codekingpro/portable-devtools

1from __future__ import annotations2 3import threading4 5 6class _HTTP2ProbeCache:7    __slots__ = (8        "_lock",9        "_cache_locks",10        "_cache_values",11    )12 13    def __init__(self) -> None:14        self._lock = threading.Lock()15        self._cache_locks: dict[tuple[str, int], threading.RLock] = {}16        self._cache_values: dict[tuple[str, int], bool | None] = {}17 18    def acquire_and_get(self, host: str, port: int) -> bool | None:19        # By the end of this block we know that20        # _cache_[values,locks] is available.21        value = None22        with self._lock:23            key = (host, port)24            try:25                value = self._cache_values[key]26                # If it's a known value we return right away.27                if value is not None:28                    return value29            except KeyError:30                self._cache_locks[key] = threading.RLock()31                self._cache_values[key] = None32 33        # If the value is unknown, we acquire the lock to signal34        # to the requesting thread that the probe is in progress35        # or that the current thread needs to return their findings.36        key_lock = self._cache_locks[key]37        key_lock.acquire()38        try:39            # If the by the time we get the lock the value has been40            # updated we want to return the updated value.41            value = self._cache_values[key]42 43        # In case an exception like KeyboardInterrupt is raised here.44        except BaseException as e:  # Defensive:45            assert not isinstance(e, KeyError)  # KeyError shouldn't be possible.46            key_lock.release()47            raise48 49        return value50 51    def set_and_release(52        self, host: str, port: int, supports_http2: bool | None53    ) -> None:54        key = (host, port)55        key_lock = self._cache_locks[key]56        with key_lock:  # Uses an RLock, so can be locked again from same thread.57            if supports_http2 is None and self._cache_values[key] is not None:58                raise ValueError(59                    "Cannot reset HTTP/2 support for origin after value has been set."60                )  # Defensive: not expected in normal usage61 62        self._cache_values[key] = supports_http263        key_lock.release()64 65    def _values(self) -> dict[tuple[str, int], bool | None]:66        """This function is for testing purposes only. Gets the current state of the probe cache"""67        with self._lock:68            return {k: v for k, v in self._cache_values.items()}69 70    def _reset(self) -> None:71        """This function is for testing purposes only. Reset the cache values"""72        with self._lock:73            self._cache_locks = {}74            self._cache_values = {}75 76 77_HTTP2_PROBE_CACHE = _HTTP2ProbeCache()78 79set_and_release = _HTTP2_PROBE_CACHE.set_and_release80acquire_and_get = _HTTP2_PROBE_CACHE.acquire_and_get81_values = _HTTP2_PROBE_CACHE._values82_reset = _HTTP2_PROBE_CACHE._reset83 84__all__ = [85    "set_and_release",86    "acquire_and_get",87]88