bitbake: bitbake: prserv: -wal and -shm sqlite lost when daemonizing

When daemonizing the PR service the -wal and -shm sqlite files were
being deleted, although they should never be. While the daemonized
process keeps the file descriptors open and thus a clean exit does
not loose any data, a power outage would loose all data in the WAL.
Removing these files also breaks sqlite collaboration between
processes and furthermore prevents taking proper backups without
stopping the PR service.

The reason this happens is that the DB connection is opened in
the initial process, before forking for daemonization. When the
DB connection is closed by the exiting parent processes it can
delete the -wal and -shm files if it considers itself to be the
last connection to the DB. This is easily fixed by opening the
DB connection after all forking.

[YOCTO #9034]

(Bitbake rev: bc867c81e3894da5bdd2e45fa695bb5f5f1bb58b)

Signed-off-by: Diego Santa Cruz <Diego.SantaCruz@spinetix.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/prserv/serv.py

@@ -62,9 +62,6 @@ class PRServer(SimpleXMLRPCServer):
         self.register_function(self.importone, "importone")
         self.register_introspection_functions()
 
-        self.db = prserv.db.PRData(self.dbfile)
-        self.table = self.db["PRMAIN"]
-
         self.requestqueue = Queue.Queue()
         self.handlerthread = threading.Thread(target = self.process_request_thread)
         self.handlerthread.daemon = False
@@ -100,10 +97,12 @@ class PRServer(SimpleXMLRPCServer):
             self.table.sync_if_dirty()
 
     def sigint_handler(self, signum, stack):
-        self.table.sync()
+        if self.table:
+            self.table.sync()
 
     def sigterm_handler(self, signum, stack):
-        self.table.sync()
+        if self.table:
+            self.table.sync()
         raise SystemExit
 
     def process_request(self, request, client_address):
@@ -145,6 +144,10 @@ class PRServer(SimpleXMLRPCServer):
 
         bb.utils.set_process_name("PRServ")
 
+        # DB connection must be created after all forks
+        self.db = prserv.db.PRData(self.dbfile)
+        self.table = self.db["PRMAIN"]
+
         logger.info("Started PRServer with DBfile: %s, IP: %s, PORT: %s, PID: %s" %
                      (self.dbfile, self.host, self.port, str(os.getpid())))