comparison mercurial/dispatch.py @ 31956:c13ff31818b0

ui: add special-purpose atexit functionality

In spite of its longstanding use, Python's built-in atexit code is
not suitable for Mercurial's purposes, for several reasons:

* Handlers run after application code has finished.

* Because of this, the code that runs handlers swallows exceptions
  (since there's no possible stacktrace to associate errors with).
  If we're lucky, we'll get something spat out to stderr (if stderr
  still works), which of course isn't any use in a big deployment
  where it's important that exceptions get logged and aggregated.

* Mercurial's current atexit handlers make unfortunate assumptions
  about process state (specifically stdio) that, coupled with the
  above problems, make it impossible to deal with certain categories
  of error (try "hg status > /dev/full" on a Linux box).

* In Python 3, the atexit implementation is completely hidden, so
  we can't hijack the platform's atexit code to run handlers at a
  time of our choosing.

As a result, here's a perfectly cromulent atexit-like implementation
over which we have control.  This lets us decide exactly when the
handlers run (after each request has completed), and control what
the process state is when that occurs (and afterwards).

31955:4c2c30bc38b4

        # input/output/error streams
        self.fin = fin
        self.fout = fout
        self.ferr = ferr

def run():
    "run the command in sys.argv"
    sys.exit((dispatch(request(pycompat.sysargv[1:])) or 0) & 255)

def _getsimilar(symbols, value):

        if req.ui.logblockedtimes:
            req.ui._blockedtimes['command_duration'] = duration * 1000
            req.ui.log('uiblocked', 'ui blocked ms', **req.ui._blockedtimes)
        req.ui.log("commandfinish", "%s exited %s after %0.2f seconds\n",
                   msg, ret or 0, duration)
    return ret

def _runcatch(req):
    def catchterm(*args):
        raise error.SignalInterrupt

31956:c13ff31818b0

        # input/output/error streams
        self.fin = fin
        self.fout = fout
        self.ferr = ferr

    def _runexithandlers(self):
        exc = None
        handlers = self.ui._exithandlers
        try:
            while handlers:
                func, args, kwargs = handlers.pop()
                try:
                    func(*args, **kwargs)
                except: # re-raises below
                    if exc is None:
                        exc = sys.exc_info()[1]
                    self.ui.warn(('error in exit handlers:\n'))
                    self.ui.traceback(force=True)
        finally:
            if exc is not None:
                raise exc

def run():
    "run the command in sys.argv"
    sys.exit((dispatch(request(pycompat.sysargv[1:])) or 0) & 255)

def _getsimilar(symbols, value):

        if req.ui.logblockedtimes:
            req.ui._blockedtimes['command_duration'] = duration * 1000
            req.ui.log('uiblocked', 'ui blocked ms', **req.ui._blockedtimes)
        req.ui.log("commandfinish", "%s exited %s after %0.2f seconds\n",
                   msg, ret or 0, duration)
        try:
            req._runexithandlers()
        except: # exiting, so no re-raises
            ret = ret or -1
    return ret

def _runcatch(req):
    def catchterm(*args):
        raise error.SignalInterrupt