import 15.2.0 Octopus source

[ceph.git] / ceph / src / seastar / src / core / stall_detector.hh

/*
 * This file is open source software, licensed to you under the terms
 * of the Apache License, Version 2.0 (the "License").  See the NOTICE file
 * distributed with this work for additional information regarding copyright
 * ownership.  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, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
/*
 * Copyright (C) 2018 ScyllaDB
 */

#pragma once

#include <signal.h>
#include <limits>
#include <chrono>
#include <functional>
#include <seastar/core/posix.hh>
#include <seastar/core/metrics_registration.hh>

namespace seastar {

class reactor;

namespace internal {

struct cpu_stall_detector_config {
    std::chrono::duration<double> threshold = std::chrono::seconds(2);
    unsigned stall_detector_reports_per_minute = 1;
    float slack = 0.3;  // fraction of threshold that we're allowed to overshoot
    std::function<void ()> report;  // alternative reporting function for tests
};

// Detects stalls in continuations that run for too long
class cpu_stall_detector {
    reactor* _r;
    timer_t _timer;
    std::atomic<uint64_t> _last_tasks_processed_seen{};
    unsigned _stall_detector_reports_per_minute;
    std::atomic<uint64_t> _stall_detector_missed_ticks = { 0 };
    unsigned _reported = 0;
    unsigned _total_reported = 0;
    unsigned _max_reports_per_minute;
    unsigned _shard_id;
    unsigned _thread_id;
    unsigned _report_at{};
    std::chrono::steady_clock::time_point _minute_mark{};
    std::chrono::steady_clock::time_point _rearm_timer_at{};
    std::chrono::steady_clock::time_point _run_started_at{};
    std::chrono::steady_clock::duration _threshold;
    std::chrono::steady_clock::duration _slack;
    cpu_stall_detector_config _config;
    seastar::metrics::metric_groups _metrics;
    friend reactor;
private:
    void maybe_report();
    void arm_timer();
    void report_suppressions(std::chrono::steady_clock::time_point now);
public:
    cpu_stall_detector(reactor* r, cpu_stall_detector_config cfg = {});
    ~cpu_stall_detector();
    static int signal_number() { return SIGRTMIN + 1; }
    void start_task_run(std::chrono::steady_clock::time_point now);
    void end_task_run(std::chrono::steady_clock::time_point now);
    void generate_trace();
    void update_config(cpu_stall_detector_config cfg);
    cpu_stall_detector_config get_config() const;
    void on_signal();
    void start_sleep();
    void end_sleep();
};

}
}