--- /dev/null
+use std::io::{Read, Seek, SeekFrom};
+use std::path::PathBuf;
+use std::sync::Arc;
+use std::time::Duration;
+use std::{fs, io};
+
+use lightning::chain::chaininterface::{BroadcasterInterface, ConfirmationTarget, FeeEstimator};
+use lightning::chain::keysinterface::{EntropySource, KeysManager, SpendableOutputDescriptor};
+use lightning::util::logger::Logger;
+use lightning::util::persist::KVStorePersister;
+use lightning::util::ser::{Readable, WithoutLength};
+
+use bitcoin::secp256k1::Secp256k1;
+
+use crate::hex_utils;
+use crate::BitcoindClient;
+use crate::FilesystemLogger;
+use crate::FilesystemPersister;
+
+/// If we have any pending claimable outputs, we should slowly sweep them to our Bitcoin Core
+/// wallet. We technically don't need to do this - they're ours to spend when we want and can just
+/// use them to build new transactions instead, but we cannot feed them direclty into Bitcoin
+/// Core's wallet so we have to sweep.
+///
+/// Note that this is unececssary for [`SpendableOutputDescriptor::StaticOutput`]s, which *do* have
+/// an associated secret key we could simply import into Bitcoin Core's wallet, but for consistency
+/// we don't do that here either.
+pub(crate) async fn periodic_sweep(
+ ldk_data_dir: String, keys_manager: Arc<KeysManager>, logger: Arc<FilesystemLogger>,
+ persister: Arc<FilesystemPersister>, bitcoind_client: Arc<BitcoindClient>,
+) {
+ // Regularly claim outputs which are exclusively spendable by us and send them to Bitcoin Core.
+ // Note that if you more tightly integrate your wallet with LDK you may not need to do this -
+ // these outputs can just be treated as normal outputs during coin selection.
+ let pending_spendables_dir =
+ format!("{}/{}", crate::PENDING_SPENDABLE_OUTPUT_DIR, ldk_data_dir);
+ let processing_spendables_dir = format!("{}/processing_spendable_outputs", ldk_data_dir);
+ let spendables_dir = format!("{}/spendable_outputs", ldk_data_dir);
+
+ // We batch together claims of all spendable outputs generated each day, however only after
+ // batching any claims of spendable outputs which were generated prior to restart. On a mobile
+ // device we likely won't ever be online for more than a minute, so we have to ensure we sweep
+ // any pending claims on startup, but for an always-online node you may wish to sweep even less
+ // frequently than this (or move the interval await to the top of the loop)!
+ //
+ // There is no particular rush here, we just have to ensure funds are availably by the time we
+ // need to send funds.
+ let mut interval = tokio::time::interval(Duration::from_secs(60 * 60 * 24));
+
+ loop {
+ interval.tick().await; // Note that the first tick completes immediately
+ if let Ok(dir_iter) = fs::read_dir(&pending_spendables_dir) {
+ // Move any spendable descriptors from pending folder so that we don't have any
+ // races with new files being added.
+ for file_res in dir_iter {
+ let file = file_res.unwrap();
+ // Only move a file if its a 32-byte-hex'd filename, otherwise it might be a
+ // temporary file.
+ if file.file_name().len() == 64 {
+ fs::create_dir_all(&processing_spendables_dir).unwrap();
+ let mut holding_path = PathBuf::new();
+ holding_path.push(&processing_spendables_dir);
+ holding_path.push(&file.file_name());
+ fs::rename(file.path(), holding_path).unwrap();
+ }
+ }
+ // Now concatenate all the pending files we moved into one file in the
+ // `spendable_outputs` directory and drop the processing directory.
+ let mut outputs = Vec::new();
+ if let Ok(processing_iter) = fs::read_dir(&processing_spendables_dir) {
+ for file_res in processing_iter {
+ outputs.append(&mut fs::read(file_res.unwrap().path()).unwrap());
+ }
+ }
+ if !outputs.is_empty() {
+ let key = hex_utils::hex_str(&keys_manager.get_secure_random_bytes());
+ persister
+ .persist(&format!("spendable_outputs/{}", key), &WithoutLength(&outputs))
+ .unwrap();
+ fs::remove_dir_all(&processing_spendables_dir).unwrap();
+ }
+ }
+ // Iterate over all the sets of spendable outputs in `spendables_dir` and try to claim
+ // them.
+ // Note that here we try to claim each set of spendable outputs over and over again
+ // forever, even long after its been claimed. While this isn't an issue per se, in practice
+ // you may wish to track when the claiming transaction has confirmed and remove the
+ // spendable outputs set. You may also wish to merge groups of unspent spendable outputs to
+ // combine batches.
+ if let Ok(dir_iter) = fs::read_dir(&spendables_dir) {
+ for file_res in dir_iter {
+ let mut outputs: Vec<SpendableOutputDescriptor> = Vec::new();
+ let mut file = fs::File::open(file_res.unwrap().path()).unwrap();
+ loop {
+ // Check if there are any bytes left to read, and if so read a descriptor.
+ match file.read_exact(&mut [0; 1]) {
+ Ok(_) => {
+ file.seek(SeekFrom::Current(-1)).unwrap();
+ }
+ Err(e) if e.kind() == io::ErrorKind::UnexpectedEof => break,
+ Err(e) => Err(e).unwrap(),
+ }
+ outputs.push(Readable::read(&mut file).unwrap());
+ }
+ let destination_address = bitcoind_client.get_new_address().await;
+ let output_descriptors = &outputs.iter().map(|a| a).collect::<Vec<_>>();
+ let tx_feerate =
+ bitcoind_client.get_est_sat_per_1000_weight(ConfirmationTarget::Background);
+ if let Ok(spending_tx) = keys_manager.spend_spendable_outputs(
+ output_descriptors,
+ Vec::new(),
+ destination_address.script_pubkey(),
+ tx_feerate,
+ &Secp256k1::new(),
+ ) {
+ // Note that, most likely, we've already sweeped this set of outputs
+ // and they're already confirmed on-chain, so this broadcast will fail.
+ bitcoind_client.broadcast_transaction(&spending_tx);
+ } else {
+ lightning::log_error!(
+ logger,
+ "Failed to sweep spendable outputs! This may indicate the outputs are dust. Will try again in a day.");
+ }
+ }
+ }
+ }
+}
projects / ldk-sample / blobdiff