1 files changed, 109 insertions, 0 deletions
diff --git a/src/mailman/utilities/uid.py b/src/mailman/utilities/uid.py
new file mode 100644
index 000000000..3d58cace5
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+++ b/src/mailman/utilities/uid.py
@@ -0,0 +1,109 @@
+# Copyright (C) 2011 by the Free Software Foundation, Inc.
+#
+# This file is part of GNU Mailman.
+#
+# GNU Mailman is free software: you can redistribute it and/or modify it under
+# the terms of the GNU General Public License as published by the Free
+# Software Foundation, either version 3 of the License, or (at your option)
+# any later version.
+#
+# GNU Mailman 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 General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# GNU Mailman.  If not, see <http://www.gnu.org/licenses/>.
+
+"""Unique ID generation.
+
+Use these functions to create unique ids rather than inlining calls to hashlib
+and whatnot.  These are better instrumented for testing purposes.
+"""
+
+from __future__ import absolute_import, unicode_literals
+
+__metaclass__ = type
+__all__ = [
+    'UniqueIDFactory',
+    'factory',
+    ]
+
+
+import os
+import time
+import errno
+import hashlib
+
+from flufl.lock import Lock
+
+from mailman.config import config
+from mailman.testing import layers
+from mailman.utilities.passwords import SALT_LENGTH
+
+
+
+class UniqueIDFactory:
+    """A factory for unique ids."""
+
+    def __init__(self):
+        # We can't call reset() when the factory is created below, because
+        # config.VAR_DIR will not be set at that time.  So initialize it at
+        # the first use.
+        self._uid_file = None
+        self._lock_file = None
+        self._lockobj = None
+
+    @property
+    def _lock(self):
+        if self._lockobj is None:
+            # These will get automatically cleaned up by the test
+            # infrastructure.
+            self._uid_file = os.path.join(config.VAR_DIR, '.uid')
+            self._lock_file = self._uid_file + '.lock'
+            self._lockobj = Lock(self._lock_file)
+        return self._lockobj
+
+    def new_uid(self, bytes=None):
+        if layers.is_testing():
+            # When in testing mode we want to produce predictable id, but we
+            # need to coordinate this among separate processes.  We could use
+            # the database, but I don't want to add schema just to handle this
+            # case, and besides transactions could get aborted, causing some
+            # ids to be recycled.  So we'll use a data file with a lock.  This
+            # may still not be ideal due to race conditions, but I think the
+            # tests will be serialized enough (and the ids reset between
+            # tests) that it will not be a problem.  Maybe.
+            return self._next_uid()
+        salt = os.urandom(SALT_LENGTH)
+        h = hashlib.sha1(repr(time.time()))
+        h.update(salt)
+        if bytes is not None:
+            h.update(bytes)
+        return unicode(h.hexdigest(), 'us-ascii')
+
+    def _next_uid(self):
+        with self._lock:
+            try:
+                with open(self._uid_file) as fp:
+                    uid = fp.read().strip()
+                    next_uid = int(uid) + 1
+                with open(self._uid_file, 'w') as fp:
+                    fp.write(str(next_uid))
+            except IOError as error:
+                if error.errno != errno.ENOENT:
+                    raise
+                with open(self._uid_file, 'w') as fp:
+                    fp.write('2')
+                return '1'
+        return unicode(uid, 'us-ascii')
+
+    def reset(self):
+        with self._lock:
+            with open(self._uid_file, 'w') as fp:
+                fp.write('1')
+
+
+
+factory = UniqueIDFactory()
+layers.MockAndMonkeyLayer.register_reset(factory.reset)