class DownloadHandler(ABC):
"""
DownloadHandler is the base class for all downloads and subsequent processing of the downloaded content.
Each download script has a derived class which handles specifics for that type of content / download.
"""
def __init__(self, feed_type, prefix=None):
self._end = None
self.feed_type = feed_type
self.prefix = prefix
self.queue = RedisQueue(name=self.feed_type)
self.file_queue = RedisQueue(name=f"{self.feed_type}:files")
self.file_queue.clear()
self.progress_bar = None
self.last_modified = None
self.do_process = True
self.logger = logging.getLogger("DownloadHandler")
self.config = Configuration()
def __repr__(self):
""" return string representation of object """
return "<< DownloadHandler:{} >>".format(self.feed_type)
def get_session(
self,
retries=3,
backoff_factor=0.3,
status_forcelist=(429, 500, 502, 503, 504),
session=None,
):
"""
Method for returning a session object per every requesting thread
"""
proxies = {
"http": self.config.getProxy(),
"https": self.config.getProxy()
}
if not hasattr(thread_local, "session"):
session = session or requests.Session()
retry = Retry(
total=retries,
read=retries,
connect=retries,
backoff_factor=backoff_factor,
status_forcelist=status_forcelist,
)
session.proxies.update(proxies)
adapter = HTTPAdapter(max_retries=retry)
session.mount("http://", adapter)
session.mount("https://", adapter)
thread_local.session = session
return thread_local.session
def process_downloads(self, sites, collection):
"""
Method to download and process files
:param sites: List of file to download and process
:type sites: list
:param collection: Mongodb Collection name
:type collection: str
:return:
:rtype:
"""
worker_size = (int(os.getenv("WORKER_SIZE"))
if os.getenv("WORKER_SIZE") else min(
32,
os.cpu_count() + 4))
start_time = time.time()
thread_map(self.download_site, sites, desc="Downloading files")
if self.do_process:
thread_map(
self.file_to_queue,
self.file_queue.get_full_list(),
desc="Processing downloaded files",
)
self._process_queue_to_db(worker_size, collection=collection)
# checking if last-modified was in the response headers and not set to default
if "01-01-1970" != self.last_modified.strftime("%d-%m-%Y"):
setColUpdate(self.feed_type.lower(), self.last_modified)
self.logger.info("Duration: {}".format(
timedelta(seconds=time.time() - start_time)))
def chunk_list(self, lst, number):
"""
Yield successive n-sized chunks from lst.
:param lst: List to be chunked
:type lst: list
:param number: Chunk size
:type number: int
:return: Chunked list
:rtype: list
"""
for i in range(0, len(lst), number):
yield lst[i:i + number]
def _handle_queue_progressbar(self, description):
"""
Method for handling the progressbar during queue processing
:param description: Description for tqdm progressbar
:type description: str
"""
max_len = self.queue.qsize()
pbar = tqdm(total=max_len, desc=description)
not_Done = True
q_len = max_len
dif_old = 0
x = 0
while not_Done:
current_q_len = self.queue.qsize()
if x % 10 == 0:
# log stats the first cycle and every 10th cycle thereafter
self.logger.debug(
"Queue max_len: {}, current_q_len: {}, q_len: {}, dif_old: {}, cycle: {}"
.format(max_len, current_q_len, q_len, dif_old, x))
if current_q_len != 0:
if current_q_len != q_len:
q_len = current_q_len
dif = max_len - q_len
pbar.update(int(dif - dif_old))
dif_old = dif
else:
pbar.update(int(max_len - dif_old))
not_Done = False
x += 1
time.sleep(5)
self.logger.debug(
"Queue max_len: {}, q_len: {}, dif_old: {}, cycles: {}".format(
max_len, q_len, dif_old, x))
pbar.close()
def _process_queue_to_db(self, max_workers, collection):
"""
Method to write the queued database transactions into the database given a Queue reference and Collection name
:param max_workers: Max amount of worker processes to use; defaults to min(32, os.cpu_count() + 4)
:type max_workers: int
:param collection: Mongodb Collection name
:type collection: str
"""
pbar = mp.Process(
target=self._handle_queue_progressbar,
args=("Transferring queue to database", ),
)
processes = [
mp.Process(target=self._db_bulk_writer, args=(collection, ))
for _ in range(max_workers)
]
for proc in processes:
proc.start()
# Put triggers in the Queue to tell the workers to exit their for-loop
self.queue.put(self._end)
pbar.start()
for proc in processes:
proc.join()
pbar.join()
def _db_bulk_writer(self, collection, threshold=1000):
"""
Method to act as worker for writing queued entries into the database
:param collection: Mongodb Collection name
:type collection: str
:param threshold: Batch size threshold; defaults to 1000
:type threshold: int
"""
database = self.config.getMongoConnection()
