Avoid panics when there are multiple failures on the same connection #1600
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zebra-network's Connection expects that `fail_with` is only called once per connection, but the overload handling code continues to process the current request after an overload error, potentially leading to further failures. Closes ZcashFoundation#1599
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.
teor2345
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C-bug
teor2345
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dconnolly
previously approved these changes
Jan 18, 2021
But keep the extra error information.
Thanks! I changed the PR to keep the panic. I think this change is good to merge now. If I end up doing some refactoring, I'll open a new PR. |
dconnolly
approved these changes
Jan 18, 2021
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Motivation
zebradkeeps panicking occasionally because it callsfail_withmultiple times on the same connection.We can fix one obvious cause of this bug, but we can't rule out correctly written code also encountering it.
Solution
fail_withthen continues to process the current requestThe code in this pull request has:
Review
@dconnolly is familiar with this bug.
Let's try to get this fix merged by the end of the sprint.
Related Issues
The original bug #1510
A partial initial fix #1531
Closes #1599
Follow Up Work
We should refactor this code so invariant violations like this are caught by the compiler, rather than happening under very specific network conditions - #1610
For bugs that we can't make into compilation errors, we should create better tests for the network code.