Fix: bt2: fix reference counting of messages returned by Python components

[babeltrace.git] / src / bindings / python / bt2 / bt2 / message_iterator.py

diff --git a/src/bindings/python/bt2/bt2/message_iterator.py b/src/bindings/python/bt2/bt2/message_iterator.py
index 7f996b007e1ec8353fb3537fd45d0fdd80823c66..b07e2450afc97b46f7b5e46c1198d6f07aeb2853 100644 (file)
--- a/src/bindings/python/bt2/bt2/message_iterator.py
+++ b/src/bindings/python/bt2/bt2/message_iterator.py
@@ -131,34 +131,27 @@ class _UserMessageIterator(_MessageIterator):
 
         utils._check_type(msg, bt2.message._Message)
 
-        # Release the reference to the native part.
-        ptr = msg._release()
-        return int(ptr)
-
-    # Validate that the presence or lack of presence of a
-    # `default_clock_snapshot` value is valid in the context of `stream_class`.
-    @staticmethod
-    def _validate_default_clock_snapshot(stream_class, default_clock_snapshot):
-        stream_class_has_default_clock_class = stream_class.default_clock_class is not None
-
-        if stream_class_has_default_clock_class and default_clock_snapshot is None:
-            raise bt2.Error(
-                'stream class has a default clock class, default_clock_snapshot should not be None')
-
-        if not stream_class_has_default_clock_class and default_clock_snapshot is not None:
-            raise bt2.Error(
-                'stream class has no default clock class, default_clock_snapshot should be None')
+        # The reference we return will be given to the message array.
+        # However, the `msg` Python object may stay alive, if the user has kept
+        # a reference to it.  Acquire a new reference to account for that.
+        msg._get_ref(msg._ptr)
+        return int(msg._ptr)
 
     def _create_event_message(self, event_class, packet, default_clock_snapshot=None):
         utils._check_type(event_class, bt2.event_class._EventClass)
         utils._check_type(packet, bt2.packet._Packet)
-        self._validate_default_clock_snapshot(packet.stream.cls, default_clock_snapshot)
 
         if default_clock_snapshot is not None:
+            if event_class.stream_class.default_clock_class is None:
+                raise ValueError('event messages in this stream must not have a default clock snapshot')
+
             utils._check_uint64(default_clock_snapshot)
             ptr = native_bt.message_event_create_with_default_clock_snapshot(
                 self._ptr, event_class._ptr, packet._ptr, default_clock_snapshot)
         else:
+            if event_class.stream_class.default_clock_class is not None:
+                raise ValueError('event messages in this stream must have a default clock snapshot')
+
             ptr = native_bt.message_event_create(
                 self._ptr, event_class._ptr, packet._ptr)
 
@@ -177,6 +170,26 @@ class _UserMessageIterator(_MessageIterator):
 
         return bt2.message._MessageIteratorInactivityMessage(ptr)
 
+    _unknown_clock_snapshot = bt2.message._StreamActivityMessageUnknownClockSnapshot()
+    _infinite_clock_snapshot = bt2.message._StreamActivityMessageInfiniteClockSnapshot()
+
+    @staticmethod
+    def _validate_stream_activity_message_default_clock_snapshot(stream, default_cs):
+        isinst_infinite = isinstance(default_cs, bt2.message._StreamActivityMessageInfiniteClockSnapshot)
+        isinst_unknown = isinstance(default_cs, bt2.message._StreamActivityMessageUnknownClockSnapshot)
+
+        if utils._is_uint64(default_cs):
+            pass
+        elif isinst_infinite or isinst_unknown:
+            if default_cs is not _UserMessageIterator._unknown_clock_snapshot and default_cs is not _UserMessageIterator._infinite_clock_snapshot:
+                raise ValueError('unexpected value for default clock snapshot')
+        else:
+            raise TypeError("unexpected type '{}' for default clock snapshot".format(default_cs.__class__.__name__))
+
+        if stream.cls.default_clock_class is None:
+            if utils._is_uint64(default_cs):
+                raise ValueError('stream activity messages in this stream cannot have a known default clock snapshot')
+
     def _create_stream_beginning_message(self, stream):
         utils._check_type(stream, bt2.stream._Stream)
 
