use chain;
use chain::{ChannelMonitorUpdateErr, Filter, WatchedOutput};
use chain::chaininterface::{BroadcasterInterface, FeeEstimator};
-use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, Balance, MonitorEvent, TransactionOutputs};
+use chain::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, Balance, MonitorEvent, TransactionOutputs, LATENCY_GRACE_PERIOD_BLOCKS};
use chain::transaction::{OutPoint, TransactionData};
use chain::keysinterface::Sign;
+use util::atomic_counter::AtomicCounter;
use util::logger::Logger;
use util::errors::APIError;
use util::events;
use prelude::*;
use sync::{RwLock, RwLockReadGuard, Mutex, MutexGuard};
use core::ops::Deref;
+use core::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
#[derive(Clone, Copy, Hash, PartialEq, Eq)]
+/// A specific update's ID stored in a `MonitorUpdateId`, separated out to make the contents
+/// entirely opaque.
enum UpdateOrigin {
+ /// An update that was generated by the `ChannelManager` (via our `chain::Watch`
+ /// implementation). This corresponds to an actual [`ChannelMonitorUpdate::update_id`] field
+ /// and [`ChannelMonitor::get_latest_update_id`].
OffChain(u64),
+ /// An update that was generated during blockchain processing. The ID here is specific to the
+ /// generating [`ChainMonitor`] and does *not* correspond to any on-disk IDs.
+ ChainSync(u64),
}
/// An opaque identifier describing a specific [`Persist`] method call.
/// closed without broadcasting the latest state. See
/// [`ChannelMonitorUpdateErr::PermanentFailure`] for more details.
pub trait Persist<ChannelSigner: Sign> {
- /// Persist a new channel's data. The data can be stored any way you want, but the identifier
- /// provided by LDK is the channel's outpoint (and it is up to you to maintain a correct
- /// mapping between the outpoint and the stored channel data). Note that you **must** persist
- /// every new monitor to disk.
+ /// Persist a new channel's data in response to a [`chain::Watch::watch_channel`] call. This is
+ /// called by [`ChannelManager`] for new channels, or may be called directly, e.g. on startup.
+ ///
+ /// The data can be stored any way you want, but the identifier provided by LDK is the
+ /// channel's outpoint (and it is up to you to maintain a correct mapping between the outpoint
+ /// and the stored channel data). Note that you **must** persist every new monitor to disk.
///
/// The `update_id` is used to identify this call to [`ChainMonitor::channel_monitor_updated`],
/// if you return [`ChannelMonitorUpdateErr::TemporaryFailure`].
/// See [`Writeable::write`] on [`ChannelMonitor`] for writing out a `ChannelMonitor`
/// and [`ChannelMonitorUpdateErr`] for requirements when returning errors.
///
+ /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
/// [`Writeable::write`]: crate::util::ser::Writeable::write
fn persist_new_channel(&self, channel_id: OutPoint, data: &ChannelMonitor<ChannelSigner>, update_id: MonitorUpdateId) -> Result<(), ChannelMonitorUpdateErr>;
/// updated monitor itself to disk/backups. See the [`Persist`] trait documentation for more
/// details.
///
+ /// During blockchain synchronization operations, this may be called with no
+ /// [`ChannelMonitorUpdate`], in which case the full [`ChannelMonitor`] needs to be persisted.
+ /// Note that after the full [`ChannelMonitor`] is persisted any previous
+ /// [`ChannelMonitorUpdate`]s which were persisted should be discarded - they can no longer be
+ /// applied to the persisted [`ChannelMonitor`] as they were already applied.
+ ///
/// If an implementer chooses to persist the updates only, they need to make
/// sure that all the updates are applied to the `ChannelMonitors` *before*
/// the set of channel monitors is given to the `ChannelManager`
/// [`ChannelMonitorUpdateErr`] for requirements when returning errors.