for batch in iter(lambda: list(islice(self.queue, threshold)), []):
try:
database[collection].bulk_write(batch, ordered=False)
except BulkWriteError as err:
self.logger.debug("Error during bulk write: {}".format(err))
pass
def store_file(self, response_content, content_type, url):
"""
Method to store the download based on the headers content type
:param response_content: Response content
:type response_content: bytes
:param content_type: Content type; e.g. 'application/zip'
:type content_type: str
:param url: Download url
:type url: str
:return: A working directory and a filename
:rtype: str and str
"""
wd = tempfile.mkdtemp()
filename = None
if (content_type == "application/zip"
or content_type == "application/x-zip"
or content_type == "application/x-zip-compressed"
or content_type == "application/zip-compressed"):
filename = os.path.join(wd, url.split("/")[-1][:-4])
self.logger.debug("Saving file to: {}".format(filename))
with zipfile.ZipFile(BytesIO(response_content)) as zip_file:
zip_file.extractall(wd)
elif (content_type == "application/x-gzip"
or content_type == "application/gzip"
or content_type == "application/x-gzip-compressed"
or content_type == "application/gzip-compressed"):
filename = os.path.join(wd, url.split("/")[-1][:-3])
self.logger.debug("Saving file to: {}".format(filename))
buf = BytesIO(response_content)
with open(filename, "wb") as f:
f.write(gzip.GzipFile(fileobj=buf).read())
elif content_type == "application/json" or content_type == "application/xml":
filename = os.path.join(wd, url.split("/")[-1])
self.logger.debug("Saving file to: {}".format(filename))
with open(filename, "wb") as output_file:
output_file.write(response_content)
elif content_type == "application/local":
filename = os.path.join(wd, url.split("/")[-1])
self.logger.debug("Saving file to: {}".format(filename))
copy(url[7:], filename)
else:
self.logger.error(
"Unhandled Content-Type encountered: {} from url".format(
content_type, url))
sys.exit(1)
return wd, filename
def download_site(self, url):
if url[:4] == "file":
self.logger.info("Scheduling local hosted file: {}".format(url))
# local file do not get last_modified header; so completely ignoring last_modified check and always asume
# local file == the last modified file and set to current time.
self.last_modified = datetime.datetime.now()
self.logger.debug("Last {} modified value: {} for URL: {}".format(
self.feed_type, self.last_modified, url))
wd, filename = self.store_file(
response_content=b"local",
content_type="application/local",
url=url,
)
if filename is not None:
self.file_queue.put((wd, filename))
else:
self.logger.error(
"Unable to retrieve a filename; something went wrong when trying to save the file"
)
sys.exit(1)
else:
self.logger.debug("Downloading from url: {}".format(url))
session = self.get_session()
try:
with session.get(url) as response:
try:
self.last_modified = parse_datetime(
response.headers["last-modified"], ignoretz=True)
except KeyError:
self.logger.error(
"Did not receive last-modified header in the response; setting to default "
"(01-01-1970) and force update! Headers received: {}"
.format(response.headers))
# setting to last_modified to default value
self.last_modified = parse_datetime("01-01-1970")
self.logger.debug(
"Last {} modified value: {} for URL: {}".format(
self.feed_type, self.last_modified, url))
i = getInfo(self.feed_type.lower())
if i is not None:
if self.last_modified == i["last-modified"]:
self.logger.info(
"{}'s are not modified since the last update".
format(self.feed_type))
self.file_queue.get_full_list()
self.do_process = False
if self.do_process:
content_type = response.headers["content-type"]
self.logger.debug(
"URL: {} fetched Content-Type: {}".format(
url, content_type))
wd, filename = self.store_file(
response_content=response.content,
content_type=content_type,
url=url,
)
if filename is not None:
self.file_queue.put((wd, filename))
else:
self.logger.error(
"Unable to retrieve a filename; something went wrong when trying to save the file"
)
sys.exit(1)
except Exception as err:
self.logger.info(
"Exception encountered during download from: {}. Please check the logs for more information!"
.format(url))
self.logger.error(
"Exception encountered during the download from: {}. Error encountered: {}"
.format(url, err))
self.do_process = False
@abstractmethod
def process_item(self, **kwargs):
raise NotImplementedError
@abstractmethod
def file_to_queue(self, *args):
raise NotImplementedError
@abstractmethod
def update(self, **kwargs):
raise NotImplementedError
@abstractmethod
def populate(self, **kwargs):
raise NotImplementedError
