simple_client_component.hpp

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#pragma once
 
/// @file userver/ugrpc/client/simple_client_component.hpp
/// @brief @copybrief ugrpc::client::SimpleClientComponent
 
#include <memory>
 
#include <userver/components/component_base.hpp>
#include <userver/utils/not_null.hpp>
 
#include <userver/ugrpc/client/client_factory.hpp>
#include <userver/ugrpc/client/fwd.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace ugrpc::client {
 
namespace impl {
 
class SimpleClientComponentAny : public components::ComponentBase {
public:
    using components::ComponentBase::ComponentBase;
 
    static yaml_config::Schema GetStaticConfigSchema();
 
protected:
    static ClientFactory&
    FindFactory(const components::ComponentConfig& config, const components::ComponentContext& context);
 
    static ClientSettings
    MakeClientSettings(const components::ComponentConfig& config, const dynamic_config::Key<ClientQos>* client_qos);
};
 
}  // namespace impl
 
// clang-format off
 
/// @ingroup userver_components
///
/// @brief Template class for a simple gRPC client
///
/// The component is used as a storage of a gRPC client if you're OK with
/// generated client and don't need to wrap it. The client can be fetched using
/// `GetClient` method.
///
/// Example usage:
///
/// ```cpp
/// int main(...)
/// {
///    ...
///    component_list.Append<ugrpc::client::SimpleClientComponent<HelloClient>>("hello-client");
///    ...
/// }
///
/// MyComponent::MyComponent(const components::ComponentConfig& config,
///                          const components::ComponentContext& context)
/// {
///    HelloClient& client = context.FindComponent<
///        ugrpc::client::SimpleClientComponent<HelloClient>>("hello-client").GetClient();
///    ... use client ...
/// }
/// ```
///
/// ## Static config options:
/// Name | Description | Default value
/// ---- | ----------- | -------------
/// endpoint | URL of the gRPC service | --
/// client-name | name of the gRPC server we talk to, for diagnostics | uses the component name
/// dedicated-channel-counts | a map of rpc method names to channel counts. Used for high-load methods | -
/// factory-component | ClientFactoryComponent name to use for client creation | --
 
// clang-format on
 
template <typename Client>
class SimpleClientComponent : public impl::SimpleClientComponentAny {
public:
    /// Main component's constructor.
    SimpleClientComponent(const components::ComponentConfig& config, const components::ComponentContext& context)
        : SimpleClientComponentAny(config, context),
          client_(utils::MakeSharedRef<Client>(
              FindFactory(config, context).MakeClient<Client>(MakeClientSettings(config, nullptr))
          )) {}
 
    /// To use a ClientQos config, derive from SimpleClientComponent and provide the parameter at construction:
    /// @snippet samples/grpc_service/src/greeter_client.hpp  component
    SimpleClientComponent(
        const components::ComponentConfig& config,
        const components::ComponentContext& context,
        const dynamic_config::Key<ClientQos>& client_qos
    )
        : SimpleClientComponentAny(config, context),
          client_(utils::MakeSharedRef<Client>(
              FindFactory(config, context).MakeClient<Client>(MakeClientSettings(config, &client_qos))
          )) {}
 
    /// @brief Get gRPC service client.
    Client& GetClient() noexcept { return *client_; }
 
protected:
    /// @brief Get gRPC service client ptr.
    utils::SharedRef<Client> GetClientPtr() noexcept { return client_; }
 
private:
    utils::SharedRef<Client> client_;
};
 
}  // namespace ugrpc::client
 
namespace components {
 
template <typename Client>
inline constexpr bool kHasValidate<ugrpc::client::SimpleClientComponent<Client>> = true;
 
}  // namespace components
 
USERVER_NAMESPACE_END