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d9a277453e
query_processor::prepare() could race with prepared statement invalidation: after loading from the prepared cache, we converted the cached object to a checked weak pointer and then continued asynchronous work (including error-injection waitpoints). If invalidation happened in that window, the weak handle could no longer be promoted and the prepare path could fail nondeterministically. This change keeps a strong cache entry reference alive across the whole critical section in prepare() by using a pinned cache accessor (get_pinned()), and only deriving the weak handle while the entry is pinned. This removes the lifetime gap without adding retry loops. Test coverage was extended in test/cluster/test_prepare_race.py: - reproduces the invalidation-during-prepare window with injection, - verifies prepare completes successfully, - then invalidates again and executes the same stale client prepared object, - confirms the driver transparently re-requests/re-prepares and execution succeeds. This change introduces: - no behavior change for normal prepare flow besides stronger lifetime guarantees, - no new protocol semantics, - preserves existing cache invalidation logic, - adds explicit cluster-level regression coverage for both the race and driver reprepare path. - pushes the re prepare operation twards the driver, the server will return unprepared error for the first time and the driver will have to re prepare during execution stage Fixes: https://github.com/scylladb/scylladb/issues/27657 Backport to active branches recommended: No node crash, but user-visible PREPARE failures under rare schema-invalidation race; low-risk timeout-bounded retry improves robustness. Closes scylladb/scylladb#28952 * github.com:scylladb/scylladb: transport/messages: hold pinned prepared entry in PREPARE result cql3: pin prepared cache entry in prepare() to avoid invalid weak handle race