The first bug fix is to resolve the race condition between goroutine
and channel on the same leases to be revoked. It's a classic mistake
in using Golang channel + goroutine. Please refer to
https://go.dev/doc/effective_go#channels
The second bug fix is to resolve the issue that etcd lessor may
continue to schedule checkpoint after stepping down the leader role.
Previously the SetConsistentIndex() is called during the apply workflow,
but it's outside the db transaction. If a commit happens between SetConsistentIndex
and the following apply workflow, and etcd crashes for whatever reason right
after the commit, then etcd commits an incomplete transaction to db.
Eventually etcd runs into the data inconsistency issue.
In this commit, we move the SetConsistentIndex into a txPostLockHook, so
it will be executed inside the transaction lock.
To avoid inconsistant behavior during cluster upgrade we are feature
gating persistance behind cluster version. This should ensure that
all cluster members are upgraded to v3.6 before changing behavior.
To allow backporting this fix to v3.5 we are also introducing flag
--experimental-enable-lease-checkpoint-persist that will allow for
smooth upgrade in v3.5 clusters with this feature enabled.
Current checkpointing mechanism is buggy. New checkpoints for any lease
are scheduled only until the first leader change. Added fix for that
and a test that will check it.
Thanks to this change:
- all the maps bucket -> buffer are indexed by int's instead of
string. No need to do: byte[] -> string -> hash conversion on each
access.
- buckets are strongly typed in backend/mvcc API.
While it appears that etcd is not vulnerable to CVE-2021-3121,
it is a good idea to update to the new generator so that new
vulnerable code isn't generated in any future APIs. Also, this
lays the issue to rest of whether there is any issue with
etcd and CVE-2021-3121.
