bt2: make `_EventConst` a mapping

The `_EventConst` class already implemented the __getitem__() method
to make it easy to access a payload, specific context, common context,
or packet context field (in this order) by name, for example:

    print(event['next_prio'])

If two root fields contain fields which share the same name, one of them
has the priority and the other one is not accessible through this
interface.

This patch makes the `_EventConst` class a full mapping protocol,
inheriting `collections.abc.Mapping`. This patch implements the
__iter__() and __len__() methods so as to let `collections.abc.Mapping`
implement __contains__(), keys(), items(), values(), get(), __eq__(),
and __ne__(). Now you can do, for example:

    if 'next_prio' in event:
        print(event['next_prio'])

__iter__() keeps a set of yielded field names so as to avoid repeating
field names.

__len__() simply reuses __iter__().

`test_event.py` is updated to test the new features.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Change-Id: I2485e0df2373005fada0d0732c6269acbce5457c
Reviewed-on: https://review.lttng.org/c/babeltrace/+/3343
Tested-by: jenkins <jenkins@lttng.org>
Reviewed-by: Simon Marchi <simon.marchi@efficios.com>

diff --git a/src/bindings/python/bt2/bt2/event.py b/src/bindings/python/bt2/bt2/event.py
index 6a6c1185987517c8c930e32b0b545e19b0daf5a8..e7ac59abc162b92b4b5b7482f629f0bbf022f45c 100644 (file)
--- a/src/bindings/python/bt2/bt2/event.py
+++ b/src/bindings/python/bt2/bt2/event.py
@@ -25,9 +25,10 @@ from bt2 import event_class as bt2_event_class
 from bt2 import packet as bt2_packet
 from bt2 import stream as bt2_stream
 from bt2 import field as bt2_field
+import collections.abc
 
 
-class _EventConst(object._UniqueObject):
+class _EventConst(object._UniqueObject, collections.abc.Mapping):
     _borrow_class_ptr = staticmethod(native_bt.event_borrow_class_const)
     _borrow_packet_ptr = staticmethod(native_bt.event_borrow_packet_const)
     _borrow_stream_ptr = staticmethod(native_bt.event_borrow_stream_const)
@@ -131,6 +132,39 @@ class _EventConst(object._UniqueObject):
 
         raise KeyError(key)
 
+    def __iter__(self):
+        # To only yield unique keys, keep a set of member names that are
+        # already yielded. Two root structure fields (for example,
+        # payload and common context) can contain immediate members
+        # which share the same name.
+        member_names = set()
+
+        if self.payload_field is not None:
+            for field_name in self.payload_field:
+                yield field_name
+                member_names.add(field_name)
+
+        if self.specific_context_field is not None:
+            for field_name in self.specific_context_field:
+                if field_name not in member_names:
+                    yield field_name
+                    member_names.add(field_name)
+
+        if self.common_context_field is not None:
+            for field_name in self.common_context_field:
+                if field_name not in member_names:
+                    yield field_name
+                    member_names.add(field_name)
+
+        if self.packet and self.packet.context_field is not None:
+            for field_name in self.packet.context_field:
+                if field_name not in member_names:
+                    yield field_name
+                    member_names.add(field_name)
+
+    def __len__(self):
+        return sum(1 for _ in self)
+
 
 class _Event(_EventConst):
     _borrow_class_ptr = staticmethod(native_bt.event_borrow_class)

diff --git a/tests/bindings/python/bt2/test_event.py b/tests/bindings/python/bt2/test_event.py
index e8effef34535ea1cb55953db817a0a2803a1d56b..150074539661642a1b7b96bea8bae511198064ff 100644 (file)
--- a/tests/bindings/python/bt2/test_event.py
+++ b/tests/bindings/python/bt2/test_event.py
@@ -96,6 +96,7 @@ class EventTestCase(unittest.TestCase):
                     cc += [
                         ('cpu_id', tc.create_signed_integer_field_class(8)),
                         ('stuff', tc.create_double_precision_real_field_class()),
+                        ('gnu', tc.create_string_field_class()),
                     ]
 
                 # packet context (stream-class-defined)
@@ -192,6 +193,7 @@ class EventTestCase(unittest.TestCase):
         def event_fields_config(event):
             event.common_context_field['cpu_id'] = 1
             event.common_context_field['stuff'] = 13.194
+            event.common_context_field['gnu'] = 'salut'
 
         msg = self._create_test_const_event_message(
             event_fields_config=event_fields_config, with_cc=True
@@ -199,6 +201,7 @@ class EventTestCase(unittest.TestCase):
 
         self.assertEqual(msg.event.common_context_field['cpu_id'], 1)
         self.assertEqual(msg.event.common_context_field['stuff'], 13.194)
+        self.assertEqual(msg.event.common_context_field['gnu'], 'salut')
         self.assertIs(
             type(msg.event.common_context_field), bt2_field._StructureFieldConst
         )
@@ -287,23 +290,30 @@ class EventTestCase(unittest.TestCase):
         msg = utils.get_event_message()
         self.assertIs(type(msg.event.stream), bt2_stream._Stream)
 
