class Indexer(Task):
def __init__(self, splitter):
super(Indexer, self).__init__(self)
self.page_storage = PageStorageClient()
self.index_storage = IndexStorageClient()
self.splitter = splitter
def __call__(self, page_info):
self.put_message(MakeIndexMessage(page_info))
def handle_MakeIndexMessage(self, page_info):
self.show_timestamped_message("Indexing ... %s" % page_info.url)
page_info.status |= PageInfo.INDEXED
self.page_storage.set_page(page_info)
index = [
("".join(ngram), (page_info.id, pos)) \
for (pos, ngram) in enumerate(self.splitter((page_info.text)))]
self.index_storage.set_index(index)
class HTTPCrawler(Task):
AcceptContentTypePatterns = re.compile("xthml | html | xml")
DaysOfFetchInterval = 7
def __init__(self, parser_task):
super(HTTPCrawler, self).__init__()
self.parser_task = parser_task
self.page_storage = PageStorageClient()
def is_page_status_allow_to_fetch(self, target_url):
if self.page_storage.has_key(target_url):
page_info = self.page_storage.get_page(target_url)
if page_info.status & page_info.IGNORED:
return False
else:
diff = (datetime.datetime.now() - page_info.last_update_timestamp).total_seconds()
return diif >= (86400 * self.DaysOfFetchInterval)
else:
return True
def is_contents_status_allow_to_fetch(self, target_url):
response = requests.head(target_url)
# 301: Moved Permanently
# 302: Found
# 303: See Other
# 307: Temporary Redirect
# 308: Permanent Redirect
if response.status_code in (301, 302, 303, 307, 308):
moved_url = response.headers.get("location")
if moved_url:
self.put_message(CrawlURLMessage(moved_url))
return False
elif response.status_code == 200:
content_type = response.headers.get("content-type")
if content_type is not None:
return self.AcceptContentTypePatterns.search(content_type) is not None
else:
return False
def make_correct_unicode_contents(self, byte_contents):
guess_endoce = chardet.detect(byte_contents)["encoding"]
return byte_contents.decode(guess_endoce)
def do_fetch(self, target_url):
try:
response = requets.get(target_url)
except Exception as exc:
self.show_timestamped_message("Error in '%s'\n%s" % (
self.name, traceback.format_exc(exc)))
return PageInfo(url=response.url,
status=PageInfo.FETCH_ERROR,
raw_contents=None)
else:
return PageInfo(url=response.url,
status=PageInfo.STORED,
raw_contents=self.make_correct_unicode_contents(response.content))
def handle_CrawlerURLMessage(self, target_url):
self.show_timestamped_message("Crawling ... %s" % target_url)
if self.is_page_status_allow_to_fetch(target_url):
if self.is_contents_status_allow_to_fetch(target_url):
page_info = self.do_fetch(target_url)
else:
page_info = PageInfo(url=target_url,
status=PageInfo.UGNORED,
raw_contents=None)
self.page_storage.set_page(page_info)
self.show_timestamped_message("Stored : %s" % target_url)
self.parser_task(page_info)
else:
self.show_timestamped_message("Ignored : %s" % target_url)
page_info = self.page_storege.get_page(target_url)
self.parser_task(page_info)
class HTMLParser(Task):
IgnoreTagNames = ("script", "noscript", "object", "applet")
def __init__(self, indexer, link_queue=None):
super(HTMLParser, self).__init__()
self.page_storage_client = PageStorageClient()
self.indexer = indexer
self.link_queue = link_queue
def __call__(self, page_info):
self.put_message(ParseHTMLMessage(page_info))
def remove_xml_declaration(self, text):
return re.sub(r"^\<\?xml\ .*\?\>\n", "", text)
def gather_white_spaces(self, text):
return re.sub(r"\s+", " ", text).strip()
def collect_text(self, document_tree):
result = list()
for element in document_tree.iter():
if isinstance(element.tag, str) and (element.tag not in self.IgnoreTagNames):
if element.text is not None:
text = self.gather_white_spaces(element.text)
if text != "":
result.append(text)
return " ".join(result)
def extract_link_urls(self, document_tree):
return set([e.attrib["href"] for e in document_tree.xpath("//a[@href]")])
def hancle_ParseHTMLMessage(self, page_info):
self.show_timestamped_message("Parsing ... %s" % page_info.url)
contents = self.remove_xml_declaration(page_info.raw_contents)
document_tree = lxml.html.fromstring(contents, base_url=page_info.url)
document_tree.make_links_absolute()
if not(page_info.status & PageInfo.PARSED):
title_elements = document_tree.xpath("//title")
if title_elements:
page_info.title = title_elements[0].text.strip()
else:
page_info.title = None
page_info.text = TextUtils.normalize_text(self.collect_text(document_tree))
self.page_storage_client.set_page(page_info)
self.indexer(page_info)
if self.link_queue:
for link_url in self.extract_link_urls(document_tree):
self.link_queue(link_url)