folly::fibers::TaskIterator< T > Class Template Reference

#include <AddTasks.h>

Classes
struct	Context

Public Types
typedef T	value_type

Public Member Functions
	TaskIterator ()
	TaskIterator (const TaskIterator &other)=delete
TaskIterator &	operator= (const TaskIterator &other)=delete
	TaskIterator (TaskIterator &&other) noexcept
TaskIterator &	operator= (TaskIterator &&other)=delete
template<typename F >
void	addTask (F &&func)
bool	hasCompleted () const
bool	hasPending () const
bool	hasNext () const
T	awaitNext ()
void	reserve (size_t n)
size_t	getTaskID () const
template<>
void	awaitNext ()

Private Member Functions
folly::Try< T >	awaitNextResult ()

Private Attributes
std::shared_ptr< Context >	context_ {std::make_shared<Context>()}
size_t	id_ {std::numeric_limits<size_t>::max()}
FiberManager &	fm_

Friends
template<class InputIterator >
TaskIterator< invoke_result_t< typename std::iterator_traits< InputIterator >::value_type > >	addTasks (InputIterator first, InputIterator last)

Detailed Description

template<typename T>
class folly::fibers::TaskIterator< T >

Definition at line 30 of file AddTasks.h.

Member Typedef Documentation

template<typename T>

typedef T folly::fibers::TaskIterator< T >::value_type

Definition at line 51 of file AddTasks.h.

Constructor & Destructor Documentation

template<typename T>

folly::fibers::TaskIterator< T >::TaskIterator ( )

inline

Definition at line 53 of file AddTasks.h.

References folly::fibers::TaskIterator< T >::addTask(), folly::fibers::TaskIterator< T >::addTasks, folly::fibers::TaskIterator< T >::awaitNext(), folly::gen::first, folly::fibers::TaskIterator< T >::getTaskID(), folly::fibers::TaskIterator< T >::hasCompleted(), folly::fibers::TaskIterator< T >::hasNext(), folly::fibers::TaskIterator< T >::hasPending(), folly::pushmi::__adl::noexcept(), folly::fibers::TaskIterator< T >::operator=(), folly::fibers::TaskIterator< T >::reserve(), and folly::T.

: fm_(FiberManager::getFiberManager()) {}

template<typename T>

folly::fibers::TaskIterator< T >::TaskIterator ( const TaskIterator< T > &  other )

delete

template<typename T >

folly::fibers::TaskIterator< T >::TaskIterator ( TaskIterator< T > &&  other )

noexcept

Definition at line 23 of file AddTasks-inl.h.

    : context_(std::move(other.context_)), id_(other.id_), fm_(other.fm_) {}

Member Function Documentation

template<typename T >

template<typename F >

void folly::fibers::TaskIterator< T >::addTask

(

F &&

func

)

Add one more task to the TaskIterator.

Parameters

func	task to be added, will be scheduled on current FiberManager

Definition at line 89 of file AddTasks-inl.h.

References context, folly::makeTryWith(), folly::gen::move, folly::T, and folly::value().

Referenced by folly::fibers::addTasks(), folly::fibers::TaskIterator< T >::TaskIterator(), and TEST().

                                      {
  static_assert(
      std::is_convertible<invoke_result_t<F>, T>::value,
      "TaskIterator<T>: T must be convertible from func()'s return type");

  auto taskId = context_->totalTasks++;

  fm_.addTask(
      [taskId, context = context_, func = std::forward<F>(func)]() mutable {
        context->results.emplace_back(
            taskId, folly::makeTryWith(std::move(func)));

        // Check for awaiting iterator.
        if (context->promise.hasValue()) {
          if (--context->tasksToFulfillPromise == 0) {
            context->promise->setValue();
            context->promise.clear();
          }
        }
      });
}

template<>

void folly::fibers::TaskIterator< void >::awaitNext ( )

inline

Definition at line 57 of file AddTasks-inl.h.

                                          {
  awaitNextResult().value();
}

template<typename T >

T folly::fibers::TaskIterator< T >::awaitNext ( )

inline

Await for another task to complete. Will not await if the result is already available.

Returns

result of the task completed.

Exceptions

exception

thrown by the task.

Definition at line 52 of file AddTasks-inl.h.

References folly::gen::move, and folly::value().

Referenced by folly::fibers::TaskIterator< T >::TaskIterator(), and TEST().

                                    {
  return std::move(awaitNextResult().value());
}

template<typename T >

folly::Try< T > folly::fibers::TaskIterator< T >::awaitNextResult ( )

private

Definition at line 42 of file AddTasks-inl.h.

References i, folly::gen::move, and folly::reserve.

