mirror of https://github.com/scrapy/scrapy.git
81 lines
3.0 KiB
Python
81 lines
3.0 KiB
Python
import logging
|
|
import pprint
|
|
from collections import defaultdict, deque
|
|
from typing import Callable, Deque, Dict
|
|
|
|
from twisted.internet import defer
|
|
|
|
from scrapy import Spider
|
|
from scrapy.exceptions import NotConfigured
|
|
from scrapy.settings import Settings
|
|
from scrapy.utils.misc import create_instance, load_object
|
|
from scrapy.utils.defer import process_parallel, process_chain, process_chain_both
|
|
|
|
logger = logging.getLogger(__name__)
|
|
|
|
|
|
class MiddlewareManager:
|
|
"""Base class for implementing middleware managers"""
|
|
|
|
component_name = 'foo middleware'
|
|
|
|
def __init__(self, *middlewares):
|
|
self.middlewares = middlewares
|
|
self.methods: Dict[str, Deque[Callable]] = defaultdict(deque)
|
|
for mw in middlewares:
|
|
self._add_middleware(mw)
|
|
|
|
@classmethod
|
|
def _get_mwlist_from_settings(cls, settings: Settings) -> list:
|
|
raise NotImplementedError
|
|
|
|
@classmethod
|
|
def from_settings(cls, settings: Settings, crawler=None):
|
|
mwlist = cls._get_mwlist_from_settings(settings)
|
|
middlewares = []
|
|
enabled = []
|
|
for clspath in mwlist:
|
|
try:
|
|
mwcls = load_object(clspath)
|
|
mw = create_instance(mwcls, settings, crawler)
|
|
middlewares.append(mw)
|
|
enabled.append(clspath)
|
|
except NotConfigured as e:
|
|
if e.args:
|
|
clsname = clspath.split('.')[-1]
|
|
logger.warning("Disabled %(clsname)s: %(eargs)s",
|
|
{'clsname': clsname, 'eargs': e.args[0]},
|
|
extra={'crawler': crawler})
|
|
|
|
logger.info("Enabled %(componentname)ss:\n%(enabledlist)s",
|
|
{'componentname': cls.component_name,
|
|
'enabledlist': pprint.pformat(enabled)},
|
|
extra={'crawler': crawler})
|
|
return cls(*middlewares)
|
|
|
|
@classmethod
|
|
def from_crawler(cls, crawler):
|
|
return cls.from_settings(crawler.settings, crawler)
|
|
|
|
def _add_middleware(self, mw) -> None:
|
|
if hasattr(mw, 'open_spider'):
|
|
self.methods['open_spider'].append(mw.open_spider)
|
|
if hasattr(mw, 'close_spider'):
|
|
self.methods['close_spider'].appendleft(mw.close_spider)
|
|
|
|
def _process_parallel(self, methodname: str, obj, *args) -> defer.Deferred:
|
|
return process_parallel(self.methods[methodname], obj, *args)
|
|
|
|
def _process_chain(self, methodname: str, obj, *args) -> defer.Deferred:
|
|
return process_chain(self.methods[methodname], obj, *args)
|
|
|
|
def _process_chain_both(self, cb_methodname: str, eb_methodname: str, obj, *args) -> defer.Deferred:
|
|
return process_chain_both(self.methods[cb_methodname],
|
|
self.methods[eb_methodname], obj, *args)
|
|
|
|
def open_spider(self, spider: Spider) -> defer.Deferred:
|
|
return self._process_parallel('open_spider', spider)
|
|
|
|
def close_spider(self, spider: Spider) -> defer.Deferred:
|
|
return self._process_parallel('close_spider', spider)
|