libminifi/src/utils/ThreadPool.cpp - nifi-minifi-cpp - Git at Google

 /**
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.
  * The ASF licenses this file to You 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,
  * 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.
  */

 #include "utils/ThreadPool.h"

 using namespace std::literals::chrono_literals;

 namespace org::apache::nifi::minifi::utils {

 ThreadPool::ThreadPool(int max_worker_threads, core::controller::ControllerServiceProvider* controller_service_provider, std::string name)
     : thread_reduction_count_(0),
       max_worker_threads_(max_worker_threads),
       adjust_threads_(false),
       running_(false),
       controller_service_provider_(controller_service_provider),
       name_(std::move(name)),
       logger_(core::logging::LoggerFactory<ThreadPool>::getLogger()) {
   current_workers_ = 0;
   thread_manager_ = nullptr;
 }

 void ThreadPool::run_tasks(const std::shared_ptr<WorkerThread>& thread) {
   thread->is_running_ = true;
   while (running_.load()) {
     if (UNLIKELY(thread_reduction_count_ > 0)) {
       if (--thread_reduction_count_ >= 0) {
         deceased_thread_queue_.enqueue(thread);
         thread->is_running_ = false;
         break;
       } else {
         thread_reduction_count_++;
       }
     }

     Worker task;
     if (worker_queue_.dequeueWait(task)) {
       {
         std::unique_lock<std::mutex> lock(worker_queue_mutex_);
         if (!task_status_[task.getIdentifier()]) {
           continue;
         } else if (!worker_queue_.isRunning()) {
           worker_queue_.enqueue(std::move(task));
           continue;
         }
         ++running_task_count_by_id_[task.getIdentifier()];
       }
       const bool taskRunResult = task.run();
       {
         std::unique_lock<std::mutex> lock(worker_queue_mutex_);
         auto& count = running_task_count_by_id_[task.getIdentifier()];
         if (count == 1) {
           running_task_count_by_id_.erase(task.getIdentifier());
         } else {
           --count;
         }
       }
       task_run_complete_.notify_all();
       if (taskRunResult) {
         if (task.getNextExecutionTime() <= std::chrono::steady_clock::now()) {
           // it can be rescheduled again as soon as there is a worker available
           worker_queue_.enqueue(std::move(task));
           continue;
         }
         // Task will be put to the delayed queue as next exec time is in the future
         std::unique_lock<std::mutex> lock(worker_queue_mutex_);
         bool need_to_notify =
             delayed_worker_queue_.empty() ||
                 task.getNextExecutionTime() < delayed_worker_queue_.top().getNextExecutionTime();

         delayed_worker_queue_.push(std::move(task));
         if (need_to_notify) {
           delayed_task_available_.notify_all();
         }
       }
     } else {
       // The threadpool is running, but the ConcurrentQueue is stopped -> shouldn't happen during normal conditions
       // Might happen during startup or shutdown for a very short time
       if (running_.load()) {
         std::this_thread::sleep_for(1ms);
       }
     }
   }
   current_workers_--;
 }

 void ThreadPool::manage_delayed_queue() {
   while (running_) {
     std::unique_lock<std::mutex> lock(worker_queue_mutex_);

     // Put the tasks ready to run in the worker queue
     while (!delayed_worker_queue_.empty() && delayed_worker_queue_.top().getNextExecutionTime() <= std::chrono::steady_clock::now()) {
       // I'm very sorry for this - committee must has been seriously drunk when the interface of prio queue was submitted.
       Worker task = std::move(const_cast<Worker&>(delayed_worker_queue_.top()));
       delayed_worker_queue_.pop();
       worker_queue_.enqueue(std::move(task));
     }
     if (delayed_worker_queue_.empty()) {
       delayed_task_available_.wait(lock);
     } else {
       auto wait_time = delayed_worker_queue_.top().getNextExecutionTime() - std::chrono::steady_clock::now();
       delayed_task_available_.wait_for(lock, std::max(wait_time, std::chrono::steady_clock::duration(1ms)));
     }
   }
 }

