Added mdc example to readme

README.md

@@ -437,7 +437,22 @@ MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent)
     logger->info("Some info message");
 }
 ```
+---
 
+#### Mapped Diagnostic Context
+```c++
+// Mapped Diagnostic Context (MDC) is a map that stores key-value pairs (string values) in thread local storage.
+// Each thread maintains its own MDC, which loggers use to append diagnostic information to log outputs.
+// Note: it is not supported in asynchronous mode due to its reliance on thread-local storage.
+#include "spdlog/mdc.h"
+void mdc_example()
+{
+    spdlog::mdc::put("key1", "value1");
+    spdlog::mdc::put("key2", "value2");
+    // if not using the default format, use the %& formatter to print mdc data
+    // spdlog::set_pattern("[%H:%M:%S %z] [%^%L%$] [%&] %v");
+}
+```
 ---
 ## Benchmarks
 

example/example.cpp

@@ -26,6 +26,7 @@ void udp_example();
 void custom_flags_example();
 void file_events_example();
 void replace_default_logger_example();
+void mdc_example();
 
 #include "spdlog/spdlog.h"
 #include "spdlog/cfg/env.h"   // support for loading levels from the environment variable
@@ -84,6 +85,7 @@ int main(int, char *[]) {
         custom_flags_example();
         file_events_example();
         replace_default_logger_example();
+        mdc_example();
 
         // Flush all *registered* loggers using a worker thread every 3 seconds.
         // note: registered loggers *must* be thread safe for this to work correctly!
@@ -376,3 +378,16 @@ void replace_default_logger_example() {
 
     spdlog::set_default_logger(old_logger);
 }
+
+// Mapped Diagnostic Context (MDC) is a map that stores key-value pairs (string values) in thread local storage.
+// Each thread maintains its own MDC, which loggers use to append diagnostic information to log outputs.
+// Note: it is not supported in asynchronous mode due to its reliance on thread-local storage.
+#include "spdlog/mdc.h"
+void mdc_example()
+{
+    spdlog::mdc::put("key1", "value1");
+    spdlog::mdc::put("key2", "value2");
+    // if not using the default format, you can use the %& formatter to print mdc data as well
+    spdlog::set_pattern("[%H:%M:%S %z] [%^%L%$] [%&] %v");
+    spdlog::info("Some log message with context");
+}

include/spdlog/common.h

@@ -81,7 +81,7 @@
     #if FMT_USE_CONSTEXPR
         #define SPDLOG_CONSTEXPR_FUNC FMT_CONSTEXPR
     #else
-	#define SPDLOG_CONSTEXPR_FUNC inline
+        #define SPDLOG_CONSTEXPR_FUNC inline
     #endif
 #endif
 

include/spdlog/details/file_helper-inl.h

@@ -98,7 +98,7 @@ SPDLOG_INLINE void file_helper::close() {
 }
 
 SPDLOG_INLINE void file_helper::write(const memory_buf_t &buf) {
-    if(fd_ == nullptr) return;
+    if (fd_ == nullptr) return;
     size_t msg_size = buf.size();
     auto data = buf.data();
     if (std::fwrite(data, 1, msg_size, fd_) != msg_size) {

include/spdlog/details/os-inl.h

@@ -534,6 +534,15 @@ SPDLOG_INLINE bool create_dir(const filename_t &path) {
         }
 
         auto subdir = path.substr(0, token_pos);
+#ifdef _WIN32
+        // if subdir is just a drive letter, add a slash e.g. "c:"=>"c:\",
+        // otherwise path_exists(subdir) returns false (issue #3079)
+        const bool is_drive = subdir.length() == 2 && subdir[1] == ':';
+        if (is_drive) {
+            subdir += '\\';
+            token_pos++;
+        }
+#endif
 
         if (!subdir.empty() && !path_exists(subdir) && !mkdir_(subdir)) {
             return false;  // return error if failed creating dir

include/spdlog/details/registry-inl.h

@@ -84,31 +84,6 @@ SPDLOG_INLINE std::shared_ptr<logger> registry::get(const std::string &logger_na
     return found == loggers_.end() ? nullptr : found->second;
 }
 
-#if __cplusplus >= 201703L  // C++17
-// if the map is small do a sequential search and avoid creating string for find(logger_name)
-// otherwise use the standard find()
-SPDLOG_INLINE std::shared_ptr<logger> registry::get(std::string_view logger_name) {
-    std::lock_guard<std::mutex> lock(logger_map_mutex_);
-    if (loggers_.size() <= 10) {
-        for (const auto &[key, val]: loggers_) {
-            if (logger_name == key) {
-                return val;
-            }
-        }
-        return nullptr;
-    }
-    // otherwise use the normal map lookup
-    else {
-        auto found = loggers_.find(std::string(logger_name));
-        return found == loggers_.end() ? nullptr : found->second;
-    }
-}
-
-SPDLOG_INLINE std::shared_ptr<logger> registry::get(const char *logger_name) {
-    return get(std::string_view(logger_name));
-}
-#endif
-
 SPDLOG_INLINE std::shared_ptr<logger> registry::default_logger() {
     std::lock_guard<std::mutex> lock(logger_map_mutex_);
     return default_logger_;
@@ -123,7 +98,7 @@ SPDLOG_INLINE logger *registry::get_default_raw() { return default_logger_.get()
 // set default logger.
