#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.

For avoiding "memory leaks", see the respective section in components::CachingComponentBase.

Static options of components::MongoCache :

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

Options inherited from components::CachingComponentBase :

Name	Description	Default value
update-types	Specifies whether incremental and/or full updates are used. Possible values: full-and-incremental, only-full, only-incremental.	–
update-interval	(required) interval between Update invocations.	–
update-jitter	Max. amount of time by which update-interval may be adjusted for requests dispersal.	update_interval / 10
updates-enabled	If false, cache updates are disabled (except for the first one if !first-update-fail-ok).	true
full-update-interval	Interval between full updates.	–
full-update-jitter	Max. amount of time by which full-update-interval may be adjusted for requests dispersal.	full-update-interval / 10
exception-interval	Sleep interval after an unhandled exception.	update_interval
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, in milliseconds.	10000
is-strong-period	Whether to include Update execution time in update-interval.	false
has-pre-assign-check	Enables the check before changing the value in the cache, by default it is the check that the new value is not empty.	false
testsuite-force-periodic-update	Override testsuite-periodic-update-enabled in TestsuiteSupport component config.	–
failed-updates-before-expiration	The number of consecutive failed updates for data expiration.	–
alert-on-failing-to-update-times	Fire an alert if the cache update failed specified amount of times in a row. If zero - alerts are disabled. Value from dynamic config takes priority over static.	0
safe-data-lifetime	Enables awaiting data destructors in the component's destructor. Can be set to `false` if the stored data does not refer to the component and its dependencies.	true
dump	Manages cache behavior after dump load.	–
dump.first-update-mode	Behavior of update after successful load from dump. `skip` - after successful load from dump, do nothing; `required` - make a synchronous update of type `first-update-type`, stop the service on failure; `best-effort` - make a synchronous update of type `first-update-type`, keep working and use data from dump on failure. Possible values: skip, required, best-effort.	skip
dump.first-update-type	Update type after successful load from dump. Possible values: full, incremental, incremental-then-async-full.	full

Options inherited from components::ComponentBase :

Name	Description	Default value
load-enabled	Set to `false` to disable loading of the component.	true

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 121 of file base_mongo_cache.hpp.

Inheritance diagram for components::MongoCache< MongoCacheTraits >:

Public Types
using	DataType

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

const std::string &	Name () const

const std::string &	Name () const

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

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

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

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

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	OnAllComponentsLoaded () override

void	OnGracefulShutdown (engine::Deadline) override

void	OnAllComponentsAreStopping () override

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

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

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

Protected Types
using	LoggableComponentBase

enum	Flag
	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	Attach (const std::shared_ptr< const MongoCacheTraits::DataType > &value_ptr)

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

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

void	OnCacheModified ()

virtual utils::Flags< Flag >	GetStartFlags () const
	Returns flags for cache start.

void	EarlyStartPeriodicUpdates (utils::Flags< Flag > flags)
	Call this to start periodic updates just now, not after the constructor.

void	EarlyStartPeriodicUpdates (utils::Flags< Flag > flags)
	Call this to start periodic updates just now, not after the constructor.


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 144 of file caching_component_base.hpp.

◆ LoggableComponentBase

using components::ComponentBase::LoggableComponentBase

protectedinherited

Deprecated: use components::ComponentBase instead.

Definition at line 79 of file component_base.hpp.

Member Enumeration Documentation

◆ Flag

enum cache::CacheUpdateTrait::Flag

strongprotectedinherited

Periodic update flags.

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 160 of file base_mongo_cache.hpp.

Member Function Documentation

◆ Attach()

void components::CachingComponentBase< MongoCacheTraits::DataType >::Attach ( const std::shared_ptr< const MongoCacheTraits::DataType > & value_ptr )

protectedinherited

Attach the value of cache. As a result the Get() member function starts returning the value passed into this function after the Update() finishes. Does not take over into sole ownership. Do not use unless absolutely necessary. The object must be strictly thread-safe.

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

Definition at line 185 of file caching_component_base.hpp.