 void ThreadPool::execute(Worker &&task, std::future<utils::TaskRescheduleInfo> &future) {
   {
     std::unique_lock<std::mutex> lock(worker_queue_mutex_);
     task_status_[task.getIdentifier()] = true;
   }
   future = task.getPromise()->get_future();
   worker_queue_.enqueue(std::move(task));
 }

 void ThreadPool::manageWorkers() {
   {
     std::unique_lock<std::mutex> lock(worker_queue_mutex_);
     for (int i = 0; i < max_worker_threads_; i++) {
       std::stringstream thread_name;
       thread_name << name_ << " #" << i;
       auto worker_thread = std::make_shared<WorkerThread>(thread_name.str());
       worker_thread->thread_ = createThread([this, worker_thread] { run_tasks(worker_thread); });
       thread_queue_.push_back(worker_thread);
       current_workers_++;
     }
   }

   if (nullptr != thread_manager_) {
     while (running_) {
       auto wait_period = 500ms;
       {
         std::unique_lock<std::recursive_mutex> manager_lock(manager_mutex_, std::try_to_lock);
         if (!manager_lock.owns_lock()) {
           // Threadpool is being stopped/started or config is being changed, better wait a bit
           std::this_thread::sleep_for(10ms);
           continue;
         }
         if (thread_manager_->isAboveMax(current_workers_)) {
           auto max = thread_manager_->getMaxConcurrentTasks();
           auto differential = current_workers_ - max;
           thread_reduction_count_ += differential;
         } else if (thread_manager_->shouldReduce()) {
           if (current_workers_ > 1)
             thread_reduction_count_++;
           thread_manager_->reduce();
         } else if (thread_manager_->canIncrease() && max_worker_threads_ > current_workers_) {  // increase slowly
           std::unique_lock<std::mutex> worker_queue_lock(worker_queue_mutex_);
           auto worker_thread = std::make_shared<WorkerThread>();
           worker_thread->thread_ = createThread([this, worker_thread] { run_tasks(worker_thread); });
           thread_queue_.push_back(worker_thread);
           current_workers_++;
         }
         std::shared_ptr<WorkerThread> thread_ref;
         while (deceased_thread_queue_.tryDequeue(thread_ref)) {
           std::unique_lock<std::mutex> worker_queue_lock(worker_queue_mutex_);
           if (thread_ref->thread_.joinable())
             thread_ref->thread_.join();
           thread_queue_.erase(std::remove(thread_queue_.begin(), thread_queue_.end(), thread_ref), thread_queue_.end());
         }
       }
       std::this_thread::sleep_for(wait_period);
     }
   } else {
     for (auto &thread : thread_queue_) {
       if (thread->thread_.joinable())
         thread->thread_.join();
     }
   }
 }

 std::shared_ptr<controllers::ThreadManagementService> ThreadPool::createThreadManager() const {
   if (!controller_service_provider_) {
     return nullptr;
   }
   auto service = controller_service_provider_->getControllerService("ThreadPoolManager");
   if (!service) {
     logger_->log_info("Could not find a ThreadPoolManager service");
     return nullptr;
   }
   auto thread_manager_service = std::dynamic_pointer_cast<controllers::ThreadManagementService>(service);
   if (!thread_manager_service) {
     logger_->log_error("Found ThreadPoolManager, but it is not a ThreadManagementService");
     return nullptr;
   }
   return thread_manager_service;
 }

 void ThreadPool::start() {
   std::lock_guard<std::recursive_mutex> lock(manager_mutex_);
   if (!running_) {
     thread_manager_ = createThreadManager();

     running_ = true;
     worker_queue_.start();
     manager_thread_ = std::thread(&ThreadPool::manageWorkers, this);

     std::lock_guard<std::mutex> quee_lock(worker_queue_mutex_);
     delayed_scheduler_thread_ = std::thread(&ThreadPool::manage_delayed_queue, this);
   }
 }

 void ThreadPool::stopTasks(const TaskId &identifier) {
   std::unique_lock<std::mutex> lock(worker_queue_mutex_);
   task_status_[identifier] = false;

   // remove tasks belonging to identifier from worker_queue_
   worker_queue_.remove([&] (const Worker& worker) { return worker.getIdentifier() == identifier; });

