You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
88 lines
2.9 KiB
Python
88 lines
2.9 KiB
Python
from __future__ import annotations
|
|
|
|
import threading
|
|
|
|
|
|
class _HTTP2ProbeCache:
|
|
__slots__ = (
|
|
"_lock",
|
|
"_cache_locks",
|
|
"_cache_values",
|
|
)
|
|
|
|
def __init__(self) -> None:
|
|
self._lock = threading.Lock()
|
|
self._cache_locks: dict[tuple[str, int], threading.RLock] = {}
|
|
self._cache_values: dict[tuple[str, int], bool | None] = {}
|
|
|
|
def acquire_and_get(self, host: str, port: int) -> bool | None:
|
|
# By the end of this block we know that
|
|
# _cache_[values,locks] is available.
|
|
value = None
|
|
with self._lock:
|
|
key = (host, port)
|
|
try:
|
|
value = self._cache_values[key]
|
|
# If it's a known value we return right away.
|
|
if value is not None:
|
|
return value
|
|
except KeyError:
|
|
self._cache_locks[key] = threading.RLock()
|
|
self._cache_values[key] = None
|
|
|
|
# If the value is unknown, we acquire the lock to signal
|
|
# to the requesting thread that the probe is in progress
|
|
# or that the current thread needs to return their findings.
|
|
key_lock = self._cache_locks[key]
|
|
key_lock.acquire()
|
|
try:
|
|
# If the by the time we get the lock the value has been
|
|
# updated we want to return the updated value.
|
|
value = self._cache_values[key]
|
|
|
|
# In case an exception like KeyboardInterrupt is raised here.
|
|
except BaseException as e: # Defensive:
|
|
assert not isinstance(e, KeyError) # KeyError shouldn't be possible.
|
|
key_lock.release()
|
|
raise
|
|
|
|
return value
|
|
|
|
def set_and_release(
|
|
self, host: str, port: int, supports_http2: bool | None
|
|
) -> None:
|
|
key = (host, port)
|
|
key_lock = self._cache_locks[key]
|
|
with key_lock: # Uses an RLock, so can be locked again from same thread.
|
|
if supports_http2 is None and self._cache_values[key] is not None:
|
|
raise ValueError(
|
|
"Cannot reset HTTP/2 support for origin after value has been set."
|
|
) # Defensive: not expected in normal usage
|
|
|
|
self._cache_values[key] = supports_http2
|
|
key_lock.release()
|
|
|
|
def _values(self) -> dict[tuple[str, int], bool | None]:
|
|
"""This function is for testing purposes only. Gets the current state of the probe cache"""
|
|
with self._lock:
|
|
return {k: v for k, v in self._cache_values.items()}
|
|
|
|
def _reset(self) -> None:
|
|
"""This function is for testing purposes only. Reset the cache values"""
|
|
with self._lock:
|
|
self._cache_locks = {}
|
|
self._cache_values = {}
|
|
|
|
|
|
_HTTP2_PROBE_CACHE = _HTTP2ProbeCache()
|
|
|
|
set_and_release = _HTTP2_PROBE_CACHE.set_and_release
|
|
acquire_and_get = _HTTP2_PROBE_CACHE.acquire_and_get
|
|
_values = _HTTP2_PROBE_CACHE._values
|
|
_reset = _HTTP2_PROBE_CACHE._reset
|
|
|
|
__all__ = [
|
|
"set_and_release",
|
|
"acquire_and_get",
|
|
]
|