Remove anchors config flag

Now that all of the core functionality for anchor outputs has landed,
we're ready to remove the config flag that was temporarily hiding it
from our API.

Author: wpaulino

.github/workflows/build.yml

@@ -194,16 +194,15 @@ jobs:
           cargo check --no-default-features --features=no-std --release
           cargo check --no-default-features --features=futures --release
           cargo doc --release
-          RUSTDOCFLAGS="--cfg=anchors" cargo doc --release
       - name: Run cargo check for Taproot build.
         run: |
           cargo check --release
           cargo check --no-default-features --features=no-std --release
           cargo check --no-default-features --features=futures --release
           cargo doc --release
         env:
-          RUSTFLAGS: '--cfg=anchors --cfg=taproot'
-          RUSTDOCFLAGS: '--cfg=anchors --cfg=taproot'
+          RUSTFLAGS: '--cfg=taproot'
+          RUSTDOCFLAGS: '--cfg=taproot'
 
   fuzz:
     runs-on: ubuntu-latest

ci/ci-tests.sh

@@ -101,9 +101,7 @@ if [ "$RUSTC_MINOR_VERSION" -gt 55 ]; then
 	popd
 fi
 
-echo -e "\n\nTest anchors builds"
-pushd lightning
-RUSTFLAGS="$RUSTFLAGS --cfg=anchors" cargo test --verbose --color always -p lightning
 echo -e "\n\nTest Taproot builds"
-RUSTFLAGS="$RUSTFLAGS --cfg=anchors --cfg=taproot" cargo test --verbose --color always -p lightning
+pushd lightning
+RUSTFLAGS="$RUSTFLAGS --cfg=taproot" cargo test --verbose --color always -p lightning
 popd

lightning/src/chain/chainmonitor.rs

@@ -782,30 +782,13 @@ impl<ChannelSigner: WriteableEcdsaChannelSigner, C: Deref, T: Deref, F: Deref, L
 	      L::Target: Logger,
 	      P::Target: Persist<ChannelSigner>,
 {
-	#[cfg(not(anchors))]
-	/// Processes [`SpendableOutputs`] events produced from each [`ChannelMonitor`] upon maturity.
-	///
-	/// An [`EventHandler`] may safely call back to the provider, though this shouldn't be needed in
-	/// order to handle these events.
-	///
-	/// [`SpendableOutputs`]: events::Event::SpendableOutputs
-	fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler {
-		let mut pending_events = Vec::new();
-		for monitor_state in self.monitors.read().unwrap().values() {
-			pending_events.append(&mut monitor_state.monitor.get_and_clear_pending_events());
-		}
-		for event in pending_events {
-			handler.handle_event(event);
-		}
-	}
-	#[cfg(anchors)]
 	/// Processes [`SpendableOutputs`] events produced from each [`ChannelMonitor`] upon maturity.
 	///
 	/// For channels featuring anchor outputs, this method will also process [`BumpTransaction`]
 	/// events produced from each [`ChannelMonitor`] while there is a balance to claim onchain
 	/// within each channel. As the confirmation of a commitment transaction may be critical to the
-	/// safety of funds, this method must be invoked frequently, ideally once for every chain tip
-	/// update (block connected or disconnected).
+	/// safety of funds, we recommend invoking this every 30 seconds, or lower if running in an
+	/// environment with spotty connections, like on mobile.
 	///
 	/// An [`EventHandler`] may safely call back to the provider, though this shouldn't be needed in
 	/// order to handle these events.

lightning/src/chain/channelmonitor.rs

@@ -43,16 +43,13 @@ use crate::chain::{BestBlock, WatchedOutput};
 use crate::chain::chaininterface::{BroadcasterInterface, FeeEstimator, LowerBoundedFeeEstimator};
 use crate::chain::transaction::{OutPoint, TransactionData};
 use crate::sign::{SpendableOutputDescriptor, StaticPaymentOutputDescriptor, DelayedPaymentOutputDescriptor, WriteableEcdsaChannelSigner, SignerProvider, EntropySource};
-#[cfg(anchors)]
-use crate::chain::onchaintx::ClaimEvent;
-use crate::chain::onchaintx::OnchainTxHandler;
+use crate::chain::onchaintx::{ClaimEvent, OnchainTxHandler};
 use crate::chain::package::{CounterpartyOfferedHTLCOutput, CounterpartyReceivedHTLCOutput, HolderFundingOutput, HolderHTLCOutput, PackageSolvingData, PackageTemplate, RevokedOutput, RevokedHTLCOutput};
 use crate::chain::Filter;
 use crate::util::logger::Logger;
 use crate::util::ser::{Readable, ReadableArgs, RequiredWrapper, MaybeReadable, UpgradableRequired, Writer, Writeable, U48};
 use crate::util::byte_utils;
 use crate::events::Event;
-#[cfg(anchors)]
 use crate::events::bump_transaction::{AnchorDescriptor, HTLCDescriptor, BumpTransactionEvent};
 
