From 7a046618f748c24ab05bd2adf683b8c24a72887b Mon Sep 17 00:00:00 2001
From: Tom Christie <tom@tomchristie.com>
Date: Fri, 27 Sep 2024 10:55:41 +0100
Subject: [PATCH] Drop `sniffio` requirement. (#3323)

---
 CHANGELOG.md              |  1 +
 httpx/_transports/asgi.py | 25 +++++++++++++++++++------
 httpx/_utils.py           | 17 ++---------------
 pyproject.toml            |  1 -
 4 files changed, 22 insertions(+), 22 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 25669250b5..50c5a5de83 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 * The deprecated `proxies` argument has now been removed.
 * The deprecated `app` argument has now been removed.
 * The `URL.raw` property has now been removed.
+* The `sniffio` project dependency has now been removed.
 
 ## 0.27.2 (27th August, 2024)
 
diff --git a/httpx/_transports/asgi.py b/httpx/_transports/asgi.py
index 8578d4aeff..2bc4efae0e 100644
--- a/httpx/_transports/asgi.py
+++ b/httpx/_transports/asgi.py
@@ -2,8 +2,6 @@
 
 import typing
 
-import sniffio
-
 from .._models import Request, Response
 from .._types import AsyncByteStream
 from .base import AsyncBaseTransport
@@ -28,15 +26,30 @@
 __all__ = ["ASGITransport"]
 
 
+def is_running_trio() -> bool:
+    try:
+        # sniffio is a dependency of trio.
+
+        # See https://github.com/python-trio/trio/issues/2802
+        import sniffio
+
+        if sniffio.current_async_library() == "trio":
+            return True
+    except ImportError:  # pragma: nocover
+        pass
+
+    return False
+
+
 def create_event() -> Event:
-    if sniffio.current_async_library() == "trio":
+    if is_running_trio():
         import trio
 
         return trio.Event()
-    else:
-        import asyncio
 
-        return asyncio.Event()
+    import asyncio
+
+    return asyncio.Event()
 
 
 class ASGIResponseStream(AsyncByteStream):
diff --git a/httpx/_utils.py b/httpx/_utils.py
index a9ece19438..cf7f5bcad5 100644
--- a/httpx/_utils.py
+++ b/httpx/_utils.py
@@ -11,8 +11,6 @@
 from pathlib import Path
 from urllib.request import getproxies
 
-import sniffio
-
 from ._types import PrimitiveData
 
 if typing.TYPE_CHECKING:  # pragma: no cover
@@ -289,29 +287,18 @@ def peek_filelike_length(stream: typing.Any) -> int | None:
 
 
 class Timer:
-    async def _get_time(self) -> float:
-        library = sniffio.current_async_library()
-        if library == "trio":
-            import trio
-
-            return trio.current_time()
-        else:
-            import asyncio
-
-            return asyncio.get_event_loop().time()
-
     def sync_start(self) -> None:
         self.started = time.perf_counter()
 
     async def async_start(self) -> None:
-        self.started = await self._get_time()
+        self.started = time.perf_counter()
 
     def sync_elapsed(self) -> float:
         now = time.perf_counter()
         return now - self.started
 
     async def async_elapsed(self) -> float:
-        now = await self._get_time()
+        now = time.perf_counter()
         return now - self.started
 
 
diff --git a/pyproject.toml b/pyproject.toml
index c4c188052e..2b83de5f12 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -32,7 +32,6 @@ dependencies = [
     "httpcore==1.*",
     "anyio",
     "idna",
-    "sniffio",
 ]
 dynamic = ["readme", "version"]