a0bf45bef1b53f8aec273f7fe89915f3d41974c0 docs: remove PersistBackend from docs, Cargo.toml and wallet README.md (Steve Myers)
feb27df180938759670afd2c9cd15529a22c4772 feat(chain)!: add `take` convenience method to `Append` trait (志宇)
1eca568be5bb0c234fa1cea2eb7f9424f60974eb feat!: rm `persist` submodule (志宇)
Pull request description:
### Description
@LLFourn suggested these changes which greatly simplifies the amount of code we have to maintain and removes the `async-trait` dependency. We remove `PersistBackend`, `PersistBackendAsync`, `StageExt` and `StageExtAsync` completely. Instead, we introduce `Wallet::take_staged(&mut self) -> Option<ChangeSet>`.
The original intention to keep a staging area (`StageExt`, `StageExtAsync`) is to enforce:
1. The caller will not persist an empty changeset.
2. The caller does not take the staged changeset if the database (`PersistBackend`) fails.
We achieve `1.` by returning `None` if the staged changeset is empty.
`2.` is not too important. The caller can try figure out what to do with the changeset if persisting to db fails.
### Notes to the reviewers
I added a `take` convenience method to the `Append` trait. I thought it would be handy for the caller to do a staging area with this.
### Changelog notice
* Remove `persist` submodule from `bdk_chain`.
* Change `Wallet` to outsource it's persistence logic by introducing `Wallet::take_staged`.
* Add `take` convenience method to `Append` trait.
### Checklists
#### All Submissions:
* [x] I've signed all my commits
* [x] I followed the [contribution guidelines](https://github.com/bitcoindevkit/bdk/blob/master/CONTRIBUTING.md)
* [x] I ran `cargo fmt` and `cargo clippy` before committing
#### New Features:
~* [ ] I've added tests for the new feature~
* [x] I've added docs for the new feature
ACKs for top commit:
notmandatory:
ACK a0bf45bef1b53f8aec273f7fe89915f3d41974c0
evanlinjin:
self-ACK a0bf45bef1b53f8aec273f7fe89915f3d41974c0
Tree-SHA512: 38939ab446c84d9baecd4cd36a7b66add5a121212ad5e06ade04a60f7903133dd9a20219e230ab8a40404c47e07b946ccd43085572d71c3a2a80240a2223a500
410ba173e4