Py-xline

:beetle: Bug Fixes

- [Bug]: Fixed a bug causing panic during the update node process. [issue 531](https://github.com/xline-kv/Xline/issues/531)
- [Bug]: Fixed a bug causing panic during the CI process due to reading state. [issue 527](https://github.com/xline-kv/Xline/issues/527)
- [Bug]: Fixed a bug in the previous version where immediately shutting down the cluster after executing "member add" would cause the leader to fail to shut down properly. [issue 526](https://github.com/xline-kv/Xline/issues/526)
- [Bug]: Fixed an issue in TXN where the conflict detection process would ignore the key of child requests. [issue 470](https://github.com/xline-kv/Xline/issues/470)
- [Bug]: Fixed a panic issue in watch caused by closing the channel. [issue 370](https://github.com/xline-kv/Xline/issues/370)
- pr 576: [fix: fix ce event tx logs](https://github.com/xline-kv/Xline/pull/576)
- pr 556: [[Fix]: kv update channel panic](https://github.com/xline-kv/Xline/pull/556)
- [Bug]: Changed the calculation method for the cluster version to a hash to avoid misjudgments. [pr 590](https://github.com/xline-kv/Xline/pull/590)
- [Bug]: Fixed a bug that caused the compact operation to behave abnormally in specific scenarios. [pr 570](https://github.com/xline-kv/Xline/pull/570)


🛠️ Refactor

- [Refactor]: Refactored the implementation of the Curp client, reducing code complexity. ：
- pr 582: [Refactor/curp client tests suits](https://github.com/xline-kv/Xline/pull/582)
- pr 584: [Refactor/curp client retry](https://github.com/xline-kv/Xline/pull/584)
- pr 585: [Refactor/replace curp client](https://github.com/xline-kv/Xline/pull/585)
- [Refactor]: Removed some command-related data structures from xline and xline-client. [pr 469](https://github.com/xline-kv/Xline/pull/469)

⭐ New Features
- [Feature]: Add membership change mechanism for CUPR consensus Protocol (Read design doc [306](https://github.com/xline-kv/Xline/issues/306) for more details)
- [Feature]: Implement cluster server and client [464](https://github.com/xline-kv/Xline/pull/464), [#465](https://github.com/xline-kv/Xline/pull/465)
- [Feature]: Implement the graceful shutdown feature.
- [Feature]: Implement the xlinctl to communicate with the xline cluster. Currently, the xlinectl covers functionalities:
- Compaction and member command: Implemented in pr [484](https://github.com/xline-kv/Xline/pull/484)
- Txn, watch and lock command: Implemented in pr [428](https://github.com/xline-kv/Xline/pull/484)
- Role command: Implemented in pr [427](https://github.com/xline-kv/Xline/pull/427)
- User command: Implemented in pr [426](https://github.com/xline-kv/Xline/pull/426)
- Snapshot and auth command: Implemented in pr [425](https://github.com/xline-kv/Xline/pull/425)
- Delete and lease command: Implemented in pr [424](https://github.com/xline-kv/Xline/pull/424)

🪲 Bug Fixes
- [Bug]: benchmark client cannot connect to server [462](https://github.com/xline-kv/Xline/pull/462)
- [Bug]: remove stop in simulation tests [458](https://github.com/xline-kv/Xline/pull/458)
- [Bug]: execute out of order [454](https://github.com/xline-kv/Xline/pull/454)
- [Bug]: check the password on leader [435](https://github.com/xline-kv/Xline/pull/435)
- [Bug]: remove recovery of uncommitted pool [419](https://github.com/xline-kv/Xline/pull/419)
- [Bug]: CURP TLA+ quorum size calculation & property check [418](https://github.com/xline-kv/Xline/pull/418)
- [Bug]: fix propose doesn't handle SyncedError [407](https://github.com/xline-kv/Xline/pull/407)

🛠️ Refactor
- [Refactor]: reduce code duplication [407](https://github.com/xline-kv/Xline/pull/407)
- [Refactor]: Take into account the interleaving states of a request broadcast in TLA+ [429](https://github.com/xline-kv/Xline/pull/429)
- [Refactor]: Refine the bench client implementation [496](https://github.com/xline-kv/Xline/pull/496)
- [Refactor]: Simplified the error handling logic [480](https://github.com/xline-kv/Xline/pull/480)
- [Refactor]: Improve readability of bootstrap errors [432](https://github.com/xline-kv/Xline/pull/432)
- [Refactor]: Imporve command serialization in execution and after-sync [421](https://github.com/xline-kv/Xline/pull/421), [#422](https://github.com/xline-kv/Xline/pull/422)

❤️ Contributors
- [EAimTY](https://github.com/EAimTY)
- [MarkGaox](https://github.com/MarkGaox)
- [Kikkon](https://github.com/Kikkon)

Note：
Known issue: If the cluster is shut down immediately after adding a member, the leader node may not shut down properly, continuously trying to send entries to the shut-down new node. Read issue 526 for more details.

