CQ: don't preserve state between runs

commit-queue/commit_queue.py

 #!/usr/bin/env python
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 """Commit queue executable.
 
 Reuse Rietveld and the Chromium Try Server to process and automatically commit
 patches.
 """
 
@@ skipping 249 matching lines @@
         pc.context.checkout = FakeCheckout()
       else:
         print 'Using read-only checkout'
         pc.context.checkout = checkout.ReadOnlyCheckout(pc.context.checkout)
       # Save pushed events on disk.
       print 'Using read-only chromium-status interface'
       pc.context.status = async_push.AsyncPushStore()
 
     db_path = os.path.join(work_dir, pc.context.checkout.project_name + '.json')
     if os.path.isfile(db_path):
-      try:
-        pc.load(db_path)
-      except ValueError:
-        os.remove(db_path)
+      # Do not load state, and in fact remove it when seen. This will hopefully
+      # help avoid issues with CQ committing changes without verification.
+      os.remove(db_path)
 
     sig_handler.installHandlers(
         signal.SIGINT,
         signal.SIGHUP
     )
 
     # Sync every 5 minutes.
     SYNC_DELAY = 5*60
     try:
       if options.query_only:
         pc.look_for_new_pending_commit()
         pc.update_status()
         print(str(pc.queue))
         return 0
 
       now = time.time()
       next_loop = now + options.poll_interval
       # First sync is on second loop.
       next_sync = now + options.poll_interval * 2
       while True:
         # In theory, we would gain in performance to parallelize these tasks. In
         # practice I'm not sure it matters.
         pc.look_for_new_pending_commit()
         pc.process_new_pending_commit()
         pc.update_status()
         pc.scan_results()
         if sig_handler.getTriggeredSignals():
           raise KeyboardInterrupt()
-        # Save the db at each loop. The db can easily be in the 1mb range so
-        # it's slowing down the CQ a tad but it in the 100ms range even for that
-        # size.
-        pc.save(db_path)
+        # We'd save the state here but its suspected to cause CQ to land changes
+        # without verification.
 
         # More than a second to wait and due to sync.
         now = time.time()
         if (next_loop - now) >= 1 and (next_sync - now) <= 0:
           if sys.stdout.isatty():
             sys.stdout.write('Syncing while waiting                \r')
             sys.stdout.flush()
           try:
             pc.context.checkout.prepare(None)
           except subprocess2.CalledProcessError as e:
@@ skipping 14 matching lines @@
           if sys.stdout.isatty():
             sys.stdout.write('Sleeping for %1.1f seconds          \r' % delay)
             sys.stdout.flush()
           time.sleep(min(delay, 0.1))
           now = time.time()
         if sys.stdout.isatty():
           sys.stdout.write('Running (please do not interrupt)   \r')
           sys.stdout.flush()
         next_loop = time.time() + options.poll_interval
     finally:
-      print >> sys.stderr, 'Saving db...     '
-      pc.save(db_path)
+      # We'd save the state here but its suspected to cause CQ to land changes
+      # without verification.
       pc.close()
-      print >> sys.stderr, 'Done!            '
   except KeyboardInterrupt as e:
     print 'Bye bye'
     # 23 is an arbitrary value to signal loop.sh that it must stop looping.
     return 23
   except SystemExit as e:
     traceback.print_exc()
     print >> sys.stderr, ('Tried to exit: %s', e)
     return e.code
   except errors.ConfigurationError as e:
     parser.error(str(e))
     return 1
   return 0
 
 
 if __name__ == '__main__':
   fix_encoding.fix_encoding()
   sys.exit(main())