Move source from 'buildstream' to 'src/buildstream'

This was discussed in #1008.

Fixes #1009.

1 files changed, 68 insertions, 0 deletions

diff --git a/src/buildstream/_cachekey.py b/src/buildstream/_cachekey.py
new file mode 100644
index 000000000..e56b582fa
--- /dev/null
+++ b/src/buildstream/_cachekey.py
@@ -0,0 +1,68 @@
+#
+#  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 ujson
+
+from . import _yaml
+
+# Internal record of the size of a cache key
+_CACHEKEY_SIZE = len(hashlib.sha256().hexdigest())
+
+
+# Hex digits
+_HEX_DIGITS = "0123456789abcdef"
+
+
+# is_key()
+#
+# Check if the passed in string *could be* a cache key.  This basically checks
+# that the length matches a sha256 hex digest, and that the string does not
+# contain any non-hex characters and is fully lower case.
+#
+# Args:
+#    key (str): The string to check
+#
+# Returns:
+#    (bool): Whether or not `key` could be a cache key
+#
+def is_key(key):
+    if len(key) != _CACHEKEY_SIZE:
+        return False
+    return not any(ch not in _HEX_DIGITS for ch in key)
+
+
+# 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)
+    ustring = ujson.dumps(ordered, sort_keys=True, escape_forward_slashes=False).encode('utf-8')
+    return hashlib.sha256(ustring).hexdigest()