Introduces `FLUSH HASHICORP_KEY_MANAGEMENT_CACHE` command to flush the
cached keys in the HashiCorp Key Management plugin, enabling rotation of
encryption keys without needing to restart the server.
The new `INFORMATION_SCHEMA.HASHICORP_KEY_MANAGEMENT_CACHE` table lists
the key id and key version from the latest version cache. The table's
content can be viewed using `SHOW HASHICORP_KEY_MANAGEMENT_CACHE` or
queried directly.
Executing the `FLUSH` command requires `RELOAD` privilege and access to
INFORMATION_SCHEMA table requires `PROCESS` privilege.
Bugfix (squashed):
MDEV-38111: SIGSEGV when multiple servers use the same Vault KV storage for encrypted tables
Problem:
A data race between InnoDB background threads reading the cached keys
and the thread executing FLUSH command clearing it without acquiring
a lock. This non-synchronized memory write caused InnoDB threads that
were concurrently reading the cache to access freed memory, leading to
a crash.
Fix:
Acquire the lock before clearing the latest version cahce. This
ensures the cache clearing operation is serialized, preventing
concurrent access and resolving the data race.
d936d36d4f