Stop panicking when fail_with is called twice on a connection

We can't rule out the connection state changing between the state checks
and any eventual failures, particularly in the presence of async code.

So we turn this panic into a warning.
This commit is contained in:
teor 2021-01-15 16:26:34 +10:00 committed by Deirdre Connolly
parent 44c8fafc29
commit a6c1cd3c35
1 changed files with 26 additions and 2 deletions

View File

@ -511,8 +511,32 @@ where
.0
.lock()
.expect("mutex should be unpoisoned");
if guard.is_some() {
panic!("called fail_with on already-failed connection state");
if let Some(original_error) = guard.clone() {
// A failed connection might experience further errors if we:
// 1. concurrently process two different messages
// 2. check for a failed state for the second message
// 3. fail the connection due to the first message
// 4. fail the connection due to the second message
//
// It's not clear:
// * if this is actually a bug,
// * how we can modify Zebra to avoid it.
//
// This warning can also happen due to these bugs:
// * we mark a connection as failed without using fail_with
// * we call fail_with without checking for a failed connection
// state
//
// See the original bug #1510, the initial fix #1531, and the later
// bug #1599.
warn!(?original_error,
new_error = ?e,
connection_state = ?self.state,
client_receiver = ?self.client_rx,
"calling fail_with on already-failed connection state: ignoring new error");
// we don't need to clean up the connection, the original call to
// fail_with does that
return;
} else {
*guard = Some(e);
}