On Wed, Nov 27, 2013, at 17:13, exarkun@twistedmatrix.com wrote:
On 02:58 pm, peter.westlake@pobox.com wrote: ... So would it be possible for
t.a.s.Service.startService to be allowed to return a Deferred? Then the next service would only be started up when the Deferred fired.
Probably not.
There is some discussion on <https://twistedmatrix.com/trac/ticket/5941>.
That's helpful, thanks. I hadn't realized that startService was called before the reactor started. Instead, I've passed in a Deferred to each service that needs to wait. How does this look? # -*- mode: python -*- from twisted.application import service from twisted.internet import defer, reactor from twisted.internet.task import deferLater application = service.Application('Dependencies') def report(error): print 'ERROR', error reactor.stop() class Runner(service.Service): def __init__(self, baton): self.baton = baton def startService(self): print 'startService', self.name, reactor.running self.baton.addCallback(lambda ignore:deferLater(reactor, 1.0, self.realStartService)) self.baton.addErrback(report) def realStartService(self): print 'realStartService', self.name, reactor.running baton = defer.succeed('pass me to each service') foo = Runner(baton) foo.setName('foo') foo.setServiceParent(application) bar = Runner(baton) bar.setName('bar') bar.setServiceParent(application) Peter.