Add shrink_disk_usage for sqlite3 base queues

Performs a ``VACUUM`` against the sqlite, and rebuild the database file, this usually takes long time and frees a lot of disk space after `get()`

fixes #176

persistqueue/sqlackqueue.py

@@ -167,11 +167,6 @@ def clear_acked_data(
         )
         return sql, AckStatus.acked
 
-    @sqlbase.with_conditional_transaction
-    def shrink_disk_usage(self):
-        sql = """VACUUM"""
-        return sql, ()
-
     @property
     def _sql_mark_ack_status(self):
         return self._SQL_MARK_ACK_UPDATE.format(

persistqueue/sqlbase.py

@@ -212,6 +212,11 @@ def queue(self):
             datarows.append(item)
         return datarows
 
+    @with_conditional_transaction
+    def shrink_disk_usage(self):
+        sql = """VACUUM"""
+        return sql, ()
+
     @property
     def size(self):
         return self.total

persistqueue/tests/test_sqlackqueue.py

@@ -75,6 +75,7 @@ def test_open_close_1000(self):
         # assert adding another one still works
         q.put('foobar')
         data = q.get()
+        q.shrink_disk_usage()
         self.assertEqual('foobar', data)
 
     def test_random_read_write(self):

persistqueue/tests/test_sqlqueue.py

@@ -75,6 +75,7 @@ def test_open_close_1000(self):
         # assert adding another one still works
         q.put('foobar')
         data = q.get()
+        q.shrink_disk_usage()
         self.assertEqual('foobar', data)
 
     def test_random_read_write(self):