148 lines
6.5 KiB
Python
148 lines
6.5 KiB
Python
#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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import aiohttp
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from dateutil import parser
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from datetime import datetime, date
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from hashlib import sha512 # Faster than sha256 on 64b machines.
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from pathlib import Path
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import logging
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from pid import PidFile, PidFileError
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import json
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from .libs.helpers import safe_create_dir, set_running, unset_running
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class Fetcher():
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def __init__(self, config_file: Path, storage_directory: Path,
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loglevel: int=logging.DEBUG):
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'''Load `config_file`, and store the fetched data into `storage_directory`
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Note: if the `config_file` does not provide a URL (the file is
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gathered by some oter mean), the fetcher is automatically stoped.'''
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with open(config_file, 'r') as f:
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module_parameters = json.load(f)
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self.vendor = module_parameters['vendor']
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self.listname = module_parameters['name']
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self.__init_logger(loglevel)
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self.fetcher = True
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if 'url' not in module_parameters:
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self.logger.info('No URL to fetch, breaking.')
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self.fetcher = False
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return
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self.url = module_parameters['url']
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self.logger.debug(f'Starting fetcher on {self.url}')
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self.directory = storage_directory / self.vendor / self.listname
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safe_create_dir(self.directory)
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self.meta = self.directory / 'meta'
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safe_create_dir(self.meta)
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self.archive_dir = self.directory / 'archive'
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safe_create_dir(self.archive_dir)
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self.first_fetch = True
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def __init_logger(self, loglevel):
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self.logger = logging.getLogger(f'{self.__class__.__name__}-{self.vendor}-{self.listname}')
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self.logger.setLevel(loglevel)
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async def __get_last_modified(self):
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async with aiohttp.ClientSession() as session:
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async with session.head(self.url) as r:
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headers = r.headers
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if 'Last-Modified' in headers:
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return parser.parse(headers['Last-Modified'])
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return None
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async def __newer(self):
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'''Check if the file available for download is newed than the one
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already downloaded by checking the `Last-Modified` header.
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Note: return False if the file containing the last header content
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is not existing, or the header doesn't have this key.
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'''
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last_modified_path = self.meta / 'lastmodified'
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if not last_modified_path.exists():
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# The file doesn't exists
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if not self.first_fetch:
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# The URL has no Last-Modified header, we cannot use it.
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self.logger.debug('No Last-Modified header available')
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return True
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self.first_fetch = False
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last_modified = await self.__get_last_modified()
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if last_modified:
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self.logger.debug('Last-Modified header available')
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with last_modified_path.open('w') as f:
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f.write(last_modified.isoformat())
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else:
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self.logger.debug('No Last-Modified header available')
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return True
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with last_modified_path.open() as f:
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file_content = f.read()
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last_modified_file = parser.parse(file_content)
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last_modified = await self.__get_last_modified()
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if not last_modified:
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# No more Last-Modified header Oo
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self.logger.warning(f'{self.listname}: Last-Modified header was present, isn\'t anymore!')
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last_modified_path.unlink()
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return True
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if last_modified > last_modified_file:
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self.logger.info('Got a new file.')
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with last_modified_path.open('w') as f:
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f.write(last_modified.isoformat())
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return True
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return False
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def __same_as_last(self, downloaded):
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'''Figure out the last downloaded file, check if it is the same as the
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newly downloaded one. Returns true if both files have been downloaded the
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same day.
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Note: we check the new and the archive directory because we may have backlog
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and the newest file is always the first one we process
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'''
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to_check = []
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to_check_new = sorted([f for f in self.directory.iterdir() if f.is_file()])
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if to_check_new:
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# we have files waiting to be processed
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self.logger.debug('{} file(s) are waiting to be processed'.format(len(to_check_new)))
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to_check.append(to_check_new[-1])
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to_check_archive = sorted([f for f in self.archive_dir.iterdir() if f.is_file()])
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if to_check_archive:
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# we have files already processed, in the archive
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self.logger.debug('{} file(s) have been processed'.format(len(to_check_archive)))
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to_check.append(to_check_archive[-1])
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if not to_check:
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self.logger.debug('New list, no hisorical files')
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# nothing has been downloaded ever, moving on
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return False
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dl_hash = sha512(downloaded)
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for last_file in to_check:
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with last_file.open('rb') as f:
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last_hash = sha512(f.read())
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if (dl_hash.digest() == last_hash.digest() and
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parser.parse(last_file.name.split('.')[0]).date() == date.today()):
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self.logger.debug('Same file already downloaded today.')
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return True
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return False
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async def fetch_list(self):
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'''Fetch & store the list'''
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if not self.fetcher:
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return
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set_running(f'{self.__class__.__name__}-{self.vendor}-{self.listname}')
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try:
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with PidFile(f'{self.listname}.pid', piddir=self.meta):
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if not await self.__newer():
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unset_running(f'{self.__class__.__name__}-{self.vendor}-{self.listname}')
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return
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async with aiohttp.ClientSession() as session:
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async with session.get(self.url) as r:
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content = await r.content.read()
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if self.__same_as_last(content):
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return
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self.logger.info('Got a new file \o/')
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with (self.directory / '{}.txt'.format(datetime.now().isoformat())).open('wb') as f:
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f.write(content)
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unset_running(f'{self.__class__.__name__}-{self.vendor}-{self.listname}')
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except PidFileError:
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self.logger.info('Fetcher already running')
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finally:
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unset_running(f'{self.__class__.__name__}-{self.vendor}-{self.listname}')
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