1 package org.ldk.structs;
3 import org.ldk.impl.bindings;
4 import org.ldk.enums.*;
6 import java.util.Arrays;
7 import java.lang.ref.Reference;
8 import javax.annotation.Nullable;
12 * `BackgroundProcessor` takes care of tasks that (1) need to happen periodically to keep
13 * Rust-Lightning running properly, and (2) either can or should be run in the background. Its
14 * responsibilities are:
15 * Processing [`Event`]s with a user-provided [`EventHandler`].
16 * Monitoring whether the [`ChannelManager`] needs to be re-persisted to disk, and if so,
17 * writing it to disk/backups by invoking the callback given to it at startup.
18 * [`ChannelManager`] persistence should be done in the background.
19 * Calling [`ChannelManager::timer_tick_occurred`] and [`PeerManager::timer_tick_occurred`]
20 * at the appropriate intervals.
21 * Calling [`NetworkGraph::remove_stale_channels`] (if a [`GossipSync`] with a [`NetworkGraph`]
22 * is provided to [`BackgroundProcessor::start`]).
24 * It will also call [`PeerManager::process_events`] periodically though this shouldn't be relied
25 * upon as doing so may result in high latency.
29 * If [`ChannelManager`] persistence fails and the persisted manager becomes out-of-date, then
30 * there is a risk of channels force-closing on startup when the manager realizes it's outdated.
31 * However, as long as [`ChannelMonitor`] backups are sound, no funds besides those used for
32 * unilateral chain closure fees are at risk.
34 * [`ChannelMonitor`]: lightning::chain::channelmonitor::ChannelMonitor
35 * [`Event`]: lightning::util::events::Event
36 * BackgroundProcessor will immediately stop on drop. It should be stored until shutdown.
38 @SuppressWarnings("unchecked") // We correctly assign various generic arrays
39 public class BackgroundProcessor extends CommonBase {
40 BackgroundProcessor(Object _dummy, long ptr) { super(ptr); }
41 @Override @SuppressWarnings("deprecation")
42 protected void finalize() throws Throwable {
44 if (ptr != 0) { bindings.BackgroundProcessor_free(ptr); }
48 * Start a background thread that takes care of responsibilities enumerated in the [top-level
51 * The thread runs indefinitely unless the object is dropped, [`stop`] is called, or
52 * [`Persister::persist_manager`] returns an error. In case of an error, the error is retrieved by calling
53 * either [`join`] or [`stop`].
57 * [`Persister::persist_manager`] is responsible for writing out the [`ChannelManager`] to disk, and/or
58 * uploading to one or more backup services. See [`ChannelManager::write`] for writing out a
59 * [`ChannelManager`]. See the `lightning-persister` crate for LDK's
60 * provided implementation.
62 * [`Persister::persist_graph`] is responsible for writing out the [`NetworkGraph`] to disk, if
63 * [`GossipSync`] is supplied. See [`NetworkGraph::write`] for writing out a [`NetworkGraph`].
64 * See the `lightning-persister` crate for LDK's provided implementation.
66 * Typically, users should either implement [`Persister::persist_manager`] to never return an
67 * error or call [`join`] and handle any error that may arise. For the latter case,
68 * `BackgroundProcessor` must be restarted by calling `start` again after handling the error.
72 * `event_handler` is responsible for handling events that users should be notified of (e.g.,
73 * payment failed). [`BackgroundProcessor`] may decorate the given [`EventHandler`] with common
74 * functionality implemented by other handlers.
75 * [`P2PGossipSync`] if given will update the [`NetworkGraph`] based on payment failures.
79 * If rapid gossip sync is meant to run at startup, pass [`RapidGossipSync`] via `gossip_sync`
80 * to indicate that the [`BackgroundProcessor`] should not prune the [`NetworkGraph`] instance
81 * until the [`RapidGossipSync`] instance completes its first sync.
83 * [top-level documentation]: BackgroundProcessor
84 * [`join`]: Self::join
85 * [`stop`]: Self::stop
86 * [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
87 * [`ChannelManager::write`]: lightning::ln::channelmanager::ChannelManager#impl-Writeable
88 * [`Persister::persist_manager`]: lightning::util::persist::Persister::persist_manager
89 * [`Persister::persist_graph`]: lightning::util::persist::Persister::persist_graph
90 * [`NetworkGraph`]: lightning::routing::gossip::NetworkGraph
91 * [`NetworkGraph::write`]: lightning::routing::gossip::NetworkGraph#impl-Writeable
93 * Note that scorer (or a relevant inner pointer) may be NULL or all-0s to represent None
95 public static BackgroundProcessor start(Persister persister, EventHandler event_handler, ChainMonitor chain_monitor, ChannelManager channel_manager, GossipSync gossip_sync, PeerManager peer_manager, Logger logger, @Nullable MultiThreadedLockableScore scorer) {
96 long ret = bindings.BackgroundProcessor_start(persister == null ? 0 : persister.ptr, event_handler == null ? 0 : event_handler.ptr, chain_monitor == null ? 0 : chain_monitor.ptr & ~1, channel_manager == null ? 0 : channel_manager.ptr & ~1, gossip_sync.ptr, peer_manager == null ? 0 : peer_manager.ptr & ~1, logger == null ? 0 : logger.ptr, scorer == null ? 0 : scorer.ptr & ~1);
97 Reference.reachabilityFence(persister);
98 Reference.reachabilityFence(event_handler);
99 Reference.reachabilityFence(chain_monitor);
100 Reference.reachabilityFence(channel_manager);
101 Reference.reachabilityFence(gossip_sync);
102 Reference.reachabilityFence(peer_manager);
103 Reference.reachabilityFence(logger);
104 Reference.reachabilityFence(scorer);
105 if (ret >= 0 && ret <= 4096) { return null; }
106 org.ldk.structs.BackgroundProcessor ret_hu_conv = null; if (ret < 0 || ret > 4096) { ret_hu_conv = new org.ldk.structs.BackgroundProcessor(null, ret); }
107 ret_hu_conv.ptrs_to.add(ret_hu_conv);
108 ret_hu_conv.ptrs_to.add(persister);
109 ret_hu_conv.ptrs_to.add(event_handler);
110 ret_hu_conv.ptrs_to.add(chain_monitor);
111 ret_hu_conv.ptrs_to.add(channel_manager);
112 ret_hu_conv.ptrs_to.add(peer_manager);
113 ret_hu_conv.ptrs_to.add(logger);
114 ret_hu_conv.ptrs_to.add(scorer);
119 * Join `BackgroundProcessor`'s thread, returning any error that occurred while persisting
120 * [`ChannelManager`].
124 * This function panics if the background thread has panicked such as while persisting or
127 * [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
129 public Result_NoneErrorZ join() {
130 long ret = bindings.BackgroundProcessor_join(this.ptr);
131 Reference.reachabilityFence(this);
132 if (ret >= 0 && ret <= 4096) { return null; }
133 Result_NoneErrorZ ret_hu_conv = Result_NoneErrorZ.constr_from_ptr(ret);
134 this.ptrs_to.add(this);
135 // Due to rust's strict-ownership memory model, in some cases we need to "move"
136 // an object to pass exclusive ownership to the function being called.
137 // In most cases, we avoid this being visible in GC'd languages by cloning the object
138 // at the FFI layer, creating a new object which Rust can claim ownership of
139 // However, in some cases (eg here), there is no way to clone an object, and thus
140 // we actually have to pass full ownership to Rust.
141 // Thus, after this call, this is reset to null and is now a dummy object.
147 * Stop `BackgroundProcessor`'s thread, returning any error that occurred while persisting
148 * [`ChannelManager`].
152 * This function panics if the background thread has panicked such as while persisting or
155 * [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
157 public Result_NoneErrorZ stop() {
158 long ret = bindings.BackgroundProcessor_stop(this.ptr);
159 Reference.reachabilityFence(this);
160 if (ret >= 0 && ret <= 4096) { return null; }
161 Result_NoneErrorZ ret_hu_conv = Result_NoneErrorZ.constr_from_ptr(ret);
162 this.ptrs_to.add(this);
163 // Due to rust's strict-ownership memory model, in some cases we need to "move"
164 // an object to pass exclusive ownership to the function being called.
165 // In most cases, we avoid this being visible in GC'd languages by cloning the object
166 // at the FFI layer, creating a new object which Rust can claim ownership of
167 // However, in some cases (eg here), there is no way to clone an object, and thus
168 // we actually have to pass full ownership to Rust.
169 // Thus, after this call, this is reset to null and is now a dummy object.