Raise a neater RuntimeError when the correct async deps are not installed.

CHANGELOG.md

@@ -7,7 +7,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ## Unreleased
 
 - Fix pool timeout to account for the total time spent retrying. (#823)
-- Fix synchronous TLS-in-TLS streams. (#840)
+- Raise a neater RuntimeError when the correct async deps are not installed. (#826)
+- Add support for synchronous TLS-in-TLS streams. (#840)
 
 ## 1.0.0 (October 6th, 2023)
 

httpcore/_async/connection_pool.py

@@ -326,6 +326,10 @@ async def aclose(self) -> None:
  self._requests = []
 
  async def __aenter__(self) -> "AsyncConnectionPool":
+ # Acquiring the pool lock here ensures that we have the
+ # correct dependencies installed as early as possible.
+ async with self._pool_lock:
+ pass
  return self
 
  async def __aexit__(

httpcore/_sync/connection_pool.py

@@ -326,6 +326,10 @@ def close(self) -> None:
  self._requests = []
 
  def __enter__(self) -> "ConnectionPool":
+ # Acquiring the pool lock here ensures that we have the
+ # correct dependencies installed as early as possible.
+ with self._pool_lock:
+ pass
  return self
 
  def __exit__(

httpcore/_synchronization.py

@@ -24,13 +24,23 @@ def current_async_library() -> str:
  try:
  import sniffio
  except ImportError: # pragma: nocover
-return "asyncio"
-
- environment = sniffio.current_async_library()
+environment = "asyncio"
+ else:
+environment = sniffio.current_async_library()
 
  if environment not in ("asyncio", "trio"): # pragma: nocover
  raise RuntimeError("Running under an unsupported async environment.")
 
+ if environment == "asyncio" and anyio is None: # pragma: nocover
+ raise RuntimeError(
+ "Running with asyncio requires installation of 'httpcore[asyncio]'."
+ )
+
+ if environment == "trio" and trio is None: # pragma: nocover
+ raise RuntimeError(
+ "Running with trio requires installation of 'httpcore[trio]'."
+ )
+
  return environment
 
 
@@ -45,16 +55,8 @@ def setup(self) -> None:
  """
  self._backend = current_async_library()
  if self._backend == "trio":
- if trio is None: # pragma: nocover
- raise RuntimeError(
- "Running with trio requires installation of 'httpcore[trio]'."
- )
  self._trio_lock = trio.Lock()
- else:
- if anyio is None: # pragma: nocover
- raise RuntimeError(
- "Running with asyncio requires installation of 'httpcore[asyncio]'."
- )
+ elif self._backend == "asyncio":
  self._anyio_lock = anyio.Lock()
 
  async def __aenter__(self) -> "AsyncLock":
@@ -63,7 +65,7 @@ async def __aenter__(self) -> "AsyncLock":
 
  if self._backend == "trio":
  await self._trio_lock.acquire()
-else:
+elif self._backend == "asyncio":
  await self._anyio_lock.acquire()
 
  return self
@@ -76,7 +78,7 @@ async def __aexit__(
  ) -> None:
  if self._backend == "trio":
  self._trio_lock.release()
-else:
+elif self._backend == "asyncio":
  self._anyio_lock.release()
 
 
@@ -91,16 +93,8 @@ def setup(self) -> None:
  """
  self._backend = current_async_library()
  if self._backend == "trio":
- if trio is None: # pragma: nocover
- raise RuntimeError(
- "Running with trio requires installation of 'httpcore[trio]'."
- )
  self._trio_event = trio.Event()
- else:
- if anyio is None: # pragma: nocover
- raise RuntimeError(
- "Running with asyncio requires installation of 'httpcore[asyncio]'."
- )
+ elif self._backend == "asyncio":
  self._anyio_event = anyio.Event()
 
  def set(self) -> None:
@@ -109,30 +103,20 @@ def set(self) -> None:
 
  if self._backend == "trio":
  self._trio_event.set()
-else:
+elif self._backend == "asyncio":
  self._anyio_event.set()
 
  async def wait(self, timeout: Optional[float] = None) -> None:
  if not self._backend:
  self.setup()
 
  if self._backend == "trio":
- if trio is None: # pragma: nocover
- raise RuntimeError(
- "Running with trio requires installation of 'httpcore[trio]'."
- )
-
  trio_exc_map: ExceptionMapping = {trio.TooSlowError: PoolTimeout}
  timeout_or_inf = float("inf") if timeout is None else timeout
  with map_exceptions(trio_exc_map):
  with trio.fail_after(timeout_or_inf):
  await self._trio_event.wait()
- else:
- if anyio is None: # pragma: nocover
- raise RuntimeError(
- "Running with asyncio requires installation of 'httpcore[asyncio]'."
- )
-
+ elif self._backend == "asyncio":
  anyio_exc_map: ExceptionMapping = {TimeoutError: PoolTimeout}
  with map_exceptions(anyio_exc_map):
  with anyio.fail_after(timeout):
@@ -151,20 +135,10 @@ def setup(self) -> None:
  """
  self._backend = current_async_library()
  if self._backend == "trio":
- if trio is None: # pragma: nocover
- raise RuntimeError(
- "Running with trio requires installation of 'httpcore[trio]'."
- )
-
  self._trio_semaphore = trio.Semaphore(
  initial_value=self._bound, max_value=self._bound
  )
- else:
- if anyio is None: # pragma: nocover
- raise RuntimeError(
- "Running with asyncio requires installation of 'httpcore[asyncio]'."
- )
-
+ elif self._backend == "asyncio":
  self._anyio_semaphore = anyio.Semaphore(
  initial_value=self._bound, max_value=self._bound
  )
@@ -175,13 +149,13 @@ async def acquire(self) -> None:
 
  if self._backend == "trio":
  await self._trio_semaphore.acquire()
-else:
+elif self._backend == "asyncio":
  await self._anyio_semaphore.acquire()
 
  async def release(self) -> None:
  if self._backend == "trio":
  self._trio_semaphore.release()
-else:
+elif self._backend == "asyncio":
  self._anyio_semaphore.release()
 
 
@@ -201,24 +175,14 @@ def __init__(self) -> None:
  self._backend = current_async_library()
 
  if self._backend == "trio":
- if trio is None: # pragma: nocover
- raise RuntimeError(
- "Running with trio requires installation of 'httpcore[trio]'."
- )
-
  self._trio_shield = trio.CancelScope(shield=True)
- else:
- if anyio is None: # pragma: nocover
- raise RuntimeError(
- "Running with asyncio requires installation of 'httpcore[asyncio]'."
- )
-
+ elif self._backend == "asyncio":
  self._anyio_shield = anyio.CancelScope(shield=True)
 
  def __enter__(self) -> "AsyncShieldCancellation":
  if self._backend == "trio":
  self._trio_shield.__enter__()
-else:
+elif self._backend == "asyncio":
  self._anyio_shield.__enter__()
  return self
 
@@ -230,7 +194,7 @@ def __exit__(
  ) -> None:
  if self._backend == "trio":
  self._trio_shield.__exit__(exc_type, exc_value, traceback)
-else:
+elif self._backend == "asyncio":
  self._anyio_shield.__exit__(exc_type, exc_value, traceback)