repertory/src/comm/packet/client_pool.cpp

/*
  Copyright <2018-2022> <scott.e.graves@protonmail.com>

  Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
  associated documentation files (the "Software"), to deal in the Software without restriction,
  including without limitation the rights to use, copy, modify, merge, publish, distribute,
  sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:

  The above copyright notice and this permission notice shall be included in all copies or
  substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
  NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
  DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT
  OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include "comm/packet/client_pool.hpp"
#include "events/events.hpp"
#include "events/event_system.hpp"

namespace repertory {
void client_pool::pool::execute(const std::uint64_t &thread_id, const worker_callback &worker,
                                const worker_complete_callback &worker_complete) {
  const auto index = static_cast<std::size_t>(thread_id % pool_queues_.size());
  auto wi = std::make_shared<work_item>(worker, worker_complete);
  auto &pool_queue = pool_queues_[index];

  unique_mutex_lock queue_lock(pool_queue->mutex);
  pool_queue->queue.emplace_back(wi);
  pool_queue->notify.notify_all();
  queue_lock.unlock();
}

client_pool::pool::pool(const std::uint8_t &pool_size) {
  thread_index_ = 0u;
  for (std::uint8_t i = 0u; i < pool_size; i++) {
    pool_queues_.emplace_back(std::make_unique<work_queue>());
  }

  for (std::size_t i = 0u; i < pool_queues_.size(); i++) {
    pool_threads_.emplace_back(std::thread([this]() {
      const auto thread_index = thread_index_++;

      auto &pool_queue = pool_queues_[thread_index];
      auto &queue = pool_queue->queue;
      auto &queue_mutex = pool_queue->mutex;
      auto &queue_notify = pool_queue->notify;

      unique_mutex_lock queue_lock(queue_mutex);
      queue_notify.notify_all();
      queue_lock.unlock();
      while (not shutdown_) {
        queue_lock.lock();
        if (queue.empty()) {
          queue_notify.wait(queue_lock);
        }

        while (not queue.empty()) {
          auto workItem = queue.front();
          queue.pop_front();
          queue_notify.notify_all();
          queue_lock.unlock();

          try {
            const auto result = workItem->work();
            workItem->work_complete(result);
          } catch (const std::exception &e) {
            workItem->work_complete(utils::translate_api_error(api_error::error));
            event_system::instance().raise<repertory_exception>(__FUNCTION__,
                                                              e.what() ? e.what() : "unknown");
          }

          queue_lock.lock();
        }

        queue_notify.notify_all();
        queue_lock.unlock();
      }

      queue_lock.lock();
      while (not queue.empty()) {
        auto wi = queue.front();
        queue.pop_front();
        queue_notify.notify_all();
        queue_lock.unlock();

        wi->work_complete(utils::translate_api_error(api_error::download_stopped));

        queue_lock.lock();
      }

      queue_notify.notify_all();
      queue_lock.unlock();
    }));
  }
}

void client_pool::pool::shutdown() {
  shutdown_ = true;

  for (auto &pool_queue : pool_queues_) {
    unique_mutex_lock l(pool_queue->mutex);
    pool_queue->notify.notify_all();
  }

  for (auto &thread : pool_threads_) {
    thread.join();
  }

  pool_queues_.clear();
  pool_threads_.clear();
}

void client_pool::execute(const std::string &client_id, const std::uint64_t &thread_id,
                          const worker_callback &worker,
                          const worker_complete_callback &worker_complete) {
  unique_mutex_lock pool_lock(pool_mutex_);
  if (shutdown_) {
    pool_lock.unlock();
    throw std::runtime_error("Client pool is shutdown");
  }

  if (not pool_lookup_[client_id]) {
    pool_lookup_[client_id] = std::make_shared<pool>(pool_size_);
  }

  pool_lookup_[client_id]->execute(thread_id, worker, worker_complete);
  pool_lock.unlock();
}

void client_pool::remove_client(const std::string &client_id) {
  mutex_lock pool_lock(pool_mutex_);
  pool_lookup_.erase(client_id);
}

void client_pool::shutdown() {
  unique_mutex_lock pool_lock(pool_mutex_);
  if (not shutdown_) {
    shutdown_ = true;
    event_system::instance().raise<service_shutdown>("client_pool");
    for (auto &kv : pool_lookup_) {
      kv.second->shutdown();
    }
    pool_lookup_.clear();
  }
  pool_lock.unlock();
}
} // namespace repertory