| | 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 |
| |
|
