#include <userver/cache/base_mongo_cache.hpp>

Detailed Description

template<class MongoCacheTraits>
class components::MongoCache< MongoCacheTraits >

Base class for all caches polling mongo collection

You have to provide a traits class in order to use this.

Avoiding memory leaks

Static options:

Name	Description	Default value
update-correction	adjusts incremental updates window to overlap with previous update	0

Traits example:

All fields below (except for function overrides) are mandatory.

struct MongoCacheTraitsExample {
  // Component name for component
  static constexpr std::string_view kName = "mongo-dynamic-config";
 
  // Collection to read from
  static constexpr auto kMongoCollectionsField =
      &storages::mongo::Collections::config;
  // Update field name to use for incremental update (optional).
  // When missing, incremental update is disabled.
  // Please use reference here to avoid global variables
  // initialization order issues.
  static constexpr const std::string& kMongoUpdateFieldName =
      mongo::db::taxi::config::kUpdated;
 
  // Cache element type
  using ObjectType = CachedObject;
  // Cache element field name that is used as an index in the cache map
  static constexpr auto kKeyField = &CachedObject::name;
  // Type of kKeyField
  using KeyType = std::string;
  // Type of cache map, e.g. unordered_map, map, bimap
  using DataType = std::unordered_map<KeyType, ObjectType>;
 
  // Whether the cache prefers to read from replica (if true, you might get stale data)
  static constexpr bool kIsSecondaryPreferred = true;
 
  // Optional function that overrides BSON to ObjectType conversion
  static constexpr auto DeserializeObject = &CachedObject::FromBson;
  // or
  static ObjectType DeserializeObject(const formats::bson::Document& doc) {
    return doc["value"].As<ObjectType>();
  }
  // (default implementation calls doc.As<ObjectType>())
  // For using default implementation
  static constexpr bool kUseDefaultDeserializeObject = true;
 
  // Optional function that overrides data retrieval operation
  static storages::mongo::operations::Find GetFindOperation(
     cache::UpdateType type,
     const std::chrono::system_clock::time_point& last_update,
     const std::chrono::system_clock::time_point& now,
     const std::chrono::system_clock::duration& correction) {
    mongo::operations::Find find_op({});
    find_op.SetOption(mongo::options::Projection{"key", "value"});
    return find_op;
  }
  // (default implementation queries kMongoUpdateFieldName: {$gt: last_update}
  // for incremental updates, and {} for full updates)
  // For using default implementation
  static constexpr bool kUseDefaultFindOperation = true;
 
  // Whether update part of the cache even if failed to parse some documents
  static constexpr bool kAreInvalidDocumentsSkipped = false;
 
  // Component to get the collections
  using MongoCollectionsComponent = components::MongoCollections;
};

Definition at line 122 of file base_mongo_cache.hpp.

Inheritance diagram for components::MongoCache< MongoCacheTraits >:

Public Types
using	DataType

Public Member Functions
	MongoCache (const ComponentConfig &, const ComponentContext &)

utils::SharedReadablePtr< MongoCacheTraits::DataType >	Get () const

utils::SharedReadablePtr< MongoCacheTraits::DataType >	GetUnsafe () const

concurrent::AsyncEventSubscriberScope	UpdateAndListen (Class obj, std::string name, void(Class::func)(const std::shared_ptr< const MongoCacheTraits::DataType > &))

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

ComponentHealth	GetComponentHealth () const override

void	OnLoadingCancelled () override

void	OnAllComponentsAreStopping () override

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

Static Public Attributes
static constexpr std::string_view	kName = MongoCacheTraits::kName

Protected Types
using	LoggableComponentBase = ComponentBase
	Legacy alias, use ComponentBase instead.

enum class	Flag { kNone = 0 , kNoFirstUpdate = 1 << 0 }
	Periodic update flags. More...

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

void	Set (MongoCacheTraits::DataType &&value)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

void	Emplace (Args &&... args)

void	Clear ()
	Clears the content of the cache by string a default constructed T.

virtual bool	MayReturnNull () const
	Whether Get is expected to return `nullptr`.

virtual void	PreAssignCheck (const MongoCacheTraits::DataType old_value_ptr, const MongoCacheTraits::DataType new_value_ptr) const
	If the option has-pre-assign-check is set true in static config, this function is called before assigning the new value to the cache.

void	InvalidateAsync (UpdateType update_type)
	Non-blocking forced cache update of specified type.