 // default logger is stored in default_logger_ (for faster retrieval) and in the loggers_ map.
 SPDLOG_INLINE void registry::set_default_logger(std::shared_ptr<logger> new_default_logger) {
-    std::lock_guard<std::mutex> lock(logger_map_mutex_);    
+    std::lock_guard<std::mutex> lock(logger_map_mutex_);
     if (new_default_logger != nullptr) {
         loggers_[new_default_logger->name()] = new_default_logger;
     }

include/spdlog/details/registry.h

@@ -18,10 +18,6 @@
 #include <string>
 #include <unordered_map>
 
-#if __cplusplus >= 201703L  // C++17
-    #include <string_view>
-#endif
-
 namespace spdlog {
 class logger;
 
@@ -37,10 +33,6 @@ public:
     void register_logger(std::shared_ptr<logger> new_logger);
     void initialize_logger(std::shared_ptr<logger> new_logger);
     std::shared_ptr<logger> get(const std::string &logger_name);
-#if __cplusplus >= 201703L  // C++17
-    std::shared_ptr<logger> get(std::string_view logger_name);
-    std::shared_ptr<logger> get(const char *logger_name);
-#endif
     std::shared_ptr<logger> default_logger();
 
     // Return raw ptr to the default logger.
@@ -52,7 +44,8 @@ public:
 
     // set default logger and add it to the registry if not registered already.
     // default logger is stored in default_logger_ (for faster retrieval) and in the loggers_ map.
-    // Note: Make sure to unregister it when no longer needed or before calling again with a new logger.
+    // Note: Make sure to unregister it when no longer needed or before calling again with a new
+    // logger.
     void set_default_logger(std::shared_ptr<logger> new_default_logger);
 
     void set_tp(std::shared_ptr<thread_pool> tp);
@@ -78,8 +71,8 @@ public:
     }
 
     std::unique_ptr<periodic_worker> &get_flusher() {
-        std::lock_guard<std::mutex> lock(flusher_mutex_); 
-        return periodic_flusher_; 
+        std::lock_guard<std::mutex> lock(flusher_mutex_);
+        return periodic_flusher_;
     }
 
     void set_error_handler(err_handler handler);

include/spdlog/details/thread_pool.h

@@ -67,9 +67,7 @@ struct async_msg : log_msg_buffer {
           worker_ptr{std::move(worker)},
           flush_promise{} {}
 
-    async_msg(async_logger_ptr &&worker,
-              async_msg_type the_type,
-              std::promise<void> &&promise)
+    async_msg(async_logger_ptr &&worker, async_msg_type the_type, std::promise<void> &&promise)
         : log_msg_buffer{},
           msg_type{the_type},
           worker_ptr{std::move(worker)},

include/spdlog/fmt/fmt.h

@@ -20,7 +20,7 @@
     #ifndef FMT_USE_WINDOWS_H
         #define FMT_USE_WINDOWS_H 0
     #endif
-    
+
     #include <spdlog/fmt/bundled/core.h>
     #include <spdlog/fmt/bundled/format.h>
 

include/spdlog/mdc.h

@@ -1,3 +1,6 @@
+// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+
 #pragma once
 
 #include <map>
@@ -5,32 +8,39 @@
 
 #include <spdlog/common.h>
 
+// MDC is a simple map of key->string values stored in thread local storage whose content will be printed by the loggers.
+// Note: Not supported in async mode (thread local storage - so the async thread pool have different copy).
