gallery-dl/gallery_dl/extractor/common.py

# -*- coding: utf-8 -*-

# Copyright 2014, 2015 Mike Fährmann
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.

"""Common classes and constants used by extractor modules."""

import time
import queue
import requests
import threading
from .message import Message
from .. import config

class Extractor():

    category = ""
    subcategory = ""
    directory_fmt = [""]
    filename_fmt = ""

    def __init__(self):
        self.session = requests.Session()

    def __iter__(self):
        return self.items()

    def items(self):
        yield Message.Version, 1

    def request(self, url, encoding=None, *args, **kwargs):
        response = safe_request(self.session, url, *args, **kwargs)
        if encoding:
            response.encoding = encoding
        return response


class AsynchronousExtractor(Extractor):

    def __init__(self):
        Extractor.__init__(self)
        queue_size = int(config.get(("queue-size",), default=5))
        self.__queue = queue.Queue(maxsize=queue_size)
        self.__thread = threading.Thread(target=self.async_items, daemon=True)

    def __iter__(self):
        get = self.__queue.get
        done = self.__queue.task_done

        self.__thread.start()
        while True:
            task = get()
            if task is None:
                return
            if isinstance(task, Exception):
                raise task
            yield task
            done()

    def async_items(self):
        put = self.__queue.put
        try:
            for task in self.items():
                put(task)
        except Exception as e:
            put(e)
        put(None)


def safe_request(session, url, method="GET", *args, **kwargs):
    tries = 0
    while True:
        # try to connect to remote source
        try:
            r = session.request(method, url, *args, **kwargs)
        except requests.exceptions.ConnectionError:
            tries += 1
            time.sleep(1)
            if tries == 5:
                raise
            continue

        # reject error-status-codes
        if r.status_code != requests.codes.ok:
            tries += 1
            time.sleep(1)
            if tries == 5:
                r.raise_for_status()
            continue

        # everything ok -- proceed to download
        return r