From 4bf300fd47de08ea5c55b50826af95befc021256 Mon Sep 17 00:00:00 2001
From: Rainer Kuemmerle <rainer.kuemmerle@gmail.com>
Date: Sat, 11 Nov 2023 18:54:20 +0100
Subject: [PATCH] Fix logger singleton

Fix #732
---
 g2o/stuff/logger.cpp | 14 ++++++++++++--
 g2o/stuff/logger.h   | 17 +++++++++++------
 2 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/g2o/stuff/logger.cpp b/g2o/stuff/logger.cpp
index 5b5044ea9..4e67c60ff 100644
--- a/g2o/stuff/logger.cpp
+++ b/g2o/stuff/logger.cpp
@@ -26,6 +26,10 @@
 
 #include "logger.h"
 
+#include <spdlog/spdlog.h>
+
+#include <string_view>
+
 #include "g2o/config.h"
 
 #ifdef G2O_HAVE_LOGGING
@@ -37,13 +41,17 @@
 
 namespace g2o::internal {
 
+constexpr std::string_view kLoggerName = "g2o";
+
 LoggerInterface::LoggerInterface() {
   spdlog::cfg::load_env_levels();
-  console_ = spdlog::stdout_color_mt("g2o");
+  console_ = spdlog::get(std::string(kLoggerName));
+  if (console_) return;
+  console_ = spdlog::stdout_color_mt(std::string(kLoggerName));
   console_->set_pattern("%+");
 }
 
-LoggerInterface::~LoggerInterface() { spdlog::drop("g2o"); }
+LoggerInterface::~LoggerInterface() { spdlog::drop(std::string(kLoggerName)); }
 
 }  // namespace g2o::internal
 #endif
@@ -54,6 +62,8 @@ void setLevel(Level level) {
 #ifdef G2O_HAVE_LOGGING
   auto toSpdLogLevel = [](Level level) {
     switch (level) {
+      case Level::kTrace:
+        return spdlog::level::trace;
       case Level::kDebug:
         return spdlog::level::debug;
       case Level::kInfo:
diff --git a/g2o/stuff/logger.h b/g2o/stuff/logger.h
index 071519795..f3129e5ff 100644
--- a/g2o/stuff/logger.h
+++ b/g2o/stuff/logger.h
@@ -79,6 +79,10 @@ using Logger = internal::Singleton<internal::LoggerInterface>;
 }  // namespace g2o
 
 // TODO(Rainer): Switch to std::source_location with c++20
+#define G2O_TRACE(...)                                      \
+  g2o::Logger::get().console().log(                         \
+      spdlog::source_loc(__FILE__, __LINE__, __FUNCTION__), \
+      spdlog::level::trace, __VA_ARGS__)
 #define G2O_DEBUG(...)                                      \
   g2o::Logger::get().console().log(                         \
       spdlog::source_loc(__FILE__, __LINE__, __FUNCTION__), \
@@ -102,16 +106,17 @@ using Logger = internal::Singleton<internal::LoggerInterface>;
 
 #else
 
-#define G2O_DEBUG(...)
-#define G2O_INFO(...)
-#define G2O_WARN(...)
-#define G2O_ERROR(...)
-#define G2O_CRITICAL(...)
+#define G2O_TRACE(...) (void)0
+#define G2O_DEBUG(...) (void)0
+#define G2O_INFO(...) (void)0
+#define G2O_WARN(...) (void)0
+#define G2O_ERROR(...) (void)0
+#define G2O_CRITICAL(...) (void)0
 
 #endif  // G2O_HAVE_LOGGING
 
 namespace g2o::logging {
-enum class Level { kDebug, kInfo, kWarn, kError, kOff };
+enum class Level { kTrace, kDebug, kInfo, kWarn, kError, kOff };
 /**
  * @brief Set the Log Level
  *