added file switch as single operation

dap/accumulator.py

@@ -52,8 +52,7 @@ def accumulate(_accumulator_host, accumulator_port): #TODO: accumulator_host is
         if run_name != run_name_before:
             run_name_before = run_name
             fname_output = f"{OUTPUT_DIR_NAME}/{detector}/{run_name}.dap"
-            output_dap.close()
-            output_dap.open(fname_output)
+            output_dap.switch(fname_output)
 
         res_is_good_frame   = results.get("is_good_frame", -1)
         res_is_hit_frame    = results.get("is_hit_frame", False)
@@ -70,6 +69,10 @@ class FileHandler:
     def __init__(self):
         self.file = None
 
+    def switch(self, fname):
+        self.close()
+        self.open(fname)
+
     def open(self, fname):
         dname = os.path.dirname(fname)
         os.makedirs(dname, exist_ok=True)