Synchronise token refreshes

The application can be run in a multi-threaded server, leading to a
situation where the multiple threads attempt to get a new JWT using
the exact same refresh token.

This synchronises the various threads ensuring only a single thread is
able to retrieve the new JWT that all the rest of the threads then
use.

1 files changed, 23 insertions, 1 deletions

diff --git a/gn2/wqflask/oauth2/session.py b/gn2/wqflask/oauth2/session.py
index eec48a7f..92181ccf 100644
--- a/gn2/wqflask/oauth2/session.py
+++ b/gn2/wqflask/oauth2/session.py
@@ -22,6 +22,7 @@ class SessionInfo(TypedDict):
     user_agent: str
     ip_addr: str
     masquerade: Optional[UserDetails]
+    refreshing_token: bool
 
 __SESSION_KEY__ = "GN::2::session_info" # Do not use this outside this module!!
 
@@ -61,7 +62,8 @@ def session_info() -> SessionInfo:
             "user_agent": request.headers.get("User-Agent"),
             "ip_addr": request.environ.get("HTTP_X_FORWARDED_FOR",
                                            request.remote_addr),
-            "masquerading": None
+            "masquerading": None,
+            "token_refreshing": False
         }))
 
 
@@ -102,3 +104,23 @@ def unset_masquerading():
         "user": the_session["masquerading"],
         "masquerading": None
     })
+
+
+def toggle_token_refreshing():
+    """Toggle the state of the token_refreshing variable."""
+    _session = session_info()
+    return save_session_info({
+        **_session,
+        "token_refreshing": not _session.get("token_refreshing", False)})
+
+
+def is_token_expired():
+    """Check whether the token is expired."""
+    return user_token().either(
+        lambda _no_token: False,
+        lambda token: datetime.now().timestamp() > token["expires_at"])
+
+
+def is_token_refreshing():
+    """Returns whether the token is being refreshed or not."""
+    return session_info().get("token_refreshing", False)