proxygen: folly::settings::detail::SettingCore< T

#include <SettingsImpl.h>

Inheritance diagram for folly::settings::detail::SettingCore< T >:

Public Types
using	Contents = SettingContents< T >

Public Member Functions
void	setFromString (StringPiece newValue, StringPiece reason, SnapshotBase *snapshot) override

std::pair< std::string, std::string >	getAsString (const SnapshotBase *snapshot) const override

void	resetToDefault (SnapshotBase *snapshot) override

const SettingMetadata &	meta () const override

std::conditional_t< IsSmallPOD< T >::value, T, const T & >	getWithHint (std::atomic< uint64_t > &trivialStorage) const

const SettingContents< T > &	getSlow () const

T	getImpl (std::true_type, std::atomic< uint64_t > &trivialStorage) const

const T &	getImpl (std::false_type, std::atomic< uint64_t > &) const

void	set (const T &t, StringPiece reason, SnapshotBase *snapshot=nullptr)

const T &	defaultValue () const

	SettingCore (SettingMetadata meta, T defaultValue, std::atomic< uint64_t > &trivialStorage)

Private Member Functions
FOLLY_ALWAYS_INLINE const std::shared_ptr< Contents > &	tlValue () const

FOLLY_NOINLINE const std::shared_ptr< Contents > &	tlValueSlow () const

Private Attributes
SettingMetadata	meta_

const T	defaultValue_

SharedMutex	globalLock_

std::shared_ptr< Contents >	globalValue_

std::atomic< uint64_t > &	trivialStorage_

CachelinePadded< std::atomic< Version > >	settingVersion_ {1}

ThreadLocal< CachelinePadded< std::pair< Version, std::shared_ptr< Contents > > > >	localValue_

Detailed Description

template<class T>
class folly::settings::detail::SettingCore< T >

Definition at line 249 of file SettingsImpl.h.

Member Typedef Documentation

template<class T>

using folly::settings::detail::SettingCore< T >::Contents = SettingContents<T>

Definition at line 251 of file SettingsImpl.h.

Constructor & Destructor Documentation

template<class T>

folly::settings::detail::SettingCore< T >::SettingCore	(	SettingMetadata	meta,
		T	defaultValue,
		std::atomic< uint64_t > &	trivialStorage
	)

inline

Definition at line 334 of file SettingsImpl.h.

References folly::settings::detail::registerSetting().

       : meta_(std::move(meta)),
         defaultValue_(std::move(defaultValue)),
         trivialStorage_(trivialStorage),
         localValue_([]() {
           return new CachelinePadded<
               std::pair<Version, std::shared_ptr<Contents>>>(0, nullptr);
         }) {
     set(defaultValue_, "default");
     registerSetting(*this);
   }

Member Function Documentation

template<class T>

const T& folly::settings::detail::SettingCore< T >::defaultValue ( ) const

inline

Definition at line 330 of file SettingsImpl.h.

                                 {
     return defaultValue_;
   }

template<class T>

std::pair<std::string, std::string> folly::settings::detail::SettingCore< T >::getAsString ( const SnapshotBase * snapshot ) const

inlineoverride

Definition at line 260 of file SettingsImpl.h.

References folly::settings::detail::getSlow().

                                                    {
     auto& contents = snapshot ? snapshot->get(*this) : getSlow();
     return std::make_pair(
         to<std::string>(contents.value), contents.updateReason);
   }

template<class T>

T folly::settings::detail::SettingCore< T >::getImpl	(	std::true_type	,
		std::atomic< uint64_t > &	trivialStorage
	)		const

inline

Definition at line 291 of file SettingsImpl.h.

References folly::pushmi::detail::t, and uint64_t.

                                                                      {
     uint64_t v = trivialStorage.load();
     T t;
     std::memcpy(&t, &v, sizeof(T));
     return t;
   }

template<class T>

const T& folly::settings::detail::SettingCore< T >::getImpl	(	std::false_type	,
		std::atomic< uint64_t > &
	)		const

inline

Non-SmallPOD version: read the thread local shared_ptr

Definition at line 301 of file SettingsImpl.h.

