add file event handlers

include/spdlog/details/file_helper-inl.h

@@ -20,6 +20,10 @@
 namespace spdlog {
 namespace details {
 
+SPDLOG_INLINE file_helper::file_helper(const file_event_handlers_t& event_handlers)
+    : event_handlers_(event_handlers)
+{}
+
 SPDLOG_INLINE file_helper::~file_helper()
 {
     close();
@@ -52,6 +56,10 @@ SPDLOG_INLINE void file_helper::open(const filename_t &fname, bool truncate)
         }
         if (!os::fopen_s(&fd_, fname, mode))
         {
+            if (event_handlers_.after_open)
+            {
+                event_handlers_.after_open(filename_, fd_);
+            }
             return;
         }
 
@@ -79,8 +87,18 @@ SPDLOG_INLINE void file_helper::close()
 {
     if (fd_ != nullptr)
     {
+        if (event_handlers_.before_close)
+        {
+            event_handlers_.before_close(filename_, fd_);
+        }
+
         std::fclose(fd_);
         fd_ = nullptr;
+
+        if (event_handlers_.after_close)
+        {
+            event_handlers_.after_close(filename_);
+        }
     }
 }
 

include/spdlog/details/file_helper.h

@@ -16,7 +16,8 @@ namespace details {
 class SPDLOG_API file_helper
 {
 public:
-    explicit file_helper() = default;
+    file_helper() = default;
+    explicit file_helper(const file_event_handlers_t& event_handlers);
 
     file_helper(const file_helper &) = delete;
     file_helper &operator=(const file_helper &) = delete;
@@ -50,6 +51,7 @@ private:
     const unsigned int open_interval_ = 10;
     std::FILE *fd_{nullptr};
     filename_t filename_;
+    file_event_handlers_t event_handlers_{nullptr, nullptr, nullptr};
 };
 } // namespace details
 } // namespace spdlog