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

const std::string &	Name () const

AllowedUpdateTypes	GetAllowedUpdateTypes () const
	Update types configured for the cache.

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

void	StopPeriodicUpdates ()
	Stops periodic updates.

void	AssertPeriodicUpdateStarted ()

void	AssertPeriodicUpdateStopped ()

void	OnCacheModified ()


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

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

Member Typedef Documentation

◆ DataType

using components::CachingComponentBase< MongoCacheTraits::DataType >::DataType

inherited

Definition at line 162 of file caching_component_base.hpp.

◆ LoggableComponentBase

using components::ComponentBase::LoggableComponentBase = ComponentBase

protectedinherited

Legacy alias, use ComponentBase instead.

Definition at line 67 of file component_base.hpp.

Member Enumeration Documentation

◆ Flag

enum class cache::CacheUpdateTrait::Flag

strongprotectedinherited

Periodic update flags.

Enumerator

kNoFirstUpdate

Disable initial update on start.

Deprecated: Use first-update-fail-ok: true instead

Definition at line 61 of file cache_update_trait.hpp.

Constructor & Destructor Documentation

◆ MongoCache()

template<class MongoCacheTraits >

components::MongoCache< MongoCacheTraits >::MongoCache	(	const ComponentConfig &	config,
		const ComponentContext &	context )

Definition at line 163 of file base_mongo_cache.hpp.

◆ ~MongoCache()

template<class MongoCacheTraits >

components::MongoCache< MongoCacheTraits >::~MongoCache ( )

Definition at line 193 of file base_mongo_cache.hpp.

Member Function Documentation

◆ Clear()

void components::CachingComponentBase< MongoCacheTraits::DataType >::Clear ( )

protectedinherited

Clears the content of the cache by string a default constructed T.

Definition at line 199 of file caching_component_base.hpp.

◆ Emplace()

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

protectedinherited

Definition at line 196 of file caching_component_base.hpp.

◆ Get()

utils::SharedReadablePtr< MongoCacheTraits::DataType > components::CachingComponentBase< MongoCacheTraits::DataType >::Get ( ) const

inherited

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

Exceptions

cache::EmptyCacheError if the contents are nullptr, and MayReturnNull returns false (which is the default behavior).

Definition at line 168 of file caching_component_base.hpp.

◆ GetComponentHealth()

ComponentHealth components::ComponentBase::GetComponentHealth ( ) const

inlineoverridevirtualinherited

Override this function to inform the world of the state of your component.

Warning: The function is called concurrently from multiple threads.

Reimplemented from components::RawComponentBase.

Reimplemented in server::handlers::Restart.

Definition at line 35 of file component_base.hpp.

◆ GetEventChannel()

concurrent::AsyncEventChannel< const std::shared_ptr< const MongoCacheTraits::DataType > & > & components::CachingComponentBase< MongoCacheTraits::DataType >::GetEventChannel ( )

inherited

Definition at line 179 of file caching_component_base.hpp.

◆ GetStaticConfigSchema()

template<class MongoCacheTraits >

yaml_config::Schema components::MongoCache< MongoCacheTraits >::GetStaticConfigSchema ( )

static

Definition at line 334 of file base_mongo_cache.hpp.

◆ GetUnsafe()

utils::SharedReadablePtr< MongoCacheTraits::DataType > components::CachingComponentBase< MongoCacheTraits::DataType >::GetUnsafe ( ) const

inherited

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

Definition at line 171 of file caching_component_base.hpp.

◆ InvalidateAsync()

void cache::CacheUpdateTrait::InvalidateAsync ( UpdateType update_type )

inherited

Non-blocking forced cache update of specified type.

See also: PeriodicTask::ForceStepAsync for behavior details

◆ MayReturnNull()

bool components::CachingComponentBase< MongoCacheTraits::DataType >::MayReturnNull ( ) const

protectedvirtualinherited

Whether Get is expected to return nullptr.

Definition at line 202 of file caching_component_base.hpp.

