Line data    Source code

       1             : #pragma once
       2             : 
       3             : // This component provides an interface, `HTTPClient`, that represents an
       4             : // asynchronous HTTP client.
       5             : //
       6             : // `HTTPClient` is used by `DatadogAgent` to send traces to the Datadog Agent.
       7             : //
       8             : // If this library was built with support for libcurl, then `Curl` implements
       9             : // `HTTPClient` in terms of libcurl.  See `curl.h`.
      10             : 
      11             : #include <chrono>
      12             : #include <functional>
      13             : 
      14             : #include "error.h"
      15             : #include "expected.h"
      16             : #include "json_fwd.hpp"
      17             : #include "optional.h"
      18             : 
      19             : namespace datadog {
      20             : namespace tracing {
      21             : 
      22             : class DictReader;
      23             : class DictWriter;
      24             : 
      25             : class HTTPClient {
      26             :  public:
      27             :   struct URL {
      28             :     std::string scheme;     // http, https, or unix
      29             :     std::string authority;  // domain:port or /path/to/socket
      30             :     std::string path;       // resource, e.g. /v0.4/traces
      31             :   };
      32             : 
      33             :   using HeadersSetter = std::function<void(DictWriter& headers)>;
      34             :   using ResponseHandler = std::function<void(
      35             :       int status, const DictReader& headers, std::string body)>;
      36             :   // `ErrorHandler` is for errors encountered by `HTTPClient`, not for
      37             :   // error-indicating HTTP responses.
      38             :   using ErrorHandler = std::function<void(Error)>;
      39             : 
      40             :   // Send a POST request to the specified `url`.  Set request headers by calling
      41             :   // the specified `set_headers` callback.  Include the specified `body` at the
      42             :   // end of the request.  Invoke the specified `on_response` callback if/when
      43             :   // a response is delivered (even if that response contains an error HTTP
      44             :   // response status).  Invoke the specified `on_error` if an error occurs
      45             :   // outside of HTTP, such as a connection failure.  If an error occurs while
      46             :   // preparing the request, return an `Error`. The behavior is undefined if
      47             :   // either of `on_response` or `on_error` throws an exception.
      48             :   virtual Expected<void> post(
      49             :       const URL& url, HeadersSetter set_headers, std::string body,
      50             :       ResponseHandler on_response, ErrorHandler on_error,
      51             :       std::chrono::steady_clock::time_point deadline) = 0;
      52             : 
      53             :   // Wait until there are no more outstanding requests, or until the specified
      54             :   // `deadline`.
      55             :   virtual void drain(std::chrono::steady_clock::time_point deadline) = 0;
      56             : 
      57             :   // Return a JSON representation of this object's configuration. The JSON
      58             :   // representation is an object with the following properties:
      59             :   //
      60             :   // - "type" is the unmangled, qualified name of the most-derived class, e.g.
      61             :   //   "datadog::tracing::Curl".
      62             :   // - "config" is an object containing this object's configuration. "config"
      63             :   //   may be omitted if the derived class has no configuration.
      64             :   virtual nlohmann::json config_json() const = 0;
      65             : 
      66         639 :   virtual ~HTTPClient() = default;
      67             : };
      68             : 
      69             : }  // namespace tracing
      70             : }  // namespace datadog