components::MongoCache< MongoCacheTraits > Class Template Reference

#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

See components::CachingComponentBase

Static options:

All options of CachingComponentBase and

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 >:

Collaboration diagram for components::MongoCache< MongoCacheTraits >:

Public Member Functions
	MongoCache (const ComponentConfig &, const ComponentContext &)
Public Member Functions inherited from components::CachingComponentBase< MongoCacheTraits::DataType >
	CachingComponentBase (const ComponentConfig &config, 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 ()
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::CachingComponentBase< MongoCacheTraits::DataType >
static yaml_config::Schema	GetStaticConfigSchema ()
Static Public Member Functions inherited from components::LoggableComponentBase
static yaml_config::Schema	GetStaticConfigSchema ()

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

Additional Inherited Members
Public Types inherited from components::CachingComponentBase< MongoCacheTraits::DataType >
using	DataType
Protected Types inherited from cache::CacheUpdateTrait
enum class	Flag {   kNone = 0 ,   kNoFirstUpdate = 1 << 0 }
	Periodic update flags. More...
Protected Member Functions inherited from components::CachingComponentBase< MongoCacheTraits::DataType >
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
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.
virtual void	WriteContents (dump::Writer &writer, const MongoCacheTraits::DataType &contents) const
virtual std::unique_ptr< const MongoCacheTraits::DataType >	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.
void	AssertPeriodicUpdateStarted ()
void	OnCacheModified ()
	CacheUpdateTrait (CacheUpdateTrait &&)=delete
CacheUpdateTrait &	operator= (CacheUpdateTrait &&)=delete
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

Constructor & Destructor Documentation

MongoCache()

template<class MongoCacheTraits >

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

Definition at line 164 of file base_mongo_cache.hpp.

~MongoCache()

template<class MongoCacheTraits >

components::MongoCache< MongoCacheTraits >::~MongoCache

(

)

Definition at line 200 of file base_mongo_cache.hpp.

Member Function Documentation

GetStaticConfigSchema()

template<class MongoCacheTraits >

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

static

Definition at line 346 of file base_mongo_cache.hpp.

Member Data Documentation

kName

template<class MongoCacheTraits >

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

staticconstexpr

Definition at line 128 of file base_mongo_cache.hpp.

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

• userver/cache/base_mongo_cache.hpp