Base class for caching components. More...

#include <userver/cache/caching_component_base.hpp>

Inheritance diagram for components::CachingComponentBase< T >:

Collaboration diagram for components::CachingComponentBase< T >:

Public Types
using	DataType = T

Public Member Functions
	CachingComponentBase (const ComponentConfig &config, const ComponentContext &)

utils::SharedReadablePtr< T >	Get () const

utils::SharedReadablePtr< T >	GetUnsafe () const

template<class Class >
concurrent::AsyncEventSubscriberScope	UpdateAndListen (Class obj, std::string name, void(Class::func)(const std::shared_ptr< const T > &))

concurrent::AsyncEventChannel< const std::shared_ptr< const T > & > &	GetEventChannel ()

Public Member Functions inherited from components::LoggableComponentBase
	LoggableComponentBase (const ComponentConfig &, const ComponentContext &)

	LoggableComponentBase (LoggableComponentBase &&)=delete

	LoggableComponentBase (const LoggableComponentBase &)=delete

	~LoggableComponentBase () override=default

ComponentHealth	GetComponentHealth () const override

void	OnLoadingCancelled () override

void	OnAllComponentsLoaded () override

void	OnAllComponentsAreStopping () override

Static Public Member Functions
static yaml_config::Schema	GetStaticConfigSchema ()

Static Public Member Functions inherited from components::LoggableComponentBase
static yaml_config::Schema	GetStaticConfigSchema ()

Protected Member Functions
void	Set (std::unique_ptr< const T > value_ptr)

void	Set (T &&value)

template<typename... Args>
void	Emplace (Args &&... args)

void	Clear ()

virtual bool	MayReturnNull () const


virtual void	WriteContents (dump::Writer &writer, const T &contents) const

virtual std::unique_ptr< const T >	ReadContents (dump::Reader &reader) const

Protected Member Functions inherited from cache::CacheUpdateTrait
AllowedUpdateTypes	GetAllowedUpdateTypes () const
	Update types configured for the cache.

void	StartPeriodicUpdates (utils::Flags< Flag > flags={})
	Starts periodic updates.

void	StopPeriodicUpdates ()
	Stops periodic updates. More...

void	AssertPeriodicUpdateStarted ()

void	OnCacheModified ()

virtual void	Update (UpdateType type, const std::chrono::system_clock::time_point &last_update, const std::chrono::system_clock::time_point &now, UpdateStatisticsScope &stats_scope)=0
	Must override in a subclass. More...

	CacheUpdateTrait (CacheUpdateTrait &&)=delete

CacheUpdateTrait &	operator= (CacheUpdateTrait &&)=delete

void	Update (UpdateType update_type)
	Forces a cache update of specified type. More...

const std::string &	Name () const

Additional Inherited Members
Protected Types inherited from cache::CacheUpdateTrait
enum class	Flag { kNone = 0 , kNoFirstUpdate = 1 << 0 }
	Periodic update flags. More...

Detailed Description

template<typename T>
class components::CachingComponentBase< T >

Base class for caching components.

Provides facilities for creating periodically updated caches. You need to override CacheUpdateTrait::Update then call CacheUpdateTrait::StartPeriodicUpdates after setup and CacheUpdateTrait::StopPeriodicUpdates before teardown.

Caching components must be configured in service config (see options below) and may be reconfigured dynamically via components::DynamicConfig.

Dynamic config

Static options:

Name	Description	Default value
update-types	specifies whether incremental and/or full updates will be used	see below
update-interval	(required) interval between Update invocations	–
update-jitter	max. amount of time by which interval may be adjusted for requests dispersal	update_interval / 10
full-update-interval	interval between full updates	–
first-update-fail-ok	whether first update failure is non-fatal	false
task-processor	the name of the TaskProcessor for running DoWork	main-task-processor
config-settings	enables dynamic reconfiguration with CacheConfigSet	true
additional-cleanup-interval	how often to run background RCU garbage collector	10 seconds
is-strong-period	whether to include Update execution time in update-interval	false
testsuite-force-periodic-update	override testsuite-periodic-update-enabled in TestsuiteSupport component config	–

Update types

full-and-incremental: both update-interval and full-update-interval must be specified. Updates with UpdateType::kIncremental will be triggered each update-interval (adjusted by jitter) unless full-update-interval has passed and UpdateType::kFull is triggered.
only-full: only update-interval must be specified. UpdateType::kFull will be triggered each update-interval (adjusted by jitter).
only-incremental: only update-interval must be specified. UpdateType::kFull is triggered on the first update, afterwards UpdateType::kIncremental will be triggered each update-interval (adjusted by jitter).

testsuite-force-periodic-update

use it to enable periodic cache update for a component in testsuite environment where testsuite-periodic-update-enabled from TestsuiteSupport config is false

By default, update types are guessed based on update intervals presence. If both update-interval and full-update-interval are present, full-and-incremental types is assumed. Otherwise only-full is used.