   // also remove from delayed_worker_queue_
   decltype(delayed_worker_queue_) new_delayed_worker_queue;
   while (!delayed_worker_queue_.empty()) {
     Worker task = std::move(const_cast<Worker&>(delayed_worker_queue_.top()));
     delayed_worker_queue_.pop();
     if (task.getIdentifier() != identifier) {
       new_delayed_worker_queue.push(std::move(task));
     }
   }
   delayed_worker_queue_ = std::move(new_delayed_worker_queue);

   // if tasks are in progress, wait for their completion
   task_run_complete_.wait(lock, [&] () {
     auto iter = running_task_count_by_id_.find(identifier);
     return iter == running_task_count_by_id_.end() || iter->second == 0;
   });
 }

 void ThreadPool::resume() {
   if (!worker_queue_.isRunning()) {
     worker_queue_.start();
   }
 }

 void ThreadPool::pause() {
   if (worker_queue_.isRunning()) {
     worker_queue_.stop();
   }
 }

 void ThreadPool::shutdown() {
   if (running_.load()) {
     std::lock_guard<std::recursive_mutex> lock(manager_mutex_);
     running_.store(false);

     drain();

     task_status_.clear();
     if (manager_thread_.joinable()) {
       manager_thread_.join();
     }

     {
       // this lock ensures that the delayed_scheduler_thread_
       // is not between checking the running_ and before the cv_.wait*
       // as then, it would survive the notify_all call
       std::lock_guard<std::mutex> worker_lock(worker_queue_mutex_);
       delayed_task_available_.notify_all();
     }
     if (delayed_scheduler_thread_.joinable()) {
       delayed_scheduler_thread_.join();
     }

     for (const auto &thread : thread_queue_) {
       if (thread->thread_.joinable())
         thread->thread_.join();
     }

     thread_queue_.clear();
     current_workers_ = 0;
     while (!delayed_worker_queue_.empty()) {
       delayed_worker_queue_.pop();
     }

     worker_queue_.clear();
   }
 }

 }  // namespace org::apache::nifi::minifi::utils
	/**
	* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with
	* this work for additional information regarding copyright ownership.
	* The ASF licenses this file to You 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,
	* 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.
	*/

	#include "utils/ThreadPool.h"

	using namespace std::literals::chrono_literals;

	namespace org::apache::nifi::minifi::utils {

	ThreadPool::ThreadPool(int max_worker_threads, core::controller::ControllerServiceProvider* controller_service_provider, std::string name)
	: thread_reduction_count_(0),
	max_worker_threads_(max_worker_threads),
	adjust_threads_(false),
	running_(false),
	controller_service_provider_(controller_service_provider),
	name_(std::move(name)),
	logger_(core::logging::LoggerFactory<ThreadPool>::getLogger()) {
	current_workers_ = 0;
	thread_manager_ = nullptr;
	}

	void ThreadPool::run_tasks(const std::shared_ptr<WorkerThread>& thread) {
	thread->is_running_ = true;
	while (running_.load()) {
	if (UNLIKELY(thread_reduction_count_ > 0)) {
	if (--thread_reduction_count_ >= 0) {
	deceased_thread_queue_.enqueue(thread);
	thread->is_running_ = false;
	break;
	} else {
	thread_reduction_count_++;
	}
	}

	Worker task;
	if (worker_queue_.dequeueWait(task)) {
	{
	std::unique_lock<std::mutex> lock(worker_queue_mutex_);
	if (!task_status_[task.getIdentifier()]) {
	continue;
	} else if (!worker_queue_.isRunning()) {
	worker_queue_.enqueue(std::move(task));
	continue;
	}
	++running_task_count_by_id_[task.getIdentifier()];
	}
	const bool taskRunResult = task.run();
	{
	std::unique_lock<std::mutex> lock(worker_queue_mutex_);
	auto& count = running_task_count_by_id_[task.getIdentifier()];
	if (count == 1) {
	running_task_count_by_id_.erase(task.getIdentifier());
	} else {
	--count;
	}
	}
	task_run_complete_.notify_all();
	if (taskRunResult) {
	if (task.getNextExecutionTime() <= std::chrono::steady_clock::now()) {
	// it can be rescheduled again as soon as there is a worker available
	worker_queue_.enqueue(std::move(task));
	continue;
	}
	// Task will be put to the delayed queue as next exec time is in the future
	std::unique_lock<std::mutex> lock(worker_queue_mutex_);
	bool need_to_notify =
	delayed_worker_queue_.empty() \|\|
	task.getNextExecutionTime() < delayed_worker_queue_.top().getNextExecutionTime();