 use crate::prelude::*;
@@ -268,7 +265,6 @@ impl_writeable_tlv_based!(HolderSignedTx, {
 	(14, htlc_outputs, vec_type)
 });
 
-#[cfg(anchors)]
 impl HolderSignedTx {
 	fn non_dust_htlcs(&self) -> Vec<HTLCOutputInCommitment> {
 		self.htlc_outputs.iter().filter_map(|(htlc, _, _)| {
@@ -2538,7 +2534,6 @@ impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
 	pub fn get_and_clear_pending_events(&mut self) -> Vec<Event> {
 		let mut ret = Vec::new();
 		mem::swap(&mut ret, &mut self.pending_events);
-		#[cfg(anchors)]
 		for (claim_id, claim_event) in self.onchain_tx_handler.get_and_clear_pending_claim_events().drain(..) {
 			match claim_event {
 				ClaimEvent::BumpCommitment {

lightning/src/chain/onchaintx.rs

@@ -12,15 +12,11 @@
 //! OnchainTxHandler objects are fully-part of ChannelMonitor and encapsulates all
 //! building, tracking, bumping and notifications functions.
 
-#[cfg(anchors)]
 use bitcoin::PackedLockTime;
 use bitcoin::blockdata::transaction::Transaction;
 use bitcoin::blockdata::transaction::OutPoint as BitcoinOutPoint;
 use bitcoin::blockdata::script::Script;
-use bitcoin::hashes::Hash;
-#[cfg(anchors)]
-use bitcoin::hashes::HashEngine;
-#[cfg(anchors)]
+use bitcoin::hashes::{Hash, HashEngine};
 use bitcoin::hashes::sha256::Hash as Sha256;
 use bitcoin::hash_types::{Txid, BlockHash};
 use bitcoin::secp256k1::{Secp256k1, ecdsa::Signature};
@@ -29,18 +25,12 @@ use bitcoin::secp256k1;
 use crate::sign::{ChannelSigner, EntropySource, SignerProvider};
 use crate::ln::msgs::DecodeError;
 use crate::ln::PaymentPreimage;
-#[cfg(anchors)]
-use crate::ln::chan_utils::{self, HTLCOutputInCommitment};
-use crate::ln::chan_utils::{ChannelTransactionParameters, HolderCommitmentTransaction};
+use crate::ln::chan_utils::{self, ChannelTransactionParameters, HTLCOutputInCommitment, HolderCommitmentTransaction};
 use crate::chain::ClaimId;
-#[cfg(anchors)]
-use crate::chain::chaininterface::ConfirmationTarget;
-use crate::chain::chaininterface::{FeeEstimator, BroadcasterInterface, LowerBoundedFeeEstimator};
+use crate::chain::chaininterface::{ConfirmationTarget, FeeEstimator, BroadcasterInterface, LowerBoundedFeeEstimator};
 use crate::chain::channelmonitor::{ANTI_REORG_DELAY, CLTV_SHARED_CLAIM_BUFFER};
 use crate::sign::WriteableEcdsaChannelSigner;
-#[cfg(anchors)]
-use crate::chain::package::PackageSolvingData;
-use crate::chain::package::PackageTemplate;
+use crate::chain::package::{PackageSolvingData, PackageTemplate};
 use crate::util::logger::Logger;
 use crate::util::ser::{Readable, ReadableArgs, MaybeReadable, UpgradableRequired, Writer, Writeable, VecWriter};
 
@@ -50,7 +40,6 @@ use alloc::collections::BTreeMap;
 use core::cmp;
 use core::ops::Deref;
 use core::mem::replace;
-#[cfg(anchors)]
 use core::mem::swap;
 use crate::ln::features::ChannelTypeFeatures;
 
