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Wake background-processor from ChainMonitor on new blocks #3033

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TheBlueMatt
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When we receive a new block we may generate
Event::SpendableOutputs in ChannelMonitors which then need to be processed by the background processor. While it will do so eventually when its normal loop goes around, this may cause user tests to be delayed in finding events, so we should notify the BP immediately to wake it on new blocks.

We implement that here, unconditionally notifying the background-processor whenever we receive a new block or confirmed transactions.

@TheBlueMatt TheBlueMatt added this to the 0.0.123 milestone Apr 30, 2024
@valentinewallace
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Would this have adverse effects if someone's on regtest and mines 100+ blocks at once? Or testnet blockstorms. That's the only reason I could see we'd want more precise notifications for pending events.

@TheBlueMatt TheBlueMatt force-pushed the 2024-04-notify-bp-on-blocks branch from 0348de2 to 8f4a107 Compare May 1, 2024 18:56
@TheBlueMatt
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It shouldn't - if we're too slow the BP won't always loop 100 times but rather will ensure it loops at least once after the last notify.

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codecov-commenter commented May 1, 2024

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.13%. Comparing base (2b14cc4) to head (8f4a107).
Report is 4 commits behind head on main.

❗ Current head 8f4a107 differs from pull request most recent head 021979b. Consider uploading reports for the commit 021979b to get more accurate results

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Additional details and impacted files
@@            Coverage Diff             @@
##             main    #3033      +/-   ##
==========================================
- Coverage   89.14%   89.13%   -0.02%     
==========================================
  Files         118      118              
  Lines       97850    97972     +122     
  Branches    97850    97972     +122     
==========================================
+ Hits        87230    87325      +95     
- Misses       8376     8400      +24     
- Partials     2244     2247       +3     

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lightning/src/chain/chainmonitor.rs Outdated Show resolved Hide resolved
@@ -738,6 +740,8 @@ where
monitor.block_connected(
header, txdata, height, &*self.broadcaster, &*self.fee_estimator, &self.logger)
});
// Assume we may have some new events and wake the event processor
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@G8XSU G8XSU May 1, 2024

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usually, i see that we notify event_notifier just after publishing the event to chainmonitor::pending_monitor_events.
but i see that we don't do so for channelmonitor::pending_monitor_events when we push new actionable events and we don't have access to event_notifier in channelmonitor.

Can you help me understand this pattern?

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Right, we don't have access to the event_notifier so we just assume there may be new events and wake. Not much reason to worry too much about it, a BP loop is pretty cheap so having to do a few extra won't kill us.

When we receive a new block we may generate
`Event::SpendableOutputs` in `ChannelMonitor`s which then need to
be processed by the background processor. While it will do so
eventually when its normal loop goes around, this may cause user
tests to be delayed in finding events, so we should notify the BP
immediately to wake it on new blocks.

We implement that here, unconditionally notifying the
`background-processor` whenever we receive a new block or confirmed
transactions.
@TheBlueMatt TheBlueMatt merged commit bd3cc00 into lightningdevkit:main May 1, 2024
15 of 16 checks passed
TheBlueMatt added a commit to TheBlueMatt/rust-lightning that referenced this pull request May 6, 2024
…fy-bp-on-blocks

Wake `background-processor` from `ChainMonitor` on new blocks
k0k0ne pushed a commit to bitlightlabs/rust-lightning that referenced this pull request Sep 30, 2024
v0.0.123 - May 08, 2024 - "BOLT12 Dust Sweeping"

