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from __future__ import with_statement
import os
from os.path import join, exists
from scrapy.utils.pqueue import PriorityQueue
from scrapy.utils.reqser import request_to_dict, request_from_dict
from scrapy.utils.misc import load_object
from scrapy.utils.job import job_dir
from scrapy.utils.py26 import json
from scrapy.stats import stats
from scrapy import log
class Scheduler(object):
def __init__(self, dupefilter, jobdir=None, dqclass=None, mqclass=None, logunser=False):
self.df = dupefilter
self.dqdir = self._dqdir(jobdir)
self.dqclass = dqclass
self.mqclass = mqclass
self.logunser = logunser
@classmethod
def from_settings(cls, settings):
dupefilter_cls = load_object(settings['DUPEFILTER_CLASS'])
dupefilter = dupefilter_cls.from_settings(settings)
dqclass = load_object(settings['SCHEDULER_DISK_QUEUE'])
mqclass = load_object(settings['SCHEDULER_MEMORY_QUEUE'])
logunser = settings.getbool('LOG_UNSERIALIZABLE_REQUESTS')
return cls(dupefilter, job_dir(settings), dqclass, mqclass, logunser)
def has_pending_requests(self):
return len(self) > 0
def open(self, spider):
self.spider = spider
self.mqs = PriorityQueue(self._newmq)
self.dqs = self._dq() if self.dqdir else None
return self.df.open()
def close(self, reason):
if self.dqs:
prios = self.dqs.close()
with open(join(self.dqdir, 'active.json'), 'w') as f:
json.dump(prios, f)
return self.df.close(reason)
def enqueue_request(self, request):
if not request.dont_filter and self.df.request_seen(request):
return
if not self._dqpush(request):
self._mqpush(request)
def next_request(self):
return self.mqs.pop() or self._dqpop()
def __len__(self):
return len(self.dqs) + len(self.mqs) if self.dqs else len(self.mqs)
def _dqpush(self, request):
if self.dqs is None:
return
try:
reqd = request_to_dict(request, self.spider)
self.dqs.push(reqd, -request.priority)
except ValueError, e: # non serializable request
if self.logunser:
log.msg("Unable to serialize request: %s - reason: %s" % \
(request, str(e)), level=log.ERROR, spider=self.spider)
return
else:
stats.inc_value('scheduler/disk_enqueued', spider=self.spider)
return True
def _mqpush(self, request):
stats.inc_value('scheduler/memory_enqueued', spider=self.spider)
self.mqs.push(request, -request.priority)
def _dqpop(self):
if self.dqs:
d = self.dqs.pop()
if d:
return request_from_dict(d, self.spider)
def _newmq(self, priority):
return self.mqclass()
def _newdq(self, priority):
return self.dqclass(join(self.dqdir, 'p%s' % priority))
def _dq(self):
activef = join(self.dqdir, 'active.json')
if exists(activef):
with open(activef) as f:
prios = json.load(f)
else:
prios = ()
q = PriorityQueue(self._newdq, startprios=prios)
if q:
log.msg("Resuming crawl (%d requests scheduled)" % len(q), \
spider=self.spider)
return q
def _dqdir(self, jobdir):
if jobdir:
dqdir = join(jobdir, 'requests.queue')
if not exists(dqdir):
os.makedirs(dqdir)
return dqdir
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