See also: dump::Dumper for more info on persistent cache dumps and corresponding config options.

Examples: samples/http_caching/http_caching.cpp.

Definition at line 86 of file caching_component_base.hpp.

Member Typedef Documentation

◆ DataType

template<typename T >

using components::CachingComponentBase< T >::DataType = T

Definition at line 94 of file caching_component_base.hpp.

Constructor & Destructor Documentation

◆ CachingComponentBase()

template<typename T >

components::CachingComponentBase< T >::CachingComponentBase	(	const ComponentConfig &	config,
		const ComponentContext &	context
	)

Definition at line 150 of file caching_component_base.hpp.

◆ ~CachingComponentBase()

template<typename T >

components::CachingComponentBase< T >::~CachingComponentBase

override

Definition at line 159 of file caching_component_base.hpp.

Member Function Documentation

◆ Clear()

template<typename T >

void components::CachingComponentBase< T >::Clear

protected

Definition at line 233 of file caching_component_base.hpp.

◆ Emplace()

template<typename T >

template<typename... Args>

void components::CachingComponentBase< T >::Emplace ( Args &&... args )

protected

Definition at line 228 of file caching_component_base.hpp.

◆ Get()

template<typename T >

utils::SharedReadablePtr< T > components::CachingComponentBase< T >::Get

Returns: cache contents. May be nullptr if and only if MayReturnNull() returns true.

Definition at line 168 of file caching_component_base.hpp.

◆ GetEventChannel()

template<typename T >

concurrent::AsyncEventChannel< const std::shared_ptr< const T > & > & components::CachingComponentBase< T >::GetEventChannel

Definition at line 189 of file caching_component_base.hpp.

◆ GetStaticConfigSchema()

template<typename T >

yaml_config::Schema components::CachingComponentBase< T >::GetStaticConfigSchema

static

Definition at line 292 of file caching_component_base.hpp.

◆ GetUnsafe()

template<typename T >

utils::SharedReadablePtr< T > components::CachingComponentBase< T >::GetUnsafe

Returns: cache contents. May be nullptr regardless of MayReturnNull().

Definition at line 194 of file caching_component_base.hpp.

◆ MayReturnNull()

template<typename T >

bool components::CachingComponentBase< T >::MayReturnNull

protectedvirtual

Whether Get() is expected to return nullptr. If MayReturnNull() returns false, Get() throws an exception instead of returning nullptr.

Definition at line 238 of file caching_component_base.hpp.

◆ ReadContents()

template<typename T >

std::unique_ptr< const T > components::CachingComponentBase< T >::ReadContents ( dump::Reader & reader ) const

protectedvirtual

Definition at line 265 of file caching_component_base.hpp.

◆ Set() [1/2]

template<typename T >

void components::CachingComponentBase< T >::Set ( std::unique_ptr< const T > value_ptr )

protected

Definition at line 199 of file caching_component_base.hpp.

◆ Set() [2/2]

template<typename T >

void components::CachingComponentBase< T >::Set ( T && value )

protected

Definition at line 222 of file caching_component_base.hpp.

◆ UpdateAndListen()

template<typename T >

template<typename Class >

concurrent::AsyncEventSubscriberScope components::CachingComponentBase< T >::UpdateAndListen	(	Class *	obj,
		std::string	name,
		void(Class::*)(const std::shared_ptr< const T > &)	func
	)

Subscribes to cache updates using a member function. Also immediately invokes the function with the current cache contents.

Definition at line 178 of file caching_component_base.hpp.

◆ WriteContents()

template<typename T >

void components::CachingComponentBase< T >::WriteContents	(	dump::Writer &	writer,
		const T &	contents
	)		const

protectedvirtual

Override to use custom serialization for cache dumps

Definition at line 255 of file caching_component_base.hpp.

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

userver/cache/caching_component_base.hpp

Public Types

Public Member Functions

Static Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

Dynamic config

Static options:

Update types

testsuite-force-periodic-update

Member Typedef Documentation

◆ DataType

Constructor & Destructor Documentation

◆ CachingComponentBase()

◆ ~CachingComponentBase()

Member Function Documentation

◆ Clear()

◆ Emplace()

◆ Get()

◆ GetEventChannel()

◆ GetStaticConfigSchema()

◆ GetUnsafe()

◆ MayReturnNull()

◆ ReadContents()

◆ Set() [1/2]

◆ Set() [2/2]

◆ UpdateAndListen()

◆ WriteContents()