File size: 7,267 Bytes
63a63dd | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 | """Crawler base class"""
import logging
import sys
import time
from importlib import import_module
from . import storage as storage_package
from .downloader import Downloader
from .feeder import Feeder
from .parser import Parser
from .storage import BaseStorage
from .utils import ProxyPool, Session, Signal
class Crawler:
"""Base class for crawlers
Attributes:
session (Session): A Session object.
feeder (Feeder): A Feeder object.
parser (Parser): A Parser object.
downloader (Downloader): A Downloader object.
signal (Signal): A Signal object shared by all components,
used for communication among threads
logger (Logger): A Logger object used for logging
"""
def __init__(
self,
feeder_cls=Feeder,
parser_cls=Parser,
downloader_cls=Downloader,
feeder_threads=1,
parser_threads=1,
downloader_threads=1,
storage={"backend": "FileSystem", "root_dir": "images"},
log_level=logging.INFO,
extra_feeder_args=None,
extra_parser_args=None,
extra_downloader_args=None,
):
"""Init components with class names and other arguments.
Args:
feeder_cls: class of feeder
parser_cls: class of parser
downloader_cls: class of downloader.
feeder_threads: thread number used by feeder
parser_threads: thread number used by parser
downloader_threads: thread number used by downloader
storage (dict or BaseStorage): storage backend configuration
log_level: logging level for the logger
"""
self.set_logger(log_level)
self.set_proxy_pool()
self.set_session()
self.init_signal()
self.set_storage(storage)
# set feeder, parser and downloader
feeder_kwargs = {} if extra_feeder_args is None else extra_feeder_args
parser_kwargs = {} if extra_parser_args is None else extra_parser_args
downloader_kwargs = {} if extra_downloader_args is None else extra_downloader_args
self.feeder = feeder_cls(feeder_threads, self.signal, self.session, **feeder_kwargs)
self.parser = parser_cls(parser_threads, self.signal, self.session, **parser_kwargs)
self.downloader = downloader_cls(
downloader_threads, self.signal, self.session, self.storage, **downloader_kwargs
)
# connect all components
self.feeder.connect(self.parser).connect(self.downloader)
def set_logger(self, log_level=logging.INFO):
"""Configure the logger with log_level."""
logging.basicConfig(
format="%(asctime)s - %(levelname)s - %(name)s - %(message)s", level=log_level, stream=sys.stderr
)
self.logger = logging.getLogger(__name__)
logging.getLogger("requests").setLevel(logging.WARNING)
def init_signal(self):
"""Init signal
3 signals are added: ``feeder_exited``, ``parser_exited`` and
``reach_max_num``.
"""
self.signal = Signal()
self.signal.set(feeder_exited=False, parser_exited=False, reach_max_num=False)
def set_storage(self, storage):
"""Set storage backend for downloader
For full list of storage backend supported, please see :mod:`storage`.
Args:
storage (dict or BaseStorage): storage backend configuration or instance
"""
if isinstance(storage, BaseStorage):
self.storage = storage
elif isinstance(storage, dict):
if "backend" not in storage and "root_dir" in storage:
storage["backend"] = "FileSystem"
try:
backend_cls = getattr(storage_package, storage["backend"])
except AttributeError:
try:
backend_cls = import_module(storage["backend"])
except ImportError:
self.logger.error("cannot find backend module %s", storage["backend"])
sys.exit()
kwargs = storage.copy()
del kwargs["backend"]
self.storage = backend_cls(**kwargs)
else:
raise TypeError('"storage" must be a storage object or dict')
def set_proxy_pool(self, pool=None):
"""Construct a proxy pool
By default no proxy is used.
Args:
pool (ProxyPool, optional): a :obj:`ProxyPool` object
"""
self.proxy_pool = ProxyPool() if pool is None else pool
def set_session(self, headers=None):
"""Init session with default or custom headers
Args:
headers: A dict of headers (default None, thus using the default
header to init the session)
"""
if headers is None:
headers = {
"Accept-Language": "zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2",
"User-Agent": (
"Mozilla/5.0 (Windows NT 10.0; Win64; x64)"
" AppleWebKit/537.36 (KHTML, like Gecko) "
"Chrome/88.0.4324.104 Safari/537.36"
),
}
elif not isinstance(headers, dict):
raise TypeError('"headers" must be a dict object')
self.session = Session(self.proxy_pool)
self.session.headers.update(headers)
def crawl(self, feeder_kwargs=None, parser_kwargs=None, downloader_kwargs=None):
"""Start crawling
This method will start feeder, parser and download and wait
until all threads exit.
Args:
feeder_kwargs (dict, optional): Arguments to be passed to ``feeder.start()``
parser_kwargs (dict, optional): Arguments to be passed to ``parser.start()``
downloader_kwargs (dict, optional): Arguments to be passed to
``downloader.start()``
"""
self.signal.reset()
self.logger.info("start crawling...")
feeder_kwargs = {} if feeder_kwargs is None else feeder_kwargs
parser_kwargs = {} if parser_kwargs is None else parser_kwargs
downloader_kwargs = {} if downloader_kwargs is None else downloader_kwargs
self.logger.info("starting %d feeder threads...", self.feeder.thread_num)
self.feeder.start(**feeder_kwargs)
self.logger.info("starting %d parser threads...", self.parser.thread_num)
self.parser.start(**parser_kwargs)
self.logger.info("starting %d downloader threads...", self.downloader.thread_num)
self.downloader.start(**downloader_kwargs)
while True:
if not self.feeder.is_alive():
self.signal.set(feeder_exited=True)
if not self.parser.is_alive():
self.signal.set(parser_exited=True)
if not self.downloader.is_alive():
break
time.sleep(1)
if not self.feeder.in_queue.empty():
self.feeder.clear_buffer()
if not self.parser.in_queue.empty():
self.parser.clear_buffer()
if not self.downloader.in_queue.empty():
self.downloader.clear_buffer(True)
self.logger.info("Crawling task done!")
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