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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 from version import paperdoorknob_version
17
18
19 _headers = {'User-Agent': f'paperdoorknob/{paperdoorknob_version} ' +
20 '(https://git.scottworley.com/paperdoorknob/)'}
21
22
23 class Fetcher(ABC):
24 @abstractmethod
25 def fetch(self, url: str) -> bytes:
26 raise NotImplementedError()
27
28
29 class _SessionFetcher(Fetcher):
30
31 def __init__(self, session: requests.Session, timeout: int) -> None:
32 self._session = session
33 self._timeout = timeout
34
35 def fetch(self, url: str) -> bytes:
36 with self._session.get(url, timeout=self._timeout, headers=_headers) as r:
37 r.raise_for_status()
38 return r.content
39
40
41 class _CachingFetcher(Fetcher):
42
43 def __init__(
44 self,
45 session: requests_cache.CachedSession,
46 timeout: int) -> None:
47 self._session = session
48 self._timeout = timeout
49 self._request_count = 0
50 self._cache_hit_count = 0
51
52 def fetch(self, url: str) -> bytes:
53 with self._session.get(url, timeout=self._timeout, headers=_headers) as r:
54 r.raise_for_status()
55 self._request_count += 1
56 self._cache_hit_count += int(r.from_cache)
57 return r.content
58
59 @property
60 def request_count(self) -> int:
61 return self._request_count
62
63 @property
64 def cache_hit_count(self) -> int:
65 return self._cache_hit_count
66
67
68 @contextmanager
69 def DirectFetcher(timeout: int) -> Iterator[_SessionFetcher]:
70 with requests.session() as session:
71 yield _SessionFetcher(session, timeout)
72
73
74 @contextmanager
75 def CachingFetcher(
76 cache_path: str,
77 timeout: int,
78 report_stream: IO[str] = stderr) -> Iterator[_CachingFetcher]:
79 with requests_cache.CachedSession(cache_path, cache_control=True) as session:
80 fetcher = _CachingFetcher(session, timeout)
81 yield fetcher
82 if fetcher.request_count > 0:
83 percent = 100.0 * fetcher.cache_hit_count / fetcher.request_count
84 print(
85 f"Fetch cache hits: {fetcher.cache_hit_count} ({percent:.1f}%)",
86 file=report_stream)
87
88
89 class FakeFetcher(Fetcher):
90
91 def __init__(self, resources: dict[str, bytes]) -> None:
92 self._resources = resources
93 self._fetch_count = 0
94
95 def fetch(self, url: str) -> bytes:
96 self._fetch_count += 1
97 if url not in self._resources:
98 raise requests.HTTPError("URL not found", url)
99 return self._resources[url]
100
101 def request_count(self) -> int:
102 return self._fetch_count