AlkantarClanX12
Current Path : /proc/self/root/opt/alt/python35/lib64/python3.5/asyncio/__pycache__/ |
Current File : //proc/self/root/opt/alt/python35/lib64/python3.5/asyncio/__pycache__/futures.cpython-35.pyc |
��Yf�D � @ sN d Z d d d d d d g Z d d l Z d d l Z d d l Z d d l Z d d l Z d d l m Z d d l m Z d Z d Z d Z e j j j Z e j j Z e j j Z e j d Z Gd d � d e � Z Gd d � d � Z d d � Z Gd d � d � Z d d � Z d d � Z d d � Z d d � Z d d d d � Z d S)z.A Future class similar to the one in PEP 3148.�CancelledError�TimeoutError�InvalidStateError�Future�wrap_future�isfuture� N� )�compat)�eventsZPENDINGZ CANCELLEDZFINISHEDc @ s e Z d Z d Z d S)r z+The operation is not allowed in this state.N)�__name__� __module__�__qualname__�__doc__� r r �4/opt/alt/python35/lib64/python3.5/asyncio/futures.pyr s c @ sL e Z d Z d Z d Z d d � Z d d � Z d d � Z d d � Z d S)�_TracebackLoggera Helper to log a traceback upon destruction if not cleared. This solves a nasty problem with Futures and Tasks that have an exception set: if nobody asks for the exception, the exception is never logged. This violates the Zen of Python: 'Errors should never pass silently. Unless explicitly silenced.' However, we don't want to log the exception as soon as set_exception() is called: if the calling code is written properly, it will get the exception and handle it properly. But we *do* want to log it if result() or exception() was never called -- otherwise developers waste a lot of time wondering why their buggy code fails silently. An earlier attempt added a __del__() method to the Future class itself, but this backfired because the presence of __del__() prevents garbage collection from breaking cycles. A way out of this catch-22 is to avoid having a __del__() method on the Future class itself, but instead to have a reference to a helper object with a __del__() method that logs the traceback, where we ensure that the helper object doesn't participate in cycles, and only the Future has a reference to it. The helper object is added when set_exception() is called. When the Future is collected, and the helper is present, the helper object is also collected, and its __del__() method will log the traceback. When the Future's result() or exception() method is called (and a helper object is present), it removes the helper object, after calling its clear() method to prevent it from logging. One downside is that we do a fair amount of work to extract the traceback from the exception, even when it is never logged. It would seem cheaper to just store the exception object, but that references the traceback, which references stack frames, which may reference the Future, which references the _TracebackLogger, and then the _TracebackLogger would be included in a cycle, which is what we're trying to avoid! As an optimization, we don't immediately format the exception; we only do the work when activate() is called, which call is delayed until after all the Future's callbacks have run. Since usually a Future has at least one callback (typically set by 'yield from') and usually that callback extracts the callback, thereby removing the need to format the exception. PS. I don't claim credit for this solution. I first heard of it in a discussion about closing files when they are collected. �loop�source_traceback�exc�tbc C s. | j | _ | j | _ | | _ d | _ d S)N)�_loopr �_source_tracebackr r r )�self�futurer r r r �__init__U s z_TracebackLogger.__init__c C s@ | j } | d k r<