feat userver: make ping handler inheritable

commit_hash:86aa4007ea1769c721921c0be19a7dbfcb822db8

Author: knkhmelevsky

core/include/userver/server/handlers/ping.hpp

@@ -12,21 +12,38 @@ namespace server::handlers {
 
 /// @ingroup userver_components userver_http_handlers
 ///
-/// @brief Handler that returns HTTP 200 if the service is OK and able to
-/// process requests.
+/// @brief Base class for handlers that returns HTTP 200 if the service
+/// is OK and able to process requests.
 ///
 /// Uses components::State::IsAnyComponentInFatalState() to detect
 /// fatal state (can not process requests).
 ///
 /// ## Static options:
 /// Inherits all the options from server::handlers::HttpHandlerBase
 /// @ref userver_http_handlers
+class PingBase : public HttpHandlerBase {
+public:
+    PingBase(const components::ComponentConfig& config, const components::ComponentContext& component_context);
+
+    std::string HandleRequestThrow(const http::HttpRequest& request, request::RequestContext& context) const override;
+
+private:
+    const components::State components_;
+};
+
+/// @ingroup userver_components userver_http_handlers
+///
+/// @brief Ping handler implementation with warmup
+///
+/// ## Static options:
+/// Inherits all the options from server::handlers::PingBase
+/// @ref userver_http_handlers
 /// and adds the following ones:
 ///
 /// Name | Description | Default value
 /// ---- | ----------- | -------------
 /// warmup-time-secs | how much time it needs to warmup the server | 0
-class Ping final : public HttpHandlerBase {
+class Ping final : public PingBase {
 public:
     Ping(const components::ComponentConfig& config, const components::ComponentContext& component_context);
 
@@ -43,8 +60,6 @@ class Ping final : public HttpHandlerBase {
 private:
     void AppendWeightHeaders(http::HttpResponse&) const;
 
-    const components::State components_;
-
     std::chrono::steady_clock::time_point load_time_{};
     std::chrono::seconds awacs_weight_warmup_time_{60};
 };

core/src/server/handlers/ping.cpp

@@ -10,12 +10,11 @@ USERVER_NAMESPACE_BEGIN
 
 namespace server::handlers {
 
-Ping::Ping(const components::ComponentConfig& config, const components::ComponentContext& component_context)
-    : HttpHandlerBase(config, component_context),
-      components_(component_context),
-      awacs_weight_warmup_time_(config["warmup-time-secs"].As<int>(0)) {}
+PingBase::PingBase(const components::ComponentConfig& config, const components::ComponentContext& component_context)
+    : HttpHandlerBase(config, component_context), components_(component_context) {}
 
-std::string Ping::HandleRequestThrow(const http::HttpRequest& request, request::RequestContext& /*context*/) const {
+std::string PingBase::HandleRequestThrow(const http::HttpRequest& /*request*/, request::RequestContext& /*context*/)
+    const {
     if (components_.IsAnyComponentInFatalState()) {
         throw InternalServerError();
     }
@@ -27,6 +26,15 @@ std::string Ping::HandleRequestThrow(const http::HttpRequest& request, request::
         throw InternalServerError();
     }
 
+    return {};
+}
+
+Ping::Ping(const components::ComponentConfig& config, const components::ComponentContext& component_context)
+    : PingBase(config, component_context), awacs_weight_warmup_time_(config["warmup-time-secs"].As<int>(0)) {}
+
+std::string Ping::HandleRequestThrow(const http::HttpRequest& request, request::RequestContext& context) const {
+    PingBase::HandleRequestThrow(request, context);
+
     auto& response = request.GetHttpResponse();
     AppendWeightHeaders(response);
 
@@ -50,7 +58,7 @@ void Ping::AppendWeightHeaders(http::HttpResponse& response) const {
 }
 
 yaml_config::Schema Ping::GetStaticConfigSchema() {
-    return yaml_config::MergeSchemas<HttpHandlerBase>(R"(
+    return yaml_config::MergeSchemas<PingBase>(R"(
 type: object
 description: ping handler config
 additionalProperties: false