add JobUnselected event to the build verb (#326)

* add pre_execution callback

* add JobUnselected event and generate it in the build verb

* add coverage for callback argument

Author: dirk-thomas

colcon_core/event/job.py

@@ -2,6 +2,20 @@
 # Licensed under the Apache License, Version 2.0
 
 
+class JobUnselected:
+    """An event containing the identifier of the unselected job."""
+
+    __slots__ = ('identifier', )
+
+    def __init__(self, identifier):
+        """
+        Construct a JobUnselected.
+
+        :param str identifier: The job identifier
+        """
+        self.identifier = identifier
+
+
 class JobQueued:
     """An event containing the identifier of the queued job."""
 

colcon_core/executor/__init__.py

@@ -263,7 +263,8 @@ def add_executor_arguments(parser):
 
 
 def execute_jobs(
-    context, jobs, *, on_error: OnError = None, abort_on_error=None
+    context, jobs, *, on_error: OnError = None, abort_on_error=None,
+    pre_execution_callback=None
 ):
     """
     Execute jobs.
@@ -282,6 +283,9 @@ def execute_jobs(
     :param on_error: The decision how to proceed when one job fails
     :param abort_on_error: The flag if pending jobs should be aborted in case
       of individual jobs failing (deprecated, use `on_error` instead)
+    :param pre_execution_callback: An optional callable taking a keyword
+      argument `event_queue` which will be invoked before the executors
+      `execute()` method
     :returns: The return code
     """
     assert on_error is None or abort_on_error is None, \
@@ -304,6 +308,10 @@ def execute_jobs(
     with create_event_reactor(context) as event_controller:
         executor.set_event_controller(event_controller)
 
+        # allow the caller to post additional events
+        if pre_execution_callback is not None:
+            pre_execution_callback(event_queue=event_controller.get_queue())
+
         # pass queue to jobs to publish events
         for job in jobs.values():
             job.set_event_queue(event_controller.get_queue())

colcon_core/verb/build.py

@@ -8,6 +8,7 @@
 
 from colcon_core.argument_parser.destination_collector \
     import DestinationCollectorDecorator
+from colcon_core.event.job import JobUnselected
 from colcon_core.event_handler import add_event_handler_arguments
 from colcon_core.executor import add_executor_arguments
 from colcon_core.executor import execute_jobs
@@ -128,11 +129,22 @@ def main(self, *, context):  # noqa: D102
 
         install_base = os.path.abspath(os.path.join(
             os.getcwd(), context.args.install_base))
-        jobs = self._get_jobs(context.args, decorators, install_base)
+        jobs, unselected_packages = self._get_jobs(
+            context.args, decorators, install_base)
 
         on_error = OnError.interrupt \
             if not context.args.continue_on_error else OnError.skip_downstream
-        rc = execute_jobs(context, jobs, on_error=on_error)
+
+        def post_unselected_packages(*, event_queue):
+            nonlocal unselected_packages
+            names = [pkg.name for pkg in unselected_packages]
+            for name in sorted(names):
+                event_queue.put(
+                    (JobUnselected(name), None))
+
+        rc = execute_jobs(
+            context, jobs, on_error=on_error,
+            pre_execution_callback=post_unselected_packages)
 
         self._create_prefix_scripts(install_base, context.args.merge_install)
 
@@ -153,11 +165,14 @@ def _create_path(self, path):
 
     def _get_jobs(self, args, decorators, install_base):
         jobs = OrderedDict()
+        unselected_packages = set()
         for decorator in decorators:
+            pkg = decorator.descriptor
+
             if not decorator.selected:
+                unselected_packages.add(pkg)
                 continue
 
-            pkg = decorator.descriptor
             extension = get_task_extension('colcon_core.task.build', pkg.type)
             if not extension:
                 logger.warning(
@@ -192,7 +207,7 @@ def _get_jobs(self, args, decorators, install_base):
                 task=extension, task_context=task_context)
 
             jobs[pkg.name] = job
-        return jobs
+        return jobs, unselected_packages
 
     def _create_prefix_scripts(self, install_base, merge_install):
         extensions = get_shell_extensions()

test/test_executor.py

@@ -230,8 +230,12 @@ def test_execute_jobs():
             extensions = get_executor_extensions()
             extensions[110]['extension2'].execute = \
                 lambda args, jobs, on_error: 0
-            rc = execute_jobs(context, jobs, on_error=OnError.interrupt)
+            callback = Mock()
+            rc = execute_jobs(
+                context, jobs, on_error=OnError.interrupt,
+                pre_execution_callback=callback)
             assert rc == 0
             assert event_reactor.get_queue().put.call_count == 1
             assert isinstance(
                 event_reactor.get_queue().put.call_args[0][0][0], JobQueued)
+            assert callback.call_count == 1