Removed the fields consistentIdx and consistentTerm from struct EtcdServer,
and added applyingIndex and applyingTerm into struct consistentIndex in
package cindex. We may remove the two fields completely if we decide to
remove the OnPreCommitUnsafe, and it will depend on the performance test
result.
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.
Problem: Defrag was implemented before custom bolt options were added.
Currently defrag doesn't restore backend options.
For example BackendFreelistType will be unset after defrag.
Solution: save bolt db options and use them in defrag.
The io/ioutil package has been deprecated as of Go 1.16, see
https://golang.org/doc/go1.16#ioutil. This commit replaces the existing
io/ioutil functions with their new definitions in io and os packages.
Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>