             {
     return const_cast<SettingCore*>(this)->tlValue()->value;
   }

template<class T>

const SettingContents<T>& folly::settings::detail::SettingCore< T >::getSlow ( ) const

inline

Definition at line 285 of file SettingsImpl.h.

                                             {
     return *tlValue();
   }

template<class T>

std::conditional_t<IsSmallPOD<T>::value, T, const T&> folly::settings::detail::SettingCore< T >::getWithHint ( std::atomic< uint64_t > & trivialStorage ) const

inline

Parameters

trivialStorage must refer to the same location as the internal trivialStorage_. This hint will generate better inlined code since the address is known at compile time at the callsite.

Definition at line 281 of file SettingsImpl.h.

                                                  {
     return getImpl(IsSmallPOD<T>(), trivialStorage);
   }

template<class T>

const SettingMetadata& folly::settings::detail::SettingCore< T >::meta ( ) const

inlineoverride

Definition at line 271 of file SettingsImpl.h.

                                                {
     return meta_;
   }

template<class T>

void folly::settings::detail::SettingCore< T >::resetToDefault ( SnapshotBase * snapshot )

inlineoverride

Definition at line 267 of file SettingsImpl.h.

                                                        {
     set(defaultValue_, "default", snapshot);
   }

template<class T>

void folly::settings::detail::SettingCore< T >::set	(	const T &	t,
		StringPiece	reason,
		SnapshotBase *	snapshot = `nullptr`
	)

inline

Definition at line 306 of file SettingsImpl.h.

References getKey(), folly::settings::detail::nextGlobalVersion(), folly::settings::detail::saveValueForOutstandingSnapshots(), folly::settings::detail::SettingCore< T >::set(), folly::pushmi::detail::t, uint64_t, and value.

Referenced by folly::settings::detail::SettingCore< T >::set().

                                                                              {
     /* Check that we can still display it (will throw otherwise) */
     to<std::string>(t);
 
     if (snapshot) {
       snapshot->set(*this, t, reason);
       return;
     }
 
     SharedMutex::WriteHolder lg(globalLock_);
 
     if (globalValue_) {
       saveValueForOutstandingSnapshots(
           getKey(), *settingVersion_, BoxedValue(*globalValue_));
     }
     globalValue_ = std::make_shared<Contents>(reason.str(), t);
     if (IsSmallPOD<T>::value) {
       uint64_t v = 0;
       std::memcpy(&v, &t, sizeof(T));
       trivialStorage_.store(v);
     }
     *settingVersion_ = nextGlobalVersion();
   }

template<class T>

void folly::settings::detail::SettingCore< T >::setFromString	(	StringPiece	newValue,
		StringPiece	reason,
		SnapshotBase *	snapshot
	)

inlineoverride

Definition at line 253 of file SettingsImpl.h.

References folly::Range< Iter >::str().

                                        {
     set(convertOrConstruct<T>(newValue), reason.str(), snapshot);
   }

template<class T>

FOLLY_ALWAYS_INLINE const std::shared_ptr<Contents>& folly::settings::detail::SettingCore< T >::tlValue ( ) const

inlineprivate

Definition at line 365 of file SettingsImpl.h.

References LIKELY, and folly::value().

                                                                      {
     auto& value = **localValue_;
     if (LIKELY(value.first == *settingVersion_)) {
       return value.second;
     }
     return tlValueSlow();
   }

template<class T>

FOLLY_NOINLINE const std::shared_ptr<Contents>& folly::settings::detail::SettingCore< T >::tlValueSlow ( ) const

inlineprivate

Definition at line 372 of file SettingsImpl.h.

References folly::value().

                                                                     {
     auto& value = **localValue_;
     while (value.first < *settingVersion_) {
       /* If this destroys the old value, do it without holding the lock */
       value.second.reset();
       SharedMutex::ReadHolder lg(globalLock_);
       value.first = *settingVersion_;
       value.second = globalValue_;
     }
     return value.second;
   }