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// Magical Bitcoin Library // Written in 2020 by // Alekos Filini <alekos.filini@gmail.com> // // Copyright (c) 2020 Magical Bitcoin // // Permission is hereby granted, free of charge, to any person obtaining a copy // of this software and associated documentation files (the "Software"), to deal // in the Software without restriction, including without limitation the rights // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell // copies of the Software, and to permit persons to whom the Software is // furnished to do so, subject to the following conditions: // // The above copyright notice and this permission notice shall be included in all // copies or substantial portions of the Software. // // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE // SOFTWARE. //! 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::collections::HashSet; use std::ops::Deref; use std::sync::mpsc::{channel, Receiver, Sender}; use std::sync::Arc; use bitcoin::{Transaction, Txid}; use crate::database::BatchDatabase; use crate::error::Error; use crate::FeeRate; pub(crate) mod utils; #[cfg(feature = "electrum")] #[cfg_attr(docsrs, doc(cfg(feature = "electrum")))] pub mod electrum; #[cfg(feature = "electrum")] pub use self::electrum::ElectrumBlockchain; #[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, } /// Marker trait for a blockchain backend /// /// This is a marker trait for blockchain types. It is automatically implemented for types that /// implement [`Blockchain`], so as a user of the library you won't have to implement this /// manually. /// /// Users of the library will probably never have to implement this trait manually, but they /// could still need to import it to define types and structs with generics; /// Implementing only the marker trait is pointless, since [`OfflineBlockchain`] /// already does that, and whenever [`Blockchain`] is implemented, the marker trait is also /// automatically implemented by the library. pub trait BlockchainMarker {} /// The [`BlockchainMarker`] marker trait is automatically implemented for [`Blockchain`] types impl<T: Blockchain> BlockchainMarker for T {} /// Type that only implements [`Blockchain`] and is always "offline" pub struct OfflineBlockchain; impl BlockchainMarker for OfflineBlockchain {} /// Trait that defines the actions that must be supported by a blockchain backend #[maybe_async] pub trait Blockchain: BlockchainMarker { /// Return the set of [`Capability`] supported by this backend fn get_capabilities(&self) -> HashSet<Capability>; /// Setup the backend and populate the internal database for the first time /// /// This method is the equivalent of [`Blockchain::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 /// [`Blockchain::sync`] defaults to calling this internally if not overridden. fn setup<D: BatchDatabase, P: 'static + Progress>( &self, stop_gap: Option<usize>, database: &mut D, progress_update: P, ) -> Result<(), Error>; /// Populate the internal database with transactions and UTXOs /// /// If not overridden, it defaults to calling [`Blockchain::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 sync<D: BatchDatabase, P: 'static + Progress>( &self, stop_gap: Option<usize>, database: &mut D, progress_update: P, ) -> Result<(), Error> { maybe_await!(self.setup(stop_gap, database, progress_update)) } /// Fetch a transaction from the blockchain given its txid fn get_tx(&self, txid: &Txid) -> Result<Option<Transaction>, Error>; /// Broadcast a transaction fn broadcast(&self, tx: &Transaction) -> Result<(), Error>; /// Return the current height fn get_height(&self) -> Result<u32, 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>; } /// 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 [`Blockchain::sync`] and /// [`Blockchain::setup`] pub trait Progress: Send { /// 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 progress < 0.0 || progress > 100.0 { return Err(Error::InvalidProgressValue(progress)); } self.send((progress, message)) .map_err(|_| Error::ProgressUpdateError) } } /// Type that implements [`Progress`] and drops every update received #[derive(Clone)] 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)] pub struct LogProgress; /// Create a nwe 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("".into())); Ok(()) } } #[maybe_async] impl<T: Blockchain> Blockchain for Arc<T> { fn get_capabilities(&self) -> HashSet<Capability> { maybe_await!(self.deref().get_capabilities()) } fn setup<D: BatchDatabase, P: 'static + Progress>( &self, stop_gap: Option<usize>, database: &mut D, progress_update: P, ) -> Result<(), Error> { maybe_await!(self.deref().setup(stop_gap, database, progress_update)) } fn sync<D: BatchDatabase, P: 'static + Progress>( &self, stop_gap: Option<usize>, database: &mut D, progress_update: P, ) -> Result<(), Error> { maybe_await!(self.deref().sync(stop_gap, database, progress_update)) } fn get_tx(&self, txid: &Txid) -> Result<Option<Transaction>, Error> { maybe_await!(self.deref().get_tx(txid)) } fn broadcast(&self, tx: &Transaction) -> Result<(), Error> { maybe_await!(self.deref().broadcast(tx)) } fn get_height(&self) -> Result<u32, Error> { maybe_await!(self.deref().get_height()) } fn estimate_fee(&self, target: usize) -> Result<FeeRate, Error> { maybe_await!(self.deref().estimate_fee(target)) } }