@@ -186,10 +199,10 @@ class _UserMessageIterator(_MessageIterator):
 
         return bt2.message._StreamBeginningMessage(ptr)
 
-    def _create_stream_activity_beginning_message(self, stream, default_clock_snapshot=None):
+    def _create_stream_activity_beginning_message(self, stream,
+                                                  default_clock_snapshot=_unknown_clock_snapshot):
         utils._check_type(stream, bt2.stream._Stream)
-        self._validate_default_clock_snapshot(stream.cls, default_clock_snapshot)
-
+        self._validate_stream_activity_message_default_clock_snapshot(stream, default_clock_snapshot)
         ptr = native_bt.message_stream_activity_beginning_create(self._ptr, stream._ptr)
 
         if ptr is None:
@@ -197,16 +210,13 @@ class _UserMessageIterator(_MessageIterator):
                 'cannot create stream activity beginning message object')
 
         msg = bt2.message._StreamActivityBeginningMessage(ptr)
-
-        if default_clock_snapshot is not None:
-            msg._default_clock_snapshot = default_clock_snapshot
-
+        msg._default_clock_snapshot = default_clock_snapshot
         return msg
 
-    def _create_stream_activity_end_message(self, stream, default_clock_snapshot=None):
+    def _create_stream_activity_end_message(self, stream,
+                                            default_clock_snapshot=_unknown_clock_snapshot):
         utils._check_type(stream, bt2.stream._Stream)
-        self._validate_default_clock_snapshot(stream.cls, default_clock_snapshot)
-
+        self._validate_stream_activity_message_default_clock_snapshot(stream, default_clock_snapshot)
         ptr = native_bt.message_stream_activity_end_create(self._ptr, stream._ptr)
 
         if ptr is None:
@@ -214,10 +224,7 @@ class _UserMessageIterator(_MessageIterator):
                 'cannot create stream activity end message object')
 
         msg = bt2.message._StreamActivityEndMessage(ptr)
-
-        if default_clock_snapshot is not None:
-            msg._default_clock_snapshot = default_clock_snapshot
-
+        msg._default_clock_snapshot = default_clock_snapshot
         return msg
 
     def _create_stream_end_message(self, stream):
@@ -234,14 +241,14 @@ class _UserMessageIterator(_MessageIterator):
 
         if packet.stream.cls.packets_have_beginning_default_clock_snapshot:
             if default_clock_snapshot is None:
-                raise ValueError("packet beginning messages in this stream must have a default clock snapshots")
+                raise ValueError("packet beginning messages in this stream must have a default clock snapshot")
 
             utils._check_uint64(default_clock_snapshot)
             ptr = native_bt.message_packet_beginning_create_with_default_clock_snapshot(
                 self._ptr, packet._ptr, default_clock_snapshot)
         else:
             if default_clock_snapshot is not None:
-                raise ValueError("packet beginning messages in this stream must not have a default clock snapshots")
+                raise ValueError("packet beginning messages in this stream must not have a default clock snapshot")
 
             ptr = native_bt.message_packet_beginning_create(self._ptr, packet._ptr)
 
@@ -255,14 +262,14 @@ class _UserMessageIterator(_MessageIterator):
 
         if packet.stream.cls.packets_have_end_default_clock_snapshot:
             if default_clock_snapshot is None:
-                raise ValueError("packet end messages in this stream must have a default clock snapshots")
+                raise ValueError("packet end messages in this stream must have a default clock snapshot")
 
             utils._check_uint64(default_clock_snapshot)
             ptr = native_bt.message_packet_end_create_with_default_clock_snapshot(
                 self._ptr, packet._ptr, default_clock_snapshot)
         else:
             if default_clock_snapshot is not None:
-                raise ValueError("packet end messages in this stream must not have a default clock snapshots")
+                raise ValueError("packet end messages in this stream must not have a default clock snapshot")
 
             ptr = native_bt.message_packet_end_create(self._ptr, packet._ptr)