This commit changes the `LocalChain` implementation to have blocks
stored as a linked-list. This allows the data-src thread to hold a
shared ref to a single checkpoint and have access to the whole history
of checkpoints without cloning or keeping a lock on `LocalChain`.
The APIs of `bdk::Wallet`, `esplora` and `electrum` are also updated to
reflect these changes. Note that the `esplora` crate is rewritten to
anchor txs in the confirmation block (using the esplora API's tx status
block_hash). This guarantees 100% consistency between anchor blocks and
their transactions (instead of anchoring txs to the latest tip).
`ExploraExt` now has separate methods for updating the `TxGraph` and
`LocalChain`.
A new method `TxGraph::missing_blocks` is introduced for finding
"floating anchors" of a `TxGraph` update (given a chain).
Additional changes:
* `test_local_chain.rs` is refactored to make test cases easier to
write. Additional tests are also added.
* Examples are updated.
* Fix `tempfile` dev dependency of `bdk_file_store` to work with MSRV
Co-authored-by: LLFourn <lloyd.fourn@gmail.com>
* Introduce `LocalChain::inner` method to get the inner map of block
height to hash.
* Replace `LocalChain::get_block` (which outputted `BlockId`, thus able
to return invalid representation) with `get_blockhash` that just
returns a `BlockHash`.
* Remove `TODO` comments that should be github tickets.
* Remove `chain_oracle::CacheBackend` for now as it is not used.
* `SparseChain` does not need to implement `ChainOracle`.
* Remove filter predicate for `list..` methods of `TxGraph` and
`IndexedTxGraph` as this is premature optimisation.
* `Append` can be implemented for all `BTreeMap`s and `BTreeSet`s,
instead of only `local_chain::ChangeSet`.
This is mostly copying over the relevant tests from `SparseChain`.
Changes are made to `local_chain::ChangeSet` to re-add the ability to
remove blocks.
The problem with the previous `ChainOracle` interface is that it had no
guarantee for consistency. For example, a block deemed to be part of the
"best chain" can be reorged out. So when `ChainOracle` is called
multiple times for an operation (such as getting the UTXO set), the
returned result may be inconsistent.
This PR changes `ChainOracle::is_block_in_chain` to take in another
input `static_block`, ensuring `block` is an ancestor of `static_block`.
Thus, if `static_block` is consistent across the operation, the result
will be consistent also.
`is_block_in_chain` now returns `Option<bool>`. The `None` case means
that the oracle implementation cannot determine whether block is an
ancestor of static block. `IndexedTxGraph::list_chain_txouts` handles
this case by checking child spends that are in chain, and if so, the
parent tx must be in chain too.
* Instead of implementing `ChainPosition` for `ObservedIn<BlockId>` to
use `FullTxOut` methods (`is_spendable_at` and `is_mature`), we create
alternative versions of those methods that require bounds with `Anchor`.
This removes all `ObservedIn<A>: ChainPosition` bounds for methods of
`IndexedTxGraph`.
* Various improvements to comments and names.
Introduce `chain_oracle::Cache` which is a cache for requests to the
chain oracle. `ChainOracle` has also been moved to the `chain_oracle`
module.
Introduce `get_tip_in_best_chain` method to the `ChainOracle` trait.
This allows for guaranteeing that chain state can be consistent across
operations with `IndexedTxGraph`.
