bt2: raise an exception if an AutoSourceComponentSpec produces no component

We don't do anything special at the moment if an AutoSourceComponentSpec
passed to TraceCollectionMessageIterator produces no component.  The
created graph will have no source component and the message iterator
will produce no message:

    In [5]: list(bt2.TraceCollectionMessageIterator('/yomadame'))
    08-12 14:43:03.938 20284 20284 W CLI-CFG-SRC-AUTO-DISC auto_discover_source_components@autodisc.c:755 No trace was found based on input `/yomadame`.
    Out[5]: []

This patch changes the behavior to be a bit more strict.  If any
AutoSourceComponentSpec passed to TraceCollectionMessageIterator ends up
producing no component, an exception is raised.  In the following example, the
directory `/home/smarchi/lttng-traces` does contain some valid traces, and
therefore produces some components, whereas the string `/yomadame` does not
produce any.

    In [2]: bt2.TraceCollectionMessageIterator(['/home/smarchi/lttng-traces', '/yomadame'])
    08-12 14:45:06.433 24428 24428 W CLI-CFG-SRC-AUTO-DISC auto_discover_source_components@autodisc.c:755 No trace was found based on input `/yomadame`.
    ---------------------------------------------------------------------------
    RuntimeError                              Traceback (most recent call last)
    <ipython-input-2-107461e1b36b> in <module>
    ----> 1 bt2.TraceCollectionMessageIterator(['/home/smarchi/lttng-traces', '/yomadame'])

    ~/build/babeltrace/src/bindings/python/bt2/build/build_lib/bt2/trace_collection_message_iterator.py in __init__(self, source_component_specs, filter_component_specs, stream_intersection_mode, begin, end, plugin_set)
        292         ]
        293         self._src_comp_specs += _auto_discover_source_component_specs(
    --> 294             auto_src_comp_specs, plugin_set
        295         )
        296

    ~/build/babeltrace/src/bindings/python/bt2/build/build_lib/bt2/trace_collection_message_iterator.py in _auto_discover_source_component_specs(auto_source_comp_specs, plugin_set)
        194
        195         msg = 'Some auto source component specs did not produce any component: ' + ', '.join(unused_inputs)
    --> 196         raise RuntimeError(msg)
        197
        198     return comp_specs

    RuntimeError: Some auto source component specs did not produce any component: /yomadame

Change-Id: I6c6df9fad18915e294559948812a8213596affdf
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1885
Tested-by: jenkins <jenkins@lttng.org>
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>

diff --git a/src/bindings/python/bt2/bt2/trace_collection_message_iterator.py b/src/bindings/python/bt2/bt2/trace_collection_message_iterator.py
index 56b48da9ff8061fe4a96e70870495ec711c313a2..3003c5f3730f8fdf9e3f4f6b7ba8a75a1e8cc9a2 100644 (file)
--- a/src/bindings/python/bt2/bt2/trace_collection_message_iterator.py
+++ b/src/bindings/python/bt2/bt2/trace_collection_message_iterator.py
@@ -130,6 +130,8 @@ def _auto_discover_source_component_specs(auto_source_comp_specs, plugin_set):
     comp_specs_raw = res['results']
     assert type(comp_specs_raw) == bt2.ArrayValue
 
+    used_input_indices = set()
+
     for comp_spec_raw in comp_specs_raw:
         assert type(comp_spec_raw) == bt2.ArrayValue
         assert len(comp_spec_raw) == 4
@@ -171,6 +173,8 @@ def _auto_discover_source_component_specs(auto_source_comp_specs, plugin_set):
             if orig_spec.obj is not AutoSourceComponentSpec._no_obj:
                 obj = orig_spec.obj
 
+            used_input_indices.add(int(idx))
+
         params['inputs'] = comp_inputs
 
         comp_specs.append(
@@ -183,6 +187,17 @@ def _auto_discover_source_component_specs(auto_source_comp_specs, plugin_set):
             )
         )
 
+    if len(used_input_indices) != len(inputs):
+        unused_input_indices = set(range(len(inputs))) - used_input_indices
+        unused_input_indices = sorted(unused_input_indices)
+        unused_inputs = [str(inputs[x]) for x in unused_input_indices]
+
+        msg = (
+            'Some auto source component specs did not produce any component: '
+            + ', '.join(unused_inputs)
+        )
+        raise RuntimeError(msg)
+
     return comp_specs
 
 

diff --git a/tests/bindings/python/bt2/test_trace_collection_message_iterator.py b/tests/bindings/python/bt2/test_trace_collection_message_iterator.py
index 22e12cdebe615d65651f3a5fe012d12cfbd88b14..162617080049f65558c2dbe752b3a092455512ac 100644 (file)
--- a/tests/bindings/python/bt2/test_trace_collection_message_iterator.py
+++ b/tests/bindings/python/bt2/test_trace_collection_message_iterator.py
@@ -215,6 +215,17 @@ class TraceCollectionMessageIteratorTestCase(unittest.TestCase):
         hist = _count_msgs_by_type(msgs)
         self.assertEqual(hist[bt2._EventMessage], 24)
 
+    def test_auto_source_component_non_existent(self):
+        with self.assertRaisesRegex(
+            RuntimeError,
+            'Some auto source component specs did not produce any component',
+        ):
+            # Test with one path known to contain a trace and one path known
+            # to not contain any trace.
+            bt2.TraceCollectionMessageIterator(
+                [_SEQUENCE_TRACE_PATH, '/this/path/better/not/exist']
+            )
+
 
 class _TestAutoDiscoverSourceComponentSpecs(unittest.TestCase):
     def setUp(self):
@@ -234,7 +245,6 @@ class TestAutoDiscoverSourceComponentSpecsGrouping(
         specs = [
             bt2.AutoSourceComponentSpec('ABCDE'),
             bt2.AutoSourceComponentSpec(_AUTO_SOURCE_DISCOVERY_GROUPING_PATH),
-            bt2.AutoSourceComponentSpec('does-not-exist'),
         ]
         it = bt2.TraceCollectionMessageIterator(specs)
         msgs = [x for x in it if type(x) is bt2._StreamBeginningMessage]