1 files changed, 112 insertions, 0 deletions
diff --git a/client/src/leap/soledad/client/mp_safe_db.py b/client/src/leap/soledad/client/mp_safe_db.py
new file mode 100644
index 00000000..780b7153
--- /dev/null
+++ b/client/src/leap/soledad/client/mp_safe_db.py
@@ -0,0 +1,112 @@
+# -*- coding: utf-8 -*-
+# mp_safe_db.py
+# Copyright (C) 2014 LEAP
+#
+# This program 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.
+#
+# This program 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 this program. If not, see <http://www.gnu.org/licenses/>.
+
+
+"""
+Multiprocessing-safe SQLite database.
+"""
+
+
+from threading import Thread
+from Queue import Queue
+from pysqlcipher import dbapi2
+
+
+# Thanks to http://code.activestate.com/recipes/526618/
+
+class MPSafeSQLiteDB(Thread):
+    """
+    A multiprocessing-safe SQLite database accessor.
+    """
+
+    CLOSE = "--close--"
+    NO_MORE = "--no more--"
+
+    def __init__(self, db_path):
+        """
+        Initialize the process
+        """
+        Thread.__init__(self)
+        self._db_path = db_path
+        self._requests = Queue()
+        self.start()
+
+    def run(self):
+        """
+        Run the multiprocessing-safe database accessor.
+        """
+        conn = dbapi2.connect(self._db_path)
+        while True:
+            req, arg, res = self._requests.get()
+            if req == self.CLOSE:
+                break
+            with conn:
+                cursor = conn.cursor()
+                cursor.execute(req, arg)
+                if res:
+                    for rec in cursor.fetchall():
+                        res.put(rec)
+                    res.put(self.NO_MORE)
+        conn.close()
+
+    def execute(self, req, arg=None, res=None):
+        """
+        Execute a request on the database.
+
+        :param req: The request to be executed.
+        :type req: str
+        :param arg: The arguments for the request.
+        :type arg: tuple
+        :param res: A queue to write request results.
+        :type res: multiprocessing.Queue
+        """
+        self._requests.put((req, arg or tuple(), res))
+
+    def select(self, req, arg=None):
+        """
+        Run a select query on the database and yield results.
+
+        :param req: The request to be executed.
+        :type req: str
+        :param arg: The arguments for the request.
+        :type arg: tuple
+        """
+        res = Queue()
+        self.execute(req, arg, res)
+        while True:
+            rec=res.get()
+            if rec == self.NO_MORE:
+                break
+            yield rec
+
+    def close(self):
+        """
+        Close the database connection.
+        """
+        self.execute(self.CLOSE)
+        self.join()
+
+    def cursor(self):
+        """
+        Return a fake cursor object.
+
+        Not really a cursor, but allows for calling db.cursor().execute().
+
+        :return: Self.
+        :rtype: MPSafeSQLiteDatabase
+        """
+        return self