///
/// [`Writeable::write`]: crate::util::ser::Writeable::write
- fn update_persisted_channel(&self, channel_id: OutPoint, update: &ChannelMonitorUpdate, data: &ChannelMonitor<ChannelSigner>, update_id: MonitorUpdateId) -> Result<(), ChannelMonitorUpdateErr>;
+ fn update_persisted_channel(&self, channel_id: OutPoint, update: &Option<ChannelMonitorUpdate>, data: &ChannelMonitor<ChannelSigner>, update_id: MonitorUpdateId) -> Result<(), ChannelMonitorUpdateErr>;
}
struct MonitorHolder<ChannelSigner: Sign> {
/// update_persisted_channel, the user returns a TemporaryFailure, and then calls
/// channel_monitor_updated immediately, racing our insertion of the pending update into the
/// contained Vec.
+ ///
+ /// Beyond the synchronization of updates themselves, we cannot handle user events until after
+ /// any chain updates have been stored on disk. Thus, we scan this list when returning updates
+ /// to the ChannelManager, refusing to return any updates for a ChannelMonitor which is still
+ /// being persisted fully to disk after a chain update.
+ ///
+ /// This avoids the possibility of handling, e.g. an on-chain claim, generating a claim monitor
+ /// event, resulting in the relevant ChannelManager generating a PaymentSent event and dropping
+ /// the pending payment entry, and then reloading before the monitor is persisted, resulting in
+ /// the ChannelManager re-adding the same payment entry, before the same block is replayed,
+ /// resulting in a duplicate PaymentSent event.
pending_monitor_updates: Mutex<Vec<MonitorUpdateId>>,
+ /// When the user returns a PermanentFailure error from an update_persisted_channel call during
+ /// block processing, we inform the ChannelManager that the channel should be closed
+ /// asynchronously. In order to ensure no further changes happen before the ChannelManager has
+ /// processed the closure event, we set this to true and return PermanentFailure for any other
+ /// chain::Watch events.
+ channel_perm_failed: AtomicBool,
+ /// The last block height at which no [`UpdateOrigin::ChainSync`] monitor updates were present
+ /// in `pending_monitor_updates`.
+ /// If it's been more than [`LATENCY_GRACE_PERIOD_BLOCKS`] since we started waiting on a chain
+ /// sync event, we let monitor events return to `ChannelManager` because we cannot hold them up
+ /// forever or we'll end up with HTLC preimages waiting to feed back into an upstream channel
+ /// forever, risking funds loss.
+ last_chain_persist_height: AtomicUsize,
}
impl<ChannelSigner: Sign> MonitorHolder<ChannelSigner> {
pending_monitor_updates_lock.iter().any(|update_id|
if let UpdateOrigin::OffChain(_) = update_id.contents { true } else { false })
}
+ fn has_pending_chainsync_updates(&self, pending_monitor_updates_lock: &MutexGuard<Vec<MonitorUpdateId>>) -> bool {
+ pending_monitor_updates_lock.iter().any(|update_id|
+ if let UpdateOrigin::ChainSync(_) = update_id.contents { true } else { false })
+ }
}
/// A read-only reference to a current ChannelMonitor.
P::Target: Persist<ChannelSigner>,
{
monitors: RwLock<HashMap<OutPoint, MonitorHolder<ChannelSigner>>>,
+ /// When we generate a [`MonitorUpdateId`] for a chain-event monitor persistence, we need a
+ /// unique ID, which we calculate by simply getting the next value from this counter. Note that
+ /// the ID is never persisted so it's ok that they reset on restart.
+ sync_persistence_id: AtomicCounter,
chain_source: Option<C>,
broadcaster: T,
logger: L,
fee_estimator: F,
persister: P,
+ /// "User-provided" (ie persistence-completion/-failed) [`MonitorEvent`]s. These came directly
+ /// from the user and not from a [`ChannelMonitor`].
pending_monitor_events: Mutex<Vec<MonitorEvent>>,
+ /// The best block height seen, used as a proxy for the passage of time.
+ highest_chain_height: AtomicUsize,
}
impl<ChannelSigner: Sign, C: Deref, T: Deref, F: Deref, L: Deref, P: Deref> ChainMonitor<ChannelSigner, C, T, F, L, P>
/// calls must not exclude any transactions matching the new outputs nor any in-block
/// descendants of such transactions. It is not necessary to re-fetch the block to obtain
/// updated `txdata`.