	delayed_worker_queue_.push(std::move(task));
	if (need_to_notify) {
	delayed_task_available_.notify_all();
	}
	}
	} else {
	// The threadpool is running, but the ConcurrentQueue is stopped -> shouldn't happen during normal conditions
	// Might happen during startup or shutdown for a very short time
	if (running_.load()) {
	std::this_thread::sleep_for(1ms);
	}
	}
	}
	current_workers_--;
	}

	void ThreadPool::manage_delayed_queue() {
	while (running_) {
	std::unique_lock<std::mutex> lock(worker_queue_mutex_);

	// Put the tasks ready to run in the worker queue
	while (!delayed_worker_queue_.empty() && delayed_worker_queue_.top().getNextExecutionTime() <= std::chrono::steady_clock::now()) {
	// I'm very sorry for this - committee must has been seriously drunk when the interface of prio queue was submitted.
	Worker task = std::move(const_cast<Worker&>(delayed_worker_queue_.top()));
	delayed_worker_queue_.pop();
	worker_queue_.enqueue(std::move(task));
	}
	if (delayed_worker_queue_.empty()) {
	delayed_task_available_.wait(lock);
	} else {
	auto wait_time = delayed_worker_queue_.top().getNextExecutionTime() - std::chrono::steady_clock::now();
	delayed_task_available_.wait_for(lock, std::max(wait_time, std::chrono::steady_clock::duration(1ms)));
	}
	}
	}

	void ThreadPool::execute(Worker &&task, std::future<utils::TaskRescheduleInfo> &future) {
	{
	std::unique_lock<std::mutex> lock(worker_queue_mutex_);
	task_status_[task.getIdentifier()] = true;
	}
	future = task.getPromise()->get_future();
	worker_queue_.enqueue(std::move(task));
	}

	void ThreadPool::manageWorkers() {
	{
	std::unique_lock<std::mutex> lock(worker_queue_mutex_);
	for (int i = 0; i < max_worker_threads_; i++) {
	std::stringstream thread_name;
	thread_name << name_ << " #" << i;
	auto worker_thread = std::make_shared<WorkerThread>(thread_name.str());
	worker_thread->thread_ = createThread([this, worker_thread] { run_tasks(worker_thread); });
	thread_queue_.push_back(worker_thread);
	current_workers_++;
	}
	}

	if (nullptr != thread_manager_) {
	while (running_) {
	auto wait_period = 500ms;
	{
	std::unique_lock<std::recursive_mutex> manager_lock(manager_mutex_, std::try_to_lock);
	if (!manager_lock.owns_lock()) {
	// Threadpool is being stopped/started or config is being changed, better wait a bit
	std::this_thread::sleep_for(10ms);
	continue;
	}
	if (thread_manager_->isAboveMax(current_workers_)) {
	auto max = thread_manager_->getMaxConcurrentTasks();
	auto differential = current_workers_ - max;
	thread_reduction_count_ += differential;
	} else if (thread_manager_->shouldReduce()) {
	if (current_workers_ > 1)
	thread_reduction_count_++;
	thread_manager_->reduce();
	} else if (thread_manager_->canIncrease() && max_worker_threads_ > current_workers_) { // increase slowly
	std::unique_lock<std::mutex> worker_queue_lock(worker_queue_mutex_);
	auto worker_thread = std::make_shared<WorkerThread>();
	worker_thread->thread_ = createThread([this, worker_thread] { run_tasks(worker_thread); });
	thread_queue_.push_back(worker_thread);
	current_workers_++;
	}
	std::shared_ptr<WorkerThread> thread_ref;
	while (deceased_thread_queue_.tryDequeue(thread_ref)) {
	std::unique_lock<std::mutex> worker_queue_lock(worker_queue_mutex_);
	if (thread_ref->thread_.joinable())
	thread_ref->thread_.join();
	thread_queue_.erase(std::remove(thread_queue_.begin(), thread_queue_.end(), thread_ref), thread_queue_.end());
	}
	}
	std::this_thread::sleep_for(wait_period);
	}
	} else {
	for (auto &thread : thread_queue_) {
	if (thread->thread_.joinable())
	thread->thread_.join();
	}
	}
	}

