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https://github.com/Garmelon/PFERD.git
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Restructure crawling and auth related modules
This commit is contained in:
Joscha
313
PFERD/crawl/crawler.py
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313
PFERD/crawl/crawler.py
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import asyncio
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from abc import ABC, abstractmethod
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from datetime import datetime
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from pathlib import Path, PurePath
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from typing import Any, Awaitable, Callable, Dict, List, Optional, Sequence, Tuple, TypeVar
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from rich.markup import escape
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from ..auth import Authenticator
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from ..config import Config, Section
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from ..limiter import Limiter
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from ..logging import ProgressBar, log
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from ..output_dir import FileSink, FileSinkToken, OnConflict, OutputDirectory, OutputDirError, Redownload
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from ..report import MarkConflictError, MarkDuplicateError
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from ..transformer import Transformer
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from ..utils import ReusableAsyncContextManager, fmt_path
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class CrawlWarning(Exception):
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pass
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class CrawlError(Exception):
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pass
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Wrapped = TypeVar("Wrapped", bound=Callable[..., None])
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def noncritical(f: Wrapped) -> Wrapped:
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"""
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Catches and logs a few noncritical exceptions occurring during the function
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call, mainly CrawlWarning.
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If any exception occurs during the function call, the crawler's error_free
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variable is set to False. This includes noncritical exceptions.
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Warning: Must only be applied to member functions of the Crawler class!
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"""
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def wrapper(*args: Any, **kwargs: Any) -> None:
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if not (args and isinstance(args[0], Crawler)):
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raise RuntimeError("@noncritical must only applied to Crawler methods")
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crawler = args[0]
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try:
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f(*args, **kwargs)
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except (CrawlWarning, OutputDirError, MarkDuplicateError, MarkConflictError) as e:
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log.warn(str(e))
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crawler.error_free = False
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except: # noqa: E722 do not use bare 'except'
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crawler.error_free = False
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raise
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return wrapper # type: ignore
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AWrapped = TypeVar("AWrapped", bound=Callable[..., Awaitable[None]])
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def anoncritical(f: AWrapped) -> AWrapped:
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"""
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An async version of @noncritical.
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Catches and logs a few noncritical exceptions occurring during the function
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call, mainly CrawlWarning.
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If any exception occurs during the function call, the crawler's error_free
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variable is set to False. This includes noncritical exceptions.
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Warning: Must only be applied to member functions of the Crawler class!
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"""
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async def wrapper(*args: Any, **kwargs: Any) -> None:
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if not (args and isinstance(args[0], Crawler)):
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raise RuntimeError("@anoncritical must only applied to Crawler methods")
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crawler = args[0]
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try:
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await f(*args, **kwargs)
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except (CrawlWarning, OutputDirError, MarkDuplicateError, MarkConflictError) as e:
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log.warn(str(e))
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crawler.error_free = False
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except: # noqa: E722 do not use bare 'except'
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crawler.error_free = False
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raise
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return wrapper # type: ignore
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class CrawlToken(ReusableAsyncContextManager[ProgressBar]):
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def __init__(self, limiter: Limiter, path: PurePath):
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super().__init__()
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self._limiter = limiter
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self._path = path
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async def _on_aenter(self) -> ProgressBar:
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bar_desc = f"[bold bright_cyan]Crawling[/] {escape(fmt_path(self._path))}"
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after_desc = f"[bold bright_cyan]Crawled[/] {escape(fmt_path(self._path))}"
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self._stack.callback(lambda: log.action(after_desc))
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await self._stack.enter_async_context(self._limiter.limit_crawl())
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bar = self._stack.enter_context(log.crawl_bar(bar_desc))
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return bar
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class DownloadToken(ReusableAsyncContextManager[Tuple[ProgressBar, FileSink]]):
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def __init__(self, limiter: Limiter, fs_token: FileSinkToken, path: PurePath):
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super().__init__()
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self._limiter = limiter
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self._fs_token = fs_token
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self._path = path
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async def _on_aenter(self) -> Tuple[ProgressBar, FileSink]:
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bar_desc = f"[bold bright_cyan]Downloading[/] {escape(fmt_path(self._path))}"
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# The "Downloaded ..." message is printed in the output dir, not here
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await self._stack.enter_async_context(self._limiter.limit_download())
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sink = await self._stack.enter_async_context(self._fs_token)
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bar = self._stack.enter_context(log.download_bar(bar_desc))
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return bar, sink
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class CrawlerSection(Section):
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def output_dir(self, name: str) -> Path:
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# TODO Use removeprefix() after switching to 3.9
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if name.startswith("crawl:"):
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name = name[len("crawl:"):]
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return Path(self.s.get("output_dir", name)).expanduser()
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def redownload(self) -> Redownload:
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value = self.s.get("redownload", "never-smart")
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try:
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return Redownload.from_string(value)
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except ValueError as e:
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self.invalid_value(
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"redownload",
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value,
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str(e).capitalize(),
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)
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def on_conflict(self) -> OnConflict:
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value = self.s.get("on_conflict", "prompt")
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try:
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return OnConflict.from_string(value)
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except ValueError as e:
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self.invalid_value(
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"on_conflict",
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value,
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str(e).capitalize(),
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)
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def transform(self) -> str:
