This fixes a crash that would occasionally occur when visiting profiles.
NdbTxn objects were being deinitialized on different threads from their
initialization, causing incorrect reference count decrements in thread-local
transaction dictionaries. This led to premature destruction of shared ndb_txn
C objects still in use by other tasks, resulting in use-after-free crashes.
The root cause is that Swift does not guarantee tasks resume on the same
thread after await suspension points, while NdbTxn's init/deinit rely on
thread-local storage to track inherited transaction reference counts.
This means that `NdbTxn` objects cannot be used in async functions, as
that may cause the garbage collector to deinitialize `NdbTxn` at the end
of such function, which may be running on a different thread at that
point, causing the issue explained above.
The fix in this case is to eliminate the `async` version of the
`NdbNoteLender.borrow` method, and update usages to utilize other
available methods.
Note: This is a rewrite of the fix in https://github.com/damus-io/damus/pull/3329
Note 2: This relates to the fix of an unreleased feature, so therefore no
changelog is needed.
Changelog-None
Co-authored-by: alltheseas <64376233+alltheseas@users.noreply.github.com>
Closes: https://github.com/damus-io/damus/issues/3327
Signed-off-by: Daniel D’Aquino <daniel@daquino.me>
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