PYCBC-1771: txcouchbase: Cleanup ObservableRequestHandler context manager creation

Changes
--------
* Add `create_or_none()` static method on `ObservableRequestHandler`
  that will return the observability context manager if observability is
  enabled, otherwise will return None
* Removed `if instruments.is_noop:` branches in KV operations to use new
  `create_or_none()` path.

Change-Id: I9caaf90fb62229281d42e644bd76b0ea8af113ee
Reviewed-on: https://review.couchbase.org/c/couchbase-python-client/+/245025
Reviewed-by: Dimitris Christodoulou <dimitris.christodoulou@couchbase.com>
Tested-by: Build Bot <build@couchbase.com>

Author: thejcfactor

couchbase/logic/observability/handler.py

@@ -305,6 +305,16 @@ def create(op_type: OpType,
             return _NOOP_OBS_HANDLER_CTX
         return ObservableRequestHandler(op_type, observability_instruments, op_type_toggle=op_type_toggle)
 
+    @staticmethod
+    def create_or_none(op_type: OpType,
+                       observability_instruments: ObservabilityInstruments,
+                       op_type_toggle: Optional[bool] = None) -> Optional[ObservableRequestHandler]:
+        if observability_instruments.is_noop:
+            return None
+        handler = ObservableRequestHandler(op_type, observability_instruments, op_type_toggle=op_type_toggle)
+        handler.__enter__()
+        return handler
+
     @staticmethod
     def get_query_context_components(query_context: str,
                                      is_analytics: Optional[bool] = False) -> Optional[Tuple[str, str]]:

txcouchbase/binary_collection.py

@@ -46,20 +46,15 @@ def increment(
         **kwargs,  # type: Any
     ) -> Deferred[CounterResult]:
         instruments = self._impl.observability_instruments
-        if instruments.is_noop:
-            req = self._impl.request_builder.build_increment_request(key, None, *opts, **kwargs)
-            d = self._impl.increment_deferred(req, None)
-            d.addBoth(self._impl._finish_span, None)
-            return d
-        obs_handler = ObservableRequestHandler(KeyValueOperationType.Increment, instruments)
-        obs_handler.__enter__()
+        obs_handler = ObservableRequestHandler.create_or_none(KeyValueOperationType.Increment, instruments)
         try:
             req = self._impl.request_builder.build_increment_request(key, obs_handler, *opts, **kwargs)
             d = self._impl.increment_deferred(req, obs_handler)
             d.addBoth(self._impl._finish_span, obs_handler)
             return d
         except Exception as e:
-            obs_handler.__exit__(type(e), e, e.__traceback__)
+            if obs_handler is not None:
+                obs_handler.__exit__(type(e), e, e.__traceback__)
             raise
 
     def decrement(
@@ -69,20 +64,15 @@ def decrement(
         **kwargs,  # type: Any
     ) -> Deferred[CounterResult]:
         instruments = self._impl.observability_instruments
-        if instruments.is_noop:
-            req = self._impl.request_builder.build_decrement_request(key, None, *opts, **kwargs)
-            d = self._impl.decrement_deferred(req, None)
-            d.addBoth(self._impl._finish_span, None)
-            return d
-        obs_handler = ObservableRequestHandler(KeyValueOperationType.Decrement, instruments)
-        obs_handler.__enter__()
+        obs_handler = ObservableRequestHandler.create_or_none(KeyValueOperationType.Decrement, instruments)
         try:
             req = self._impl.request_builder.build_decrement_request(key, obs_handler, *opts, **kwargs)
             d = self._impl.decrement_deferred(req, obs_handler)
             d.addBoth(self._impl._finish_span, obs_handler)
             return d
         except Exception as e:
-            obs_handler.__exit__(type(e), e, e.__traceback__)
+            if obs_handler is not None:
+                obs_handler.__exit__(type(e), e, e.__traceback__)
             raise
 
     def append(
@@ -93,20 +83,15 @@ def append(
         **kwargs,  # type: Any
     ) -> Deferred[MutationResult]:
         instruments = self._impl.observability_instruments
-        if instruments.is_noop:
-            req = self._impl.request_builder.build_append_request(key, value, None, *opts, **kwargs)
-            d = self._impl.append_deferred(req, None)
-            d.addBoth(self._impl._finish_span, None)
-            return d
-        obs_handler = ObservableRequestHandler(KeyValueOperationType.Append, instruments)
-        obs_handler.__enter__()
+        obs_handler = ObservableRequestHandler.create_or_none(KeyValueOperationType.Append, instruments)
         try:
             req = self._impl.request_builder.build_append_request(key, value, obs_handler, *opts, **kwargs)
             d = self._impl.append_deferred(req, obs_handler)
             d.addBoth(self._impl._finish_span, obs_handler)
             return d
         except Exception as e:
-            obs_handler.__exit__(type(e), e, e.__traceback__)
+            if obs_handler is not None:
+                obs_handler.__exit__(type(e), e, e.__traceback__)
             raise
 
     def prepend(
@@ -117,18 +102,13 @@ def prepend(
         **kwargs,  # type: Any
     ) -> Deferred[MutationResult]:
         instruments = self._impl.observability_instruments
-        if instruments.is_noop:
-            req = self._impl.request_builder.build_prepend_request(key, value, None, *opts, **kwargs)
-            d = self._impl.prepend_deferred(req, None)
-            d.addBoth(self._impl._finish_span, None)
-            return d
-        obs_handler = ObservableRequestHandler(KeyValueOperationType.Prepend, instruments)
-        obs_handler.__enter__()
+        obs_handler = ObservableRequestHandler.create_or_none(KeyValueOperationType.Prepend, instruments)
         try:
             req = self._impl.request_builder.build_prepend_request(key, value, obs_handler, *opts, **kwargs)
             d = self._impl.prepend_deferred(req, obs_handler)
             d.addBoth(self._impl._finish_span, obs_handler)
             return d
         except Exception as e:
-            obs_handler.__exit__(type(e), e, e.__traceback__)
+            if obs_handler is not None:
+                obs_handler.__exit__(type(e), e, e.__traceback__)
             raise