The suggested pattern for Raft proposals is that they be retried
periodically until they succeed. This turns out to be an issue
when a leader cannot commit entries because the leader will continue
to append re-proposed entries to its log without committing anything.
This can result in the uncommitted tail of a leader's log growing
without bound until it is able to commit entries.
This change add a safeguard to protect against this case where a
leader's log can grow without bound during loss of quorum scenarios.
It does so by introducing a new, optional ``MaxUncommittedEntriesSize
configuration. This config limits the max aggregate size of uncommitted
entries that may be appended to a leader's log. Once this limit
is exceeded, proposals will begin to return ErrProposalDropped
errors.
See cockroachdb/cockroach#27772
The error message is different to the condition it checks for. This PR
modifies the error message accordingly.
Closes#9717.
Signed-off-by: Kostas Christidis <kostas@christidis.io>
Save the snapshot index to the WAL before saving the snapshot to the
filesystem. This ensures that we'll only ever call wal.Open with a
snapshot that was previously saved to the WAL.
Travis claimed errors of gosimple like below
(https://travis-ci.org/coreos/etcd/jobs/208098545):
gosimple checking failed:
contrib/raftexample/raftexample_test.go:78:6: should write erri := <-clus.errorC[i] instead of erri, _ := <-clus.errorC[i]
contrib/raftexample/raftexample_test.go:114:10: should write err := <-eC instead of err, _ := <-eC
This commit fixes the errors.
From (systemd NetworkTarget description)[https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget/]:
```
[...]since the shutdown ordering of units in systemd is the reverse of the startup ordering, any unit that is order After=network.target can be sure that it is stopped before the network is shut down if the system is powered off. This allows services to cleanly terminate connections before going down, instead of abruptly losing connectivity for ongoing connections, leaving them in an undefined state.[...]
```
