class FronteraScheduler(Scheduler):
def __init__(self, crawler, manager=None):
self.crawler = crawler
self.stats_manager = StatsManager(crawler.stats)
self._pending_requests = deque()
self.redirect_enabled = crawler.settings.get("REDIRECT_ENABLED")
settings = ScrapySettingsAdapter(crawler.settings)
self.frontier = ScrapyFrontierManager(settings, manager)
self._delay_on_empty = self.frontier.manager.settings.get("DELAY_ON_EMPTY")
self._delay_next_call = 0.0
self.logger = getLogger("frontera.contrib.scrapy.schedulers.FronteraScheduler")
@classmethod
def from_crawler(cls, crawler):
return cls(crawler)
def enqueue_request(self, request):
if not self._request_is_redirected(request):
self.frontier.add_seeds([request])
self.stats_manager.add_seeds()
return True
elif self.redirect_enabled:
self._add_pending_request(request)
self.stats_manager.add_redirected_requests()
return True
return False
def next_request(self):
request = self._get_next_request()
if request:
self.stats_manager.add_returned_requests()
return request
def process_spider_output(self, response, result, spider):
links = []
for element in result:
if isinstance(element, Request):
links.append(element)
else:
yield element
frontier_request = response.meta[b"frontier_request"]
self.frontier.page_crawled(response) # removed frontier part from .meta
# putting it back, to persist .meta from original request
response.meta[b"frontier_request"] = frontier_request
self.frontier.links_extracted(response.request, links)
self.stats_manager.add_crawled_page(response.status, len(links))
def process_exception(self, request, exception, spider):
error_code = self._get_exception_code(exception)
self.frontier.request_error(request=request, error=error_code)
self.stats_manager.add_request_error(error_code)
def open(self, spider):
self.frontier.set_spider(spider)
self.logger.info("Starting frontier")
if not self.frontier.manager.auto_start:
self.frontier.start()
def close(self, reason):
self.logger.info("Finishing frontier (%s)", reason)
self.frontier.stop()
self.stats_manager.set_iterations(self.frontier.manager.iteration)
self.stats_manager.set_pending_requests(len(self))
def __len__(self):
return len(self._pending_requests)
def has_pending_requests(self):
return not self.frontier.finished()
def _get_next_request(self):
if (
not self.frontier.manager.finished
and len(self) < self.crawler.engine.downloader.total_concurrency
and self._delay_next_call < time()
):
info = self._get_downloader_info()
requests = self.frontier.get_next_requests(key_type=info["key_type"], overused_keys=info["overused_keys"])
for request in requests:
self._add_pending_request(request)
self._delay_next_call = time() + self._delay_on_empty if not requests else 0.0
return self._get_pending_request()
def _add_pending_request(self, request):
return self._pending_requests.append(request)
def _get_pending_request(self):
return self._pending_requests.popleft() if self._pending_requests else None
def _get_exception_code(self, exception):
try:
return exception.__class__.__name__
except:
return "?"
def _request_is_redirected(self, request):
return request.meta.get(b"redirect_times", 0) > 0
def _get_downloader_info(self):
downloader = self.crawler.engine.downloader
info = {"key_type": "ip" if downloader.ip_concurrency else "domain", "overused_keys": []}
for key, slot in six.iteritems(downloader.slots):
overused_factor = len(slot.active) / float(slot.concurrency)
if overused_factor > self.frontier.manager.settings.get("OVERUSED_SLOT_FACTOR"):
info["overused_keys"].append(key)
return info
class FronteraScheduler(Scheduler):
def __init__(self, crawler, manager=None):
self.crawler = crawler
self.stats_manager = StatsManager(crawler.stats)
self._pending_requests = deque()
self.redirect_enabled = crawler.settings.get('REDIRECT_ENABLED')
settings = ScrapySettingsAdapter(crawler.settings)
self.frontier = ScrapyFrontierManager(settings, manager)
self._delay_on_empty = self.frontier.manager.settings.get(
'DELAY_ON_EMPTY')
self._delay_next_call = 0.0
self.logger = getLogger(
'frontera.contrib.scrapy.schedulers.FronteraScheduler')
@classmethod
def from_crawler(cls, crawler):
return cls(crawler)
def enqueue_request(self, request):
if not self._request_is_redirected(request):
self.frontier.add_seeds([request])
self.stats_manager.add_seeds()
return True
elif self.redirect_enabled:
self._add_pending_request(request)
self.stats_manager.add_redirected_requests()
return True
return False
def next_request(self):
request = self._get_next_request()
if request:
self.stats_manager.add_returned_requests()
return request
def process_spider_output(self, response, result, spider):
links = []
for element in result:
if isinstance(element, Request):
links.append(element)
yield element
frontier_request = response.meta[b'frontier_request']
self.frontier.page_crawled(
response) # removed frontier part from .meta
# putting it back, to persist .meta from original request
response.meta[b'frontier_request'] = frontier_request
self.frontier.links_extracted(response.request, links)
self.stats_manager.add_crawled_page(response.status, len(links))
def process_exception(self, request, exception, spider):
error_code = self._get_exception_code(exception)
self.frontier.request_error(request=request, error=error_code)
self.stats_manager.add_request_error(error_code)
def open(self, spider):
self.frontier.set_spider(spider)
self.logger.info("Starting frontier")
if not self.frontier.manager.auto_start:
self.frontier.start()
def close(self, reason):
self.logger.info("Finishing frontier (%s)", reason)
self.frontier.stop()
self.stats_manager.set_iterations(self.frontier.manager.iteration)
self.stats_manager.set_pending_requests(len(self))
def __len__(self):
return len(self._pending_requests)
def has_pending_requests(self):
return not self.frontier.finished()
def _get_next_request(self):
if not self.frontier.manager.finished and \
len(self) < self.crawler.engine.downloader.total_concurrency and \
self._delay_next_call < time():
info = self._get_downloader_info()
requests = self.frontier.get_next_requests(
key_type=info['key_type'], overused_keys=info['overused_keys'])
for request in requests:
self._add_pending_request(request)
self._delay_next_call = time(
) + self._delay_on_empty if not requests else 0.0
return self._get_pending_request()
def _add_pending_request(self, request):
return self._pending_requests.append(request)
def _get_pending_request(self):
return self._pending_requests.popleft(
) if self._pending_requests else None
def _get_exception_code(self, exception):
try:
return exception.__class__.__name__
except:
return '?'
