1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391
// Bitcoin Dev Kit
// Written in 2020 by Alekos Filini <alekos.filini@gmail.com>
//
// Copyright (c) 2020-2021 Bitcoin Dev Kit Developers
//
// This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
// or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
// You may not use this file except in accordance with one or both of these
// licenses.
//! Blockchain backends
//!
//! This module provides the implementation of a few commonly-used backends like
//! [Electrum](crate::blockchain::electrum), [Esplora](crate::blockchain::esplora) and
//! [Compact Filters/Neutrino](crate::blockchain::compact_filters), along with a generalized trait
//! [`Blockchain`] that can be implemented to build customized backends.
use std::cell::RefCell;
use std::collections::HashSet;
use std::ops::Deref;
use std::sync::mpsc::{channel, Receiver, Sender};
use std::sync::Arc;
use bitcoin::{BlockHash, Transaction, Txid};
use crate::database::BatchDatabase;
use crate::error::Error;
use crate::wallet::{wallet_name_from_descriptor, Wallet};
use crate::{FeeRate, KeychainKind};
#[cfg(any(
feature = "electrum",
feature = "esplora",
feature = "compact_filters",
feature = "rpc"
))]
pub mod any;
mod script_sync;
#[cfg(any(
feature = "electrum",
feature = "esplora",
feature = "compact_filters",
feature = "rpc"
))]
pub use any::{AnyBlockchain, AnyBlockchainConfig};
#[cfg(feature = "electrum")]
#[cfg_attr(docsrs, doc(cfg(feature = "electrum")))]
pub mod electrum;
#[cfg(feature = "electrum")]
pub use self::electrum::ElectrumBlockchain;
#[cfg(feature = "electrum")]
pub use self::electrum::ElectrumBlockchainConfig;
#[cfg(feature = "rpc")]
#[cfg_attr(docsrs, doc(cfg(feature = "rpc")))]
pub mod rpc;
#[cfg(feature = "rpc")]
pub use self::rpc::RpcBlockchain;
#[cfg(feature = "rpc")]
pub use self::rpc::RpcConfig;
#[cfg(feature = "esplora")]
#[cfg_attr(docsrs, doc(cfg(feature = "esplora")))]
pub mod esplora;
#[cfg(feature = "esplora")]
pub use self::esplora::EsploraBlockchain;
#[cfg(feature = "compact_filters")]
#[cfg_attr(docsrs, doc(cfg(feature = "compact_filters")))]
pub mod compact_filters;
#[cfg(feature = "compact_filters")]
pub use self::compact_filters::CompactFiltersBlockchain;
/// Capabilities that can be supported by a [`Blockchain`] backend
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
pub enum Capability {
/// Can recover the full history of a wallet and not only the set of currently spendable UTXOs
FullHistory,
/// Can fetch any historical transaction given its txid
GetAnyTx,
/// Can compute accurate fees for the transactions found during sync
AccurateFees,
}
/// Trait that defines the actions that must be supported by a blockchain backend
#[maybe_async]
pub trait Blockchain: WalletSync + GetHeight + GetTx + GetBlockHash {
/// Return the set of [`Capability`] supported by this backend
fn get_capabilities(&self) -> HashSet<Capability>;
/// Broadcast a transaction
fn broadcast(&self, tx: &Transaction) -> Result<(), Error>;
/// Estimate the fee rate required to confirm a transaction in a given `target` of blocks
fn estimate_fee(&self, target: usize) -> Result<FeeRate, Error>;
}
/// Trait for getting the current height of the blockchain.
#[maybe_async]
pub trait GetHeight {
/// Return the current height
fn get_height(&self) -> Result<u32, Error>;
}
#[maybe_async]
/// Trait for getting a transaction by txid
pub trait GetTx {
/// Fetch a transaction given its txid
fn get_tx(&self, txid: &Txid) -> Result<Option<Transaction>, Error>;
}
#[maybe_async]
/// Trait for getting block hash by block height
pub trait GetBlockHash {
/// fetch block hash given its height
fn get_block_hash(&self, height: u64) -> Result<BlockHash, Error>;
}
/// Trait for blockchains that can sync by updating the database directly.
#[maybe_async]
pub trait WalletSync {
/// Setup the backend and populate the internal database for the first time
///
/// This method is the equivalent of [`Self::wallet_sync`], but it's guaranteed to only be
/// called once, at the first [`Wallet::sync`](crate::wallet::Wallet::sync).
///
/// The rationale behind the distinction between `sync` and `setup` is that some custom backends
/// might need to perform specific actions only the first time they are synced.