-    def test_const_getitem(self):
-        def event_fields_config(event):
-            event.payload_field['giraffe'] = 1
-            event.payload_field['gnu'] = 23
-            event.payload_field['mosquito'] = 42
-            event.specific_context_field['ant'] = -1
-            event.specific_context_field['msg'] = 'hellooo'
-            event.common_context_field['cpu_id'] = 1
-            event.common_context_field['stuff'] = 13.194
-
-        def packet_fields_config(packet):
-            packet.context_field['something'] = 154
-            packet.context_field['something_else'] = 17.2
+    @staticmethod
+    def _event_payload_fields_config(event):
+        event.payload_field['giraffe'] = 1
+        event.payload_field['gnu'] = 23
+        event.payload_field['mosquito'] = 42
+
+    @staticmethod
+    def _event_fields_config(event):
+        EventTestCase._event_payload_fields_config(event)
+        event.specific_context_field['ant'] = -1
+        event.specific_context_field['msg'] = 'hellooo'
+        event.common_context_field['cpu_id'] = 1
+        event.common_context_field['stuff'] = 13.194
+        event.common_context_field['gnu'] = 'salut'
+
+    @staticmethod
+    def _packet_fields_config(packet):
+        packet.context_field['something'] = 154
+        packet.context_field['something_else'] = 17.2
 
+    def test_const_getitem(self):
         msg = self._create_test_const_event_message(
-            packet_fields_config=packet_fields_config,
-            event_fields_config=event_fields_config,
+            packet_fields_config=self._packet_fields_config,
+            event_fields_config=self._event_fields_config,
             with_cc=True,
             with_sc=True,
             with_ep=True,
@@ -332,13 +342,8 @@ class EventTestCase(unittest.TestCase):
             ev['yes']
 
     def test_const_getitem_no_packet(self):
-        def event_fields_config(event):
-            event.payload_field['giraffe'] = 1
-            event.payload_field['gnu'] = 23
-            event.payload_field['mosquito'] = 42
-
         msg = self._create_test_const_event_message(
-            event_fields_config=event_fields_config, with_ep=True,
+            event_fields_config=self._event_payload_fields_config, with_ep=True,
         )
         ev = msg.event
 
@@ -357,6 +362,110 @@ class EventTestCase(unittest.TestCase):
         self.assertEqual(ev['something'], 154)
         self.assertIs(type(ev['something']), bt2_field._UnsignedIntegerField)
 
+    def test_iter_full(self):
+        msg = self._create_test_const_event_message(
+            packet_fields_config=self._packet_fields_config,
+            event_fields_config=self._event_fields_config,
+            with_cc=True,
+            with_sc=True,
+            with_ep=True,
+            with_packet=True,
+        )
+        expected_field_names = [
+            # payload
+            'giraffe',
+            'gnu',
+            'mosquito',
+            # specific context
+            'ant',
+            'msg',
+            # common context
+            'cpu_id',
+            'stuff',
+            # packet context
+            'something',
+            'something_else',
+        ]
+        self.assertEqual(list(msg.event), expected_field_names)
+
+    def test_iter_payload_only(self):
+        msg = self._create_test_const_event_message(
+            event_fields_config=self._event_payload_fields_config, with_ep=True,
+        )
+        expected_field_names = [
+            # payload
+            'giraffe',
+            'gnu',
+            'mosquito',
+        ]
+        self.assertEqual(list(msg.event), expected_field_names)
+
+    def test_len_full(self):
+        msg = self._create_test_const_event_message(
+            packet_fields_config=self._packet_fields_config,
+            event_fields_config=self._event_fields_config,
+            with_cc=True,
+            with_sc=True,
+            with_ep=True,
+            with_packet=True,
+        )
+        self.assertEqual(len(msg.event), 9)
+
+    def test_len_payload_only(self):
+        msg = self._create_test_const_event_message(
+            packet_fields_config=None,
+            event_fields_config=self._event_payload_fields_config,
+            with_ep=True,
+        )
+        self.assertEqual(len(msg.event), 3)
+
+    def test_in_full(self):
+        msg = self._create_test_const_event_message(
+            packet_fields_config=self._packet_fields_config,
+            event_fields_config=self._event_fields_config,
+            with_cc=True,
+            with_sc=True,
+            with_ep=True,
+            with_packet=True,
+        )
+        field_names = [
+            # payload
+            'giraffe',
+            'gnu',
+            'mosquito',
+            # specific context
+            'ant',
+            'msg',
+            # common context
+            'cpu_id',
+            'stuff',
+            # packet context
+            'something',
+            'something_else',
+        ]
+
+        for field_name in field_names:
+            self.assertTrue(field_name in msg.event)
+
+        self.assertFalse('lol' in msg.event)
+
+    def test_in_payload_only(self):
+        msg = self._create_test_const_event_message(
+            packet_fields_config=None,
+            event_fields_config=self._event_payload_fields_config,
+            with_ep=True,
+        )
+        field_names = [
+            'giraffe',
+            'gnu',
+            'mosquito',
+        ]
+
+        for field_name in field_names:
+            self.assertTrue(field_name in msg.event)
+
+        self.assertFalse('lol' in msg.event)
+
 
 if __name__ == "__main__":
     unittest.main()