PrometheusMetric.java

package com.huihui.stat;

import io.prometheus.client.CollectorRegistry;
import io.prometheus.client.Counter;
import io.prometheus.client.Histogram;
import io.prometheus.client.exporter.PushGateway;

import java.io.IOException;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

public class PrometheusMetric {

    private final CollectorRegistry registry = CollectorRegistry.defaultRegistry;

    private final ConcurrentMap<String, Counter> counters = new ConcurrentHashMap<String, Counter>();
    private final ConcurrentMap<String, Histogram> histograms = new ConcurrentHashMap<String, Histogram>();

    private static volatile PrometheusMetric instance;

    public static PrometheusMetric getInstance() {
        if (instance == null) {
            synchronized (PrometheusMetric.class) {
                if (instance == null) {
                    instance = new PrometheusMetric();
                }
            }
        }
        return instance;
    }

    private PrometheusMetric() {
    }

    public void increment(String name) {
        Counter counter = getOrRegisterCounter(name);
        counter.inc();
    }

    public void increment(String name, double amt) {
        Counter counter = getOrRegisterCounter(name);
        counter.inc(amt);
    }


    public Histogram.Timer startTimer(String name) {
        Histogram summary = getOrRegisterHistogram(name);
        return summary.startTimer();
    }


    private Counter getOrRegisterCounter(String name) {
        if (counters.containsKey(name)) {
            return counters.get(name);
        }

        Counter counter = Counter.build().name(name).help(name).create();
        Counter prev = counters.putIfAbsent(name, counter);
        if (prev == null) {
            registry.register(counter);
            return counter;
        } else {
            return prev;
        }
    }

    private Histogram getOrRegisterHistogram(String name) {
        if (histograms.containsKey(name)) {
            return histograms.get(name);
        }

        Histogram histogram = Histogram.build().name(name).help(name).create();
        Histogram prev = histograms.putIfAbsent(name, histogram);
        if (prev == null) {
            registry.register(histogram);
            return histogram;
        } else {
            return prev;
        }
    }


    public void push(String host, String jobName) throws IOException {
        PushGateway pg = new PushGateway(host);
        pg.push(registry, jobName);
    }

}