:star: New Features

- [Feature]: Implemented the Compact feature, which includes the following two aspects (Read issue [188](https://github.com/xline-kv/Xline/issues/188) for more details about compaction design):
- Implemented historical version compaction feature. The compaction API is compatible with the etcd interface. Resolved in pr [311](https://github.com/xline-kv/Xline/pull/311)
- Implemented an automatic compaction mode, supporting both periodic Strategy and Revision Strategy. It is not enabled by default. Resolved in pr [401](https://github.com/xline-kv/Xline/pull/401)
- [Feature]: Implement a Rust SDK for the Xline client (xline-client crate) to fully leverage the performance of CURP protocol. Currently, the SDK covers functionalities:
- Watch: Implemented in pr [321](https://github.com/xline-kv/Xline/pull/321)
- Kv: Implemented in pr [318](https://github.com/xline-kv/Xline/pull/318)
- Maintenance: Implemented in pr [323](https://github.com/xline-kv/Xline/pull/323)
- Auth: Implemented in pr [320](https://github.com/xline-kv/Xline/pull/320)
- Lease: Implemented in pr [319](https://github.com/xline-kv/Xline/pull/319)
- Lock: Implemented in pr [322](https://github.com/xline-kv/Xline/pull/322)
- Compaction: Implemented in pr [389](https://github.com/xline-kv/Xline/pull/389)
- [Feature]: Implement a command line tool for Xline, which is named xlinectl. Resolved in pr [348](https://github.com/xline-kv/Xline/pull/348)
- [Feature]: Support single node cluster [335](https://github.com/xline-kv/Xline/issues/335)
- [Feature]: Support multiplatform for Xline. Read [doc](https://github.com/xline-kv/Xline/tree/master/doc/quick-start) for more details.
- [Feature]: Support dns resolution for Xline cluster [351](https://github.com/xline-kv/Xline/issues/351)
- [Feature]: Support grpc health checking protocol, resolved in pr [385](https://github.com/xline-kv/Xline/pull/385)
- [Feature]: Add madsim simulation in Curp tests [282](https://github.com/xline-kv/Xline/issues/282)


:beetle: Bug Fixes

- [Bug]: Madsim Curp integration tests sometimes fail [361](https://github.com/xline-kv/Xline/issues/361)
- [Bug]: lease may not synced in lease server [343](https://github.com/xline-kv/Xline/issues/343)
- [Bug]: EventListener will lose event since it's not cancellation safe. [339](https://github.com/xline-kv/Xline/issues/339)
- [Bug]: Resolve failing tests related to serialized size. [259](https://github.com/xline-kv/Xline/issues/259)


:heart: Contributors

We'd like to thank all the contributors who worked on this release!

- [liubog2008](https://github.com/liubog2008)

:star: New Features

- [Feature]: Watch Progress Notify [309](https://github.com/datenlord/Xline/issues/309)

:hammer_and_wrench: Refactors
- [Refactor]: sharing state between CurpServer and CurpClient [299](https://github.com/datenlord/Xline/issues/299)
- [Refactor]: refactor the XlineServer [293](https://github.com/datenlord/Xline/issues/293)
- [Refactor]：Refactor curp fast read implementation [270](https://github.com/datenlord/Xline/issues/270)
- [Refactor]: improve the read and write logic for the RocksSnapshot [263](https://github.com/datenlord/Xline/issues/263)
- [Refactor]: refactor the watch server implementation [253](https://github.com/datenlord/Xline/issues/253)
- [Refactor]: refactor the dependencies of lease server [251](https://github.com/datenlord/Xline/issues/251)

:beetle: Bug Fixes

- [Bug]: `test_kv_authorization` block [291](https://github.com/datenlord/Xline/issues/291)
- [Bug]: The background command workers will panic in the integration test "recovery_after_compaction" [285](https://github.com/datenlord/Xline/issues/285)
- [Bug]: `handle_propose` in `raw_cup` will panic when try notify events [280](https://github.com/datenlord/Xline/issues/280)
- [Bug]: Watch prev_kv [277](https://github.com/datenlord/Xline/issues/277)
:heart: Contributors

We'd like to thank all the contributors who worked on this release!

- [themanforfree](https://github.com/themanforfree)
- [Phoenix500526](https://github.com/Phoenix500526)

Features：
1. Introduce batching mechanism to improve network bandwidth utilization
2. Implement the snapshot feature for CURP consensus protocol,
3. Implement the snapshot relevant API，which is compatible with etcdctl. The rest of other APIs in etcdctl maintenance will be implemented in the future.

Fix Bugs：
1. Fix a bug that commands will execute out of order in some concurrent cases (issue 197）, resolve in the pr 195
2. Fix a bug that the gc task will panic during benchmark(issue 206), resolve in the pr 210
3. Fix a bug that the lock feature will work abnormally in some cases(issue 209), resolve in the pr 212
4. Fix a bug that some concurrent put requests will get wrong revisions (issue 209), resolve in the pr 238

Benchmark:
Since we implemented the persistence feature for xline in v0.3.0, we have re-benchmarked xline in this release. The benchmark report can be viewed in the [Performance Comparison](https://github.com/datenlord/Xline/blob/master/README.md#performance-comparison) section in our README file.

Features:
* Implement a persistent storage layer to enable durability, including:
* Implement a storage engine layer to abstract the concrete storage engine, like `rocksdb`,
and enable upper layer storage function (185, 187)
* Enable recover logic for `curp` and `xline` (194, 184)

Fix Bugs:
* Fix concurrent cmd order bug (197)