Move utils._generate_key() into a new 'cachekey' module

This avoids a circular dependency between the 'utils' and '_yaml'
modules.

1 files changed, 43 insertions, 0 deletions

diff --git a/buildstream/_cachekey.py b/buildstream/_cachekey.py
new file mode 100644
index 000000000..3d0c19b44
--- /dev/null
+++ b/buildstream/_cachekey.py
@@ -0,0 +1,43 @@
+#!/usr/bin/env python3
+#
+#  Copyright (C) 2018 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>
+
+
+import hashlib
+import pickle
+
+from . import _yaml
+
+
+# generate_key()
+#
+# Generate an sha256 hex digest from the given value. The value
+# can be a simple value or recursive dictionary with lists etc,
+# anything simple enough to serialize.
+#
+# Args:
+#    value: A value to get a key for
+#
+# Returns:
+#    (str): An sha256 hex digest of the given value
+#
+def generate_key(value):
+    ordered = _yaml.node_sanitize(value)
+    string = pickle.dumps(ordered)
+    return hashlib.sha256(string).hexdigest()