Execute vacuum command after cleaning up DB

After deleting rows from DB, database size on the disk
was still same, where it should be changed.
It is because vacuum was not executed [1]. With this
command, size will be changed.

[1] https://www.sqlite.org/lang_vacuum.html

Change-Id: I33cb868e66fe79f16f893ccf698cbd62a033d61b

logscraper/logscraper.py

@@ -284,6 +284,7 @@ class BuildCache:
 
         # clean builds that are older than 1 day
         self.clean()
+        self.vacuum()
 
         rows = self.fetch_data()
         if rows:
@@ -315,6 +316,10 @@ class BuildCache:
     def add(self, uid):
         self.builds[uid] = int(datetime.datetime.now().timestamp())
 
+    def vacuum(self):
+        self.cursor.execute("vacuum")
+        self.connection.commit()
+
     def clean(self):
         # Remove old builds
         yesterday = datetime.datetime.now() - datetime.timedelta(days=1)

logscraper/tests/test_logscraper.py

@@ -566,7 +566,7 @@ class TestBuildCache(base.TestCase):
         mock_execute = mock_connect.return_value.cursor.return_value.execute
         mock_execute.assert_called()
         self.assertEqual('SELECT uid, timestamp FROM logscraper',
-                         mock_execute.call_args_list[2].args[0])
+                         mock_execute.call_args_list[3].args[0])
 
     def test_clean(self):
         # add old data