Sitemap generator
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import logging
import asyncio
import re
import urllib.parse
from pysitemap.format_processors.xml import XMLWriter
from pysitemap.format_processors.text import TextWriter
import aiohttp
class Crawler:
format_processors = {
'xml': XMLWriter,
'txt': TextWriter
}
def __init__(self, rooturl, out_file, out_format='xml', maxtasks=100,
todo_queue_backend=set, done_backend=dict):
"""
Crawler constructor
:param rooturl: root url of site
:type rooturl: str
:param out_file: file to save sitemap result
:type out_file: str
:param out_format: sitemap type [xml | txt]. Default xml
:type out_format: str
:param maxtasks: maximum count of tasks. Default 100
:type maxtasks: int
"""
self.rooturl = rooturl
self.todo_queue = todo_queue_backend()
self.busy = set()
self.done = done_backend()
self.tasks = set()
self.sem = asyncio.Semaphore(maxtasks)
# connector stores cookies between requests and uses connection pool
self.session = aiohttp.ClientSession()
self.writer = self.format_processors.get(out_format)(out_file)
async def run(self):
"""
Main function to start parsing site
:return:
"""
t = asyncio.ensure_future(self.addurls([(self.rooturl, '')]))
await asyncio.sleep(1)
while self.busy:
await asyncio.sleep(1)
await t
await self.session.close()
await self.writer.write([key for key, value in self.done.items() if value])
async def addurls(self, urls):
"""
Add urls in queue and run process to parse
:param urls:
:return:
"""
for url, parenturl in urls:
url = urllib.parse.urljoin(parenturl, url)
url, frag = urllib.parse.urldefrag(url)
if (url.startswith(self.rooturl) and
url not in self.busy and
url not in self.done and
url not in self.todo_queue):
self.todo_queue.add(url)
# Acquire semaphore
await self.sem.acquire()
# Create async task
task = asyncio.ensure_future(self.process(url))
# Add collback into task to release semaphore
task.add_done_callback(lambda t: self.sem.release())
# Callback to remove task from tasks
task.add_done_callback(self.tasks.remove)
# Add task into tasks
self.tasks.add(task)
async def process(self, url):
"""
Process single url
:param url:
:return:
"""
print('processing:', url)
# remove url from basic queue and add it into busy list
self.todo_queue.remove(url)
self.busy.add(url)
try:
resp = await self.session.get(url) # await response
except Exception as exc:
# on any exception mark url as BAD
print('...', url, 'has error', repr(str(exc)))
self.done[url] = False
else:
# only url with status == 200 and content type == 'text/html' parsed
if (resp.status == 200 and
('text/html' in resp.headers.get('content-type'))):
data = (await resp.read()).decode('utf-8', 'replace')
urls = re.findall(r'(?i)href=["\']?([^\s"\'<>]+)', data)
asyncio.Task(self.addurls([(u, url) for u in urls]))
# even if we have no exception, we can mark url as good
resp.close()
self.done[url] = True
self.busy.remove(url)
logging.info(len(self.done), 'completed tasks,', len(self.tasks),
'still pending, todo_queue', len(self.todo_queue))