◆ Clear()

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

protectedinherited

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

Definition at line 192 of file caching_component_base.hpp.

◆ Emplace()

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

protectedinherited

Definition at line 189 of file caching_component_base.hpp.

◆ Get()

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

finalvirtualinherited

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).

Implements cache::DataProvider< MongoCacheTraits::DataType >.

Definition at line 150 of file caching_component_base.hpp.

◆ GetComponentHealth()

ComponentHealth components::ComponentBase::GetComponentHealth ( ) const

inlineoverrideinherited

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

Warning: The function is called concurrently from multiple threads.

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 164 of file caching_component_base.hpp.

◆ GetStaticConfigSchema()

template<class MongoCacheTraits>

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

static

Definition at line 329 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 153 of file caching_component_base.hpp.

◆ InvalidateAsync() [1/3]

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

inherited

Non-blocking forced cache update of specified type.

See also: PeriodicTask::ForceStepAsync for behavior details

◆ InvalidateAsync() [2/3]

( UpdateType update_type )

inherited

Non-blocking forced cache update of specified type.

See also: PeriodicTask::ForceStepAsync for behavior details

◆ InvalidateAsync() [3/3]

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 195 of file caching_component_base.hpp.

◆ Name() [1/2]

( ) const

inherited

Returns: name of the component

◆ Name() [2/2]

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

inherited

Returns: name of the component

◆ OnAllComponentsAreStopping()

void components::ComponentBase::OnAllComponentsAreStopping ( )

inlineoverrideinherited

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.

Definition at line 70 of file component_base.hpp.

◆ OnAllComponentsLoaded()

void components::ComponentBase::OnAllComponentsLoaded ( )

inlineoverrideinherited

Component may use this function to finalize registration of other components that depend on it (for example, handler components register in server component, and the latter uses OnAllComponentsLoaded() to start processing requests).

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

Definition at line 51 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

◆ OnGracefulShutdown()

void components::ComponentBase::OnGracefulShutdown ( engine::Deadline )

overrideinherited

Serving components like HTTP and gRPC servers may use this function to stop accepting new requests and shutdown serving in the given time interval. Application components likely do not need to override it.

Parameters

[in] serving_shutdown_deadline The deadline until already running requests should be allowed to complete. The component is supposed to stop accepting new requests and continue processing of already active requests until this deadline (unless those requests finish earlier). And it might completely shutdown requests processing when the deadline is reached (or when no active requests left).

◆ OnLoadingCancelled()

void components::ComponentBase::OnLoadingCancelled ( )

inlineoverrideinherited

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.

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 207 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 201 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 177 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 174 of file caching_component_base.hpp.

◆ UpdateAndListen()

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

inherited

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

Definition at line 158 of file caching_component_base.hpp.

◆ UpdateSyncDebug() [1/2]

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

inherited

Forces a cache update of specified type.

Exceptions

If	`Update` throws

◆ UpdateSyncDebug() [2/2]

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 199 of file caching_component_base.hpp.

Member Data Documentation

◆ kName

template<class MongoCacheTraits>

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

staticconstexpr

Definition at line 125 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

Static options of components::MongoCache :

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()

Member Function Documentation

◆ Attach()

◆ Clear()

◆ Emplace()

◆ Get()

◆ GetComponentHealth()

◆ GetEventChannel()

◆ GetStaticConfigSchema()

◆ GetUnsafe()

◆ InvalidateAsync() [1/3]

◆ InvalidateAsync() [2/3]

◆ InvalidateAsync() [3/3]

◆ MayReturnNull()

◆ Name() [1/2]

◆ Name() [2/2]

◆ OnAllComponentsAreStopping()

◆ OnAllComponentsLoaded()

◆ OnCacheModified()

◆ OnGracefulShutdown()

◆ OnLoadingCancelled()

◆ PreAssignCheck()

◆ ReadContents()

◆ Set() [1/2]

◆ Set() [2/2]

◆ UpdateAndListen()

◆ UpdateSyncDebug() [1/2]

◆ UpdateSyncDebug() [2/2]

◆ WriteContents()

Member Data Documentation

◆ kName