/
scraper.py
259 lines (224 loc) · 10.5 KB
/
scraper.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
"""This module implements the Scraper component which parses responses and
extracts information from them"""
import logging
from collections import deque
from twisted.python.failure import Failure
from twisted.internet import defer
from scrapy.utils.defer import defer_result, defer_succeed, parallel, iter_errback
from scrapy.utils.spider import iterate_spider_output
from scrapy.utils.misc import load_object, warn_on_generator_with_return_value
from scrapy.utils.log import logformatter_adapter, failure_to_exc_info
from scrapy.exceptions import CloseSpider, DropItem, IgnoreRequest
from scrapy import signals
from scrapy.http import Request, Response
from scrapy.item import _BaseItem
from scrapy.core.spidermw import SpiderMiddlewareManager
logger = logging.getLogger(__name__)
class Slot:
"""Scraper slot (one per running spider)"""
MIN_RESPONSE_SIZE = 1024
def __init__(self, max_active_size=5000000):
self.max_active_size = max_active_size
self.queue = deque()
self.active = set()
self.active_size = 0
self.itemproc_size = 0
self.closing = None
def add_response_request(self, response, request):
deferred = defer.Deferred()
self.queue.append((response, request, deferred))
if isinstance(response, Response):
self.active_size += max(len(response.body), self.MIN_RESPONSE_SIZE)
else:
self.active_size += self.MIN_RESPONSE_SIZE
return deferred
def next_response_request_deferred(self):
response, request, deferred = self.queue.popleft()
self.active.add(request)
return response, request, deferred
def finish_response(self, response, request):
self.active.remove(request)
if isinstance(response, Response):
self.active_size -= max(len(response.body), self.MIN_RESPONSE_SIZE)
else:
self.active_size -= self.MIN_RESPONSE_SIZE
def is_idle(self):
return not (self.queue or self.active)
def needs_backout(self):
return self.active_size > self.max_active_size
class Scraper:
def __init__(self, crawler):
self.slot = None
self.spidermw = SpiderMiddlewareManager.from_crawler(crawler)
itemproc_cls = load_object(crawler.settings['ITEM_PROCESSOR'])
self.itemproc = itemproc_cls.from_crawler(crawler)
self.concurrent_items = crawler.settings.getint('CONCURRENT_ITEMS')
self.crawler = crawler
self.signals = crawler.signals
self.logformatter = crawler.logformatter
@defer.inlineCallbacks
def open_spider(self, spider):
"""Open the given spider for scraping and allocate resources for it"""
self.slot = Slot(self.crawler.settings.getint('SCRAPER_SLOT_MAX_ACTIVE_SIZE'))
yield self.itemproc.open_spider(spider)
def close_spider(self, spider):
"""Close a spider being scraped and release its resources"""
slot = self.slot
slot.closing = defer.Deferred()
slot.closing.addCallback(self.itemproc.close_spider)
self._check_if_closing(spider, slot)
return slot.closing
def is_idle(self):
"""Return True if there isn't any more spiders to process"""
return not self.slot
def _check_if_closing(self, spider, slot):
if slot.closing and slot.is_idle():
slot.closing.callback(spider)
def enqueue_scrape(self, response, request, spider):
slot = self.slot
dfd = slot.add_response_request(response, request)
def finish_scraping(_):
slot.finish_response(response, request)
self._check_if_closing(spider, slot)
self._scrape_next(spider, slot)
return _
dfd.addBoth(finish_scraping)
dfd.addErrback(
lambda f: logger.error('Scraper bug processing %(request)s',
{'request': request},
exc_info=failure_to_exc_info(f),
extra={'spider': spider}))
self._scrape_next(spider, slot)
return dfd
def _scrape_next(self, spider, slot):
while slot.queue:
response, request, deferred = slot.next_response_request_deferred()
self._scrape(response, request, spider).chainDeferred(deferred)
def _scrape(self, response, request, spider):
"""Handle the downloaded response or failure through the spider
callback/errback"""
if not isinstance(response, (Response, Failure)):
raise TypeError(
"Incorrect type: expected Response or Failure, got %s: %r"
% (type(response), response)
)
dfd = self._scrape2(response, request, spider) # returns spider's processed output
dfd.addErrback(self.handle_spider_error, request, response, spider)
dfd.addCallback(self.handle_spider_output, request, response, spider)
return dfd
def _scrape2(self, request_result, request, spider):
