build(deps): bump async-raft from v0.6.2-alpha.14 to v0.6.2-alpha.16

[dependabot]

Bumps async-raft from v0.6.2-alpha.14 to v0.6.2-alpha.16.

Changelog

Sourced from async-raft's changelog.

changelog

This changelog follows the patterns described here: https://keepachangelog.com/en/1.0.0/.

[unreleased]

fixed

• Fixed 122 a conflict is expected even when appending empty enties.

  append_entries should get a response with non-none ConflictOpt even if the entries in the message is empty. Otherwise if no conflict is found the leader will never be able to sync logs to a new added NonVoter, until a next log, is proposed on the leader.

• Fixed 117 last_applied should be updated only when logs actually applied.

async-raft 0.6.1

fixed

• Fixed #105 where function set_target_state missing else condition.
• Fixed #106 which ensures that counting of replicas to determine a new commit value only considers entries replicated as part of the current term.
• Fixed a bug where NonVoter nodes could be restarted and come back as voting members.

async-raft 0.6.0

The big news for this release is that we are now based on Tokio 1.0! Big shoutout to @​xu-cheng for doing all of the heavy lifting for the Tokio 1.0 update, along with many other changes which are part of this release.

It is important to note that 0.6.0 does include two breaking changes from 0.5: the new RaftStorage::ShutdownError associated type, and Tokio 1.0. Both of these changes are purely code related, and it is not expected that they will negatively impact running systems.

changed

• Updated to Tokio 1.0!
• BREAKING: this introduces a RaftStorage::ShutdownError associated type. This allows for the Raft system to differentiate between fatal storage errors which should cause the system to shutdown vs errors which should be propagated back to the client for application specific error handling. These changes only apply to the RaftStorage::apply_entry_to_state_machine method.
• A small change to Raft startup semantics. When a node comes online and successfully recovers state (the node was already part of a cluster), the node will start with a 30 second election timeout, ensuring that it does not disrupt a running cluster.
• #89 removes the Debug bounds requirement on the AppData & AppDataResponse types.
• The Raft type can now be cloned. The clone is very cheap and helps to facilitate async workflows while feeding client requests and Raft RPCs into the Raft instance.
• The Raft.shutdown interface has been changed slightly. Instead of returning a JoinHandle, the method is now async and simply returns a result.
• The ClientWriteError::ForwardToLeader error variant has been modified slightly. It now exposes the data (generic type D of the type) of the original client request directly. This ensures that the data can actually be used for forwarding, if that is what the parent app wants to do.
• Implemented #12. This is a pretty old issue and a pretty solid optimization. The previous implementation of this algorithm would go to storage (typically disk) for every process of replicating entries to the state machine. Now, we are caching entries as they come in from the leader, and using only the cache as the source of data. There are a few simple measures needed to ensure this is correct, as the leader entry replication protocol takes care of most of the work for us in this case.
• Updated / clarified the interface for log compaction. See the guide or the updated do_log_compaction method docs for more details.

added

• #97 adds the new Raft.current_leader method. This is a convenience method which builds upon the Raft metrics system to quickly and easily identify the current cluster leader.

fixed

• Fixed #98 where heartbeats were being passed along into the log consistency check algorithm. This had the potential to cause a Raft node to go into shutdown under some circumstances.
• Fixed a bug where the timestamp of the last received heartbeat from a leader was not being stored, resulting in degraded cluster stability under some circumstances.

memstore 0.2.0

changed

• Updated async-raft dependency to 0.6.0 & updated storage interface as needed.

fixed

... (truncated)

Commits

• ca6ba30 doc: update bug fixed in README
• 9540c90 fix: when append-entries, deleting entries after prev-log-id causes committed...
• 05ecf7e doc: update fixed bugs in README
• 6d53aa1 fix: too many(50) inconsistent log should not live lock append-entries
• ab6689d feature: RaftStore::get_last_log_id() to get the last known log id in log or ...
• 9086044 refactor: make lagging loop a method instead of a class
• 9d5d28e refactor: make line-rate loop a method instead of a class
• 1cbf54a refactor: change xxx_index, xxx_term to a LogId in replication/mod.rs
• 8f464a6 test: a delete-log operation must be with a half open range
• 1c46a71 change: RaftStore::get_log_entries use range as arg; add try_get_log_entry() ...
• Additional commits viewable in compare view

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