add callback while rotate the log file

include/spdlog/common.h

@@ -255,6 +255,8 @@ struct source_loc
     const char *funcname{nullptr};
 };
 
+typedef void (*rotate_file_callback)(const filename_t& pre, const filename_t& next);
+
 namespace details {
 // make_unique support for pre c++14
 

include/spdlog/sinks/daily_file_sink.h

@@ -68,12 +68,13 @@ class daily_file_sink final : public base_sink<Mutex>
 {
 public:
     // create daily file sink which rotates on given time
-    daily_file_sink(filename_t base_filename, int rotation_hour, int rotation_minute, bool truncate = false, uint16_t max_files = 0)
+    daily_file_sink(filename_t base_filename, int rotation_hour, int rotation_minute, bool truncate = false, uint16_t max_files = 0, rotate_file_callback cb = nullptr)
         : base_filename_(std::move(base_filename))
         , rotation_h_(rotation_hour)
         , rotation_m_(rotation_minute)
         , truncate_(truncate)
         , max_files_(max_files)
+        , rotate_cb(cb)
         , filenames_q_()
     {
         if (rotation_hour < 0 || rotation_hour > 23 || rotation_minute < 0 || rotation_minute > 59)
@@ -106,6 +107,9 @@ protected:
         if (should_rotate)
         {
             auto filename = FileNameCalc::calc_filename(base_filename_, now_tm(time));
+            if (rotate_cb) {
+                rotate_cb(file_helper_.filename(), filename);
+            }
             file_helper_.open(filename, truncate_);
             rotation_tp_ = next_rotation_tp_();
         }
@@ -193,6 +197,7 @@ private:
     }
 
     filename_t base_filename_;
+    rotate_file_callback rotate_cb;
     int rotation_h_;
     int rotation_m_;
     log_clock::time_point rotation_tp_;

include/spdlog/sinks/hourly_file_sink.h

@@ -46,10 +46,11 @@ class hourly_file_sink final : public base_sink<Mutex>
 {
 public:
     // create hourly file sink which rotates on given time
-    hourly_file_sink(filename_t base_filename, bool truncate = false, uint16_t max_files = 0)
+    hourly_file_sink(filename_t base_filename, bool truncate = false, uint16_t max_files = 0, rotate_file_callback cb = nullptr)
         : base_filename_(std::move(base_filename))
         , truncate_(truncate)
         , max_files_(max_files)
+        , rotate_cb(cb)
         , filenames_q_()
     {
         auto now = log_clock::now();
@@ -77,6 +78,9 @@ protected:
         if (should_rotate)
         {
             auto filename = FileNameCalc::calc_filename(base_filename_, now_tm(time));
+            if (rotate_cb) {
+                rotate_cb(file_helper_.filename(), filename);
+            }
             file_helper_.open(filename, truncate_);
             rotation_tp_ = next_rotation_tp_();
         }
@@ -163,6 +167,7 @@ private:
     }
 
     filename_t base_filename_;
+    rotate_file_callback rotate_cb;
     log_clock::time_point rotation_tp_;
     details::file_helper file_helper_;
     bool truncate_;