Updated

Scripts/reporter_lib/py38+/urllib3/http2/probe.py

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+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",
+]