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 [`NetGraphMsgHandler`] is provided to
22 * [`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29 * If [`ChannelManager`] persistence fails and the persisted manager becomes out-of-date, then
30 * there is a risk of channels force-closing on startup when the manager realizes it's outdated.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 * `persist_manager` returns an error. In case of an error, the error is retrieved by calling
53 * either [`join`] or [`stop`].
57 * `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 [`FilesystemPersister::persist_manager`] for Rust-Lightning's
60 * provided implementation.
62 * Typically, users should either implement [`ChannelManagerPersister`] to never return an
63 * error or call [`join`] and handle any error that may arise. For the latter case,
64 * `BackgroundProcessor` must be restarted by calling `start` again after handling the error.
68 * `event_handler` is responsible for handling events that users should be notified of (e.g.,
69 * payment failed). [`BackgroundProcessor`] may decorate the given [`EventHandler`] with common
70 * functionality implemented by other handlers.
71 * [`NetGraphMsgHandler`] if given will update the [`NetworkGraph`] based on payment failures.
73 * [top-level documentation]: BackgroundProcessor
74 * [`join`]: Self::join
75 * [`stop`]: Self::stop
76 * [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
77 * [`ChannelManager::write`]: lightning::ln::channelmanager::ChannelManager#impl-Writeable
78 * [`FilesystemPersister::persist_manager`]: lightning_persister::FilesystemPersister::persist_manager
79 * [`NetworkGraph`]: lightning::routing::network_graph::NetworkGraph
81 * Note that net_graph_msg_handler (or a relevant inner pointer) may be NULL or all-0s to represent None
83 public static BackgroundProcessor start(ChannelManagerPersister persister, EventHandler event_handler, ChainMonitor chain_monitor, ChannelManager channel_manager, @Nullable NetGraphMsgHandler net_graph_msg_handler, PeerManager peer_manager, Logger logger) {
84 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, net_graph_msg_handler == null ? 0 : net_graph_msg_handler.ptr & ~1, peer_manager == null ? 0 : peer_manager.ptr & ~1, logger == null ? 0 : logger.ptr);
85 Reference.reachabilityFence(persister);
86 Reference.reachabilityFence(event_handler);
87 Reference.reachabilityFence(chain_monitor);
88 Reference.reachabilityFence(channel_manager);
89 Reference.reachabilityFence(net_graph_msg_handler);
90 Reference.reachabilityFence(peer_manager);
91 Reference.reachabilityFence(logger);
92 if (ret >= 0 && ret <= 4096) { return null; }
93 BackgroundProcessor ret_hu_conv = null; if (ret < 0 || ret > 4096) { ret_hu_conv = new BackgroundProcessor(null, ret); }
94 ret_hu_conv.ptrs_to.add(ret_hu_conv);
95 ret_hu_conv.ptrs_to.add(persister);
96 ret_hu_conv.ptrs_to.add(event_handler);
97 ret_hu_conv.ptrs_to.add(chain_monitor);
98 ret_hu_conv.ptrs_to.add(channel_manager);
99 ret_hu_conv.ptrs_to.add(net_graph_msg_handler);
100 ret_hu_conv.ptrs_to.add(peer_manager);
101 ret_hu_conv.ptrs_to.add(logger);
106 * Join `BackgroundProcessor`'s thread, returning any error that occurred while persisting
107 * [`ChannelManager`].
111 * This function panics if the background thread has panicked such as while persisting or
114 * [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
116 public Result_NoneErrorZ join() {
117 long ret = bindings.BackgroundProcessor_join(this.ptr);
118 Reference.reachabilityFence(this);
119 if (ret >= 0 && ret <= 4096) { return null; }
120 Result_NoneErrorZ ret_hu_conv = Result_NoneErrorZ.constr_from_ptr(ret);
121 this.ptrs_to.add(this);
122 // Due to rust's strict-ownership memory model, in some cases we need to "move"
123 // an object to pass exclusive ownership to the function being called.
124 // In most cases, we avoid this being visible in GC'd languages by cloning the object
125 // at the FFI layer, creating a new object which Rust can claim ownership of
126 // However, in some cases (eg here), there is no way to clone an object, and thus
127 // we actually have to pass full ownership to Rust.
128 // Thus, after this call, this is reset to null and is now a dummy object.
134 * Stop `BackgroundProcessor`'s thread, returning any error that occurred while persisting
135 * [`ChannelManager`].
139 * This function panics if the background thread has panicked such as while persisting or
142 * [`ChannelManager`]: lightning::ln::channelmanager::ChannelManager
144 public Result_NoneErrorZ stop() {
145 long ret = bindings.BackgroundProcessor_stop(this.ptr);
146 Reference.reachabilityFence(this);
147 if (ret >= 0 && ret <= 4096) { return null; }
148 Result_NoneErrorZ ret_hu_conv = Result_NoneErrorZ.constr_from_ptr(ret);
149 this.ptrs_to.add(this);
150 // Due to rust's strict-ownership memory model, in some cases we need to "move"
151 // an object to pass exclusive ownership to the function being called.
152 // In most cases, we avoid this being visible in GC'd languages by cloning the object
153 // at the FFI layer, creating a new object which Rust can claim ownership of
154 // However, in some cases (eg here), there is no way to clone an object, and thus
155 // we actually have to pass full ownership to Rust.
156 // Thus, after this call, this is reset to null and is now a dummy object.