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return self.s.get("transform", "")
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def max_concurrent_tasks(self) -> int:
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value = self.s.getint("max_concurrent_tasks", fallback=1)
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if value <= 0:
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self.invalid_value("max_concurrent_tasks", value,
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"Must be greater than 0")
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return value
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def max_concurrent_downloads(self) -> int:
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tasks = self.max_concurrent_tasks()
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value = self.s.getint("max_concurrent_downloads", fallback=None)
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if value is None:
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return tasks
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if value <= 0:
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self.invalid_value("max_concurrent_downloads", value,
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"Must be greater than 0")
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if value > tasks:
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self.invalid_value("max_concurrent_downloads", value,
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"Must not be greater than max_concurrent_tasks")
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return value
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def delay_between_tasks(self) -> float:
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value = self.s.getfloat("delay_between_tasks", fallback=0.0)
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if value < 0:
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self.invalid_value("delay_between_tasks", value,
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"Must not be negative")
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return value
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def auth(self, authenticators: Dict[str, Authenticator]) -> Authenticator:
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value = self.s.get("auth")
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if value is None:
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self.missing_value("auth")
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auth = authenticators.get(value)
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if auth is None:
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self.invalid_value("auth", value, "No such auth section exists")
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return auth
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class Crawler(ABC):
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def __init__(
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self,
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name: str,
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section: CrawlerSection,
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config: Config,
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) -> None:
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"""
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Initialize a crawler from its name and its section in the config file.
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If you are writing your own constructor for your own crawler, make sure
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to call this constructor first (via super().__init__).
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May throw a CrawlerLoadException.
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"""
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self.name = name
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self.error_free = True
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self._limiter = Limiter(
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task_limit=section.max_concurrent_tasks(),
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download_limit=section.max_concurrent_downloads(),
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task_delay=section.delay_between_tasks(),
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)
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self._transformer = Transformer(section.transform())
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self._output_dir = OutputDirectory(
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config.default_section.working_dir() / section.output_dir(name),
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section.redownload(),
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section.on_conflict(),
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)
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@staticmethod
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async def gather(awaitables: Sequence[Awaitable[Any]]) -> List[Any]:
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"""
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Similar to asyncio.gather. However, in the case of an exception, all
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still running tasks are cancelled and the exception is rethrown.
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This should always be preferred over asyncio.gather in crawler code so
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that an exception like CrawlError may actually stop the crawler.
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"""
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tasks = [asyncio.ensure_future(aw) for aw in awaitables]
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result = asyncio.gather(*tasks)
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try:
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return await result
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except: # noqa: E722
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for task in tasks:
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task.cancel()
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raise
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async def crawl(self, path: PurePath) -> Optional[CrawlToken]:
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log.explain_topic(f"Decision: Crawl {fmt_path(path)}")
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if self._transformer.transform(path) is None:
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log.explain("Answer: No")
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return None
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log.explain("Answer: Yes")
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return CrawlToken(self._limiter, path)
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async def download(
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self,
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path: PurePath,
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mtime: Optional[datetime] = None,
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redownload: Optional[Redownload] = None,
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on_conflict: Optional[OnConflict] = None,
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) -> Optional[DownloadToken]:
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log.explain_topic(f"Decision: Download {fmt_path(path)}")
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transformed_path = self._transformer.transform(path)
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if transformed_path is None:
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log.explain("Answer: No")
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return None
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fs_token = await self._output_dir.download(path, transformed_path, mtime, redownload, on_conflict)
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if fs_token is None:
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log.explain("Answer: No")
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return None
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log.explain("Answer: Yes")
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return DownloadToken(self._limiter, fs_token, path)
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async def _cleanup(self) -> None:
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log.explain_topic("Decision: Clean up files")
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if self.error_free:
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log.explain("No warnings or errors occurred during this run")
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log.explain("Answer: Yes")
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await self._output_dir.cleanup()
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else:
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log.explain("Warnings or errors occurred during this run")
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log.explain("Answer: No")
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async def run(self) -> None:
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"""
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Start the crawling process. Call this function if you want to use a
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crawler.
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"""
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with log.show_progress():
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self._output_dir.prepare()
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await self._run()
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await self._cleanup()
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@abstractmethod
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async def _run(self) -> None:
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"""
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Overwrite this function if you are writing a crawler.
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This function must not return before all crawling is complete. To crawl
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multiple things concurrently, asyncio.gather can be used.
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"""
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pass
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