- fn process_chain_data<FN>(&self, header: &BlockHeader, txdata: &TransactionData, process: FN)
+ ///
+ /// Calls which represent a new blockchain tip height should set `best_height`.
+ fn process_chain_data<FN>(&self, header: &BlockHeader, best_height: Option<u32>, txdata: &TransactionData, process: FN)
where
FN: Fn(&ChannelMonitor<ChannelSigner>, &TransactionData) -> Vec<TransactionOutputs>
{
let mut dependent_txdata = Vec::new();
- let monitor_states = self.monitors.read().unwrap();
- for monitor_state in monitor_states.values() {
- let mut txn_outputs = process(&monitor_state.monitor, txdata);
+ {
+ let monitor_states = self.monitors.write().unwrap();
+ if let Some(height) = best_height {
+ // If the best block height is being updated, update highest_chain_height under the
+ // monitors write lock.
+ let old_height = self.highest_chain_height.load(Ordering::Acquire);
+ let new_height = height as usize;
+ if new_height > old_height {
+ self.highest_chain_height.store(new_height, Ordering::Release);
+ }
+ }
- // Register any new outputs with the chain source for filtering, storing any dependent
- // transactions from within the block that previously had not been included in txdata.
- if let Some(ref chain_source) = self.chain_source {
- let block_hash = header.block_hash();
- for (txid, mut outputs) in txn_outputs.drain(..) {
- for (idx, output) in outputs.drain(..) {
- // Register any new outputs with the chain source for filtering and recurse
- // if it indicates that there are dependent transactions within the block
- // that had not been previously included in txdata.
- let output = WatchedOutput {
- block_hash: Some(block_hash),
- outpoint: OutPoint { txid, index: idx as u16 },
- script_pubkey: output.script_pubkey,
- };
- if let Some(tx) = chain_source.register_output(output) {
- dependent_txdata.push(tx);
+ for (funding_outpoint, monitor_state) in monitor_states.iter() {
+ let monitor = &monitor_state.monitor;
+ let mut txn_outputs;
+ {
+ txn_outputs = process(monitor, txdata);
+ let update_id = MonitorUpdateId {
+ contents: UpdateOrigin::ChainSync(self.sync_persistence_id.get_increment()),
+ };
+ let mut pending_monitor_updates = monitor_state.pending_monitor_updates.lock().unwrap();
+ if let Some(height) = best_height {
+ if !monitor_state.has_pending_chainsync_updates(&pending_monitor_updates) {
+ // If there are not ChainSync persists awaiting completion, go ahead and
+ // set last_chain_persist_height here - we wouldn't want the first
+ // TemporaryFailure to always immediately be considered "overly delayed".
+ monitor_state.last_chain_persist_height.store(height as usize, Ordering::Release);
+ }
+ }
+
+ log_trace!(self.logger, "Syncing Channel Monitor for channel {}", log_funding_info!(monitor));
+ match self.persister.update_persisted_channel(*funding_outpoint, &None, monitor, update_id) {
+ Ok(()) =>
+ log_trace!(self.logger, "Finished syncing Channel Monitor for channel {}", log_funding_info!(monitor)),
+ Err(ChannelMonitorUpdateErr::PermanentFailure) => {
+ monitor_state.channel_perm_failed.store(true, Ordering::Release);
+ self.pending_monitor_events.lock().unwrap().push(MonitorEvent::UpdateFailed(*funding_outpoint));
+ },
+ Err(ChannelMonitorUpdateErr::TemporaryFailure) => {
+ log_debug!(self.logger, "Channel Monitor sync for channel {} in progress, holding events until completion!", log_funding_info!(monitor));
+ pending_monitor_updates.push(update_id);
+ },
+ }
+ }
+
+ // Register any new outputs with the chain source for filtering, storing any dependent
+ // transactions from within the block that previously had not been included in txdata.
+ if let Some(ref chain_source) = self.chain_source {
+ let block_hash = header.block_hash();
+ for (txid, mut outputs) in txn_outputs.drain(..) {
+ for (idx, output) in outputs.drain(..) {
+ // Register any new outputs with the chain source for filtering and recurse
+ // if it indicates that there are dependent transactions within the block
+ // that had not been previously included in txdata.
