bitbake: prserv: enable database sharing

sqlite3 can allow multiple processes to access the database
simultaneously, but it must be opened correctly. The key change is that
the database is no longer opened in "exclusive" mode (defaulting to
shared mode). In addition, the journal is set to "WAL" mode, as this is
the most efficient for dealing with simultaneous access between
different processes. In order to keep the database performance,
synchronous mode is set to "off". The WAL journal will protect against
incomplete transactions in any given client, however the database will
not be protected against unexpected power loss from the OS (which is a
fine trade off for performance, and also the same as the previous
implementation).

The use of a database cursor enabled to remove the _execute() wrapper.
The cursor automatically makes sure that the query happens in an atomic
transaction and commits when finished.

This also removes the need for a "dirty" flag for the database and
for explicit database syncing, which simplifies the code.

(Bitbake rev: 385833243c495dc68ec26a963136c1ced3f272d0)

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
Cc: Tim Orling <ticotimo@gmail.com>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/prserv/serv.py

@@ -42,10 +42,7 @@ class PRServerClient(bb.asyncrpc.AsyncServerConnection):
         try:
             return await super().dispatch_message(msg)
         except:
-            self.server.table.sync()
             raise
-        else:
-            self.server.table.sync_if_dirty()
 
     async def handle_test_pr(self, request):
         '''Finds the PR value corresponding to the request. If not found, returns None and doesn't insert a new value'''
@@ -233,15 +230,9 @@ class PRServer(bb.asyncrpc.AsyncServer):
         return tasks
 
     async def stop(self):
-        self.table.sync_if_dirty()
         self.db.disconnect()
         await super().stop()
 
-    def signal_handler(self):
-        super().signal_handler()
-        if self.table:
-            self.table.sync()
-
 class PRServSingleton(object):
     def __init__(self, dbfile, logfile, host, port, upstream):
         self.dbfile = dbfile