Do not count invalid attributes for dropped

CHANGELOG.md

@@ -8,6 +8,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - `opentelemetry-semantic-conventions` Update to semantic conventions v1.6.1
   ([#2077](https://github.com/open-telemetry/opentelemetry-python/pull/2077))
+- Do not count invalid attributes for dropped
+  ([#2096](https://github.com/open-telemetry/opentelemetry-python/pull/2096))
 - Fix propagation bug caused by counting skipped entries
   ([#2071](https://github.com/open-telemetry/opentelemetry-python/pull/2071))
 

opentelemetry-api/src/opentelemetry/attributes/__init__.py

@@ -172,14 +172,16 @@ def __setitem__(self, key, value):
                 self.dropped += 1
                 return
 
-            if key in self._dict:
-                del self._dict[key]
-            elif self.maxlen is not None and len(self._dict) == self.maxlen:
-                del self._dict[next(iter(self._dict.keys()))]
-                self.dropped += 1
-
             value = _clean_attribute(key, value, self.max_value_len)
             if value is not None:
+                if key in self._dict:
+                    del self._dict[key]
+                elif (
+                    self.maxlen is not None and len(self._dict) == self.maxlen
+                ):
+                    self._dict.popitem(last=False)
+                    self.dropped += 1
+
                 self._dict[key] = value
 
     def __delitem__(self, key):

opentelemetry-api/tests/attributes/test_attributes.py

@@ -137,6 +137,9 @@ def test_bounded_dict(self):
 
         self.assertEqual(len(bdict), dic_len)
         self.assertEqual(bdict.dropped, dic_len)
+        # Invalid values shouldn't be considered for `dropped`
+        bdict["invalid-seq"] = [None, 1, "2"]
+        self.assertEqual(bdict.dropped, dic_len)
 
         # test that elements in the dict are the new ones
         for key in self.base: