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import datetime
import tldextract
from urllib.parse import urldefrag
import scrapy
from scrapy.crawler import CrawlerProcess
from scrapy.exceptions import NotSupported
from scrapy.linkextractors import LinkExtractor
from django.conf import settings
from django.db import transaction, IntegrityError
from django.utils import timezone
from . import models
"""
nb_facebook
nb_twitter
nb_instagram
nb_youtube
nb_dailymotion
nb_vimeo
nb_video
nb_audio
nb_internal_pdf
nb_external_pdf
nb_internal_office
nb_external_office
redirection
CrawlLink
"""
def clean_url(url):
url, __ = urldefrag(url) # remove anchors
return url
MAX_LINKS = None # if None no max
TIMEOUT = datetime.timedelta(minutes=settings.CRAWL_TIMEOUT)
class DefaultSpider:
name = None
start_urls = None
allowed_domains = []
excluded_domains = []
crawl_id = None
target_id = None
crawl_result = None
links_reached = set()
def start_requests(self):
q = {
"crawl_id": self.crawl_id,
"target_id": self.target_id,
"status__in": ["F", "T"],
}
if models.CrawlResult.objects.filter(**q).count():
return []
q.pop("status__in")
if models.CrawlResult.objects.filter(**q).count():
# delete a previous interrupted attempt
res = models.CrawlResult.objects.get(**q)
res.delete()
for url in self.start_urls:
yield scrapy.Request(url, self.parse)
def _parse_image(self, response, result):
if "images" not in result:
result["images"] = []
for img in response.css('img'):
attributes = img.attrib
if "src" not in attributes:
continue
src = attributes["src"]
is_a_real_src = src.startswith("http") or src.startswith("/")
if not src or not is_a_real_src or src in result["images"]:
continue
result["images"].append(src)
def timeout(self):
if not self.crawl_result:
q = {
"crawl_id": self.crawl_id,
"target_id": self.target_id,
}
if not models.CrawlResult.objects.filter(**q).count():
return
self.crawl_result = models.CrawlResult.objects.get(**q)
duration = timezone.now() - self.crawl_result.started
if duration < TIMEOUT:
return
with transaction.atomic():
result = models.CrawlResult.objects.select_for_update().get(
pk=self.crawl_result.pk)
result.status = "T"
result.save()
return True
def parse(self, response):
result = {
"url": response.url,
}
if self.timeout():
return []
for domain in self.excluded_domains:
if domain in response.url:
result["is_online"] = False
if result.get("is_online", None) is False:
yield result
else:
result["is_online"] = True
try:
self._parse_image(response, result)
for link in LinkExtractor().extract_links(response):
url = clean_url(link.url)
if url is None or url in self.links_reached:
continue
is_internal = False
for domain in self.allowed_domains:
if domain in url:
is_internal = True
self.links_reached.add(link.url)
if not MAX_LINKS or \
len(self.links_reached) < MAX_LINKS:
yield response.follow(link.url, self.parse)
else:
print("MAX", self.allowed_domains,
self.links_reached)
if not is_internal:
if "external_link" not in result:
result["external_link"] = []
result["external_link"].append(url)
except NotSupported:
print("No response", response.url)
yield result
def closed(self, reason):
DbPipeline().close(self)
class DbPipeline:
BASE_KEYS = ["url", "crawl_id", "target_id"]
NB_KEYS = ["external_link", "internal_link", "images",
"facebook", "twitter", "instagram", "youtube",
"dailymotion", "vimeo", "video", "audio",
"internal_pdf", "external_pdf", "internal_office",
"external_office"]
def _get_result_pk(self, spider):
"""
Atomic creation
:param spider: current spider
:return: result_pk, created
"""
pks = {
"crawl_id": spider.crawl_id,
"target_id": spider.target_id,
}
created = False
try:
result = models.CrawlResult.objects.get(**pks)
except models.CrawlResult.DoesNotExist:
try:
with transaction.atomic():
result = models.CrawlResult.objects.create(**pks)
created = True
except IntegrityError:
result = models.CrawlResult.objects.get(**pks)
return result.pk, created
def _update(self, result_pk, item, result_created):
"""
Atomic update
"""
with transaction.atomic():
result = models.CrawlResult.objects.select_for_update().get(
pk=result_pk)
crawl_result = result.crawl_result
if crawl_result:
crawl_result = crawl_result[0]
else:
crawl_result = {}
if "urls" not in crawl_result:
crawl_result["urls"] = []
url = item.pop("url")
if url in crawl_result["urls"]:
return
crawl_result["urls"].append(url)
result.nb_internal_links = len(crawl_result["urls"]) - 1
for k, value in item.items():
if k == "is_online":
if result_created: # only update on the first link
result.is_online = value
elif k in self.NB_KEYS:
if k not in crawl_result:
crawl_result[k] = []
for subvalue in value:
if subvalue in crawl_result[k]:
continue
crawl_result[k].append(subvalue)
setattr(result, "nb_" + k, len(crawl_result[k]))
result.crawl_result = [crawl_result]
result.save()
return True
def process_item(self, item, spider):
result_pk, created = self._get_result_pk(spider)
self._update(result_pk, item, created)
return item
def close(self, spider):
result_pk, created = self._get_result_pk(spider)
with transaction.atomic():
result = models.CrawlResult.objects.select_for_update().get(
pk=result_pk)
if result.status == "P":
result.status = "F"
result.duration = (timezone.now() - result.started)
result.save()
def get_domain(url):
ext = tldextract.extract(url)
return '{}.{}'.format(ext.domain, ext.suffix)
def create_spider(name, urls, crawl, target, excluded_domains=None):
if not excluded_domains:
excluded_domains = []
return type(
name, (DefaultSpider, scrapy.Spider),
{"name": name, "start_urls": urls,
"allowed_domains": [get_domain(url) for url in urls],
"crawl_id": crawl.pk, "target_id": target.pk, "links_reached": set(),
"excluded_domains": excluded_domains}
)
def launch_crawl(crawl_item, excluded_domains=None):
scrap_settings = settings.SCRAPPY_SETTINGS.copy()
process = CrawlerProcess(settings=scrap_settings)
for target in crawl_item.targets.all():
process.crawl(
create_spider(
"Crawl{}Target{}".format(crawl_item.pk, target.pk),
[target.url],
crawl_item, target,
excluded_domains
)
)
process.start()
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