[part 4] fix(telemetry): report logs (#199)

Changes:
 - Add unit tests.
 - Report `stack_trace` and `timestamp`.

Author: dmehala

include/datadog/telemetry/telemetry.h

@@ -87,4 +87,10 @@ void report_warning_log(std::string message);
 /// @param message The error message.
 void report_error_log(std::string message);
 
+/// Report internal error message to Datadog.
+///
+/// @param message The error message.
+/// @param stacktrace Stacktrace leading to the error.
+void report_error_log(std::string message, std::string stacktrace);
+
 }  // namespace datadog::telemetry

src/datadog/telemetry/log.h

@@ -1,3 +1,6 @@
+#include <datadog/optional.h>
+#include <datadog/string_view.h>
+
 #include <string>
 
 namespace datadog::telemetry {
@@ -7,6 +10,20 @@ enum class LogLevel : char { ERROR, WARNING };
 struct LogMessage final {
   std::string message;
   LogLevel level;
+  tracing::Optional<std::string> stacktrace;
+  std::chrono::seconds::rep timestamp;
 };
 
+inline tracing::StringView to_string(LogLevel level) {
+  switch (level) {
+    case LogLevel::ERROR:
+      return "ERROR";
+    case LogLevel::WARNING:
+      return "WARNING";
+  }
+
+  // Unreachable.
+  return "";
+}
+
 }  // namespace datadog::telemetry

src/datadog/telemetry/telemetry.cpp

@@ -116,4 +116,14 @@ void report_error_log(std::string message) {
              instance());
 }
 
+void report_error_log(std::string message, std::string stacktrace) {
+  std::visit(details::Overload{
+                 [&](Telemetry& telemetry) {
+                   telemetry.log_error(message, stacktrace);
+                 },
+                 [](auto&&) {},
+             },
+             instance());
+}
+
 }  // namespace datadog::telemetry

src/datadog/telemetry/telemetry_impl.cpp

@@ -201,6 +201,10 @@ void Telemetry::log_error(std::string message) {
   tracer_telemetry_->log(std::move(message), LogLevel::ERROR);
 }
 
+void Telemetry::log_error(std::string message, std::string stacktrace) {
+  tracer_telemetry_->log(std::move(message), LogLevel::ERROR, stacktrace);
+}
+
 void Telemetry::log_warning(std::string message) {
   tracer_telemetry_->log(std::move(message), LogLevel::WARNING);
 }

src/datadog/telemetry/telemetry_impl.h

@@ -58,6 +58,7 @@ class Telemetry final {
   ///
   /// @param message The error message.
   void log_error(std::string message);
+  void log_error(std::string message, std::string stacktrace);
 
   /// capture and report internal warning message to Datadog.
   ///

src/datadog/tracer_telemetry.cpp

@@ -55,6 +55,18 @@ std::string to_string(datadog::tracing::ConfigName name) {
   std::abort();
 }
 
+nlohmann::json encode_log(const telemetry::LogMessage& log) {
+  auto encoded = nlohmann::json{
+      {"message", log.message},
+      {"level", to_string(log.level)},
+      {"tracer_time", log.timestamp},
+  };
+  if (log.stacktrace) {
+    encoded.emplace("stack_trace", *log.stacktrace);
+  }
+  return encoded;
+}
+
 }  // namespace
 
 TracerTelemetry::TracerTelemetry(
@@ -275,8 +287,7 @@ std::string TracerTelemetry::heartbeat_and_telemetry() {
   if (!logs_.empty()) {
     auto encoded_logs = nlohmann::json::array();
     for (const auto& log : logs_) {
-      auto encoded =
-          nlohmann::json{{"message", log.message}, {"level", log.level}};
+      auto encoded = encode_log(log);
       encoded_logs.emplace_back(std::move(encoded));
     }
 
@@ -352,8 +363,7 @@ std::string TracerTelemetry::app_closing() {
   if (!logs_.empty()) {
     auto encoded_logs = nlohmann::json::array();
     for (const auto& log : logs_) {
-      auto encoded =
-          nlohmann::json{{"message", log.message}, {"level", log.level}};
+      auto encoded = encode_log(log);
       encoded_logs.emplace_back(std::move(encoded));
     }
 

src/datadog/tracer_telemetry.h

@@ -111,8 +111,13 @@ class TracerTelemetry {
   // Construct an `app-client-configuration-change` message.
   Optional<std::string> configuration_change();
 
-  inline void log(std::string message, telemetry::LogLevel level) {
-    logs_.emplace_back(telemetry::LogMessage{std::move(message), level});
+  inline void log(std::string message, telemetry::LogLevel level,
+                  Optional<std::string> stacktrace = nullopt) {
+    auto timestamp = std::chrono::duration_cast<std::chrono::seconds>(
+                         clock_().wall.time_since_epoch())
+                         .count();
+    logs_.emplace_back(telemetry::LogMessage{std::move(message), level,
+                                             stacktrace, timestamp});
   }
 };
 

test/telemetry/test_telemetry.cpp

@@ -274,4 +274,74 @@ TEST_CASE("Tracer telemetry", "[telemetry]") {
     auto heartbeat = message_batch["payload"][0];
     REQUIRE(heartbeat["request_type"] == "app-closing");
   }
+
+  SECTION("logs serialization") {
+    SECTION("log level is correct") {
+      struct TestCase {
+        std::string_view name;
+        std::string input;
+        Optional<std::string> stacktrace;
+        std::function<void(Telemetry&, const std::string&,
+                           const Optional<std::string>& stacktrace)>
+            apply;
+        std::string expected_log_level;
+      };
+
+      auto test_case = GENERATE(values<TestCase>({
+          {
+              "warning log",
+              "This is a warning log!",
+              nullopt,
+              [](Telemetry& telemetry, const std::string& input,
+                 const Optional<std::string>&) {
+                telemetry.log_warning(input);
+              },
+              "WARNING",
+          },
+          {
+              "error log",
+              "This is an error log!",
+              nullopt,
+              [](Telemetry& telemetry, const std::string& input,
+                 const Optional<std::string>&) { telemetry.log_error(input); },
+              "ERROR",
+          },
+          {
+              "error log with stacktrace",
+              "This is an error log with a fake stacktrace!",
+              "error here\nthen here\nfinally here\n",
+              [](Telemetry& telemetry, const std::string& input,
+                 Optional<std::string> stacktrace) {
+                telemetry.log_error(input, *stacktrace);
+              },
+              "ERROR",
+          },
+      }));
+
+      CAPTURE(test_case.name);
+
+      client->clear();
+      test_case.apply(telemetry, test_case.input, test_case.stacktrace);
+      trigger_heartbeat();
+
+      auto message_batch = nlohmann::json::parse(client->request_body);
+      REQUIRE(is_valid_telemetry_payload(message_batch));
+      REQUIRE(message_batch["payload"].size() == 2);
+
+      auto logs_message = message_batch["payload"][1];
+      REQUIRE(logs_message["request_type"] == "logs");
+
+      auto logs_payload = logs_message["payload"]["logs"];
+      REQUIRE(logs_payload.size() == 1);
+      CHECK(logs_payload[0]["level"] == test_case.expected_log_level);
+      CHECK(logs_payload[0]["message"] == test_case.input);
+      CHECK(logs_payload[0].contains("tracer_time"));
+
+      if (test_case.stacktrace) {
+        CHECK(logs_payload[0]["stack_trace"] == test_case.stacktrace);
+      } else {
+        CHECK(logs_payload[0].contains("stack_trace") == false);
+      }
+    }
+  }
 }