A `is_spent` field is added to LocalUtxo; when a txo is spent we set
this field to true instead of deleting the entire utxo from the
database.
This allows us to create txs double-spending txs already in blockchain.
Listunspent won't return spent utxos, effectively excluding them from the
coin selection and balance calculation
Add a unit test that passes a required utxo to the coin selection
algorithm that is less than the required spend. This tests that we get
that utxo included as well as tests that the rest of the coin selection
algorithm code also executes (i.e., that we do not short circuit
incorrectly).
If the required UTXO set is already bigger (including fees) than the
amount required for the transaction we can return early, no need to go
through the BNB algorithm or random selection.
It was just pointed out that we are calculating the virtual bytes
incorrectly by forgetting to take the ceiling after division by 4 [1]
Add helper functions to encapsulate all weight unit -> virtual byte
calculations including fee to and from fee rate. This makes the code
easier to read, easier to write, and gives us a better chance that bugs
like this will be easier to see.
As an added bonus we can also stop using f32 values for fee amount,
which is by definition an amount in sats so should be a u64. This
removes a bunch of casts and the need for epsilon comparisons and just
deep down feels nice :)
[1] https://github.com/bitcoindevkit/bdk/pull/386#discussion_r670882678
Clippy emits:
warning: struct constructor field order is inconsistent with struct
definition field order
As suggested, re-order the fields to be consistent with the struct
definition.
Adds fix for edge-cases involving small UTXOs (where value < fee) where the coin_select calculation would panic with overflow/underflow errors.
Bitcoin is limited to 21*(10^6), so any Bitcoin amount fits into i64.
To allow adding UTXOs external to the current wallet.
The caller must provide the psbt::Input so we can create a coherent PSBT
at the end and so this is compatible with existing PSBT workflows.
Main changes:
- There are now two types of UTXOs, local and foreign reflected in a
`Utxo` enum.
- `WeightedUtxo` now captures floating `(Utxo, usize)` tuples
- `CoinSelectionResult` now has methods on it for distinguishing between
local amount included vs total.
Fixes#251
TxBuilders are now not created directly but are created through the
wallet with `build_tx` and `build_fee_bump`.
The advantages of this realised in this commit are:
1. Normal tx creation and fee bumping use the code internally. The only
difference between normal tx and fee bump is how the builder is created.
2. The TxBuilder now has a refernce to the wallet and can therefore
lookup things as methods are called on it. `add_utxo` now uses this to
look up UTXO deta when it is called (rather than having to do it and
possibly error later on).
To support these changes `get_utxo` and `get_descriptor_for_keychain`
public methods have been added to Wallet. I could have kept them
pub(crate) but they seem like fine APIs to have publicly.
