// Copyright 2016 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.

use criterion::{criterion_group, criterion_main, Criterion};
use prometheus::{core::Collector, Histogram, HistogramOpts, HistogramVec};
use std::sync::{atomic, Arc};
use std::thread;

fn bench_histogram_with_label_values(c: &mut Criterion) {
    let histogram = HistogramVec::new(
        HistogramOpts::new("benchmark_histogram", "A histogram to benchmark it."),
        &["one", "two", "three"],
    )
    .unwrap();
    c.bench_function("bench_histogram_with_label_values", |b| {
        b.iter(|| {
            histogram
                .with_label_values(&["eins", "zwei", "drei"])
                .observe(3.1415)
        })
    });
}

fn bench_histogram_no_labels(c: &mut Criterion) {
    let histogram = Histogram::with_opts(HistogramOpts::new(
        "benchmark_histogram",
        "A histogram to benchmark it.",
    ))
    .unwrap();
    c.bench_function("bench_histogram_no_labels", |b| {
        b.iter(|| histogram.observe(3.1415))
    });
}

fn bench_histogram_timer(c: &mut Criterion) {
    let histogram = Histogram::with_opts(HistogramOpts::new(
        "benchmark_histogram_timer",
        "A histogram to benchmark it.",
    ))
    .unwrap();
    c.bench_function("bench_histogram_timer", |b| {
        b.iter(|| histogram.start_timer())
    });
}
fn bench_histogram_local(c: &mut Criterion) {
    let histogram = Histogram::with_opts(HistogramOpts::new(
        "benchmark_histogram_local",
        "A histogram to benchmark it.",
    ))
    .unwrap();
    let local = histogram.local();
    c.bench_function("bench_histogram_local", |b| {
        b.iter(|| local.observe(3.1415));
    });
    local.flush();
}

fn bench_local_histogram_timer(c: &mut Criterion) {
    let histogram = Histogram::with_opts(HistogramOpts::new(
        "benchmark_histogram_local_timer",
        "A histogram to benchmark it.",
    ))
    .unwrap();
    let local = histogram.local();
    c.bench_function("bench_local_histogram_timer", |b| {
        b.iter(|| local.start_timer());
    });
    local.flush();
}

fn concurrent_observe_and_collect(c: &mut Criterion) {
    let signal_exit = Arc::new(atomic::AtomicBool::new(false));
    let opts = HistogramOpts::new("test_name", "test help").buckets(vec![1.0]);
    let histogram = Histogram::with_opts(opts).unwrap();

    let mut handlers = vec![];

    for _ in 0..4 {
        let histogram = histogram.clone();
        let signal_exit = signal_exit.clone();
        handlers.push(thread::spawn(move || {
            while !signal_exit.load(atomic::Ordering::Relaxed) {
                for _ in 0..1_000 {
                    histogram.observe(1.0);
                }

                histogram.collect();
            }
        }));
    }

    c.bench_function("concurrent_observe_and_collect", |b| {
        b.iter(|| histogram.observe(1.0));
    });

    signal_exit.store(true, atomic::Ordering::Relaxed);
    for handler in handlers {
        handler.join().unwrap();
    }
}

criterion_group!(
    benches,
    bench_histogram_with_label_values,
    bench_histogram_no_labels,
    bench_histogram_timer,
    bench_histogram_local,
    bench_local_histogram_timer,
    concurrent_observe_and_collect,
);
criterion_main!(benches);

/*
#[bench]
#[cfg(feature = "nightly")]
fn bench_histogram_coarse_timer(c: &mut Criterion) {
    let histogram = Histogram::with_opts(HistogramOpts::new(
        "benchmark_histogram_timer",
        "A histogram to benchmark it.",
    ))
    .unwrap();
    b.iter(|| histogram.start_coarse_timer())
}

#[bench]
#[cfg(feature = "nightly")]
fn bench_local_histogram_coarse_timer(c: &mut Criterion) {
    let histogram = Histogram::with_opts(HistogramOpts::new(
        "benchmark_histogram_timer",
        "A histogram to benchmark it.",
    ))
    .unwrap();
    let local = histogram.local();
    b.iter(|| local.start_coarse_timer());
    local.flush();
}
*/