	std::shared_ptr<controllers::ThreadManagementService> ThreadPool::createThreadManager() const {
	if (!controller_service_provider_) {
	return nullptr;
	}
	auto service = controller_service_provider_->getControllerService("ThreadPoolManager");
	if (!service) {
	logger_->log_info("Could not find a ThreadPoolManager service");
	return nullptr;
	}
	auto thread_manager_service = std::dynamic_pointer_cast<controllers::ThreadManagementService>(service);
	if (!thread_manager_service) {
	logger_->log_error("Found ThreadPoolManager, but it is not a ThreadManagementService");
	return nullptr;
	}
	return thread_manager_service;
	}

	void ThreadPool::start() {
	std::lock_guard<std::recursive_mutex> lock(manager_mutex_);
	if (!running_) {
	thread_manager_ = createThreadManager();

	running_ = true;
	worker_queue_.start();
	manager_thread_ = std::thread(&ThreadPool::manageWorkers, this);

	std::lock_guard<std::mutex> quee_lock(worker_queue_mutex_);
	delayed_scheduler_thread_ = std::thread(&ThreadPool::manage_delayed_queue, this);
	}
	}

	void ThreadPool::stopTasks(const TaskId &identifier) {
	std::unique_lock<std::mutex> lock(worker_queue_mutex_);
	task_status_[identifier] = false;

	// remove tasks belonging to identifier from worker_queue_
	worker_queue_.remove([&] (const Worker& worker) { return worker.getIdentifier() == identifier; });

	// also remove from delayed_worker_queue_
	decltype(delayed_worker_queue_) new_delayed_worker_queue;
	while (!delayed_worker_queue_.empty()) {
	Worker task = std::move(const_cast<Worker&>(delayed_worker_queue_.top()));
	delayed_worker_queue_.pop();
	if (task.getIdentifier() != identifier) {
	new_delayed_worker_queue.push(std::move(task));
	}
	}
	delayed_worker_queue_ = std::move(new_delayed_worker_queue);

	// if tasks are in progress, wait for their completion
	task_run_complete_.wait(lock, [&] () {
	auto iter = running_task_count_by_id_.find(identifier);
	return iter == running_task_count_by_id_.end() \|\| iter->second == 0;
	});
	}

	void ThreadPool::resume() {
	if (!worker_queue_.isRunning()) {
	worker_queue_.start();
	}
	}

	void ThreadPool::pause() {
	if (worker_queue_.isRunning()) {
	worker_queue_.stop();
	}
	}

	void ThreadPool::shutdown() {
	if (running_.load()) {
	std::lock_guard<std::recursive_mutex> lock(manager_mutex_);
	running_.store(false);

	drain();

	task_status_.clear();
	if (manager_thread_.joinable()) {
	manager_thread_.join();
	}

	{
	// this lock ensures that the delayed_scheduler_thread_
	// is not between checking the running_ and before the cv_.wait*
	// as then, it would survive the notify_all call
	std::lock_guard<std::mutex> worker_lock(worker_queue_mutex_);
	delayed_task_available_.notify_all();
	}
	if (delayed_scheduler_thread_.joinable()) {
	delayed_scheduler_thread_.join();
	}

	for (const auto &thread : thread_queue_) {
	if (thread->thread_.joinable())
	thread->thread_.join();
	}

	thread_queue_.clear();
	current_workers_ = 0;
	while (!delayed_worker_queue_.empty()) {
	delayed_worker_queue_.pop();
	}

	worker_queue_.clear();
	}
	}

	} // namespace org::apache::nifi::minifi::utils