◆ Name()

const std::string & cache::CacheUpdateTrait::Name ( ) const

inherited

Returns: name of the component

◆ OnAllComponentsAreStopping()

void components::ComponentBase::OnAllComponentsAreStopping ( )

inlineoverridevirtualinherited

Component may use this function to stop doing work before the stop of the components that depend on it.

Base components may override it and make final to do some work before the derived object constructor is called. Don't use it otherwise.

Reimplemented from components::RawComponentBase.

Reimplemented in urabbitmq::ConsumerComponentBase, and components::Server.

Definition at line 58 of file component_base.hpp.

◆ OnCacheModified()

void cache::CacheUpdateTrait::OnCacheModified ( )

protectedinherited

Called in CachingComponentBase::Set during update to indicate that the cached data has been modified

◆ OnLoadingCancelled()

void components::ComponentBase::OnLoadingCancelled ( )

inlineoverridevirtualinherited

Called once if the creation of any other component failed. If the current component expects some other component to take any action with the current component, this call is a signal that such action may never happen due to components loading was cancelled. Application components might not want to override it.

Reimplemented from components::RawComponentBase.

Definition at line 42 of file component_base.hpp.

◆ PreAssignCheck()

void components::CachingComponentBase< MongoCacheTraits::DataType >::PreAssignCheck	(	const MongoCacheTraits::DataType *	old_value_ptr,
		const MongoCacheTraits::DataType *	new_value_ptr ) const

protectedvirtualinherited

If the option has-pre-assign-check is set true in static config, this function is called before assigning the new value to the cache.

Note: old_value_ptr and new_value_ptr can be nullptr.

Definition at line 214 of file caching_component_base.hpp.

◆ ReadContents()

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

protectedvirtualinherited

Definition at line 208 of file caching_component_base.hpp.

◆ Set() [1/2]

void components::CachingComponentBase< MongoCacheTraits::DataType >::Set ( MongoCacheTraits::DataType && value )

protectedinherited

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 192 of file caching_component_base.hpp.

◆ Set() [2/2]

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

protectedinherited

Sets the new value of cache. As a result the Get() member function starts returning the value passed into this function after the Update() finishes.

Warning: Do not forget to update cache::UpdateStatisticsScope, otherwise the behavior is undefined.

Definition at line 189 of file caching_component_base.hpp.

◆ StopPeriodicUpdates()

void cache::CacheUpdateTrait::StopPeriodicUpdates ( )

protectedinherited

Stops periodic updates.

Warning: Should be called in destructor of derived class.

◆ UpdateAndListen()

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

inherited

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

Definition at line 177 of file caching_component_base.hpp.

◆ UpdateSyncDebug()

void cache::CacheUpdateTrait::UpdateSyncDebug ( UpdateType update_type )

inherited

Forces a cache update of specified type.

Exceptions

If	`Update` throws

◆ WriteContents()

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

protectedvirtualinherited

Override to use custom serialization for cache dumps

Definition at line 206 of file caching_component_base.hpp.

Member Data Documentation

◆ kName

template<class MongoCacheTraits >

constexpr std::string_view components::MongoCache< MongoCacheTraits >::kName = MongoCacheTraits::kName

staticconstexpr

Definition at line 126 of file base_mongo_cache.hpp.

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

userver/cache/base_mongo_cache.hpp

Detailed Description

Avoiding memory leaks

Static options:

Traits example:

Public Types

Public Member Functions

Static Public Member Functions

Static Public Attributes

Protected Types

Protected Member Functions

Member Typedef Documentation

◆ DataType

◆ LoggableComponentBase

Member Enumeration Documentation

◆ Flag

Constructor & Destructor Documentation

◆ MongoCache()

◆ ~MongoCache()

Member Function Documentation

◆ Clear()

◆ Emplace()

◆ Get()

◆ GetComponentHealth()

◆ GetEventChannel()

◆ GetStaticConfigSchema()

◆ GetUnsafe()

◆ InvalidateAsync()

◆ MayReturnNull()

◆ Name()

◆ OnAllComponentsAreStopping()

◆ OnCacheModified()

◆ OnLoadingCancelled()

◆ PreAssignCheck()

◆ ReadContents()

◆ Set() [1/2]

◆ Set() [2/2]

◆ StopPeriodicUpdates()

◆ UpdateAndListen()

◆ UpdateSyncDebug()

◆ WriteContents()

Member Data Documentation

◆ kName