///
/// For types that do not have that distinction, only this method can be implemented, since
/// [`WalletSync::wallet_sync`] defaults to calling this internally if not overridden.
/// Populate the internal database with transactions and UTXOs
fn wallet_setup<D: BatchDatabase>(
&self,
database: &RefCell<D>,
progress_update: Box<dyn Progress>,
) -> Result<(), Error>;
/// If not overridden, it defaults to calling [`Self::wallet_setup`] internally.
///
/// This method should implement the logic required to iterate over the list of the wallet's
/// script_pubkeys using [`Database::iter_script_pubkeys`] and look for relevant transactions
/// in the blockchain to populate the database with [`BatchOperations::set_tx`] and
/// [`BatchOperations::set_utxo`].
///
/// This method should also take care of removing UTXOs that are seen as spent in the
/// blockchain, using [`BatchOperations::del_utxo`].
///
/// The `progress_update` object can be used to give the caller updates about the progress by using
/// [`Progress::update`].
///
/// [`Database::iter_script_pubkeys`]: crate::database::Database::iter_script_pubkeys
/// [`BatchOperations::set_tx`]: crate::database::BatchOperations::set_tx
/// [`BatchOperations::set_utxo`]: crate::database::BatchOperations::set_utxo
/// [`BatchOperations::del_utxo`]: crate::database::BatchOperations::del_utxo
fn wallet_sync<D: BatchDatabase>(
&self,
database: &RefCell<D>,
progress_update: Box<dyn Progress>,
) -> Result<(), Error> {
maybe_await!(self.wallet_setup(database, progress_update))
}
}
/// Trait for [`Blockchain`] types that can be created given a configuration
pub trait ConfigurableBlockchain: Blockchain + Sized {
/// Type that contains the configuration
type Config: std::fmt::Debug;
/// Create a new instance given a configuration
fn from_config(config: &Self::Config) -> Result<Self, Error>;
}
/// Trait for blockchains that don't contain any state
///
/// Statless blockchains can be used to sync multiple wallets with different descriptors.
///
/// [`BlockchainFactory`] is automatically implemented for `Arc<T>` where `T` is a stateless
/// blockchain.
pub trait StatelessBlockchain: Blockchain {}
/// Trait for a factory of blockchains that share the underlying connection or configuration
#[cfg_attr(
not(feature = "async-interface"),
doc = r##"
## Example
This example shows how to sync multiple walles and return the sum of their balances
```no_run
# use bdk::Error;
# use bdk::blockchain::*;
# use bdk::database::*;
# use bdk::wallet::*;
# use bdk::*;
fn sum_of_balances<B: BlockchainFactory>(blockchain_factory: B, wallets: &[Wallet<MemoryDatabase>]) -> Result<Balance, Error> {
Ok(wallets
.iter()
.map(|w| -> Result<_, Error> {
blockchain_factory.sync_wallet(&w, None, SyncOptions::default())?;
w.get_balance()
})
.collect::<Result<Vec<_>, _>>()?
.into_iter()
.sum())
}
```
"##
)]
pub trait BlockchainFactory {
/// The type returned when building a blockchain from this factory
type Inner: Blockchain;
/// Build a new blockchain for the given descriptor wallet_name
///
/// If `override_skip_blocks` is `None`, the returned blockchain will inherit the number of blocks
/// from the factory. Since it's not possible to override the value to `None`, set it to
/// `Some(0)` to rescan from the genesis.
fn build(
&self,
wallet_name: &str,
override_skip_blocks: Option<u32>,
) -> Result<Self::Inner, Error>;
/// Build a new blockchain for a given wallet
///
/// Internally uses [`wallet_name_from_descriptor`] to derive the name, and then calls
/// [`BlockchainFactory::build`] to create the blockchain instance.
fn build_for_wallet<D: BatchDatabase>(
&self,
wallet: &Wallet<D>,
override_skip_blocks: Option<u32>,
) -> Result<Self::Inner, Error> {
let wallet_name = wallet_name_from_descriptor(
wallet.public_descriptor(KeychainKind::External)?.unwrap(),
wallet.public_descriptor(KeychainKind::Internal)?,
wallet.network(),
wallet.secp_ctx(),
)?;
self.build(&wallet_name, override_skip_blocks)
}
/// Use [`BlockchainFactory::build_for_wallet`] to get a blockchain, then sync the wallet
///
/// This can be used when a new blockchain would only be used to sync a wallet and then
/// immediately dropped. Keep in mind that specific blockchain factories may perform slow
/// operations to build a blockchain for a given wallet, so if a wallet needs to be synced
/// often it's recommended to use [`BlockchainFactory::build_for_wallet`] to reuse the same
/// blockchain multiple times.
