Base Classes

Detailed Description

Base classes that simplify implementation of functionality.

Classes
class	server::handlers::HttpHandlerBase
	Base class for all the Userver HTTP Handlers. More...
class	ugrpc::server::ServiceComponentBase
	Base class for all the gRPC service components. More...
class	utils::TracefulException
	Exception that remembers the backtrace at the point of its construction. More...
class	cache::CacheUpdateTrait
	Base class for periodically updated caches. More...
class	components::CachingComponentBase< T >
	Base class for caching components. More...
class	cache::LruCacheComponent< Key, Value, Hash, Equal >
	Base class for LRU-cache components. More...
class	components::ComponentBase
	Base class for all application components, it depends on components::Logger and components::Tracer. More...
class	components::TcpAcceptorBase
	Component for accepting incoming TCP connections. More...
class	dist_lock::DistLockStrategyBase
	Interface for distributed lock strategies. More...
class	components::DynamicConfigUpdatesSinkBase
	Base class for components acting as dynamic config updates sinks. More...
class	engine::io::ReadAwaiter
class	engine::io::ReadableBase
class	engine::io::WriteAwaiter
class	engine::io::WritableBase
class	engine::io::RwBase
class	middlewares::MiddlewareFactoryComponentBase< MiddlewareBaseType, HandlerInfo >
	Base class for middleware factory component. More...
class	server::handlers::auth::digest::AuthCheckerBase
	Base class for digest authentication checkers. Implements a digest-authentication logic. More...
class	server::handlers::auth::digest::AuthStandaloneCheckerBase
	Class for digest authentication checker. Implements a stand-alone digest-authentication logic. More...
class	server::handlers::HttpHandlerFlatbufBase< InputType, ReturnType >
	Convenient base for handlers that accept requests with body in Flatbuffer format and respond with body in Flatbuffer format. More...
class	server::handlers::HttpHandlerJsonBase
	Convenient base for handlers that accept requests with body in JSON format and respond with body in JSON format. More...
class	server::handlers::WebsocketHandlerBase
	Base class for WebSocket handler. More...
class	server::middlewares::PipelineBuilder
	Base class to build a server-wide middleware pipeline. One may inherit from it and implement any custom logic, if desired. More...
class	server::middlewares::HandlerPipelineBuilder
	Base class to build a per-handler middleware pipeline. One may inherit from it and implement any custom logic, if desired. By default the behavior is to use the server-wide pipeline. More...
class	server::middlewares::HttpMiddlewareBase
	Base class for a http middleware. More...
class	server::middlewares::HttpMiddlewareFactoryBase
	Base class for a http middleware-factory. More...
class	tracing::TracingManagerBase
	Base class for propagating trace context information in headers. More...
class	storages::mongo::DistLockComponentBase
	Base class for mongo-based distlock worker components. More...
class	storages::postgres::DistLockComponentBase
	Base class for postgres-based distlock worker components. More...
class	ugrpc::client::MiddlewareBase
	Base class for client gRPC middleware. More...
class	ugrpc::client::RetryLimiter
	Interface for controlling retry behavior based on request outcomes. More...
class	ugrpc::client::RetryLimiterFactory
	Abstract factory for creating RetryLimiter instances. More...
class	ugrpc::server::middlewares::access_log::Component
	gRPC server access log middleware component. Writes one TSKV log line per handled RPC in a static format. This log is intended to be collected, parsed and stored for audit or extended statistics purposes. More...
class	ugrpc::server::MiddlewareBase
	Base class for server gRPC middleware. More...
class	ugrpc::server::middlewares::congestion_control::Component
	Component for gRPC server logging. More...
class	ugrpc::server::middlewares::graceful_shutdown_headers::Component
	Component for gRPC server graceful_shutdown_headers. More...
class	ugrpc::server::middlewares::headers_propagator::Component
	Component for gRPC server headers_propagator. More...
class	ugrpc::server::middlewares::log::Component
	Component for gRPC server logging. More...
class	urabbitmq::ConsumerBase
	Base class for your consumers. You should derive from it and override Process method, which gets called when a new message arrives from the broker. More...
class	urabbitmq::ConsumerComponentBase
	Base component for your consumers. Basically a ConsumerBase but in a nice component-ish way. More...
class	ydb::DistLockComponentBase
	Base class for YDB-based distlock worker components. More...
struct	s3api::authenticators::Authenticator
	Base class for all authenticators - classes that sign the request with auth data. More...

