy of the License at
9//
10// 	http://www.apache.org/licenses/LICENSE-2.0
11//
12// Unless required by applicable law or agreed to in writing, software
13// distributed under the License is distributed on an "AS IS" BASIS,
14// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15// See the License for the specific language governing permissions and
16// limitations under the License.
17
18//! Metrics that are collected from existing sources.
19
20use prometheus::{
21	core::{Collector, Desc, Describer, Number, Opts},
22	proto,
23};
24use std::{cmp::Ordering, marker::PhantomData};
25
26/// A counter whose values are obtained from an existing source.
27///
28/// > **Note*: The counter values provided by the source `S`
29/// > must be monotonically increasing. Otherwise use a
30/// > [`SourcedGauge`] instead.
31pub type SourcedCounter<S> = SourcedMetric<Counter, S>;
32
33/// A gauge whose values are obtained from an existing source.
34pub type SourcedGauge<S> = SourcedMetric<Gauge, S>;
35
36/// The type of a sourced counter.
37#[derive(Copy, Clone)]
38pub enum Counter {}
39
40/// The type of a sourced gauge.
41#[derive(Copy, Clone)]
42pub enum Gauge {}
43
44/// A metric whose values are obtained from an existing source,
45/// instead of being independently recorded.
46#[derive(Debug, Clone)]
47pub struct SourcedMetric<T, S> {
48	source: S,
49	desc: Desc,
50	_type: PhantomData<T>,
51}
52
53/// A source of values for a [`SourcedMetric`].
54pub trait MetricSource: Sync + Send + Clone {
55	/// The type of the collected values.
56	type N: Number;
57	/// Collects the current values of the metrics from the source.
58	fn collect(&self, set: impl FnMut(&[&str], Self::N));
59}
60
61impl<T: SourcedType, S: MetricSource> SourcedMetric<T, S> {
62	/// Creates a new metric that obtains its values from the given source.
63	pub fn new(opts: &Opts, source: S) -> prometheus::Result<Self> {
64		let desc = opts.describe()?;
65		Ok(Self { source, desc, _type: PhantomData })
66	}
67}
68
69impl<T: SourcedType, S: MetricSource> Collector for SourcedMetric<T, S> {
70	fn desc(&self) -> Vec<&Desc> {
71		vec![&self.desc]
72	}
73
74	fn collect(&self) -> Vec<proto::MetricFamily> {
75		let mut counters = Vec::new();
76
77		self.source.collect(|label_values, value| {
78			let mut m = proto::Metric::default();
79
80			match T::proto() {
81				proto::MetricType::COUNTER => {
82					let mut c = proto::Counter::default();
83					c.set_value(value.into_f64());
84					m.set_counter(c);
85				},
86				proto::MetricType::GAUGE => {
87					let mut g = proto::Gauge::default();
88					g.set_value(value.into_f64());
89					m.set_gauge(g);
90				},
91				t => {
92					log::error!("Unsupported sourced metric type: {:?}", t);
93				},
94			}
95
96			debug_assert_eq!(self.desc.variable_labels.len(), label_values.len());
97			match self.desc.variable_labels.len().cmp(&label_values.len()) {
98				Ordering::Greater => {
99					log::warn!("Missing label values for sourced metric {}", self.desc.fq_name)
100				},
101				Ordering::Less => {
102					log::warn!("Too many label values for sourced metric {}", self.desc.fq_name)
103				},
104				Ordering::Equal => {},
105			}
106
107			m.set_label(
108				self.desc
109					.variable_labels
110					.iter()
111					.zip(label_values)
112					.map(|(l_name, l_value)| {
113						let mut l = proto::LabelPair::default();
114						l.set_name(l_name.to_string());
115						l.set_value(l_value.to_string());
116						l
117					})
118					.chain(self.desc.const_label_pairs.iter().cloned())
119					.collect::<Vec<_>>(),
120			);
121
122			counters.push(m);
123		});
124
125		let mut m = proto::MetricFamily::default();
126		m.set_name(self.desc.fq_name.clone());
127		m.set_help(self.desc.help.clone());
128		m.set_field_type(T::proto());
129		m.set_metric(counters);
130
131		vec![m]
132	}
133}
134
135/// Types of metrics that can obtain their values from an existing source.
136pub trait SourcedType: private::Sealed + Sync + Send {
137	#[doc(hidden)]
138	fn proto() -> proto::MetricType;
139}
140
141impl SourcedType for Counter {
142	fn proto() -> proto::MetricType {
143		proto::MetricType::COUNTER
144	}
145}
146
147impl SourcedType for Gauge {
148	fn proto() -> proto::MetricType {
149		proto::MetricType::GAUGE
150	}
151}
152
153mod private {
154	pub trait Sealed {}
155	impl Sealed for super::Counter {}
156	impl Sealed for super::Gauge {}
157}
substrate_prometheus_endpoint/sourced.rs

substrate_prometheus_endpoint/
sourced.rs
