ref: minor speed-up for QueueCollectorThread

CHANGELOG

@@ -1,6 +1,7 @@
 0.25.1
  - ref: replace np.string_ with np.bytes_
  - ref: remove unused `data` argument to QueueCollectorThread
+ - ref: minor speed-up for QueueCollectorThread
 0.25.0
  - feat: identify flickering in raw data via dcnum.read.detect_flickering
  - fix: handle out-of-bounds slice indexing for BaseImageChunkCache

src/dcnum/write/queue_collector_thread.py

@@ -59,11 +59,10 @@ def add_events(self, index, events):
             Event dictionary
         """
         idx_loc = index - self.index_offset
-        idx_stop = self.nev_idx[idx_loc]
-        self._tracker[idx_loc] = True
 
         if events:
             slice_loc = None
+            idx_stop = self.nev_idx[idx_loc]
             for feat in events:
                 dev = events[feat]
                 if dev.size:
@@ -74,6 +73,8 @@ def add_events(self, index, events):
             if slice_loc:
                 self.indices_for_data[slice_loc] = index
 
+        self._tracker[idx_loc] = True
+
     def require_feature(self, feat, sample_data):
         """Create a new empty feature array in `self.events` and return it
 
@@ -85,10 +86,10 @@ def require_feature(self, feat, sample_data):
             Sample data for one event of the feature (used to determine
             shape and dtype of the feature array)
         """
-        sample_data = np.array(sample_data)
-        event_shape = sample_data.shape
-        dtype = sample_data.dtype
         if feat not in self.events:
+            sample_data = np.array(sample_data)
+            event_shape = sample_data.shape
+            dtype = sample_data.dtype
             darr = np.zeros((self.size,) + tuple(event_shape),
                             dtype=dtype)
             self.events[feat] = darr