feat: add NetBox plugin store

netbox_plugin/netbox_plugin_store/locking.py

@@ -0,0 +1,65 @@
+from __future__ import annotations
+
+import os
+import time
+from pathlib import Path
+
+
+class LockTimeoutError(TimeoutError):
+    pass
+
+
+class FileLock:
+    """Small cross-platform inter-process exclusive lock."""
+
+    def __init__(self, path: Path, timeout: float = 30):
+        self.path = Path(path)
+        self.timeout = timeout
+        self._file = None
+
+    def __enter__(self):
+        self.path.parent.mkdir(parents=True, exist_ok=True)
+        self._file = self.path.open("a+b")
+        deadline = time.monotonic() + self.timeout
+        while True:
+            try:
+                self._acquire()
+                return self
+            except (BlockingIOError, OSError):
+                if time.monotonic() >= deadline:
+                    self._file.close()
+                    self._file = None
+                    raise LockTimeoutError("Another plugin lifecycle operation is still running.")
+                time.sleep(0.1)
+
+    def _acquire(self) -> None:
+        if os.name == "nt":
+            import msvcrt
+
+            self._file.seek(0)
+            if self._file.read(1) == b"":
+                self._file.write(b"\0")
+                self._file.flush()
+            self._file.seek(0)
+            msvcrt.locking(self._file.fileno(), msvcrt.LK_NBLCK, 1)
+        else:
+            import fcntl
+
+            fcntl.flock(self._file.fileno(), fcntl.LOCK_EX | fcntl.LOCK_NB)
+
+    def __exit__(self, exc_type, exc, tb):
+        if self._file is None:
+            return
+        try:
+            if os.name == "nt":
+                import msvcrt
+
+                self._file.seek(0)
+                msvcrt.locking(self._file.fileno(), msvcrt.LK_UNLCK, 1)
+            else:
+                import fcntl
+
+                fcntl.flock(self._file.fileno(), fcntl.LOCK_UN)
+        finally:
+            self._file.close()
+            self._file = None