proxygen: folly::observer::detail::ObserverCreatorContext< Observable, Traits

#include <Observable-inl.h>

Public Member Functions
template<typename... Args>
	ObserverCreatorContext (Args &&...args)

	~ObserverCreatorContext ()

void	setCore (observer_detail::Core::WeakPtr coreWeak)

std::shared_ptr< const T >	get ()

void	update ()

template<typename F >
void	subscribe (F &&callback)

Private Types
using	T = typename Traits::element_type

Private Member Functions
bool	updateValue ()

Private Attributes
folly::Synchronized< std::shared_ptr< const T > >	value_

std::atomic< bool >	updateRequested_ {false}

observer_detail::Core::WeakPtr	coreWeak_

Observable	observable_

std::mutex	updateMutex_

Detailed Description

template<typename Observable, typename Traits>
class folly::observer::detail::ObserverCreatorContext< Observable, Traits >

Definition at line 24 of file Observable-inl.h.

Member Typedef Documentation

template<typename Observable , typename Traits >

using folly::observer::detail::ObserverCreatorContext< Observable, Traits >::T = typename Traits::element_type

private

Definition at line 25 of file Observable-inl.h.

Constructor & Destructor Documentation

template<typename Observable , typename Traits >

template<typename... Args>

folly::observer::detail::ObserverCreatorContext< Observable, Traits >::ObserverCreatorContext ( Args &&... args )

inline

Definition at line 29 of file Observable-inl.h.

References folly::observer::detail::ObserverCreatorContext< Observable, Traits >::updateValue().

       : observable_(std::forward<Args>(args)...) {
     updateValue();
   }

template<typename Observable , typename Traits >

folly::observer::detail::ObserverCreatorContext< Observable, Traits >::~ObserverCreatorContext ( )

inline

Definition at line 34 of file Observable-inl.h.

References folly::Synchronized< T, Mutex >::copy(), folly::observer::detail::ObserverCreatorContext< Observable, Traits >::observable_, and folly::observer::detail::ObserverCreatorContext< Observable, Traits >::value_.

                             {
     if (value_.copy()) {
       Traits::unsubscribe(observable_);
     }
   }

Member Function Documentation

template<typename Observable , typename Traits >

std::shared_ptr<const T> folly::observer::detail::ObserverCreatorContext< Observable, Traits >::get ( )

inline

Definition at line 44 of file Observable-inl.h.

References folly::Synchronized< T, Mutex >::copy(), folly::observer::detail::ObserverCreatorContext< Observable, Traits >::updateRequested_, and folly::observer::detail::ObserverCreatorContext< Observable, Traits >::value_.

Referenced by folly::observer::ObserverCreator< Observable, Traits >::getObserver().

                                {
     updateRequested_ = false;
     return value_.copy();
   }

template<typename Observable , typename Traits >

void folly::observer::detail::ObserverCreatorContext< Observable, Traits >::setCore ( observer_detail::Core::WeakPtr coreWeak )

inline

Definition at line 40 of file Observable-inl.h.

References folly::observer::detail::ObserverCreatorContext< Observable, Traits >::coreWeak_, and folly::gen::move.

                                                     {
     coreWeak_ = std::move(coreWeak);
   }

template<typename Observable , typename Traits >

template<typename F >

void folly::observer::detail::ObserverCreatorContext< Observable, Traits >::subscribe ( F && callback )

inline

Definition at line 69 of file Observable-inl.h.

References folly::observer::detail::ObserverCreatorContext< Observable, Traits >::observable_, and subscribe().

                                {
     Traits::subscribe(observable_, std::forward<F>(callback));
   }

template<typename Observable , typename Traits >

void folly::observer::detail::ObserverCreatorContext< Observable, Traits >::update ( )

inline

Definition at line 49 of file Observable-inl.h.

References folly::observer::detail::ObserverCreatorContext< Observable, Traits >::coreWeak_, folly::observer_detail::ObserverManager::scheduleRefreshNewVersion(), folly::observer::detail::ObserverCreatorContext< Observable, Traits >::updateMutex_, folly::observer::detail::ObserverCreatorContext< Observable, Traits >::updateRequested_, and folly::observer::detail::ObserverCreatorContext< Observable, Traits >::updateValue().

                 {
     // This mutex ensures there's no race condition between initial update()
     // call and update() calls from the subsciption callback.
     //
     // Additionally it helps avoid races between two different subscription
     // callbacks (getting new value from observable and storing it into value_
     // is not atomic).
     std::lock_guard<std::mutex> lg(updateMutex_);
     if (!updateValue()) {
       // Value didn't change, so we can skip the version update.
       return;
     }
 
     bool expected = false;
     if (updateRequested_.compare_exchange_strong(expected, true)) {
       observer_detail::ObserverManager::scheduleRefreshNewVersion(coreWeak_);
     }
   }

template<typename Observable , typename Traits >

bool folly::observer::detail::ObserverCreatorContext< Observable, Traits >::updateValue ( )

inlineprivate

Definition at line 74 of file Observable-inl.h.

References folly::pushmi::operators::get, folly::observer::detail::ObserverCreatorContext< Observable, Traits >::observable_, folly::Synchronized< T, Mutex >::swap(), and folly::observer::detail::ObserverCreatorContext< Observable, Traits >::value_.

Referenced by folly::observer::detail::ObserverCreatorContext< Observable, Traits >::ObserverCreatorContext(), and folly::observer::detail::ObserverCreatorContext< Observable, Traits >::update().

                      {
     auto newValue = Traits::get(observable_);
     auto newValuePtr = newValue.get();
     if (!newValue) {
       throw std::logic_error("Observable returned nullptr.");
     }
     value_.swap(newValue);
     return newValuePtr != newValue.get();
   }