clan-cli: clan_cli.locked_open -> clan_lib.locked_open

pkgs/clan-cli/clan_lib/locked_open/__init__.py

@@ -0,0 +1,33 @@
+import fcntl
+import json
+from collections.abc import Generator
+from contextlib import contextmanager
+from pathlib import Path
+from typing import Any
+
+from clan_cli.jsonrpc import ClanJSONEncoder
+
+from clan_lib.dirs import user_history_file
+
+
+@contextmanager
+def locked_open(filename: Path, mode: str = "r") -> Generator:
+    """
+    This is a context manager that provides an advisory write lock on the file specified by `filename` when entering the context, and releases the lock when leaving the context. The lock is acquired using the `fcntl` module's `LOCK_EX` flag, which applies an exclusive write lock to the file.
+    """
+    with filename.open(mode) as fd:
+        fcntl.flock(fd, fcntl.LOCK_EX)
+        yield fd
+        fcntl.flock(fd, fcntl.LOCK_UN)
+
+
+def write_history_file(data: Any) -> None:
+    with locked_open(user_history_file(), "w+") as f:
+        f.write(json.dumps(data, cls=ClanJSONEncoder, indent=4))
+
+
+def read_history_file() -> list[dict]:
+    with locked_open(user_history_file(), "r") as f:
+        content: str = f.read()
+        parsed: list[dict] = json.loads(content)
+        return parsed