feat: add daemon module with cross-platform process lifecycle

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/jianda_proxy/daemon.py

@@ -0,0 +1,129 @@
+import os
+import sys
+import time
+import signal
+from jianda_proxy.config import get_pid_path
+
+
+def read_pid():
+    path = get_pid_path()
+    if not os.path.exists(path):
+        return None
+    try:
+        with open(path) as f:
+            return int(f.read().strip())
+    except (ValueError, OSError):
+        return None
+
+
+def write_pid(pid):
+    path = get_pid_path()
+    os.makedirs(os.path.dirname(path), exist_ok=True)
+    with open(path, "w") as f:
+        f.write(str(pid))
+
+
+def remove_pid():
+    path = get_pid_path()
+    if os.path.exists(path):
+        os.remove(path)
+
+
+def is_process_alive(pid):
+    if os.name == "nt":
+        import ctypes
+        import ctypes.wintypes
+
+        kernel32 = ctypes.windll.kernel32
+        PROCESS_QUERY_LIMITED_INFORMATION = 0x1000
+        STILL_ACTIVE = 259
+        handle = kernel32.OpenProcess(PROCESS_QUERY_LIMITED_INFORMATION, False, pid)
+        if not handle:
+            return False
+        try:
+            exit_code = ctypes.wintypes.DWORD()
+            kernel32.GetExitCodeProcess(handle, ctypes.byref(exit_code))
+            return exit_code.value == STILL_ACTIVE
+        finally:
+            kernel32.CloseHandle(handle)
+    else:
+        try:
+            os.kill(pid, 0)
+            return True
+        except ProcessLookupError:
+            return False
+        except PermissionError:
+            return True
+
+
+def is_running():
+    pid = read_pid()
+    if pid is None:
+        return False
+    return is_process_alive(pid)
+
+
+def stop_daemon():
+    pid = read_pid()
+    if pid is None:
+        return "not_running"
+
+    if not is_process_alive(pid):
+        remove_pid()
+        return "not_running"
+
+    if os.name == "nt":
+        os.system(f"taskkill /PID {pid} /T")
+    else:
+        try:
+            os.kill(pid, signal.SIGTERM)
+        except ProcessLookupError:
+            remove_pid()
+            return "stopped"
+
+    for _ in range(6):
+        time.sleep(0.5)
+        if not is_process_alive(pid):
+            remove_pid()
+            return "stopped"
+
+    if os.name == "nt":
+        os.system(f"taskkill /F /PID {pid} /T")
+    else:
+        try:
+            os.kill(pid, signal.SIGKILL)
+        except ProcessLookupError:
+            pass
+
+    remove_pid()
+    return "stopped"
+
+
+def get_status():
+    pid = read_pid()
+    if pid is None or not is_process_alive(pid):
+        return {"running": False, "pid": None}
+    return {"running": True, "pid": pid}
+
+
+def daemonize():
+    if os.name == "nt":
+        import subprocess
+
+        creation_flags = subprocess.CREATE_NEW_PROCESS_GROUP | subprocess.DETACHED_PROCESS
+        subprocess.Popen(
+            [sys.executable] + sys.argv + ["--_daemon_child"],
+            creationflags=creation_flags,
+            close_fds=True,
+            stdin=subprocess.DEVNULL,
+            stdout=subprocess.DEVNULL,
+            stderr=subprocess.DEVNULL,
+        )
+    else:
+        pid = os.fork()
+        if pid > 0:
+            os._exit(0)
+        os.setsid()
+        pid = os.fork()
+        if pid > 0:
+            os._exit(0)