+ let output = WatchedOutput {
+ block_hash: Some(block_hash),
+ outpoint: OutPoint { txid, index: idx as u16 },
+ script_pubkey: output.script_pubkey,
+ };
+ if let Some(tx) = chain_source.register_output(output) {
+ dependent_txdata.push(tx);
+ }
}
}
}
dependent_txdata.sort_unstable_by_key(|(index, _tx)| *index);
dependent_txdata.dedup_by_key(|(index, _tx)| *index);
let txdata: Vec<_> = dependent_txdata.iter().map(|(index, tx)| (*index, tx)).collect();
- self.process_chain_data(header, &txdata, process);
+ self.process_chain_data(header, None, &txdata, process); // We skip the best height the second go-around
}
}
pub fn new(chain_source: Option<C>, broadcaster: T, logger: L, feeest: F, persister: P) -> Self {
Self {
monitors: RwLock::new(HashMap::new()),
+ sync_persistence_id: AtomicCounter::new(),
chain_source,
broadcaster,
logger,
fee_estimator: feeest,
persister,
pending_monitor_events: Mutex::new(Vec::new()),
+ highest_chain_height: AtomicUsize::new(0),
}
}
pending_monitor_updates.retain(|update_id| *update_id != completed_update_id);
match completed_update_id {
- MonitorUpdateId { .. } => {
+ MonitorUpdateId { contents: UpdateOrigin::OffChain(_) } => {
// Note that we only check for `UpdateOrigin::OffChain` failures here - if
// we're being told that a `UpdateOrigin::OffChain` monitor update completed,
// we only care about ensuring we don't tell the `ChannelManager` to restore
// `MonitorEvent`s from the monitor back to the `ChannelManager` until they
// complete.
let monitor_is_pending_updates = monitor_data.has_pending_offchain_updates(&pending_monitor_updates);
- if monitor_is_pending_updates {
- // If there are still monitor updates pending, we cannot yet construct an
+ if monitor_is_pending_updates || monitor_data.channel_perm_failed.load(Ordering::Acquire) {
+ // If there are still monitor updates pending (or an old monitor update
+ // finished after a later one perm-failed), we cannot yet construct an
// UpdateCompleted event.
return Ok(());
}
funding_txo,
monitor_update_id: monitor_data.monitor.get_latest_update_id(),
});
- }
+ },
+ MonitorUpdateId { contents: UpdateOrigin::ChainSync(_) } => {
+ if !monitor_data.has_pending_chainsync_updates(&pending_monitor_updates) {
+ monitor_data.last_chain_persist_height.store(self.highest_chain_height.load(Ordering::Acquire), Ordering::Release);
+ // The next time release_pending_monitor_events is called, any events for this
+ // ChannelMonitor will be returned.
+ }
+ },
}
Ok(())
}
let header = &block.header;
let txdata: Vec<_> = block.txdata.iter().enumerate().collect();
log_debug!(self.logger, "New best block {} at height {} provided via block_connected", header.block_hash(), height);
- self.process_chain_data(header, &txdata, |monitor, txdata| {
+ self.process_chain_data(header, Some(height), &txdata, |monitor, txdata| {
monitor.block_connected(
header, txdata, height, &*self.broadcaster, &*self.fee_estimator, &*self.logger)
});
{
fn transactions_confirmed(&self, header: &BlockHeader, txdata: &TransactionData, height: u32) {
log_debug!(self.logger, "{} provided transactions confirmed at height {} in block {}", txdata.len(), height, header.block_hash());
- self.process_chain_data(header, txdata, |monitor, txdata| {
+ self.process_chain_data(header, None, txdata, |monitor, txdata| {
monitor.transactions_confirmed(
header, txdata, height, &*self.broadcaster, &*self.fee_estimator, &*self.logger)
});
fn best_block_updated(&self, header: &BlockHeader, height: u32) {
log_debug!(self.logger, "New best block {} at height {} provided via best_block_updated", header.block_hash(), height);
- self.process_chain_data(header, &[], |monitor, txdata| {
+ self.process_chain_data(header, Some(height), &[], |monitor, txdata| {
// While in practice there shouldn't be any recursive calls when given empty txdata,
// it's still possible if a chain::Filter implementation returns a transaction.