API Updates
===========

 * To reduce risk of force-closures and improve HTLC reliability the default
   dust exposure limit has been increased to
   `MaxDustHTLCExposure::FeeRateMultiplier(10_000)`. Users with existing
   channels might want to consider using
   `ChannelManager::update_channel_config` to apply the new default (lightningdevkit#3045).
 * `ChainMonitor::archive_fully_resolved_channel_monitors` is now provided to
   remove from memory `ChannelMonitor`s that have been fully resolved on-chain
   and are now not needed. It uses the new `Persist::archive_persisted_channel`
   to inform the storage layer that such a monitor should be archived (lightningdevkit#2964).
 * An `OutputSweeper` is now provided which will automatically sweep
   `SpendableOutputDescriptor`s, retrying until the sweep confirms (lightningdevkit#2825).
 * After initiating an outbound channel, a peer disconnection no longer results
   in immediate channel closure. Rather, if the peer is reconnected before the
   channel times out LDK will automatically retry opening it (lightningdevkit#2725).
 * `PaymentPurpose` now has separate variants for BOLT12 payments, which
   include fields from the `invoice_request` as well as the `OfferId` (lightningdevkit#2970).
 * `ChannelDetails` now includes a list of in-flight HTLCs (lightningdevkit#2442).
 * `Event::PaymentForwarded` now includes `skimmed_fee_msat` (lightningdevkit#2858).
 * The `hashbrown` dependency has been upgraded and the use of `ahash` as the
   no-std hash table hash function has been removed. As a consequence, LDK's
   `Hash{Map,Set}`s no longer feature several constructors when LDK is built
   with no-std; see the `util::hash_tables` module instead. On platforms that
   `getrandom` supports, setting the `possiblyrandom/getrandom` feature flag
   will ensure hash tables are resistant to HashDoS attacks, though the
   `possiblyrandom` crate should detect most common platforms (lightningdevkit#2810, lightningdevkit#2891).
 * `ChannelMonitor`-originated requests to the `ChannelSigner` can now fail and
   be retried using `ChannelMonitor::signer_unblocked` (lightningdevkit#2816).
 * `SpendableOutputDescriptor::to_psbt_input` now includes the `witness_script`
   where available as well as new proprietary data which can be used to
   re-derive some spending keys from the base key (lightningdevkit#2761, lightningdevkit#3004).
 * `OutPoint::to_channel_id` has been removed in favor of
   `ChannelId::v1_from_funding_outpoint` in preparation for v2 channels with a
   different `ChannelId` derivation scheme (lightningdevkit#2797).
 * `PeerManager::get_peer_node_ids` has been replaced with `list_peers` and
   `peer_by_node_id`, which provide more details (lightningdevkit#2905).
 * `Bolt11Invoice::get_payee_pub_key` is now provided (lightningdevkit#2909).
 * `Default[Message]Router` now take an `entropy_source` argument (lightningdevkit#2847).
 * `ClosureReason::HTLCsTimedOut` has been separated out from
   `ClosureReason::HolderForceClosed` as it is the most common case (lightningdevkit#2887).
 * `ClosureReason::CooperativeClosure` is now split into
   `{Counterparty,Locally}Initiated` variants (lightningdevkit#2863).
 * `Event::ChannelPending::channel_type` is now provided (lightningdevkit#2872).
 * `PaymentForwarded::{prev,next}_user_channel_id` are now provided (lightningdevkit#2924).
 * Channel init messages have been refactored towards V2 channels (lightningdevkit#2871).
 * `BumpTransactionEvent` now contains the channel and counterparty (lightningdevkit#2873).
 * `util::scid_utils` is now public, with some trivial utilities to examine
   short channel ids (lightningdevkit#2694).
 * `DirectedChannelInfo::{source,target}` are now public (lightningdevkit#2870).
 * Bounds in `lightning-background-processor` were simplified by using
   `AChannelManager` (lightningdevkit#2963).
 * The `Persist` impl for `KVStore` no longer requires `Sized`, allowing for
   the use of `dyn KVStore` as `Persist` (lightningdevkit#2883, lightningdevkit#2976).
 * `From<PaymentPreimage>` is now implemented for `PaymentHash` (lightningdevkit#2918).
 * `NodeId::from_slice` is now provided (lightningdevkit#2942).
 * `ChannelManager` deserialization may now fail with `DangerousValue` when
    LDK's persistence API was violated (lightningdevkit#2974).

