AP_Logger: fixed LOG_FILE_DSRMROT with delayed log stop

now that we persist logging for 15s after disarm we need to also delay
the log rotation if LOG_FILE_DSRMROT=1. Otherwise we will put the log
data into the next log, which defeats the purpose of the 15s
persistance

libraries/AP_Logger/AP_Logger_File.cpp

@@ -129,6 +129,12 @@ bool AP_Logger_File::log_exists(const uint16_t lognum) const
 
 void AP_Logger_File::periodic_1Hz()
 {
+    if (_rotate_pending && !logging_enabled()) {
+        _rotate_pending = false;
+        // handle log rotation once we stop logging
+        stop_logging();
+    }
+
     if (!io_thread_alive()) {
         if (io_thread_warning_decimation_counter == 0 && _initialised) {
             // we don't print this error unless we did initialise. When _initialised is set to true
@@ -1077,7 +1083,7 @@ void AP_Logger_File::vehicle_was_disarmed()
         // rotate our log.  Closing the current one and letting the
         // logging restart naturally based on log_disarmed should do
         // the trick:
-        stop_logging();
+        _rotate_pending = true;
     }
 }
 

libraries/AP_Logger/AP_Logger_File.h

@@ -87,6 +87,9 @@ private:
 
     uint16_t _cached_oldest_log;
 
+    // should we rotate when we next stop logging
+    bool _rotate_pending;
+
     uint16_t _log_num_from_list_entry(const uint16_t list_entry);
 
     // possibly time-consuming preparations handling