WIP RFC Avoid fetching or building artifacts unnecessarilytiagogomes/systems-build-time

This patch modifies morph to adopt the following behaviour:

    If the root artifact is a system and it is cached, don't fetch or
    build the system's stratum and chunk artifacts.

This will speed up building times if the system is cached, and will
enable having an archive of deployable old systems, without having to
keep around the system's chunk and stratum artifacts.

TODO: option to control this behavior.

Change-Id: I541cb375208e2091d271bcdc42f6d8a95ac977de

1 files changed, 14 insertions, 0 deletions

diff --git a/morphlib/buildcommand.py b/morphlib/buildcommand.py
index a0922165..82080b8c 100644
--- a/morphlib/buildcommand.py
+++ b/morphlib/buildcommand.py
@@ -283,8 +283,22 @@ class BuildCommand(object):
     def build_in_order(self, root_artifact):
         '''Build everything specified in a build order.'''
 
+        # If the root artifact is a system and it is cached, don't fetch
+        # or build the system's stratum and chunk artifacts
+        if root_artifact.source.morphology['kind'] == 'system':
+            if self.rac is not None:
+                try:
+                    self.cache_artifacts_locally([root_artifact])
+                except morphlib.remoteartifactcache.GetError:
+                    pass
+                else:
+                    return
+            if self.lac.has(root_artifact):
+                return
+
         self.app.status(msg='Starting build of %(name)s',
                         name=root_artifact.source.name)
+
         build_env = root_artifact.build_env
         ordered_sources = list(self.get_ordered_sources(root_artifact.walk()))
         old_prefix = self.app.status_prefix