debug_assert!(txdata.is_empty());
monitor.load_outputs_to_watch(chain_source);
}
}
- entry.insert(MonitorHolder { monitor, pending_monitor_updates: Mutex::new(pending_monitor_updates) });
+ entry.insert(MonitorHolder {
+ monitor,
+ pending_monitor_updates: Mutex::new(pending_monitor_updates),
+ channel_perm_failed: AtomicBool::new(false),
+ last_chain_persist_height: AtomicUsize::new(self.highest_chain_height.load(Ordering::Acquire)),
+ });
persist_res
}
// still be changed. So, persist the updated monitor despite the error.
let update_id = MonitorUpdateId::from_monitor_update(&update);
let mut pending_monitor_updates = monitor_state.pending_monitor_updates.lock().unwrap();
- let persist_res = self.persister.update_persisted_channel(funding_txo, &update, monitor, update_id);
+ let persist_res = self.persister.update_persisted_channel(funding_txo, &Some(update), monitor, update_id);
if let Err(e) = persist_res {
if e == ChannelMonitorUpdateErr::TemporaryFailure {
pending_monitor_updates.push(update_id);
+ } else {
+ monitor_state.channel_perm_failed.store(true, Ordering::Release);
}
log_error!(self.logger, "Failed to persist channel monitor update: {:?}", e);
}
if update_res.is_err() {
Err(ChannelMonitorUpdateErr::PermanentFailure)
+ } else if monitor_state.channel_perm_failed.load(Ordering::Acquire) {
+ Err(ChannelMonitorUpdateErr::PermanentFailure)
} else {
persist_res
}
fn release_pending_monitor_events(&self) -> Vec<MonitorEvent> {
let mut pending_monitor_events = self.pending_monitor_events.lock().unwrap().split_off(0);
for monitor_state in self.monitors.read().unwrap().values() {
- pending_monitor_events.append(&mut monitor_state.monitor.get_and_clear_pending_monitor_events());
+ let is_pending_monitor_update = monitor_state.has_pending_chainsync_updates(&monitor_state.pending_monitor_updates.lock().unwrap());
+ if is_pending_monitor_update &&
+ monitor_state.last_chain_persist_height.load(Ordering::Acquire) + LATENCY_GRACE_PERIOD_BLOCKS as usize
+ > self.highest_chain_height.load(Ordering::Acquire)
+ {
+ log_info!(self.logger, "A Channel Monitor sync is still in progress, refusing to provide monitor events!");
+ } else {
+ if monitor_state.channel_perm_failed.load(Ordering::Acquire) {
+ // If a `UpdateOrigin::ChainSync` persistence failed with `PermanantFailure`,
+ // we don't really know if the latest `ChannelMonitor` state is on disk or not.
+ // We're supposed to hold monitor updates until the latest state is on disk to
+ // avoid duplicate events, but the user told us persistence is screw-y and may
+ // not complete. We can't hold events forever because we may learn some payment
+ // preimage, so instead we just log and hope the user complied with the
+ // `PermanentFailure` requirements of having at least the local-disk copy
+ // updated.
+ log_info!(self.logger, "A Channel Monitor sync returned PermanentFailure. Returning monitor events but duplicate events may appear after reload!");
+ }
+ if is_pending_monitor_update {
+ log_error!(self.logger, "A ChannelMonitor sync took longer than {} blocks to complete.", LATENCY_GRACE_PERIOD_BLOCKS);
+ log_error!(self.logger, " To avoid funds-loss, we are allowing monitor updates to be released.");
+ log_error!(self.logger, " This may cause duplicate payment events to be generated.");
+ }
+ pending_monitor_events.append(&mut monitor_state.monitor.get_and_clear_pending_monitor_events());
+ }
}
pending_monitor_events
}
projects / rust-lightning / blobdiff