#[cfg(not(feature = "async-interface"))]
#[cfg_attr(docsrs, doc(cfg(not(feature = "async-interface"))))]
fn sync_wallet<D: BatchDatabase>(
&self,
wallet: &Wallet<D>,
override_skip_blocks: Option<u32>,
sync_options: crate::wallet::SyncOptions,
) -> Result<(), Error> {
let blockchain = self.build_for_wallet(wallet, override_skip_blocks)?;
wallet.sync(&blockchain, sync_options)
}
}
impl<T: StatelessBlockchain> BlockchainFactory for Arc<T> {
type Inner = Self;
fn build(&self, _wallet_name: &str, _override_skip_blocks: Option<u32>) -> Result<Self, Error> {
Ok(Arc::clone(self))
}
}
/// Data sent with a progress update over a [`channel`]
pub type ProgressData = (f32, Option<String>);
/// Trait for types that can receive and process progress updates during [`WalletSync::wallet_sync`] and
/// [`WalletSync::wallet_setup`]
pub trait Progress: Send + 'static + core::fmt::Debug {
/// Send a new progress update
///
/// The `progress` value should be in the range 0.0 - 100.0, and the `message` value is an
/// optional text message that can be displayed to the user.
fn update(&self, progress: f32, message: Option<String>) -> Result<(), Error>;
}
/// Shortcut to create a [`channel`] (pair of [`Sender`] and [`Receiver`]) that can transport [`ProgressData`]
pub fn progress() -> (Sender<ProgressData>, Receiver<ProgressData>) {
channel()
}
impl Progress for Sender<ProgressData> {
fn update(&self, progress: f32, message: Option<String>) -> Result<(), Error> {
if !(0.0..=100.0).contains(&progress) {
return Err(Error::InvalidProgressValue(progress));
}
self.send((progress, message))
.map_err(|_| Error::ProgressUpdateError)
}
}
/// Type that implements [`Progress`] and drops every update received
#[derive(Clone, Copy, Default, Debug)]
pub struct NoopProgress;
/// Create a new instance of [`NoopProgress`]
pub fn noop_progress() -> NoopProgress {
NoopProgress
}
impl Progress for NoopProgress {
fn update(&self, _progress: f32, _message: Option<String>) -> Result<(), Error> {
Ok(())
}
}
/// Type that implements [`Progress`] and logs at level `INFO` every update received
#[derive(Clone, Copy, Default, Debug)]
pub struct LogProgress;
/// Create a new instance of [`LogProgress`]
pub fn log_progress() -> LogProgress {
LogProgress
}
impl Progress for LogProgress {
fn update(&self, progress: f32, message: Option<String>) -> Result<(), Error> {
log::info!(
"Sync {:.3}%: `{}`",
progress,
message.unwrap_or_else(|| "".into())
);
Ok(())
}
}
#[maybe_async]
impl<T: Blockchain> Blockchain for Arc<T> {
fn get_capabilities(&self) -> HashSet<Capability> {
maybe_await!(self.deref().get_capabilities())
}
fn broadcast(&self, tx: &Transaction) -> Result<(), Error> {
maybe_await!(self.deref().broadcast(tx))
}
fn estimate_fee(&self, target: usize) -> Result<FeeRate, Error> {
maybe_await!(self.deref().estimate_fee(target))
}
}
#[maybe_async]
impl<T: GetTx> GetTx for Arc<T> {
fn get_tx(&self, txid: &Txid) -> Result<Option<Transaction>, Error> {
maybe_await!(self.deref().get_tx(txid))
}
}
#[maybe_async]
impl<T: GetHeight> GetHeight for Arc<T> {
fn get_height(&self) -> Result<u32, Error> {
maybe_await!(self.deref().get_height())
}
}
#[maybe_async]
impl<T: GetBlockHash> GetBlockHash for Arc<T> {
fn get_block_hash(&self, height: u64) -> Result<BlockHash, Error> {
maybe_await!(self.deref().get_block_hash(height))
}
}
#[maybe_async]
impl<T: WalletSync> WalletSync for Arc<T> {
fn wallet_setup<D: BatchDatabase>(
&self,
database: &RefCell<D>,
progress_update: Box<dyn Progress>,
) -> Result<(), Error> {
maybe_await!(self.deref().wallet_setup(database, progress_update))
}
fn wallet_sync<D: BatchDatabase>(
&self,
database: &RefCell<D>,
progress_update: Box<dyn Progress>,
) -> Result<(), Error> {
maybe_await!(self.deref().wallet_sync(database, progress_update))
}
}