workaround

Author: dmehala

examples/CMakeLists.txt

@@ -1,3 +1,4 @@
 add_subdirectory(baggage)
+add_subdirectory(elsa)
 add_subdirectory(hasher)
 add_subdirectory(http-server)

examples/elsa/CMakeLists.txt

@@ -0,0 +1,4 @@
+add_executable(telemetry-example main.cpp)
+set_target_properties(telemetry-example PROPERTIES OUTPUT_NAME example)
+
+target_link_libraries(telemetry-example dd_trace_cpp-static)

examples/elsa/httpclient.h

@@ -0,0 +1,67 @@
+#pragma once
+
+#include <datadog/dict_writer.h>
+#include <datadog/http_client.h>
+
+#include "httplib.h"
+
+struct HttplibClient : public datadog::tracing::HTTPClient {
+  class HeaderWriter final : public datadog::tracing::DictWriter {
+    httplib::Headers& headers_;
+
+   public:
+    explicit HeaderWriter(httplib::Headers& headers) : headers_(headers) {}
+
+    void set(std::string_view key, std::string_view value) override {
+      auto found = headers_.find(std::string(key));
+      if (found == headers_.cend()) {
+        headers_.emplace(key, value);
+      } else {
+        found->second = value;
+      }
+    }
+  };
+  httplib::Client cli;
+
+  HttplibClient(std::string_view agent_url) : cli(agent_url.data()) {}
+
+  datadog::tracing::Expected<void> post(
+      const URL& url, HeadersSetter set_headers, std::string body,
+      ResponseHandler on_response, ErrorHandler on_error,
+      std::chrono::steady_clock::time_point deadline) override {
+    httplib::Request req;
+    req.method = "POST";
+    req.path = url.path;
+    req.body = body;
+
+    HeaderWriter writer(req.headers);
+    set_headers(writer);
+
+    auto result = cli.send(req);
+    if (result.error() != httplib::Error::Success) {
+      on_error(datadog::tracing::Error{
+          datadog::tracing::Error::Code::CURL_HTTP_CLIENT_ERROR,
+          to_string(result.error())});
+    }
+    return {};
+  }
+
+  // Wait until there are no more outstanding requests, or until the specified
+  // `deadline`.
+  inline void drain(std::chrono::steady_clock::time_point deadline) override {
+    return;
+  };
+
+  // Return a JSON representation of this object's configuration. The JSON
+  // representation is an object with the following properties:
+  //
+  // - "type" is the unmangled, qualified name of the most-derived class, e.g.
+  //   "datadog::tracing::Curl".
+  // - "config" is an object containing this object's configuration. "config"
+  //   may be omitted if the derived class has no configuration.
+  inline std::string config() const override {
+    return "{\"type\": \"httplib\"}";
+  };
+
+  ~HttplibClient() = default;
+};