@@ -181,7 +170,6 @@ impl Writeable for Option<Vec<Option<(usize, Signature)>>> {
 	}
 }
 
-#[cfg(anchors)]
 /// The claim commonly referred to as the pre-signed second-stage HTLC transaction.
 pub(crate) struct ExternalHTLCClaim {
 	pub(crate) commitment_txid: Txid,
@@ -193,7 +181,6 @@ pub(crate) struct ExternalHTLCClaim {
 
 // Represents the different types of claims for which events are yielded externally to satisfy said
 // claims.
-#[cfg(anchors)]
 pub(crate) enum ClaimEvent {
 	/// Event yielded to signal that the commitment transaction fee must be bumped to claim any
 	/// encumbered funds and proceed to HTLC resolution, if any HTLCs exist.
@@ -216,7 +203,6 @@ pub(crate) enum ClaimEvent {
 pub(crate) enum OnchainClaim {
 	/// A finalized transaction pending confirmation spending the output to claim.
 	Tx(Transaction),
-	#[cfg(anchors)]
 	/// An event yielded externally to signal additional inputs must be added to a transaction
 	/// pending confirmation spending the output to claim.
 	Event(ClaimEvent),
@@ -263,7 +249,6 @@ pub struct OnchainTxHandler<ChannelSigner: WriteableEcdsaChannelSigner> {
 	//	- A channel has been force closed by broadcasting the holder's latest commitment transaction
 	//	- A block being connected/disconnected
 	//	- Learning the preimage for an HTLC we can claim onchain
-	#[cfg(anchors)]
 	pending_claim_events: Vec<(ClaimId, ClaimEvent)>,
 
 	// Used to link outpoints claimed in a connected block to a pending claim request. The keys
@@ -440,7 +425,6 @@ impl<'a, 'b, ES: EntropySource, SP: SignerProvider> ReadableArgs<(&'a ES, &'b SP
 			locktimed_packages,
 			pending_claim_requests,
 			onchain_events_awaiting_threshold_conf,
-			#[cfg(anchors)]
 			pending_claim_events: Vec::new(),
 			secp_ctx,
 		})
@@ -461,7 +445,6 @@ impl<ChannelSigner: WriteableEcdsaChannelSigner> OnchainTxHandler<ChannelSigner>
 			claimable_outpoints: HashMap::new(),
 			locktimed_packages: BTreeMap::new(),
 			onchain_events_awaiting_threshold_conf: Vec::new(),
-			#[cfg(anchors)]
 			pending_claim_events: Vec::new(),
 			secp_ctx,
 		}
@@ -475,7 +458,6 @@ impl<ChannelSigner: WriteableEcdsaChannelSigner> OnchainTxHandler<ChannelSigner>
 		self.holder_commitment.to_broadcaster_value_sat()
 	}
 
