plugin.hpp

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#pragma once
 
/// @file userver/clients/http/plugin.hpp
/// @brief @copybrief clients::http::Plugin
 
#include <chrono>
#include <string>
#include <vector>
 
#include <userver/utils/not_null.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace clients::http {
 
class RequestState;
class Response;
 
/// @brief Auxiliary entity that allows editing request to a client
/// from plugins
class PluginRequest final {
 public:
  /// @cond
  explicit PluginRequest(RequestState& state);
  /// @endcond
 
  void SetHeader(std::string_view name, std::string value);
 
  void SetTimeout(std::chrono::milliseconds ms);
 
 private:
  RequestState& state_;
};
 
/// @brief Base class for HTTP Client plugins
class Plugin {
 public:
  explicit Plugin(std::string name);
 
  virtual ~Plugin() = default;
 
  /// @brief Get plugin name
  const std::string& GetName() const;
 
  /// @brief The hook is called before actual HTTP request sending and before
  ///        DNS name resolution. You might want to use the hook for most of the
  ///        hook job.
  virtual void HookPerformRequest(PluginRequest& request) = 0;
 
  /// @brief The hook is called just after the "external" Span is created.
  ///        You might want to add custom tags from the hook.
  virtual void HookCreateSpan(PluginRequest& request) = 0;
 
  /// @brief The hook is called after the HTTP response is received or the
  ///        timeout is passed.
  ///
  /// @warning The hook is called in libev thread, not in coroutine context! Do
  ///          not do any heavy work here, offload it to other hooks.
  virtual void HookOnCompleted(PluginRequest& request, Response& response) = 0;
 
 private:
  const std::string name_;
};
 
namespace impl {
 
class PluginPipeline final {
 public:
  PluginPipeline(const std::vector<utils::NotNull<Plugin*>>& plugins);
 
  void HookPerformRequest(RequestState& request);
 
  void HookCreateSpan(RequestState& request);
 
  void HookOnCompleted(RequestState& request, Response& response);
 
 private:
  const std::vector<utils::NotNull<Plugin*>> plugins_;
};
 
}  // namespace impl
 
}  // namespace clients::http
 
USERVER_NAMESPACE_END