1 files changed, 66 insertions, 0 deletions
diff --git a/src/buildstream/_scheduler/queues/pullqueue.py b/src/buildstream/_scheduler/queues/pullqueue.py
new file mode 100644
index 000000000..013ee6489
--- /dev/null
+++ b/src/buildstream/_scheduler/queues/pullqueue.py
@@ -0,0 +1,66 @@
+#
+#  Copyright (C) 2016 Codethink Limited
+#
+#  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/>.
+#
+#  Authors:
+#        Tristan Van Berkom <tristan.vanberkom@codethink.co.uk>
+#        Jürg Billeter <juerg.billeter@codethink.co.uk>
+
+# Local imports
+from . import Queue, QueueStatus
+from ..resources import ResourceType
+from ..jobs import JobStatus
+from ..._exceptions import SkipJob
+
+
+# A queue which pulls element artifacts
+#
+class PullQueue(Queue):
+
+    action_name = "Pull"
+    complete_name = "Pulled"
+    resources = [ResourceType.DOWNLOAD, ResourceType.CACHE]
+
+    def process(self, element):
+        # returns whether an artifact was downloaded or not
+        if not element._pull():
+            raise SkipJob(self.action_name)
+
+    def status(self, element):
+        if not element._is_required():
+            # Artifact is not currently required but it may be requested later.
+            # Keep it in the queue.
+            return QueueStatus.WAIT
+
+        if not element._can_query_cache():
+            return QueueStatus.WAIT
+
+        if element._pull_pending():
+            return QueueStatus.READY
+        else:
+            return QueueStatus.SKIP
+
+    def done(self, _, element, result, status):
+
+        if status == JobStatus.FAIL:
+            return
+
+        element._pull_done()
+
+        # Build jobs will check the "approximate" size first. Since we
+        # do not get an artifact size from pull jobs, we have to
+        # actually check the cache size.
+        if status == JobStatus.OK:
+            self._scheduler.check_cache_size()