                                             {
  assert(hasCompleted() || hasPending());
  reserve(1);

  size_t i = context_->tasksConsumed++;
  id_ = context_->results[i].first;
  return std::move(context_->results[i].second);
}

template<typename T >

size_t folly::fibers::TaskIterator< T >::getTaskID ( ) const

inline

Returns

id of the last task that was processed by awaitNext().

Definition at line 82 of file AddTasks-inl.h.

Referenced by folly::fibers::TaskIterator< T >::TaskIterator().

                                               {
  assert(id_ != static_cast<size_t>(-1));
  return id_;
}

template<typename T >

bool folly::fibers::TaskIterator< T >::hasCompleted ( ) const

inline

Returns

True if there are tasks immediately available to be consumed (no need to await on them).

Definition at line 27 of file AddTasks-inl.h.

Referenced by folly::fibers::TaskIterator< T >::TaskIterator().

                                                {
  return context_->tasksConsumed < context_->results.size();
}

template<typename T >

bool folly::fibers::TaskIterator< T >::hasNext ( ) const

inline

Returns

True if there are any tasks (hasCompleted() || hasPending()).

Definition at line 37 of file AddTasks-inl.h.

Referenced by folly::fibers::TaskIterator< T >::TaskIterator().

                                           {
  return hasPending() || hasCompleted();
}

template<typename T >

bool folly::fibers::TaskIterator< T >::hasPending ( ) const

inline

Returns

True if there are tasks pending execution (need to awaited on).

Definition at line 32 of file AddTasks-inl.h.

Referenced by folly::fibers::TaskIterator< T >::TaskIterator().

                                              {
  return !context_.unique();
}

template<typename T>

TaskIterator& folly::fibers::TaskIterator< T >::operator= ( const TaskIterator< T > &  other )

delete

Referenced by folly::fibers::TaskIterator< T >::TaskIterator().

template<typename T>

TaskIterator& folly::fibers::TaskIterator< T >::operator= ( TaskIterator< T > &&  other )

delete

template<typename T >

void folly::fibers::TaskIterator< T >::reserve ( size_t  n )

inline

Await until the specified number of tasks completes or there are no tasks left to await for. Note: Will not await if there are already the specified number of tasks available.

Parameters

n	Number of tasks to await for completition.

Definition at line 62 of file AddTasks-inl.h.

References folly::fibers::await(), min, and folly::gen::move.

Referenced by folly::fibers::TaskIterator< T >::TaskIterator().

                                             {
  size_t tasksReady = context_->results.size() - context_->tasksConsumed;

  // we don't need to do anything if there are already n or more tasks complete
  // or if we have no tasks left to execute.
  if (!hasPending() || tasksReady >= n) {
    return;
  }

  n -= tasksReady;
  size_t tasksLeft = context_->totalTasks - context_->results.size();
  n = std::min(n, tasksLeft);

  await([this, n](Promise<void> promise) {
    context_->tasksToFulfillPromise = n;
    context_->promise.assign(std::move(promise));
  });
}

Friends And Related Function Documentation

template<typename T>

template<class InputIterator >

TaskIterator< invoke_result_t<typename std::iterator_traits<InputIterator>::value_type> > addTasks ( InputIterator  first, InputIterator  last  )

friend

Schedules several tasks and immediately returns an iterator, that allow one to traverse tasks in the order of their completion. All results and exceptions thrown are stored alongside with the task id and are accessible via iterator.

Parameters

first	Range of tasks to be scheduled
last

Returns

movable, non-copyable iterator

Definition at line 114 of file AddTasks-inl.h.

Referenced by folly::fibers::TaskIterator< T >::TaskIterator().

                                                  {
  typedef invoke_result_t<
      typename std::iterator_traits<InputIterator>::value_type>
      ResultType;
  typedef TaskIterator<ResultType> IteratorType;

  IteratorType iterator;

  for (; first != last; ++first) {
    iterator.addTask(std::move(*first));
  }

  iterator.context_->results.reserve(iterator.context_->totalTasks);

  return std::move(iterator);
}

Member Data Documentation

template<typename T>

std::shared_ptr<Context> folly::fibers::TaskIterator< T >::context_ {std::make_shared<Context>()}

private

Definition at line 125 of file AddTasks.h.

template<typename T>

FiberManager& folly::fibers::TaskIterator< T >::fm_

private

Definition at line 127 of file AddTasks.h.

template<typename T>

size_t folly::fibers::TaskIterator< T >::id_ {std::numeric_limits<size_t>::max()}

private

Definition at line 126 of file AddTasks.h.

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The documentation for this class was generated from the following files:

• proxygen/folly/folly/fibers/AddTasks.h
• proxygen/folly/folly/fibers/AddTasks-inl.h