Bug Fixes
=========

 * Excess fees on counterparty commitment transactions are now included in the
   dust exposure calculation. This lines behavior up with some cases where
   transaction fees can be burnt, making them effectively dust exposure (lightningdevkit#3045).
 * `Future`s used as an `std::...::Future` could grow in size unbounded if it
   was never woken. For those not using async persistence and using the async
   `lightning-background-processor`, this could cause a memory leak in the
   `ChainMonitor` (lightningdevkit#2894).
 * Inbound channel requests that fail in
   `ChannelManager::accept_inbound_channel` would previously have stalled from
   the peer's perspective as no `error` message was sent (lightningdevkit#2953).
 * Blinded path construction has been tuned to select paths more likely to
   succeed, improving BOLT12 payment reliability (lightningdevkit#2911, lightningdevkit#2912).
 * After a reorg, `lightning-transaction-sync` could have failed to follow a
   transaction that LDK needed information about (lightningdevkit#2946).
 * `RecipientOnionFields`' `custom_tlvs` are now propagated to recipients when
   paying with blinded paths (lightningdevkit#2975).
 * `Event::ChannelClosed` is now properly generated and peers are properly
   notified for all channels that as a part of a batch channel open fail to be
   funded (lightningdevkit#3029).
 * In cases where user event processing is substantially delayed such that we
   complete multiple round-trips with our peers before a `PaymentSent` event is
   handled and then restart without persisting the `ChannelManager` after having
   persisted a `ChannelMonitor[Update]`, on startup we may have `Err`d trying to
   deserialize the `ChannelManager` (lightningdevkit#3021).
 * If a peer has relatively high latency, `PeerManager` may have failed to
   establish a connection (lightningdevkit#2993).
 * `ChannelUpdate` messages broadcasted for our own channel closures are now
   slightly more robust (lightningdevkit#2731).
 * Deserializing malformed BOLT11 invoices may have resulted in an integer
   overflow panic in debug builds (lightningdevkit#3032).
 * In exceedingly rare cases (no cases of this are known), LDK may have created
   an invalid serialization for a `ChannelManager` (lightningdevkit#2998).
 * Message processing latency handling BOLT12 payments has been reduced (lightningdevkit#2881).
 * Latency in processing `Event::SpendableOutputs` may be reduced (lightningdevkit#3033).

Node Compatibility
==================

 * LDK's blinded paths were inconsistent with other implementations in several
   ways, which have been addressed (lightningdevkit#2856, lightningdevkit#2936, lightningdevkit#2945).
 * LDK's messaging blinded paths now support the latest features which some
   nodes may begin relying on soon (lightningdevkit#2961).
 * LDK's BOLT12 structs have been updated to support some last-minute changes to
   the spec (lightningdevkit#3017, lightningdevkit#3018).
 * CLN v24.02 requires the `gossip_queries` feature for all peers, however LDK
   by default does not set it for those not using a `P2PGossipSync` (e.g. those
   using RGS). This change was reverted in CLN v24.02.2 however for now LDK
   always sets the `gossip_queries` feature. This change is expected to be
   reverted in a future LDK release (lightningdevkit#2959).

Security
========
0.0.123 fixes a denial-of-service vulnerability which we believe to be reachable
from untrusted input when parsing invalid BOLT11 invoices containing non-ASCII
characters.
 * BOLT11 invoices with non-ASCII characters in the human-readable-part may
   cause an out-of-bounds read attempt leading to a panic (lightningdevkit#3054). Note that all
   BOLT11 invoices containing non-ASCII characters are invalid.

In total, this release features 150 files changed, 19307 insertions, 6306
deletions in 360 commits since 0.0.121 from 17 authors, in alphabetical order:

 * Arik Sosman
 * Duncan Dean
 * Elias Rohrer
 * Evan Feenstra
 * Jeffrey Czyz
 * Keyue Bao
 * Matt Corallo
 * Orbital
 * Sergi Delgado Segura
 * Valentine Wallace
 * Willem Van Lint
 * Wilmer Paulino
 * benthecarman
 * jbesraa
 * olegkubrakov
 * optout
 * shaavan
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4 participants