#include "source/server/worker_impl.h"

#include <functional>

#include <memory>

#include "envoy/event/dispatcher.h"

#include "envoy/event/timer.h"

#include "envoy/network/exception.h"

#include "envoy/server/configuration.h"

#include "envoy/thread_local/thread_local.h"

#include "source/common/config/utility.h"

#include "source/server/listener_manager_factory.h"

namespace Envoy {

namespace Server {

namespace {

std::unique_ptr<ConnectionHandler> getHandler(Event::Dispatcher& dispatcher, uint32_t index,

                                              OverloadManager& overload_manager) {

  auto* factory = Config::Utility::getFactoryByName<ConnectionHandlerFactory>(

      "envoy.connection_handler.default");

  if (factory) {

    return factory->createConnectionHandler(dispatcher, index, overload_manager);

  }

  ENVOY_LOG_MISC(debug, "Unable to find envoy.connection_handler.default factory");

  return nullptr;

}

} // namespace

WorkerPtr ProdWorkerFactory::createWorker(uint32_t index, OverloadManager& overload_manager,

                                          const std::string& worker_name) {

  Event::DispatcherPtr dispatcher(

      api_.allocateDispatcher(worker_name, overload_manager.scaledTimerFactory()));

  auto conn_handler = getHandler(*dispatcher, index, overload_manager);

  return std::make_unique<WorkerImpl>(tls_, hooks_, std::move(dispatcher), std::move(conn_handler),

                                      overload_manager, api_, stat_names_);

}

WorkerImpl::WorkerImpl(ThreadLocal::Instance& tls, ListenerHooks& hooks,

                       Event::DispatcherPtr&& dispatcher, Network::ConnectionHandlerPtr handler,

                       OverloadManager& overload_manager, Api::Api& api,

                       WorkerStatNames& stat_names)

    : tls_(tls), hooks_(hooks), dispatcher_(std::move(dispatcher)), handler_(std::move(handler)),

      api_(api), reset_streams_counter_(

                     api_.rootScope().counterFromStatName(stat_names.reset_high_memory_stream_)) {

  tls_.registerThread(*dispatcher_, false);

  overload_manager.registerForAction(

      OverloadActionNames::get().StopAcceptingConnections, *dispatcher_,

      [this](OverloadActionState state) { stopAcceptingConnectionsCb(state); });

  overload_manager.registerForAction(

      OverloadActionNames::get().RejectIncomingConnections, *dispatcher_,

      [this](OverloadActionState state) { rejectIncomingConnectionsCb(state); });

  overload_manager.registerForAction(

      OverloadActionNames::get().ResetStreams, *dispatcher_,

      [this](OverloadActionState state) { resetStreamsUsingExcessiveMemory(state); });

}

void WorkerImpl::addListener(absl::optional<uint64_t> overridden_listener,

                             Network::ListenerConfig& listener, AddListenerCompletion completion,

                             Runtime::Loader& runtime) {

  dispatcher_->post([this, overridden_listener, &listener, &runtime, completion]() -> void {

    handler_->addListener(overridden_listener, listener, runtime);

    hooks_.onWorkerListenerAdded();

    completion();

  });

}

uint64_t WorkerImpl::numConnections() const {

  uint64_t ret = 0;

  if (handler_) {

    ret = handler_->numConnections();

  }

  return ret;

}

void WorkerImpl::removeListener(Network::ListenerConfig& listener,

                                std::function<void()> completion) {

  ASSERT(thread_);

  const uint64_t listener_tag = listener.listenerTag();

  dispatcher_->post([this, listener_tag, completion]() -> void {

    handler_->removeListeners(listener_tag);

    completion();

    hooks_.onWorkerListenerRemoved();

  });

}

void WorkerImpl::removeFilterChains(uint64_t listener_tag,

                                    const std::list<const Network::FilterChain*>& filter_chains,

                                    std::function<void()> completion) {

  ASSERT(thread_);

  dispatcher_->post(

      [this, listener_tag, &filter_chains, completion = std::move(completion)]() -> void {

        handler_->removeFilterChains(listener_tag, filter_chains, completion);

      });

}

void WorkerImpl::start(GuardDog& guard_dog, const std::function<void()>& cb) {

  ASSERT(!thread_);

  // In posix, thread names are limited to 15 characters, so contrive to make

  // sure all interesting data fits there. The naming occurs in

  // ListenerManagerImpl's constructor: absl::StrCat("worker_", i). Let's say we

  // have 9999 threads. We'd need, so we need 7 bytes for "worker_", 4 bytes

  // for the thread index, leaving us 4 bytes left to distinguish between the

  // two threads used per dispatcher. We'll call this one "dsp:" and the

  // one allocated in guarddog_impl.cc "dog:".

  //

  // TODO(jmarantz): consider refactoring how this naming works so this naming

  // architecture is centralized, resulting in clearer names.

  Thread::Options options{absl::StrCat("wrk:", dispatcher_->name())};

  thread_ = api_.threadFactory().createThread(

      [this, &guard_dog, cb]() -> void { threadRoutine(guard_dog, cb); }, options);

}

void WorkerImpl::initializeStats(Stats::Scope& scope) { dispatcher_->initializeStats(scope); }

void WorkerImpl::stop() {

  // It's possible for the server to cleanly shut down while cluster initialization during startup

  // is happening, so we might not yet have a thread.

  if (thread_) {

    dispatcher_->exit();

    thread_->join();

  }

}

void WorkerImpl::stopListener(Network::ListenerConfig& listener,

                              const Network::ExtraShutdownListenerOptions& options,

                              std::function<void()> completion) {

  const uint64_t listener_tag = listener.listenerTag();

  dispatcher_->post([this, listener_tag, options, completion]() -> void {

    handler_->stopListeners(listener_tag, options);

    if (completion != nullptr) {

      completion();

    }

  });

}

void WorkerImpl::threadRoutine(GuardDog& guard_dog, const std::function<void()>& cb) {

  ENVOY_LOG(debug, "worker entering dispatch loop");

  // The watch dog must be created after the dispatcher starts running and has post events flushed,

  // as this is when TLS stat scopes start working.

  dispatcher_->post([this, &guard_dog, cb]() {

    cb();

    watch_dog_ = guard_dog.createWatchDog(api_.threadFactory().currentThreadId(),

                                          dispatcher_->name(), *dispatcher_);

  });

  dispatcher_->run(Event::Dispatcher::RunType::Block);

  ENVOY_LOG(debug, "worker exited dispatch loop");

  guard_dog.stopWatching(watch_dog_);

  dispatcher_->shutdown();

  // We must close all active connections before we actually exit the thread. This prevents any

  // destructors from running on the main thread which might reference thread locals. Destroying

  // the handler does this which additionally purges the dispatcher delayed deletion list.

  handler_.reset();

  tls_.shutdownThread();

  watch_dog_.reset();

}

void WorkerImpl::stopAcceptingConnectionsCb(OverloadActionState state) {

  if (state.isSaturated()) {

    handler_->disableListeners();

  } else {

    handler_->enableListeners();

  }

}

void WorkerImpl::rejectIncomingConnectionsCb(OverloadActionState state) {

  handler_->setListenerRejectFraction(state.value());

}

void WorkerImpl::resetStreamsUsingExcessiveMemory(OverloadActionState state) {

  uint64_t streams_reset_count =

      dispatcher_->getWatermarkFactory().resetAccountsGivenPressure(state.value().value());

  reset_streams_counter_.add(streams_reset_count);

}

} // namespace Server

} // namespace Envoy