+//
+// Usage example:
+// spdlog::mdc::put("mdc_key_1", "mdc_value_1");
+// spdlog::info("Hello, {}", "World!");  // => [2024-04-26 02:08:05.040] [info] [mdc_key_1:mdc_value_1] Hello, World!
+
 namespace spdlog {
-    class SPDLOG_API mdc {
-    public:
-        using mdc_map_t = std::map<std::string, std::string>;
+class SPDLOG_API mdc {
+public:
+    using mdc_map_t = std::map<std::string, std::string>;
 
-        static void put(const std::string &key, const std::string &value) {
-            get_context()[key] = value;
+    static void put(const std::string &key, const std::string &value) {
+        get_context()[key] = value;
+    }
+
+    static std::string get(const std::string &key) {
+        auto &context = get_context();
+        auto it = context.find(key);
+        if (it != context.end()) {
+            return it->second;
         }
+        return "";
+    }
 
-        static std::string get(const std::string &key) {
-            auto &context = get_context();
-            auto it = context.find(key);
-            if (it != context.end()) {
-                return it->second;
-            }
-            return "";
-        }
+    static void remove(const std::string &key) { get_context().erase(key); }
 
-        static void remove(const std::string &key) { get_context().erase(key); }
+    static void clear() { get_context().clear(); }
 
-        static void clear() { get_context().clear(); }
-
-        static mdc_map_t &get_context() {
-            static thread_local mdc_map_t context;
-            return context;
-        }
-    };
+    static mdc_map_t &get_context() {
+        static thread_local mdc_map_t context;
+        return context;
+    }
+};
 
 }  // namespace spdlog

include/spdlog/pattern_formatter-inl.h

@@ -790,7 +790,7 @@ template <typename ScopedPadder>
 class mdc_formatter : public flag_formatter {
 public:
     explicit mdc_formatter(padding_info padinfo)
-            : flag_formatter(padinfo) {}
+        : flag_formatter(padinfo) {}
 
     void format(const details::log_msg &, const std::tm &, memory_buf_t &dest) override {
         auto &mdc_map = mdc::get_context();
@@ -802,7 +802,7 @@ public:
         }
     }
 
-    void format_mdc(const mdc::mdc_map_t &mdc_map, memory_buf_t &dest){
+    void format_mdc(const mdc::mdc_map_t &mdc_map, memory_buf_t &dest) {
         auto last_element = --mdc_map.end();
         for (auto it = mdc_map.begin(); it != mdc_map.end(); ++it) {
             auto &pair = *it;
@@ -825,8 +825,6 @@ public:
     }
 };
 
-
-
 // Full info formatter
 // pattern: [%Y-%m-%d %H:%M:%S.%e] [%n] [%l] [%s:%#] %v
 class full_formatter final : public flag_formatter {
@@ -921,8 +919,6 @@ private:
     mdc_formatter<null_scoped_padder> mdc_formatter_{padding_info{}};
 };
 
-
-
 }  // namespace details
 
 SPDLOG_INLINE pattern_formatter::pattern_formatter(std::string pattern,

include/spdlog/spdlog-inl.h

@@ -20,16 +20,6 @@ SPDLOG_INLINE std::shared_ptr<logger> get(const std::string &name) {
     return details::registry::instance().get(name);
 }
 
-#if __cplusplus >= 201703L  // C++17
-SPDLOG_INLINE std::shared_ptr<logger> get(std::string_view name) {
-    return details::registry::instance().get(name);
-}
-
-SPDLOG_INLINE std::shared_ptr<logger> get(const char *name) {
-    return details::registry::instance().get(name);
-}
-#endif
-
 SPDLOG_INLINE void set_formatter(std::unique_ptr<spdlog::formatter> formatter) {
     details::registry::instance().set_formatter(std::move(formatter));
 }

include/spdlog/spdlog.h

@@ -20,10 +20,6 @@
 #include <memory>
 #include <string>
 
-#if __cplusplus >= 201703L  // C++17
-    #include <string_view>
-#endif
-
 namespace spdlog {
 
 using default_factory = synchronous_factory;
@@ -54,10 +50,6 @@ SPDLOG_API void initialize_logger(std::shared_ptr<logger> logger);
 // exist.
