Merge branch 'juerg/local-junctions' into 'master'

Optimization for local junctions

See merge request BuildStream/buildstream!290

3 files changed, 31 insertions, 5 deletions

diff --git a/buildstream/_loader/loader.py b/buildstream/_loader/loader.py
index 22600b9e9..a3c4ea8f0 100644
--- a/buildstream/_loader/loader.py
+++ b/buildstream/_loader/loader.py
@@ -563,17 +563,23 @@ class Loader():
                                 "Subproject has no ref for junction: {}".format(filename),
                                 detail=detail)
 
-        # Stage sources
-        os.makedirs(self._context.builddir, exist_ok=True)
-        basedir = tempfile.mkdtemp(prefix="{}-".format(element.normal_name), dir=self._context.builddir)
-        element._stage_sources_at(basedir, mount_workspaces=False)
+        if len(sources) == 1 and sources[0]._get_local_path():
+            # Optimization for junctions with a single local source
+            basedir = sources[0]._get_local_path()
+            tempdir = None
+        else:
+            # Stage sources
+            os.makedirs(self._context.builddir, exist_ok=True)
+            basedir = tempfile.mkdtemp(prefix="{}-".format(element.normal_name), dir=self._context.builddir)
+            element._stage_sources_at(basedir, mount_workspaces=False)
+            tempdir = basedir
 
         # Load the project
         project_dir = os.path.join(basedir, element.path)
         try:
             from .._project import Project
             project = Project(project_dir, self._context, junction=element,
-                              parent_loader=self, tempdir=basedir)
+                              parent_loader=self, tempdir=tempdir)
         except LoadError as e:
             if e.reason == LoadErrorReason.MISSING_PROJECT_CONF:
                 raise LoadError(reason=LoadErrorReason.INVALID_JUNCTION,
diff --git a/buildstream/plugins/sources/local.py b/buildstream/plugins/sources/local.py
index bbb42d06a..55cdc14d3 100644
--- a/buildstream/plugins/sources/local.py
+++ b/buildstream/plugins/sources/local.py
@@ -124,6 +124,9 @@ class LocalSource(Source):
                     else:
                         os.chmod(path, stat.S_IRUSR | stat.S_IWUSR | stat.S_IRGRP | stat.S_IROTH)
 
+    def _get_local_path(self):
+        return self.fullpath
+
 
 # Create a unique key for a file
 def unique_key(filename):
diff --git a/buildstream/source.py b/buildstream/source.py
index f346fdf83..d6681b963 100644
--- a/buildstream/source.py
+++ b/buildstream/source.py
@@ -616,6 +616,23 @@ class Source(Plugin):
             yield tempdir
 
     #############################################################
+    #       Private Abstract Methods used in BuildStream        #
+    #############################################################
+
+    # Returns the local path to the source
+    #
+    # If the source is locally available, this method returns the absolute
+    # path. Otherwise, the return value is None.
+    #
+    # This is an optimization for local sources and optional to implement.
+    #
+    # Returns:
+    #    (str): The local absolute path, or None
+    #
+    def _get_local_path(self):
+        return None
+
+    #############################################################
     #            Private Methods used in BuildStream            #
     #############################################################