From 51bcff820e40a6d26c684284509a9fcf27b10c0a Mon Sep 17 00:00:00 2001
From: afshinpir <afshinpir@users.noreply.github.com>
Date: Sat, 25 Feb 2023 13:37:33 +0330
Subject: [PATCH] Added `apply_logger_env_levels` (#2649)

This method applies levels which is set by environment variable
`SPDLOG_LEVEL` to the a single controller. Usefull for loading
configuration into manually created loggers.
---
 include/spdlog/details/registry-inl.h | 8 ++++++++
 include/spdlog/details/registry.h     | 2 ++
 include/spdlog/spdlog-inl.h           | 5 +++++
 include/spdlog/spdlog.h               | 9 +++++++++
 4 files changed, 24 insertions(+)

diff --git a/include/spdlog/details/registry-inl.h b/include/spdlog/details/registry-inl.h
index e6ecc9b0..323a5c13 100644
--- a/include/spdlog/details/registry-inl.h
+++ b/include/spdlog/details/registry-inl.h
@@ -287,6 +287,14 @@ SPDLOG_INLINE registry &registry::instance()
     return s_instance;
 }
 
+SPDLOG_INLINE void registry::apply_logger_env_levels(std::shared_ptr<logger> new_logger)
+{
+    std::lock_guard<std::mutex> lock(logger_map_mutex_);
+    auto it = log_levels_.find(new_logger->name());
+    auto new_level = it != log_levels_.end() ? it->second : global_log_level_;
+    new_logger->set_level(new_level);
+}
+
 SPDLOG_INLINE void registry::throw_if_exists_(const std::string &logger_name)
 {
     if (loggers_.find(logger_name) != loggers_.end())
diff --git a/include/spdlog/details/registry.h b/include/spdlog/details/registry.h
index 6a4a5abc..4666fa29 100644
--- a/include/spdlog/details/registry.h
+++ b/include/spdlog/details/registry.h
@@ -91,6 +91,8 @@ public:
 
     static registry &instance();
 
+    void apply_logger_env_levels(std::shared_ptr<logger> new_logger);
+
 private:
     registry();
     ~registry();
diff --git a/include/spdlog/spdlog-inl.h b/include/spdlog/spdlog-inl.h
index 708399c1..22ea22bb 100644
--- a/include/spdlog/spdlog-inl.h
+++ b/include/spdlog/spdlog-inl.h
@@ -117,4 +117,9 @@ SPDLOG_INLINE void set_default_logger(std::shared_ptr<spdlog::logger> default_lo
     details::registry::instance().set_default_logger(std::move(default_logger));
 }
 
+SPDLOG_INLINE void apply_logger_env_levels(std::shared_ptr<logger> logger)
+{
+    details::registry::instance().apply_logger_env_levels(std::move(logger));
+}
+
 } // namespace spdlog
diff --git a/include/spdlog/spdlog.h b/include/spdlog/spdlog.h
index ee83e8de..6b7b221a 100644
--- a/include/spdlog/spdlog.h
+++ b/include/spdlog/spdlog.h
@@ -131,6 +131,15 @@ SPDLOG_API spdlog::logger *default_logger_raw();
 
 SPDLOG_API void set_default_logger(std::shared_ptr<spdlog::logger> default_logger);
 
+// Initialize logger level based on environment configs.
+//
+// Useful for applying SPDLOG_LEVEL to manually created loggers.
+//
+// Example:
+//   auto mylogger = std::make_shared<spdlog::logger>("mylogger", ...);
+//   spdlog::apply_logger_env_levels(mylogger);
+SPDLOG_API void apply_logger_env_levels(std::shared_ptr<logger> logger);
+
 template<typename... Args>
 inline void log(source_loc source, level::level_enum lvl, format_string_t<Args...> fmt, Args &&... args)
 {