Replace logging API

Allow clients to provide a callback function that the LOOT API will use
when logging. This provides more flexibility than the previous choice of
outputting to an exclusive file or the console.

CMakeLists.txt

@@ -187,7 +187,7 @@ set (LOOT_API_HEADERS "${CMAKE_SOURCE_DIR}/include/loot/api.h"
                       "${CMAKE_SOURCE_DIR}/include/loot/exception/file_access_error.h"
                       "${CMAKE_SOURCE_DIR}/include/loot/exception/git_state_error.h"
                       "${CMAKE_SOURCE_DIR}/include/loot/enum/game_type.h"
-                      "${CMAKE_SOURCE_DIR}/include/loot/enum/log_verbosity.h"
+                      "${CMAKE_SOURCE_DIR}/include/loot/enum/log_level.h"
                       "${CMAKE_SOURCE_DIR}/include/loot/enum/message_type.h"
                       "${CMAKE_SOURCE_DIR}/include/loot/game_interface.h"
                       "${CMAKE_SOURCE_DIR}/include/loot/loot_version.h"

include/loot/api.h

@@ -25,6 +25,7 @@
 #ifndef LOOT_API_H
 #define LOOT_API_H
 
+#include <functional>
 #include <string>
 #include <memory>
 
@@ -36,7 +37,7 @@
 #include "loot/exception/file_access_error.h"
 #include "loot/exception/git_state_error.h"
 #include "loot/enum/game_type.h"
-#include "loot/enum/log_verbosity.h"
+#include "loot/enum/log_level.h"
 #include "loot/loot_version.h"
 
 namespace loot {
@@ -47,21 +48,14 @@ namespace loot {
 /**@{*/
 
 /**
- * @brief Set the API's logging verbosity.
- * @details The default is ``LogVerbosity::off``.
- * @param verbosity
- *        The logging verbosity to set.
+ * @brief Set the callback function that is called when logging.
+ * @details If this function is not called, the default behaviour is to 
+ *          print messages to the console.
+ * @param callback
+ *        The function called when logging. The first parameter is the
+ *        level of the message being logged, and the second is the message.
  */
-LOOT_API void SetLoggingVerbosity(LogVerbosity verbosity);
-
-/**
- * @brief Set the file path that logging statements are written to.
- * @details If no file is set the default behaviour is to print logging
- *          statements to the console.
- * @param path
- *        The log file path.
- */
-LOOT_API void SetLogFile(const std::string& path);
+LOOT_API void SetLoggingCallback(std::function<void(LogLevel, const char*)> callback);
 
 /**@}*/
 /**********************************************************************//**

include/loot/enum/log_level.h

@@ -22,20 +22,23 @@ along with LOOT.  If not, see
 <https://www.gnu.org/licenses/>.
 */
 
-#ifndef LOOT_LOG_VERBOSITY
-#define LOOT_LOG_VERBOSITY
+#ifndef LOOT_LOG_LEVEL
+#define LOOT_LOG_LEVEL
 
 /**
  * The namespace used by the LOOT API.
  */
 namespace loot {
 /**
- * @brief Codes used to specify different levels of API logging verbosity.
+ * @brief Codes used to specify different levels of API logging.
  */
-enum struct LogVerbosity : unsigned int {
-  off,
-  warning,
+enum struct LogLevel : unsigned int {
   trace,
+  debug,
+  info,
+  warning,
+  error,
+  fatal
 };
 }
 

src/api/api.cpp

@@ -46,34 +46,54 @@ std::string ResolvePath(const std::string& path) {
   return fs::read_symlink(path).string();
 }
 
-LOOT_API void SetLoggingVerbosity(LogVerbosity verbosity) {
-  switch (verbosity) {
-  case LogVerbosity::off:
-    boost::log::core::get()->set_logging_enabled(false);
-    break;
-  case LogVerbosity::warning:
-    boost::log::core::get()->set_filter(boost::log::trivial::severity > boost::log::trivial::warning);
-    boost::log::core::get()->set_logging_enabled(true);
-    break;
-  case LogVerbosity::trace:
-    boost::log::core::get()->reset_filter();
-    boost::log::core::get()->set_logging_enabled(true);
-    break;
+LogLevel mapFromBoostLog(boost::log::trivial::severity_level severity) {
+  using boost::log::trivial::severity_level;
+  switch (severity) {
+    case severity_level::trace:
+      return LogLevel::trace;
+    case severity_level::debug:
+      return LogLevel::debug;
+    case severity_level::info:
+      return LogLevel::info;
+    case severity_level::warning:
+      return LogLevel::warning;
+    case severity_level::error:
+      return LogLevel::error;
+    case severity_level::fatal:
+      return LogLevel::fatal;
+    default:
+      return LogLevel::trace;
   }
 }
 