-	#[cfg(anchors)]
 	pub(crate) fn get_and_clear_pending_claim_events(&mut self) -> Vec<(ClaimId, ClaimEvent)> {
 		let mut events = Vec::new();
 		swap(&mut events, &mut self.pending_claim_events);
@@ -516,7 +498,6 @@ impl<ChannelSigner: WriteableEcdsaChannelSigner> OnchainTxHandler<ChannelSigner>
 							log_info!(logger, "{} onchain {}", log_start, log_tx!(tx));
 							broadcaster.broadcast_transactions(&[&tx]);
 						},
-						#[cfg(anchors)]
 						OnchainClaim::Event(event) => {
 							let log_start = if bumped_feerate { "Yielding fee-bumped" } else { "Replaying" };
 							log_info!(logger, "{} onchain event to spend inputs {:?}", log_start,
@@ -593,25 +574,22 @@ impl<ChannelSigner: WriteableEcdsaChannelSigner> OnchainTxHandler<ChannelSigner>
 		// didn't receive confirmation of it before, or not enough reorg-safe depth on top of it).
 		let new_timer = cached_request.get_height_timer(cur_height);
 		if cached_request.is_malleable() {
-			#[cfg(anchors)]
-			{ // Attributes are not allowed on if expressions on our current MSRV of 1.41.
-				if cached_request.requires_external_funding() {
-					let target_feerate_sat_per_1000_weight = cached_request.compute_package_feerate(
-						fee_estimator, ConfirmationTarget::HighPriority, force_feerate_bump
-					);
-					if let Some(htlcs) = cached_request.construct_malleable_package_with_external_funding(self) {
-						return Some((
-							new_timer,
-							target_feerate_sat_per_1000_weight as u64,
-							OnchainClaim::Event(ClaimEvent::BumpHTLC {
-								target_feerate_sat_per_1000_weight,
-								htlcs,
-								tx_lock_time: PackedLockTime(cached_request.package_locktime(cur_height)),
-							}),
-						));
-					} else {
-						return None;
-					}
+			if cached_request.requires_external_funding() {
+				let target_feerate_sat_per_1000_weight = cached_request.compute_package_feerate(
+					fee_estimator, ConfirmationTarget::HighPriority, force_feerate_bump
+				);
+				if let Some(htlcs) = cached_request.construct_malleable_package_with_external_funding(self) {
+					return Some((
+						new_timer,
+						target_feerate_sat_per_1000_weight as u64,
+						OnchainClaim::Event(ClaimEvent::BumpHTLC {
+							target_feerate_sat_per_1000_weight,
+							htlcs,
+							tx_lock_time: PackedLockTime(cached_request.package_locktime(cur_height)),
+						}),
+					));
+				} else {
+					return None;
 				}
 			}
 
@@ -633,9 +611,6 @@ impl<ChannelSigner: WriteableEcdsaChannelSigner> OnchainTxHandler<ChannelSigner>
 			// Untractable packages cannot have their fees bumped through Replace-By-Fee. Some
 			// packages may support fee bumping through Child-Pays-For-Parent, indicated by those
 			// which require external funding.
-			#[cfg(not(anchors))]
-			let inputs = cached_request.inputs();
-			#[cfg(anchors)]
 			let mut inputs = cached_request.inputs();
 			debug_assert_eq!(inputs.len(), 1);
 			let tx = match cached_request.finalize_untractable_package(self, logger) {
@@ -645,7 +620,6 @@ impl<ChannelSigner: WriteableEcdsaChannelSigner> OnchainTxHandler<ChannelSigner>
 			if !cached_request.requires_external_funding() {
 				return Some((new_timer, 0, OnchainClaim::Tx(tx)));
 			}
-			#[cfg(anchors)]
 			return inputs.find_map(|input| match input {
 				// Commitment inputs with anchors support are the only untractable inputs supported
 				// thus far that require external funding.
@@ -771,7 +745,6 @@ impl<ChannelSigner: WriteableEcdsaChannelSigner> OnchainTxHandler<ChannelSigner>
 						broadcaster.broadcast_transactions(&[&tx]);
 						ClaimId(tx.txid().into_inner())
 					},
-					#[cfg(anchors)]
 					OnchainClaim::Event(claim_event) => {
 						log_info!(logger, "Yielding onchain event to spend inputs {:?}", req.outpoints());
 						let claim_id = match claim_event {
@@ -886,14 +859,12 @@ impl<ChannelSigner: WriteableEcdsaChannelSigner> OnchainTxHandler<ChannelSigner>
 								// input(s) that already have a confirmed spend. If such spend is
 								// reorged out of the chain, then we'll attempt to re-spend the
 								// inputs once we see it.
-								#[cfg(anchors)] {
-									#[cfg(debug_assertions)] {
-										let existing = self.pending_claim_events.iter()
-											.filter(|entry| entry.0 == *claim_id).count();
-										assert!(existing == 0 || existing == 1);
-									}
-									self.pending_claim_events.retain(|entry| entry.0 != *claim_id);
+								#[cfg(debug_assertions)] {
+									let existing = self.pending_claim_events.iter()
+										.filter(|entry| entry.0 == *claim_id).count();
+									assert!(existing == 0 || existing == 1);
 								}
+								self.pending_claim_events.retain(|entry| entry.0 != *claim_id);
 							}
 						}
 						break; //No need to iterate further, either tx is our or their
@@ -930,14 +901,12 @@ impl<ChannelSigner: WriteableEcdsaChannelSigner> OnchainTxHandler<ChannelSigner>
 									outpoint, log_bytes!(claim_id.0));
 								self.claimable_outpoints.remove(outpoint);
 							}
-							#[cfg(anchors)] {
-								#[cfg(debug_assertions)] {
-									let num_existing = self.pending_claim_events.iter()
-										.filter(|entry| entry.0 == claim_id).count();
-									assert!(num_existing == 0 || num_existing == 1);
-								}
-								self.pending_claim_events.retain(|(id, _)| *id != claim_id);
+							#[cfg(debug_assertions)] {
+								let num_existing = self.pending_claim_events.iter()
+									.filter(|entry| entry.0 == claim_id).count();
+								assert!(num_existing == 0 || num_existing == 1);
 							}
+							self.pending_claim_events.retain(|(id, _)| *id != claim_id);
 						}
 					},
 					OnchainEvent::ContentiousOutpoint { package } => {
@@ -969,7 +938,6 @@ impl<ChannelSigner: WriteableEcdsaChannelSigner> OnchainTxHandler<ChannelSigner>
 						log_info!(logger, "Broadcasting RBF-bumped onchain {}", log_tx!(bump_tx));
 						broadcaster.broadcast_transactions(&[&bump_tx]);
 					},
-					#[cfg(anchors)]
 					OnchainClaim::Event(claim_event) => {
 						log_info!(logger, "Yielding RBF-bumped onchain event to spend inputs {:?}", request.outpoints());
 						#[cfg(debug_assertions)] {
@@ -1055,7 +1023,6 @@ impl<ChannelSigner: WriteableEcdsaChannelSigner> OnchainTxHandler<ChannelSigner>
 						log_info!(logger, "Broadcasting onchain {}", log_tx!(bump_tx));
 						broadcaster.broadcast_transactions(&[&bump_tx]);
 					},
-					#[cfg(anchors)]
 					OnchainClaim::Event(claim_event) => {
 						log_info!(logger, "Yielding onchain event after reorg to spend inputs {:?}", request.outpoints());
 						#[cfg(debug_assertions)] {
@@ -1185,7 +1152,6 @@ impl<ChannelSigner: WriteableEcdsaChannelSigner> OnchainTxHandler<ChannelSigner>
 		htlc_tx
 	}
 
