WorkQueue.hpp

//------------------------------------------------------------------------------
/*
    This file is part of clio: https://github.com/XRPLF/clio
    Copyright (c) 2022, the clio developers.
 
    Permission to use, copy, modify, and distribute this software for any
    purpose with or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.
 
    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
//==============================================================================
 
#pragma once
 
#include "util/Assert.hpp"
#include "util/Mutex.hpp"
#include "util/Spawn.hpp"
#include "util/config/ConfigDefinition.hpp"
#include "util/log/Logger.hpp"
#include "util/prometheus/Counter.hpp"
#include "util/prometheus/Gauge.hpp"
 
#include <boost/asio.hpp>
#include <boost/asio/spawn.hpp>
#include <boost/asio/thread_pool.hpp>
#include <boost/json.hpp>
#include <boost/json/object.hpp>
 
#include <atomic>
#include <chrono>
#include <cstddef>
#include <cstdint>
#include <functional>
#include <limits>
 
namespace rpc {
 
class WorkQueue {
    // these are cumulative for the lifetime of the process
    std::reference_wrapper<util::prometheus::CounterInt> queued_;
    std::reference_wrapper<util::prometheus::CounterInt> durationUs_;
 
    std::reference_wrapper<util::prometheus::GaugeInt> curSize_;
    uint32_t maxSize_ = std::numeric_limits<uint32_t>::max();
 
    util::Logger log_{"RPC"};
    boost::asio::thread_pool ioc_;
 
    std::atomic_bool stopping_;
 
    class OneTimeCallable {
        std::function<void()> func_;
        bool called_{false};
 
    public:
        void
        setCallable(std::function<void()> func);
 
        void
        operator()();
 
        operator bool() const;
    };
    util::Mutex<OneTimeCallable> onQueueEmpty_;
 
public:
    WorkQueue(std::uint32_t numWorkers, uint32_t maxSize = 0);
    ~WorkQueue();
 
    void
    stop(std::function<void()> onQueueEmpty);
 
    static WorkQueue
    makeWorkQueue(util::config::ClioConfigDefinition const& config);
 
    template <typename FnType>
    bool
    postCoro(FnType&& func, bool isWhiteListed)
    {
        if (stopping_) {
            LOG(log_.warn()) << "Queue is stopping, rejecting incoming task.";
            return false;
        }
 
        if (curSize_.get().value() >= maxSize_ && !isWhiteListed) {
            LOG(log_.warn()) << "Queue is full. rejecting job. current size = " << curSize_.get().value()
                             << "; max size = " << maxSize_;
            return false;
        }
 
        ++curSize_.get();
 
        // Each time we enqueue a job, we want to post a symmetrical job that will dequeue and run the job at the front
        // of the job queue.
        util::spawn(
            ioc_,
            [this, func = std::forward<FnType>(func), start = std::chrono::system_clock::now()](auto yield) mutable {
                auto const run = std::chrono::system_clock::now();
                auto const wait = std::chrono::duration_cast<std::chrono::microseconds>(run - start).count();
 
                ++queued_.get();
                durationUs_.get() += wait;
                LOG(log_.info()) << "WorkQueue wait time = " << wait << " queue size = " << curSize_.get().value();
 
                func(yield);
                --curSize_.get();
                if (curSize_.get().value() == 0 && stopping_) {
                    auto onTasksComplete = onQueueEmpty_.lock();
                    ASSERT(onTasksComplete->operator bool(), "onTasksComplete must be set when stopping is true.");
                    onTasksComplete->operator()();
                }
            }
        );
 
        return true;
    }
 
    boost::json::object
    report() const;
 
    void
    join();
 
    size_t
    size() const;
};
 
}  // namespace rpc