Initial commit

venv/Lib/site-packages/uvicorn/_subprocess.py

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+"""
+Some light wrappers around Python's multiprocessing, to deal with cleanly
+starting child processes.
+"""
+from __future__ import annotations
+
+import multiprocessing
+import os
+import sys
+from multiprocessing.context import SpawnProcess
+from socket import socket
+from typing import Callable, Optional
+
+from uvicorn.config import Config
+
+multiprocessing.allow_connection_pickling()
+spawn = multiprocessing.get_context("spawn")
+
+
+def get_subprocess(
+    config: Config,
+    target: Callable[..., None],
+    sockets: list[socket],
+) -> SpawnProcess:
+    """
+    Called in the parent process, to instantiate a new child process instance.
+    The child is not yet started at this point.
+
+    * config - The Uvicorn configuration instance.
+    * target - A callable that accepts a list of sockets. In practice this will
+               be the `Server.run()` method.
+    * sockets - A list of sockets to pass to the server. Sockets are bound once
+                by the parent process, and then passed to the child processes.
+    """
+    # We pass across the stdin fileno, and reopen it in the child process.
+    # This is required for some debugging environments.
+    stdin_fileno: Optional[int]
+    try:
+        stdin_fileno = sys.stdin.fileno()
+    except OSError:
+        stdin_fileno = None
+
+    kwargs = {
+        "config": config,
+        "target": target,
+        "sockets": sockets,
+        "stdin_fileno": stdin_fileno,
+    }
+
+    return spawn.Process(target=subprocess_started, kwargs=kwargs)
+
+
+def subprocess_started(
+    config: Config,
+    target: Callable[..., None],
+    sockets: list[socket],
+    stdin_fileno: int | None,
+) -> None:
+    """
+    Called when the child process starts.
+
+    * config - The Uvicorn configuration instance.
+    * target - A callable that accepts a list of sockets. In practice this will
+               be the `Server.run()` method.
+    * sockets - A list of sockets to pass to the server. Sockets are bound once
+                by the parent process, and then passed to the child processes.
+    * stdin_fileno - The file number of sys.stdin, so that it can be reattached
+                     to the child process.
+    """
+    # Re-open stdin.
+    if stdin_fileno is not None:
+        sys.stdin = os.fdopen(stdin_fileno)
+
+    # Logging needs to be setup again for each child.
+    config.configure_logging()
+
+    # Now we can call into `Server.run(sockets=sockets)`
+    target(sockets=sockets)