Typedefs
using	ugrpc::server::middlewares::deadline_propagation::Component = SimpleMiddlewareFactoryComponent<Middleware>
	Component for gRPC server deadline propagation.
using	ugrpc::client::MiddlewareFactoryComponentBase
	Factory that creates specific client middlewares for clients.
using	ugrpc::server::middlewares::baggage::Component = SimpleMiddlewareFactoryComponent<Middleware>
	Component for gRPC server baggage.
using	ugrpc::server::MiddlewareFactoryComponentBase
	Factory that creates specific server middlewares for services.

Typedef Documentation

Component [1/2]

using ugrpc::server::middlewares::baggage::Component = SimpleMiddlewareFactoryComponent<Middleware>

Component for gRPC server baggage.

The component does not have any options for service config.

Static configuration example:

        grpc-server-baggage:
        # Nothing

See also

gRPC server middlewares

Definition at line 27 of file component.hpp.

Component [2/2]

using ugrpc::server::middlewares::deadline_propagation::Component = SimpleMiddlewareFactoryComponent<Middleware>

Component for gRPC server deadline propagation.

See also

Deadline propagation

The component does not have any options for service config.

Static configuration example:

        grpc-server-deadline-propagation:
        # Nothing

See also

gRPC server middlewares

Definition at line 32 of file component.hpp.

MiddlewareFactoryComponentBase [1/2]

using ugrpc::client::MiddlewareFactoryComponentBase

Initial value:

 
    ::middlewares::MiddlewareFactoryComponentBase<MiddlewareBase, ClientInfo>

Factory that creates specific client middlewares for clients.

Override ugrpc::client::SimpleMiddlewareFactoryComponent::CreateMiddleware to create middleware for your gRPC client. If you declare a static config for a middleware, you must override ugrpc::client::SimpleMiddlewareFactoryComponent::GetMiddlewareConfigSchema.

If you are not going to use static config, ugrpc::client::ClientInfo and your middleware is default constructible, just use ugrpc::client::SimpleMiddlewareFactoryComponent.

Static options:

Options inherited from middlewares::MiddlewareFactoryComponentBase :

Name	Description	Default value
enabled	The flag to enable/disable middleware in the pipeline.	true

Options inherited from components::ComponentBase :

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

Example:

class ChaosComponent final : public ugrpc::client::MiddlewareFactoryComponentBase {
public:
    static constexpr std::string_view kName = "grpc-chaos-client";
 
    ChaosComponent(const components::ComponentConfig& config, const components::ComponentContext& context);
 
    // Needed to pass static config options to the middleware.
    yaml_config::Schema GetMiddlewareConfigSchema() const override;
 
    static yaml_config::Schema GetStaticConfigSchema();
 
    std::shared_ptr<const MiddlewareBase> CreateMiddleware(
        const ugrpc::client::ClientInfo&,
        const yaml_config::YamlConfig& middleware_config
    ) const override;
};

ChaosComponent::ChaosComponent(const components::ComponentConfig& config, const components::ComponentContext& context)
    : ugrpc::client::MiddlewareFactoryComponentBase(config, context) {}
 
std::shared_ptr<const ugrpc::client::MiddlewareBase> ChaosComponent::CreateMiddleware(
    const ugrpc::client::ClientInfo&,
    const yaml_config::YamlConfig& middleware_config
) const {
    return std::make_shared<ChaosMiddleware>(middleware_config["x-my-experiments-enabled"].As<bool>(false));
}
 
yaml_config::Schema ChaosComponent::GetMiddlewareConfigSchema() const { return GetStaticConfigSchema(); }
 
yaml_config::Schema ChaosComponent::GetStaticConfigSchema() {
    return yaml_config::MergeSchemas<ugrpc::client::MiddlewareFactoryComponentBase>(R"(
type: object
description: gRPC service logger component
additionalProperties: false
properties:
    x-my-experiments-enabled:
        type: boolean
        description: enable or disable feature
)");
}

Definition at line 143 of file base.hpp.