 // example: spdlog::get("my_logger")->info("hello {}", "world");
 SPDLOG_API std::shared_ptr<logger> get(const std::string &name);
-#if __cplusplus >= 201703L  // C++17
-SPDLOG_API std::shared_ptr<logger> get(std::string_view name);
-SPDLOG_API std::shared_ptr<logger> get(const char *name);
-#endif
 
 // Set global formatter. Each sink in each logger will get a clone of this object
 SPDLOG_API void set_formatter(std::unique_ptr<spdlog::formatter> formatter);

include/spdlog/version.h

@@ -5,7 +5,7 @@
 
 #define SPDLOG_VER_MAJOR 1
 #define SPDLOG_VER_MINOR 14
-#define SPDLOG_VER_PATCH 0
+#define SPDLOG_VER_PATCH 1
 
 #define SPDLOG_TO_VERSION(major, minor, patch) (major * 10000 + minor * 100 + patch)
 #define SPDLOG_VERSION SPDLOG_TO_VERSION(SPDLOG_VER_MAJOR, SPDLOG_VER_MINOR, SPDLOG_VER_PATCH)

tests/test_async.cpp

@@ -132,8 +132,8 @@ TEST_CASE("multithread flush", "[async]") {
     }
     REQUIRE(test_sink->flush_counter() >= 1);
     REQUIRE(test_sink->flush_counter() + errmsgs.size() == n_threads * flush_count);
-    if (errmsgs.size() > 0) { 
-        REQUIRE(errmsgs[0] == "Broken promise"); 
+    if (errmsgs.size() > 0) {
+        REQUIRE(errmsgs[0] == "Broken promise");
     }
 }
 

tests/test_create_dir.cpp

@@ -81,3 +81,64 @@ TEST_CASE("dir_name", "[create_dir]") {
     REQUIRE(dir_name(SPDLOG_FILENAME_T("../file.txt")) == SPDLOG_FILENAME_T(".."));
     REQUIRE(dir_name(SPDLOG_FILENAME_T("./file.txt")) == SPDLOG_FILENAME_T("."));
 }
+
+#ifdef _WIN32
+
+    //
+    // test windows cases when drive letter is given e.g. C:\\some-folder
+    //
+    #include <windows.h>
+    #include <fileapi.h>
+
+std::string get_full_path(const std::string &relative_folder_path) {
+    char full_path[MAX_PATH];
+
+    DWORD result = ::GetFullPathNameA(relative_folder_path.c_str(), MAX_PATH, full_path, nullptr);
+    // Return an empty string if failed to get full path
+    return result > 0 && result < MAX_PATH ? std::string(full_path) : std::string();
+}
+
+std::wstring get_full_path(const std::wstring &relative_folder_path) {
+    wchar_t full_path[MAX_PATH];
+    DWORD result = ::GetFullPathNameW(relative_folder_path.c_str(), MAX_PATH, full_path, nullptr);
+    return result > 0 && result < MAX_PATH ? std::wstring(full_path) : std::wstring();
+}
+
+spdlog::filename_t::value_type find_non_existing_drive() {
+    for (char drive = 'A'; drive <= 'Z'; ++drive) {
+        std::string root_path = std::string(1, drive) + ":\\";
+        UINT drive_type = GetDriveTypeA(root_path.c_str());
+        if (drive_type == DRIVE_NO_ROOT_DIR) {
+            return static_cast<spdlog::filename_t::value_type>(drive);
+        }
+    }
+    return '\0';  // No available drive found
+}
+
+TEST_CASE("create_abs_path1", "[create_dir]") {
+    prepare_logdir();
+    auto abs_path = get_full_path(SPDLOG_FILENAME_T("test_logs\\logdir1"));
+    REQUIRE(!abs_path.empty());
+    REQUIRE(create_dir(abs_path) == true);
+}
+
+TEST_CASE("create_abs_path2", "[create_dir]") {
+    prepare_logdir();
+    auto abs_path = get_full_path(SPDLOG_FILENAME_T("test_logs/logdir2"));
+    REQUIRE(!abs_path.empty());
+    REQUIRE(create_dir(abs_path) == true);
+}
+
+TEST_CASE("non_existing_drive", "[create_dir]") {
+    prepare_logdir();
+    spdlog::filename_t path;
+
+    auto non_existing_drive = find_non_existing_drive();
+    path += non_existing_drive;
+    path += SPDLOG_FILENAME_T(":\\");
+    REQUIRE(create_dir(path) == false);
+    path += SPDLOG_FILENAME_T("subdir");
+    REQUIRE(create_dir(path) == false);
+}
+// #endif  // SPDLOG_WCHAR_FILENAMES
+#endif  // _WIN32