Struct ChainSource 

pub struct ChainSource { /* private fields */ }

Client for interacting with the configured on-chain backend.

ChainSource abstracts over multiple backends using ChainSourceSpec to provide:

• Chain queries (tip, block headers/blocks, transaction status and fetching)
• Mempool-related utilities (ancestor fee/weight, spending lookups)
• Broadcasting single transactions or packages (RBF/CPFP workflows)
• Fee estimation and caching with optional fallback values

Behavior notes:

• ChainSource::update_fee_rates refreshes internal fee estimates; if backend estimates fail and a fallback fee is provided, it will be used for all tiers.
• ChainSource::fee_rates returns the last cached FeeRates.

Examples:

use bark::onchain::{ChainSource, ChainSourceSpec};
use bdk_bitcoind_rpc::bitcoincore_rpc::Auth;
use bitcoin::{FeeRate, Network};

let spec = ChainSourceSpec::Bitcoind {
    url: "http://localhost:8332".into(),
    auth: Auth::UserPass("user".into(), "password".into()),
};
let network = Network::Bitcoin;
let fallback_fee = FeeRate::from_sat_per_vb(5);

let instance = ChainSource::new(spec, network, fallback_fee).await.unwrap();

Implementations

impl ChainSource

pub fn require_version(&self) -> Result<()>

Checks that the version of the chain source is compatible with Bark.

For bitcoind, it checks if the version is at least 29.0 This is the first version for which 0 fee-anchors are considered standard

pub async fn fee_rates(&self) -> FeeRates

Gets a cached copy of the calculated network FeeRates

pub fn network(&self) -> Network

Gets the network that the ChainSource was validated against.

pub async fn new( spec: ChainSourceSpec, network: Network, fallback_fee: Option<FeeRate>, ) -> Result<Self>

Creates a new instance of the object with the specified chain source, network, and optional fallback fee rate.

This function initializes the internal chain source client based on the provided chain_source:

• If chain_source is of type ChainSourceSpec::Bitcoind, it creates a Bitcoin Core RPC client using the provided URL and authentication parameters.
• If chain_source is of type ChainSourceSpec::Esplora, it creates an Esplora client with the given URL.

Both clients are initialized asynchronously, and any errors encountered during their creation will be returned as part of the anyhow::Result.

Additionally, the function performs a network consistency check to ensure the specified network (e.g., mainnet or signet) matches the network configuration of the initialized chain source client.

The fallback_fee parameter is optional. If provided, it is used as the default fee rate for transactions. If not specified, the FeeRate::BROADCAST_MIN is used as the default fee rate.

Arguments

• chain_source - Specifies the backend to use for blockchain data.
• network - The Bitcoin network to operate on (e.g., mainnet, testnet, regtest).
• fallback_fee - An optional fallback fee rate to use for transaction fee estimation. If not provided, a default fee rate of FeeRate::BROADCAST_MIN will be used.

Returns

• Ok(Self) - If the object is successfully created with all necessary configurations.
• Err(anyhow::Error) - If there is an error in initializing the chain source client or verifying the network.

pub async fn tip(&self) -> Result<BlockHeight>

pub async fn block_ref(&self, height: BlockHeight) -> Result<BlockRef>

pub async fn block(&self, hash: BlockHash) -> Result<Option<Block>>

pub async fn mempool_ancestor_info( &self, txid: Txid, ) -> Result<MempoolAncestorInfo>

Retrieves basic CPFP ancestry information of the given transaction. Confirmed transactions are ignored as they are not relevant to CPFP.

pub async fn txs_spending_inputs<T: IntoIterator<Item = OutPoint>>( &self, outpoints: T, block_scan_start: BlockHeight, ) -> Result<TxsSpendingInputsResult>

For each provided outpoint, fetches the ID of any confirmed or unconfirmed in which the outpoint is spent.

pub async fn broadcast_tx(&self, tx: &Transaction) -> Result<()>

pub async fn broadcast_package( &self, txs: &[impl Borrow<Transaction>], ) -> Result<()>

pub async fn get_tx(&self, txid: &Txid) -> Result<Option<Transaction>>

pub async fn tx_confirmed(&self, txid: Txid) -> Result<Option<BlockHeight>>

Returns the block height the tx is confirmed in, if any.

pub async fn tx_status(&self, txid: Txid) -> Result<TxStatus>

Returns the status of the given transaction, including the block height if it is confirmed

pub async fn txout_value(&self, outpoint: &OutPoint) -> Result<Amount>

pub async fn update_fee_rates( &self, fallback_fee: Option<FeeRate>, ) -> Result<()>

Gets the current fee rates from the chain source, falling back to user-specified values if necessary