-LOOT_API void SetLogFile(const std::string& path) {
-  boost::log::add_file_log(
-    boost::log::keywords::file_name = path,
-    boost::log::keywords::auto_flush = true,
-    boost::log::keywords::format = (
-      boost::log::expressions::stream
-      << "[" << boost::log::expressions::format_date_time< boost::posix_time::ptime >("TimeStamp", "%H:%M:%S.%f") << "]"
-      << " [" << boost::log::trivial::severity << "]: "
-      << boost::log::expressions::smessage
-      )
-  );
-  boost::log::add_common_attributes();
+class LoggingSink : public boost::log::sinks::basic_formatted_sink_backend<char, boost::log::sinks::concurrent_feeding> {
+public:
+  LoggingSink(std::function<void(LogLevel, const char*)> callback) {
+    this->callback = callback;
+  }
+
+  void consume(const boost::log::record_view& rec, const std::string& str) {
+    using boost::log::trivial::severity_level;
+    auto severity = rec.attribute_values()[boost::log::aux::default_attribute_names::severity()].extract<severity_level>();
+    if (!severity) {
+      return;
+    }
+
+    callback(mapFromBoostLog(*severity), str.c_str());
+  }
+
+private:
+  std::function<void(LogLevel, const char*)> callback;
+};
+
+LOOT_API void SetLoggingCallback(std::function<void(LogLevel, const char*)> callback) {
+  typedef boost::log::sinks::synchronous_sink<LoggingSink> sink_t;
+
+  auto sink_backend = boost::make_shared<LoggingSink>(callback);
+  boost::shared_ptr<sink_t> sink(new sink_t(sink_backend));
+
+  boost::log::core::get()->remove_all_sinks();
+  boost::log::core::get()->add_sink(sink);
 }
 
 LOOT_API bool IsCompatible(const unsigned int versionMajor, const unsigned int versionMinor, const unsigned int versionPatch) {

src/tests/api/interface/main.cpp

@@ -24,6 +24,7 @@
 
 #include <gtest/gtest.h>
 
+#include "loot/api.h"
 #include "tests/api/interface/create_game_handle_test.h"
 #include "tests/api/interface/database_interface_test.h"
 #include "tests/api/interface/game_interface_test.h"
@@ -33,15 +34,37 @@
 #include <boost/locale.hpp>
 
 int main(int argc, char **argv) {
-    //Set the locale to get encoding conversions working correctly.
+  //Set the locale to get encoding conversions working correctly.
   std::locale::global(boost::locale::generator().generate(""));
   boost::filesystem::path::imbue(std::locale());
   loot::InitialiseLocale("");
 
-  //Disable logging or else stdout will get overrun.
-  boost::log::core::get()->set_logging_enabled(false);
-  loot::SetLoggingVerbosity(loot::LogVerbosity::off);
+  //Set a null log callback or else stdout will get overrun.
+  loot::SetLoggingCallback([](loot::LogLevel, const char *) {});
 
   ::testing::InitGoogleTest(&argc, argv);
   return RUN_ALL_TESTS();
 }
+
+namespace loot {
+namespace test {
+TEST(SetLoggingCallback, shouldWriteMessagesToGivenCallback) {
+  std::string loggedMessages;
+  SetLoggingCallback([&](LogLevel level, const char * string) {
+    loggedMessages += std::string(string);
+  });
+
+  try {
+    CreateGameHandle(GameType::tes4, "", "");
+  }
+  catch (...) {
+    EXPECT_EQ("Initialising load order data for game of type 0 at: \"\"", loggedMessages);
+
+    SetLoggingCallback([](LogLevel, const char *) {});
+    return;
+  }
+
+  FAIL();
+}
+}
+}