| from __future__ import absolute_import |
|
|
| import functools |
| import logging |
|
|
| log = logging.getLogger(__name__) |
|
|
|
|
| class Future(object): |
| error_on_callbacks = False |
|
|
| def __init__(self): |
| self.is_done = False |
| self.value = None |
| self.exception = None |
| self._callbacks = [] |
| self._errbacks = [] |
|
|
| def succeeded(self): |
| return self.is_done and not bool(self.exception) |
|
|
| def failed(self): |
| return self.is_done and bool(self.exception) |
|
|
| def retriable(self): |
| try: |
| return self.exception.retriable |
| except AttributeError: |
| return False |
|
|
| def success(self, value): |
| assert not self.is_done, 'Future is already complete' |
| self.value = value |
| self.is_done = True |
| if self._callbacks: |
| self._call_backs('callback', self._callbacks, self.value) |
| return self |
|
|
| def failure(self, e): |
| assert not self.is_done, 'Future is already complete' |
| self.exception = e if type(e) is not type else e() |
| assert isinstance(self.exception, BaseException), ( |
| 'future failed without an exception') |
| self.is_done = True |
| self._call_backs('errback', self._errbacks, self.exception) |
| return self |
|
|
| def add_callback(self, f, *args, **kwargs): |
| if args or kwargs: |
| f = functools.partial(f, *args, **kwargs) |
| if self.is_done and not self.exception: |
| self._call_backs('callback', [f], self.value) |
| else: |
| self._callbacks.append(f) |
| return self |
|
|
| def add_errback(self, f, *args, **kwargs): |
| if args or kwargs: |
| f = functools.partial(f, *args, **kwargs) |
| if self.is_done and self.exception: |
| self._call_backs('errback', [f], self.exception) |
| else: |
| self._errbacks.append(f) |
| return self |
|
|
| def add_both(self, f, *args, **kwargs): |
| self.add_callback(f, *args, **kwargs) |
| self.add_errback(f, *args, **kwargs) |
| return self |
|
|
| def chain(self, future): |
| self.add_callback(future.success) |
| self.add_errback(future.failure) |
| return self |
|
|
| def _call_backs(self, back_type, backs, value): |
| for f in backs: |
| try: |
| f(value) |
| except Exception as e: |
| log.exception('Error processing %s', back_type) |
| if self.error_on_callbacks: |
| raise e |
|
|