def _request_is_redirected(self, request):
return request.meta.get(b'redirect_times', 0) > 0
def _get_downloader_info(self):
downloader = self.crawler.engine.downloader
info = {
'key_type': 'ip' if downloader.ip_concurrency else 'domain',
'overused_keys': []
}
for key, slot in six.iteritems(downloader.slots):
overused_factor = len(slot.active) / float(slot.concurrency)
if overused_factor > self.frontier.manager.settings.get(
'OVERUSED_SLOT_FACTOR'):
info['overused_keys'].append(key)
return info
class FronteraScheduler(Scheduler):
"""
Custom Scheduler for Scrapy.
Adapts Frontera manager interface to Scrapy.
Important remarks:
- it doesn't enqueue majority of requests produced by middlewares or direct calls to engine, see self.enqueue_request
method, and override if needed,
- requires SchedulerSpiderMiddleware and SchedulerDownloaderMiddleware.
"""
def __init__(self, crawler, manager=None):
self.crawler = crawler
self.stats_manager = StatsManager(crawler.stats)
self._pending_requests = deque()
settings = ScrapySettingsAdapter(crawler.settings)
self.frontier = ScrapyFrontierManager(settings, manager)
self._delay_on_empty = self.frontier.manager.settings.get(
'DELAY_ON_EMPTY')
self._redirect_enabled = crawler.settings.get('REDIRECT_ENABLED')
self._delay_next_call = 0.0
self.logger = getLogger(
'frontera.contrib.scrapy.schedulers.frontier.FronteraScheduler')
@classmethod
def from_crawler(cls, crawler):
return cls(crawler)
def enqueue_request(self, request):
# add directly to in-memory queue if request comes as part of redirect chain from RedirectMiddleware
if self._redirect_enabled and self._request_is_redirected(request):
self._add_pending_request(request)
self.stats_manager.add_redirected_requests()
return True
# add as seed if request is explicitly marked as seed
if self._request_is_seed(request):
self.frontier.add_seeds([request])
self.stats_manager.add_seeds()
return True
self.logger.warning("Request to URL %s is skipped.", request.url)
return False
def next_request(self):
request = self._get_next_request()
if request:
self.stats_manager.add_returned_requests()
return request
def process_spider_output(self, response, result, spider):
links = []
for element in result:
if isinstance(element, Request):
links.append(element)
else:
yield element
frontier_request = response.meta[b'frontier_request']
self.frontier.page_crawled(
response) # removed frontier part from .meta
# putting it back, to persist .meta from original request
response.meta[b'frontier_request'] = frontier_request
self.frontier.links_extracted(response.request, links)
self.stats_manager.add_crawled_page(response.status, len(links))
def process_exception(self, request, exception, spider):
error_code = self._get_exception_code(exception)
self.frontier.request_error(request=request, error=error_code)
self.stats_manager.add_request_error(error_code)
def open(self, spider):
self.frontier.set_spider(spider)
self.logger.info("Starting frontier")
if not self.frontier.manager.auto_start:
self.frontier.start()
def close(self, reason):
self.logger.info("Finishing frontier (%s)", reason)
self.frontier.stop()
self.stats_manager.set_iterations(self.frontier.manager.iteration)
self.stats_manager.set_pending_requests(len(self))
def __len__(self):
return len(self._pending_requests)
def has_pending_requests(self):
return not self.frontier.finished()
def _get_next_request(self):
if not self.frontier.manager.finished and \
len(self) < self.crawler.engine.downloader.total_concurrency and \
self._delay_next_call < time():
info = self._get_downloader_info()
requests = self.frontier.get_next_requests(
key_type=info['key_type'], overused_keys=info['overused_keys'])
for request in requests:
self._add_pending_request(request)
self._delay_next_call = time(
) + self._delay_on_empty if not requests else 0.0
return self._get_pending_request()
def _add_pending_request(self, request):
return self._pending_requests.append(request)
def _get_pending_request(self):
return self._pending_requests.popleft(
) if self._pending_requests else None
def _get_exception_code(self, exception):
try:
return exception.__class__.__name__
except:
return '?'
def _request_is_redirected(self, request):
return request.meta.get('redirect_times', 0) > 0
def _request_is_seed(self, request):
return bool(request.meta.get('seed', False))
def _get_downloader_info(self):
downloader = self.crawler.engine.downloader
info = {
'key_type': 'ip' if downloader.ip_concurrency else 'domain',
'overused_keys': []
}
for key, slot in six.iteritems(downloader.slots):
overused_factor = len(slot.active) / float(slot.concurrency)
if overused_factor > self.frontier.manager.settings.get(
'OVERUSED_SLOT_FACTOR'):
info['overused_keys'].append(key)
return info