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[paperdoorknob] / fetch.py
1 # paperdoorknob: Print glowfic
2 #
3 # This program is free software: you can redistribute it and/or modify it
4 # under the terms of the GNU General Public License as published by the
5 # Free Software Foundation, version 3.
6
7
8 from abc import ABC, abstractmethod
9 from contextlib import contextmanager
10 from sys import stderr
11 from typing import IO, Iterator
12
13 import requests
14 import requests_cache
15
16
17 _headers = {
18 'User-Agent': 'paperdoorknob/0.0.1 (https://git.scottworley.com/paperdoorknob/)'}
19
20
21 class Fetcher(ABC):
22 @abstractmethod
23 def fetch(self, url: str) -> bytes:
24 raise NotImplementedError()
25
26
27 class _SessionFetcher(Fetcher):
28
29 def __init__(self, session: requests.Session, timeout: int) -> None:
30 self._session = session
31 self._timeout = timeout
32
33 def fetch(self, url: str) -> bytes:
34 with self._session.get(url, timeout=self._timeout, headers=_headers) as r:
35 r.raise_for_status()
36 return r.content
37
38
39 class _CachingFetcher(Fetcher):
40
41 def __init__(
42 self,
43 session: requests_cache.CachedSession,
44 timeout: int) -> None:
45 self._session = session
46 self._timeout = timeout
47 self._request_count = 0
48 self._cache_hit_count = 0
49
50 def fetch(self, url: str) -> bytes:
51 with self._session.get(url, timeout=self._timeout, headers=_headers) as r:
52 r.raise_for_status()
53 self._request_count += 1
54 self._cache_hit_count += int(r.from_cache)
55 return r.content
56
57 @property
58 def request_count(self) -> int:
59 return self._request_count
60
61 @property
62 def cache_hit_count(self) -> int:
63 return self._cache_hit_count
64
65
66 @contextmanager
67 def DirectFetcher(timeout: int) -> Iterator[_SessionFetcher]:
68 with requests.session() as session:
69 yield _SessionFetcher(session, timeout)
70
71
72 @contextmanager
73 def CachingFetcher(
74 cache_path: str,
75 timeout: int,
76 report_stream: IO[str] = stderr) -> Iterator[_CachingFetcher]:
77 with requests_cache.CachedSession(cache_path, cache_control=True) as session:
78 fetcher = _CachingFetcher(session, timeout)
79 yield fetcher
80 if fetcher.request_count > 0:
81 percent = 100.0 * fetcher.cache_hit_count / fetcher.request_count
82 print(
83 f"Fetch cache hits: {fetcher.cache_hit_count} ({percent:.1f}%)",
84 file=report_stream)
85
86
87 class FakeFetcher(Fetcher):
88
89 def __init__(self, resources: dict[str, bytes]) -> None:
90 self._resources = resources
91 self._fetch_count = 0
92
93 def fetch(self, url: str) -> bytes:
94 self._fetch_count += 1
95 if url not in self._resources:
96 raise requests.HTTPError("URL not found", url)
97 return self._resources[url]
98
99 def request_count(self) -> int:
100 return self._fetch_count