MiddlewareFactoryComponentBase [2/2]

using ugrpc::server::MiddlewareFactoryComponentBase

Initial value:

 
    ::middlewares::MiddlewareFactoryComponentBase<MiddlewareBase, ServiceInfo>

Factory that creates specific server middlewares for services.

Override CreateMiddleware to create middleware for your gRPC service. If you declare a static config for a middleware, you must override GetMiddlewareConfigSchema.

Note

If you are not going to use a static config, ugrpc::server::ServiceInfo and your middleware is default constructible, just use ugrpc::server::SimpleMiddlewareFactoryComponent.

Static options:

Options inherited from middlewares::MiddlewareFactoryComponentBase :

Name	Description	Default value
enabled	The flag to enable/disable middleware in the pipeline.	true

Options inherited from components::ComponentBase :

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

Example:

struct MiddlewareConfig final {
    std::vector<std::string> headers{};
};
 
class MetaFilterComponent final : public ugrpc::server::MiddlewareFactoryComponentBase {
public:
    static constexpr std::string_view kName = "grpc-server-meta-filter";
 
    MetaFilterComponent(const components::ComponentConfig& config, const components::ComponentContext& context);
 
    static yaml_config::Schema GetStaticConfigSchema();
 
    // Needed to pass static config options to the middleware.
    yaml_config::Schema GetMiddlewareConfigSchema() const override;
 
    std::shared_ptr<const MiddlewareBase> CreateMiddleware(
        const ugrpc::server::ServiceInfo&,
        const yaml_config::YamlConfig& middleware_config
    ) const override;
};

 
MiddlewareConfig Parse(const yaml_config::YamlConfig& value, formats::parse::To<MiddlewareConfig>) {
    MiddlewareConfig config;
    config.headers = value["headers"].As<std::vector<std::string>>();
    return config;
}

MetaFilterComponent::MetaFilterComponent(
    const components::ComponentConfig& config,
    const components::ComponentContext& context
)
    : ugrpc::server::MiddlewareFactoryComponentBase(
          config,
          context,
          middlewares::MiddlewareDependencyBuilder()
              .InGroup<middlewares::groups::User>()
              .After<ugrpc::server::middlewares::headers_propagator::Component>()
      ) {}
 
std::shared_ptr<const ugrpc::server::MiddlewareBase> MetaFilterComponent::CreateMiddleware(
    const ugrpc::server::ServiceInfo&,
    const yaml_config::YamlConfig& middleware_config
) const {
    return std::make_shared<MetaFilter>(middleware_config.As<MiddlewareConfig>());
}
 
yaml_config::Schema MetaFilterComponent::GetMiddlewareConfigSchema() const { return GetStaticConfigSchema(); }
 
yaml_config::Schema MetaFilterComponent::GetStaticConfigSchema() {
    return yaml_config::MergeSchemas<MiddlewareFactoryComponentBase>(R"(
type: object
description: gRPC service logger component
additionalProperties: false
properties:
    headers:
        type: array
        description: headers names to filter
        items:
            type: string
            description: header name
)");
}

And there is a possibility to override the middleware config per service:

        # yaml
        greeter-service:
            task-processor: main-task-processor
            greeting-prefix: Hello
            middlewares:
                grpc-server-meta-filter:
                    # The middleware of this service will get this header instead of 'global-header'
                    headers:
                      - specific-header

Examples

samples/grpc_middleware_service/src/middlewares/server/meta_filter.cpp.

Definition at line 188 of file base.hpp.