servers/
metrics_handler.rs

1// Copyright 2023 Greptime Team
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15#[cfg(target_os = "linux")]
16use common_stat::CgroupsMetricsCollector;
17use prometheus::{Encoder, TextEncoder};
18
19/// a server that serves metrics
20/// only start when datanode starts in distributed mode
21#[derive(Copy, Clone)]
22pub struct MetricsHandler;
23
24impl MetricsHandler {
25    pub fn render(&self) -> String {
26        let mut buffer = Vec::new();
27        let encoder = TextEncoder::new();
28
29        #[cfg(target_os = "linux")]
30        {
31            static ONCE: std::sync::Once = std::sync::Once::new();
32            ONCE.call_once(|| {
33                // It's unlikely to fail to register the collector.
34                prometheus::register(Box::new(CgroupsMetricsCollector::default())).unwrap();
35            });
36        }
37
38        // Gather the metrics.
39        let metric_families = prometheus::gather();
40        // Encode them to send.
41        match encoder.encode(&metric_families, &mut buffer) {
42            Ok(_) => match String::from_utf8(buffer) {
43                Ok(s) => s,
44                Err(e) => e.to_string(),
45            },
46            Err(e) => e.to_string(),
47        }
48    }
49}
servers/metrics_handler.rs

servers/
metrics_handler.rs
