app.py: Create stream before loading project

This is in preparation for moving subproject fetching to the Stream
class. Project loading may require subproject fetching as part of
processing include directives.

2 files changed, 39 insertions, 26 deletions

diff --git a/src/buildstream/_frontend/app.py b/src/buildstream/_frontend/app.py
index a9dd46b34..b55c743e2 100644
--- a/src/buildstream/_frontend/app.py
+++ b/src/buildstream/_frontend/app.py
@@ -216,33 +216,12 @@ class App():
         except BstError as e:
             self._error_exit(e, "Error instantiating artifact cache")
 
-        #
-        # Load the Project
-        #
-        try:
-            self.project = Project(directory, self.context, cli_options=self._main_options['option'],
-                                   default_mirror=self._main_options.get('default_mirror'))
-        except LoadError as e:
-
-            # Help users that are new to BuildStream by suggesting 'init'.
-            # We don't want to slow down users that just made a mistake, so
-            # don't stop them with an offer to create a project for them.
-            if e.reason == LoadErrorReason.MISSING_PROJECT_CONF:
-                click.echo("No project found. You can create a new project like so:", err=True)
-                click.echo("", err=True)
-                click.echo("    bst init", err=True)
-
-            self._error_exit(e, "Error loading project")
-
-        except BstError as e:
-            self._error_exit(e, "Error loading project")
-
         # Now that we have a logger and message handler,
         # we can override the global exception hook.
         sys.excepthook = self._global_exception_handler
 
         # Create the stream right away, we'll need to pass it around
-        self.stream = Stream(self.context, self.project, self._session_start,
+        self.stream = Stream(self.context, self._session_start,
                              session_start_callback=self.session_start_cb,
                              interrupt_callback=self._interrupt_handler,
                              ticker_callback=self._tick,
@@ -259,6 +238,29 @@ class App():
         if session_name:
             self._message(MessageType.START, session_name)
 
+        #
+        # Load the Project
+        #
+        try:
+            self.project = Project(directory, self.context, cli_options=self._main_options['option'],
+                                   default_mirror=self._main_options.get('default_mirror'))
+
+            self.stream.set_project(self.project)
+        except LoadError as e:
+
+            # Help users that are new to BuildStream by suggesting 'init'.
+            # We don't want to slow down users that just made a mistake, so
+            # don't stop them with an offer to create a project for them.
+            if e.reason == LoadErrorReason.MISSING_PROJECT_CONF:
+                click.echo("No project found. You can create a new project like so:", err=True)
+                click.echo("", err=True)
+                click.echo("    bst init", err=True)
+
+            self._error_exit(e, "Error loading project")
+
+        except BstError as e:
+            self._error_exit(e, "Error loading project")
+
         # Run the body of the session here, once everything is loaded
         try:
             yield
diff --git a/src/buildstream/_stream.py b/src/buildstream/_stream.py
index c5e056280..c9e847319 100644
--- a/src/buildstream/_stream.py
+++ b/src/buildstream/_stream.py
@@ -49,7 +49,6 @@ from . import Scope, Consistency
 #
 # Args:
 #    context (Context): The Context object
-#    project (Project): The Project object
 #    session_start (datetime): The time when the session started
 #    session_start_callback (callable): A callback to invoke when the session starts
 #    interrupt_callback (callable): A callback to invoke when we get interrupted
@@ -59,7 +58,7 @@ from . import Scope, Consistency
 #
 class Stream():
 
-    def __init__(self, context, project, session_start, *,
+    def __init__(self, context, session_start, *,
                  session_start_callback=None,
                  interrupt_callback=None,
                  ticker_callback=None,
@@ -80,8 +79,8 @@ class Stream():
         self._artifacts = context.artifactcache
         self._sourcecache = context.sourcecache
         self._context = context
-        self._project = project
-        self._pipeline = Pipeline(context, project, self._artifacts)
+        self._project = None
+        self._pipeline = None
         self._scheduler = Scheduler(context, session_start,
                                     interrupt_callback=interrupt_callback,
                                     ticker_callback=ticker_callback,
@@ -98,6 +97,18 @@ class Stream():
         if self._project:
             self._project.cleanup()
 
+    # set_project()
+    #
+    # Set the top-level project.
+    #
+    # Args:
+    #    project (Project): The Project object
+    #
+    def set_project(self, project):
+        assert self._project is None
+        self._project = project
+        self._pipeline = Pipeline(self._context, project, self._artifacts)
+
     # load_selection()
     #
     # An all purpose method for loading a selection of elements, this