"""Handle the different cases of request's result been a Response or a
Failure"""
if not isinstance(request_result, Failure):
return self.spidermw.scrape_response(
self.call_spider, request_result, request, spider)
else:
dfd = self.call_spider(request_result, request, spider)
return dfd.addErrback(
self._log_download_errors, request_result, request, spider)
def call_spider(self, result, request, spider):
result.request = request
dfd = defer_result(result)
callback = request.callback or spider.parse
warn_on_generator_with_return_value(spider, callback)
warn_on_generator_with_return_value(spider, request.errback)
dfd.addCallbacks(callback=callback,
errback=request.errback,
callbackKeywords=request.cb_kwargs)
return dfd.addCallback(iterate_spider_output)
def handle_spider_error(self, _failure, request, response, spider):
exc = _failure.value
if isinstance(exc, CloseSpider):
self.crawler.engine.close_spider(spider, exc.reason or 'cancelled')
return
logkws = self.logformatter.spider_error(_failure, request, response, spider)
logger.log(
*logformatter_adapter(logkws),
exc_info=failure_to_exc_info(_failure),
extra={'spider': spider}
)
self.signals.send_catch_log(
signal=signals.spider_error,
failure=_failure, response=response,
spider=spider
)
self.crawler.stats.inc_value(
"spider_exceptions/%s" % _failure.value.__class__.__name__,
spider=spider
)
def handle_spider_output(self, result, request, response, spider):
if not result:
return defer_succeed(None)
it = iter_errback(result, self.handle_spider_error, request, response, spider)
dfd = parallel(it, self.concurrent_items, self._process_spidermw_output,
request, response, spider)
return dfd
def _process_spidermw_output(self, output, request, response, spider):
"""Process each Request/Item (given in the output parameter) returned
from the given spider
"""
if isinstance(output, Request):
self.crawler.engine.crawl(request=output, spider=spider)
elif isinstance(output, (_BaseItem, dict)):
self.slot.itemproc_size += 1
dfd = self.itemproc.process_item(output, spider)
dfd.addBoth(self._itemproc_finished, output, response, spider)
return dfd
elif output is None:
pass
else:
typename = type(output).__name__
logger.error('Spider must return Request, BaseItem, dict or None, '
'got %(typename)r in %(request)s',
{'request': request, 'typename': typename},
extra={'spider': spider})
def _log_download_errors(self, spider_failure, download_failure, request, spider):
"""Log and silence errors that come from the engine (typically download
errors that got propagated thru here)
"""
if isinstance(download_failure, Failure) and not download_failure.check(IgnoreRequest):
if download_failure.frames:
logkws = self.logformatter.download_error(download_failure, request, spider)
logger.log(
*logformatter_adapter(logkws),
extra={'spider': spider},
exc_info=failure_to_exc_info(download_failure),
)
else:
errmsg = download_failure.getErrorMessage()
if errmsg:
logkws = self.logformatter.download_error(
download_failure, request, spider, errmsg)
logger.log(
*logformatter_adapter(logkws),
extra={'spider': spider},
)
if spider_failure is not download_failure:
return spider_failure
def _itemproc_finished(self, output, item, response, spider):
"""ItemProcessor finished for the given ``item`` and returned ``output``
"""
self.slot.itemproc_size -= 1
if isinstance(output, Failure):
ex = output.value
if isinstance(ex, DropItem):
logkws = self.logformatter.dropped(item, ex, response, spider)
if logkws is not None:
logger.log(*logformatter_adapter(logkws), extra={'spider': spider})
return self.signals.send_catch_log_deferred(
signal=signals.item_dropped, item=item, response=response,
spider=spider, exception=output.value)
else:
logkws = self.logformatter.item_error(item, ex, response, spider)
logger.log(*logformatter_adapter(logkws), extra={'spider': spider},
exc_info=failure_to_exc_info(output))
return self.signals.send_catch_log_deferred(
signal=signals.item_error, item=item, response=response,
spider=spider, failure=output)
else:
logkws = self.logformatter.scraped(output, response, spider)
if logkws is not None:
logger.log(*logformatter_adapter(logkws), extra={'spider': spider})
return self.signals.send_catch_log_deferred(
signal=signals.item_scraped, item=output, response=response,
spider=spider)