-	#[cfg(anchors)]
 	pub(crate) fn generate_external_htlc_claim(
 		&self, outp: &::bitcoin::OutPoint, preimage: &Option<PaymentPreimage>
 	) -> Option<ExternalHTLCClaim> {

lightning/src/chain/package.rs

@@ -26,16 +26,13 @@ use crate::ln::chan_utils;
 use crate::ln::msgs::DecodeError;
 use crate::chain::chaininterface::{FeeEstimator, ConfirmationTarget, MIN_RELAY_FEE_SAT_PER_1000_WEIGHT};
 use crate::sign::WriteableEcdsaChannelSigner;
-#[cfg(anchors)]
-use crate::chain::onchaintx::ExternalHTLCClaim;
-use crate::chain::onchaintx::OnchainTxHandler;
+use crate::chain::onchaintx::{ExternalHTLCClaim, OnchainTxHandler};
 use crate::util::logger::Logger;
 use crate::util::ser::{Readable, Writer, Writeable, RequiredWrapper};
 
 use crate::io;
 use crate::prelude::*;
 use core::cmp;
-#[cfg(anchors)]
 use core::convert::TryInto;
 use core::mem;
 use core::ops::Deref;
@@ -866,7 +863,6 @@ impl PackageTemplate {
 		let output_weight = (8 + 1 + destination_script.len()) * WITNESS_SCALE_FACTOR;
 		inputs_weight + witnesses_weight + transaction_weight + output_weight
 	}
-	#[cfg(anchors)]
 	pub(crate) fn construct_malleable_package_with_external_funding<Signer: WriteableEcdsaChannelSigner>(
 		&self, onchain_handler: &mut OnchainTxHandler<Signer>,
 	) -> Option<Vec<ExternalHTLCClaim>> {
@@ -971,7 +967,6 @@ impl PackageTemplate {
 		None
 	}
 
-	#[cfg(anchors)]
 	/// Computes a feerate based on the given confirmation target. If a previous feerate was used,
 	/// the new feerate is below it, and `force_feerate_bump` is set, we'll use a 25% increase of
 	/// the previous feerate instead of the new feerate.