Source code for scrapy.downloadermiddlewares.retry

"""
An extension to retry failed requests that are potentially caused by temporary
problems such as a connection timeout or HTTP 500 error.

You can change the behaviour of this middleware by modifying the scraping settings:
RETRY_TIMES - how many times to retry a failed page
RETRY_HTTP_CODES - which HTTP response codes to retry

Failed pages are collected on the scraping process and rescheduled at the end,
once the spider has finished crawling all regular (non failed) pages.
"""

from __future__ import annotations

import warnings
from logging import Logger, getLogger
from typing import TYPE_CHECKING, Any, Optional, Tuple, Type, Union

from scrapy.crawler import Crawler
from scrapy.exceptions import NotConfigured, ScrapyDeprecationWarning
from scrapy.http import Response
from scrapy.http.request import Request
from scrapy.settings import BaseSettings, Settings
from scrapy.spiders import Spider
from scrapy.utils.misc import load_object
from scrapy.utils.python import global_object_name
from scrapy.utils.response import response_status_message

if TYPE_CHECKING:
    # typing.Self requires Python 3.11
    from typing_extensions import Self

retry_logger = getLogger(__name__)


def backwards_compatibility_getattr(self: Any, name: str) -> Tuple[Any, ...]:
    if name == "EXCEPTIONS_TO_RETRY":
        warnings.warn(
            "Attribute RetryMiddleware.EXCEPTIONS_TO_RETRY is deprecated. "
            "Use the RETRY_EXCEPTIONS setting instead.",
            ScrapyDeprecationWarning,
            stacklevel=2,
        )
        return tuple(
            load_object(x) if isinstance(x, str) else x
            for x in Settings().getlist("RETRY_EXCEPTIONS")
        )
    raise AttributeError(
        f"{self.__class__.__name__!r} object has no attribute {name!r}"
    )


class BackwardsCompatibilityMetaclass(type):
    __getattr__ = backwards_compatibility_getattr


[docs]def get_retry_request( request: Request, *, spider: Spider, reason: Union[str, Exception, Type[Exception]] = "unspecified", max_retry_times: Optional[int] = None, priority_adjust: Optional[int] = None, logger: Logger = retry_logger, stats_base_key: str = "retry", ) -> Optional[Request]: """ Returns a new :class:`~scrapy.Request` object to retry the specified request, or ``None`` if retries of the specified request have been exhausted. For example, in a :class:`~scrapy.Spider` callback, you could use it as follows:: def parse(self, response): if not response.text: new_request_or_none = get_retry_request( response.request, spider=self, reason='empty', ) return new_request_or_none *spider* is the :class:`~scrapy.Spider` instance which is asking for the retry request. It is used to access the :ref:`settings <topics-settings>` and :ref:`stats <topics-stats>`, and to provide extra logging context (see :func:`logging.debug`). *reason* is a string or an :class:`Exception` object that indicates the reason why the request needs to be retried. It is used to name retry stats. *max_retry_times* is a number that determines the maximum number of times that *request* can be retried. If not specified or ``None``, the number is read from the :reqmeta:`max_retry_times` meta key of the request. If the :reqmeta:`max_retry_times` meta key is not defined or ``None``, the number is read from the :setting:`RETRY_TIMES` setting. *priority_adjust* is a number that determines how the priority of the new request changes in relation to *request*. If not specified, the number is read from the :setting:`RETRY_PRIORITY_ADJUST` setting. *logger* is the logging.Logger object to be used when logging messages *stats_base_key* is a string to be used as the base key for the retry-related job stats """ settings = spider.crawler.settings assert spider.crawler.stats stats = spider.crawler.stats retry_times = request.meta.get("retry_times", 0) + 1 if max_retry_times is None: max_retry_times = request.meta.get("max_retry_times") if max_retry_times is None: max_retry_times = settings.getint("RETRY_TIMES") if retry_times <= max_retry_times: logger.debug( "Retrying %(request)s (failed %(retry_times)d times): %(reason)s", {"request": request, "retry_times": retry_times, "reason": reason}, extra={"spider": spider}, ) new_request: Request = request.copy() new_request.meta["retry_times"] = retry_times new_request.dont_filter = True if priority_adjust is None: priority_adjust = settings.getint("RETRY_PRIORITY_ADJUST") new_request.priority = request.priority + priority_adjust if callable(reason): reason = reason() if isinstance(reason, Exception): reason = global_object_name(reason.__class__) stats.inc_value(f"{stats_base_key}/count") stats.inc_value(f"{stats_base_key}/reason_count/{reason}") return new_request stats.inc_value(f"{stats_base_key}/max_reached") logger.error( "Gave up retrying %(request)s (failed %(retry_times)d times): " "%(reason)s", {"request": request, "retry_times": retry_times, "reason": reason}, extra={"spider": spider}, ) return None
[docs]class RetryMiddleware(metaclass=BackwardsCompatibilityMetaclass): def __init__(self, settings: BaseSettings): if not settings.getbool("RETRY_ENABLED"): raise NotConfigured self.max_retry_times = settings.getint("RETRY_TIMES") self.retry_http_codes = {int(x) for x in settings.getlist("RETRY_HTTP_CODES")} self.priority_adjust = settings.getint("RETRY_PRIORITY_ADJUST") try: self.exceptions_to_retry = self.__getattribute__("EXCEPTIONS_TO_RETRY") except AttributeError: # If EXCEPTIONS_TO_RETRY is not "overridden" self.exceptions_to_retry = tuple( load_object(x) if isinstance(x, str) else x for x in settings.getlist("RETRY_EXCEPTIONS") ) @classmethod def from_crawler(cls, crawler: Crawler) -> Self: return cls(crawler.settings) def process_response( self, request: Request, response: Response, spider: Spider ) -> Union[Request, Response]: if request.meta.get("dont_retry", False): return response if response.status in self.retry_http_codes: reason = response_status_message(response.status) return self._retry(request, reason, spider) or response return response def process_exception( self, request: Request, exception: Exception, spider: Spider ) -> Union[Request, Response, None]: if isinstance(exception, self.exceptions_to_retry) and not request.meta.get( "dont_retry", False ): return self._retry(request, exception, spider) return None def _retry( self, request: Request, reason: Union[str, Exception, Type[Exception]], spider: Spider, ) -> Optional[Request]: max_retry_times = request.meta.get("max_retry_times", self.max_retry_times) priority_adjust = request.meta.get("priority_adjust", self.priority_adjust) return get_retry_request( request, reason=reason, spider=spider, max_retry_times=max_retry_times, priority_adjust=priority_adjust, ) __getattr__ = backwards_compatibility_getattr