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"""
Scheduler queues
"""
from __future__ import annotations
import marshal
import pickle
from pathlib import Path
from typing import TYPE_CHECKING, Any
from queuelib import queue
from scrapy.utils.request import request_from_dict
if TYPE_CHECKING:
from collections.abc import Callable
from os import PathLike
# typing.Self requires Python 3.11
from typing_extensions import Self
from scrapy import Request
from scrapy.crawler import Crawler
def _with_mkdir(queue_class: type[queue.BaseQueue]) -> type[queue.BaseQueue]:
class DirectoriesCreated(queue_class): # type: ignore[valid-type,misc]
def __init__(self, path: str | PathLike, *args: Any, **kwargs: Any):
dirname = Path(path).parent
if not dirname.exists():
dirname.mkdir(parents=True, exist_ok=True)
super().__init__(path, *args, **kwargs)
return DirectoriesCreated
def _serializable_queue(
queue_class: type[queue.BaseQueue],
serialize: Callable[[Any], bytes],
deserialize: Callable[[bytes], Any],
) -> type[queue.BaseQueue]:
class SerializableQueue(queue_class): # type: ignore[valid-type,misc]
def push(self, obj: Any) -> None:
s = serialize(obj)
super().push(s)
def pop(self) -> Any | None:
s = super().pop()
if s:
return deserialize(s)
return None
def peek(self) -> Any | None:
"""Returns the next object to be returned by :meth:`pop`,
but without removing it from the queue.
Raises :exc:`NotImplementedError` if the underlying queue class does
not implement a ``peek`` method, which is optional for queues.
"""
try:
s = super().peek()
except AttributeError as ex:
raise NotImplementedError(
"The underlying queue class does not implement 'peek'"
) from ex
if s:
return deserialize(s)
return None
return SerializableQueue
def _scrapy_serialization_queue(
queue_class: type[queue.BaseQueue],
) -> type[queue.BaseQueue]:
class ScrapyRequestQueue(queue_class): # type: ignore[valid-type,misc]
def __init__(self, crawler: Crawler, key: str):
self.spider = crawler.spider
super().__init__(key)
@classmethod
def from_crawler(
cls, crawler: Crawler, key: str, *args: Any, **kwargs: Any
) -> Self:
return cls(crawler, key)
def push(self, request: Request) -> None:
request_dict = request.to_dict(spider=self.spider)
super().push(request_dict)
def pop(self) -> Request | None:
request = super().pop()
if not request:
return None
return request_from_dict(request, spider=self.spider)
def peek(self) -> Request | None:
"""Returns the next object to be returned by :meth:`pop`,
but without removing it from the queue.
Raises :exc:`NotImplementedError` if the underlying queue class does
not implement a ``peek`` method, which is optional for queues.
"""
request = super().peek()
if not request:
return None
return request_from_dict(request, spider=self.spider)
return ScrapyRequestQueue
def _scrapy_non_serialization_queue(
queue_class: type[queue.BaseQueue],
) -> type[queue.BaseQueue]:
class ScrapyRequestQueue(queue_class): # type: ignore[valid-type,misc]
@classmethod
def from_crawler(cls, crawler: Crawler, *args: Any, **kwargs: Any) -> Self:
return cls()
def peek(self) -> Any | None:
"""Returns the next object to be returned by :meth:`pop`,
but without removing it from the queue.
Raises :exc:`NotImplementedError` if the underlying queue class does
not implement a ``peek`` method, which is optional for queues.
"""
try:
s = super().peek()
except AttributeError as ex:
raise NotImplementedError(
"The underlying queue class does not implement 'peek'"
) from ex
return s
return ScrapyRequestQueue
def _pickle_serialize(obj: Any) -> bytes:
try:
return pickle.dumps(obj, protocol=4)
# Both pickle.PicklingError and AttributeError can be raised by pickle.dump(s)
# TypeError is raised from parsel.Selector
except (pickle.PicklingError, AttributeError, TypeError) as e:
raise ValueError(str(e)) from e
# queue.*Queue aren't subclasses of queue.BaseQueue
_PickleFifoSerializationDiskQueue = _serializable_queue(
_with_mkdir(queue.FifoDiskQueue), # type: ignore[arg-type]
_pickle_serialize,
pickle.loads,
)
_PickleLifoSerializationDiskQueue = _serializable_queue(
_with_mkdir(queue.LifoDiskQueue), # type: ignore[arg-type]
_pickle_serialize,
pickle.loads,
)
_MarshalFifoSerializationDiskQueue = _serializable_queue(
_with_mkdir(queue.FifoDiskQueue), # type: ignore[arg-type]
marshal.dumps,
marshal.loads,
)
_MarshalLifoSerializationDiskQueue = _serializable_queue(
_with_mkdir(queue.LifoDiskQueue), # type: ignore[arg-type]
marshal.dumps,
marshal.loads,
)
# public queue classes
PickleFifoDiskQueue = _scrapy_serialization_queue(_PickleFifoSerializationDiskQueue)
PickleLifoDiskQueue = _scrapy_serialization_queue(_PickleLifoSerializationDiskQueue)
MarshalFifoDiskQueue = _scrapy_serialization_queue(_MarshalFifoSerializationDiskQueue)
MarshalLifoDiskQueue = _scrapy_serialization_queue(_MarshalLifoSerializationDiskQueue)
FifoMemoryQueue = _scrapy_non_serialization_queue(queue.FifoMemoryQueue) # type: ignore[arg-type]
LifoMemoryQueue = _scrapy_non_serialization_queue(queue.LifoMemoryQueue) # type: ignore[arg-type]
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