workspace.py: add workspace source plugin

The `workspace.init_workspace()` call should wrap
`source._init_workspace` for held sources to support those sources not
publishing `BST_VIRTUAL_DIRECTORY`

This object owns a directory digest attribute used inplace of the source
ref.

1 files changed, 138 insertions, 0 deletions

diff --git a/src/buildstream/plugins/sources/workspace.py b/src/buildstream/plugins/sources/workspace.py
new file mode 100644
index 000000000..f696410e0
--- /dev/null
+++ b/src/buildstream/plugins/sources/workspace.py
@@ -0,0 +1,138 @@
+#
+#  Copyright (C) 2019 Bloomberg Finance LP
+#
+#  This program is free software; you can redistribute it and/or
+#  modify it under the terms of the GNU Lesser General Public
+#  License as published by the Free Software Foundation; either
+#  version 2 of the License, or (at your option) any later version.
+#
+#  This library is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+#  Lesser General Public License for more details.
+#
+#  You should have received a copy of the GNU Lesser General Public
+#  License along with this library. If not, see <http://www.gnu.org/licenses/>.
+
+"""
+:orphan:
+
+workspace - stage an opened workspace directory
+===============================================
+
+**Usage:**
+
+The workspace plugin must not be directly used. This plugin is used as the
+kind for a synthetic node representing the sources of an element with an open
+workspace. The node constructed would be specified as follows:
+
+.. code:: yaml
+
+   # Specify the workspace source kind
+   kind: workspace
+
+   # Specify the absolute path to the directory
+   path: /path/to/workspace
+"""
+
+import os
+from buildstream.storage.directory import Directory
+from buildstream import Source, SourceError, Consistency
+from buildstream import utils
+from buildstream.types import SourceRef
+
+
+class WorkspaceSource(Source):
+    # pylint: disable=attribute-defined-outside-init
+
+    BST_STAGE_VIRTUAL_DIRECTORY = True
+
+    def __init__(self, context, project, meta):
+        super().__init__(context, project, meta)
+
+        # Cached unique key to avoid multiple file system traversal if the unique key is requested multiple times.
+        self.__unique_key = None
+        self.__element_sources = []
+        self.__source_digest = None
+
+    def set_element_sources(self, _element_sources):
+        self.__element_sources = _element_sources
+
+    def get_element_sources(self):
+        return self.__element_sources
+
+    def track(self) -> SourceRef:
+        return self.__source_digest
+
+    def configure(self, node):
+        node.validate_keys(['path', 'ref', 'kind'])
+        self.path = node.get_str('path')
+        self.__source_digest = node.get_str('ref')
+
+    def preflight(self):
+        return
+
+    def get_ref(self) -> None:
+        return None
+
+    def load_ref(self, node) -> None:
+        pass  # pragma: nocover
+
+    def set_ref(self, ref, node) -> None:
+        pass  # pragma: nocover
+
+    def get_unique_key(self):
+        return (self.path, self.__source_digest)
+
+    def init_workspace(self, directory):
+        # for each source held by the workspace we must call init_workspace
+        # those sources may override `init_workspace` expecting str or Directory
+        # and this will need to be extracted from the directory passed to this method
+        assert isinstance(directory, Directory)
+        directory = directory.external_directory
+        for source in self.get_element_sources():
+            source._init_workspace(directory)
+
+    def get_consistency(self):
+        if self.__source_digest is None:
+            return Consistency.INCONSISTENT
+        return Consistency.RESOLVED
+
+    def fetch(self):
+        pass  # pragma: nocover
+
+    def stage(self, directory):
+        # directory should always be a Directory object
+        assert isinstance(directory, Directory)
+        with self.timed_activity("Staging local files into CAS"):
+            if os.path.isdir(self.path) and not os.path.islink(self.path):
+                result = directory.import_files(self.path)
+            else:
+                result = directory.import_single_file(self.path)
+
+            if result.overwritten or result.ignored:
+                raise SourceError(
+                    "Failed to stage source: files clash with existing directory",
+                    reason='ensure-stage-dir-fail')
+
+    def _get_local_path(self):
+        return self.path
+
+
+# Create a unique key for a file
+def unique_key(filename):
+
+    # Return some hard coded things for files which
+    # have no content to calculate a key for
+    if os.path.islink(filename):
+        # For a symbolic link, use the link target as its unique identifier
+        return os.readlink(filename)
+    elif os.path.isdir(filename):
+        return "0"
+
+    return utils.sha256sum(filename)
+
+
+# Plugin entry point
+def setup():
+    return WorkspaceSource