6 namespace org { namespace ldk { namespace structs {
10 * Implements [`Persist`] in a way that writes and reads both [`ChannelMonitor`]s and
11 * [`ChannelMonitorUpdate`]s.
15 * The main benefit this provides over the [`KVStore`]'s [`Persist`] implementation is decreased
16 * I/O bandwidth and storage churn, at the expense of more IOPS (including listing, reading, and
17 * deleting) and complexity. This is because it writes channel monitor differential updates,
18 * whereas the other (default) implementation rewrites the entire monitor on each update. For
19 * routing nodes, updates can happen many times per second to a channel, and monitors can be tens
20 * of megabytes (or more). Updates can be as small as a few hundred bytes.
22 * Note that monitors written with `MonitorUpdatingPersister` are _not_ backward-compatible with
23 * the default [`KVStore`]'s [`Persist`] implementation. They have a prepended byte sequence,
24 * [`MONITOR_UPDATING_PERSISTER_PREPEND_SENTINEL`], applied to prevent deserialization with other
25 * persisters. This is because monitors written by this struct _may_ have unapplied updates. In
26 * order to downgrade, you must ensure that all updates are applied to the monitor, and remove the
31 * Monitors are stored by implementing the [`Persist`] trait, which has two functions:
33 * - [`Persist::persist_new_channel`], which persists whole [`ChannelMonitor`]s.
34 * - [`Persist::update_persisted_channel`], which persists only a [`ChannelMonitorUpdate`]
36 * Whole [`ChannelMonitor`]s are stored in the [`CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE`],
37 * using the familiar encoding of an [`OutPoint`] (for example, `[SOME-64-CHAR-HEX-STRING]_1`).
39 * Each [`ChannelMonitorUpdate`] is stored in a dynamic secondary namespace, as follows:
41 * - primary namespace: [`CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE`]
42 * - secondary namespace: [the monitor's encoded outpoint name]
44 * Under that secondary namespace, each update is stored with a number string, like `21`, which
45 * represents its `update_id` value.
47 * For example, consider this channel, named for its transaction ID and index, or [`OutPoint`]:
49 * - Transaction ID: `deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef`
52 * Full channel monitors would be stored at a single key:
54 * `[CHANNEL_MONITOR_PERSISTENCE_PRIMARY_NAMESPACE]/deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef_1`
56 * Updates would be stored as follows (with `/` delimiting primary_namespace/secondary_namespace/key):
59 * [CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE]/deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef_1/1
60 * [CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE]/deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef_1/2
61 * [CHANNEL_MONITOR_UPDATE_PERSISTENCE_PRIMARY_NAMESPACE]/deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef_1/3
65 * # Reading channel state from storage
67 * Channel state can be reconstructed by calling
68 * [`MonitorUpdatingPersister::read_all_channel_monitors_with_updates`]. Alternatively, users can
69 * list channel monitors themselves and load channels individually using
70 * [`MonitorUpdatingPersister::read_channel_monitor_with_updates`].
72 * ## EXTREMELY IMPORTANT
74 * It is extremely important that your [`KVStore::read`] implementation uses the
75 * [`io::ErrorKind::NotFound`] variant correctly: that is, when a file is not found, and _only_ in
76 * that circumstance (not when there is really a permissions error, for example). This is because
77 * neither channel monitor reading function lists updates. Instead, either reads the monitor, and
78 * using its stored `update_id`, synthesizes update storage keys, and tries them in sequence until
79 * one is not found. All _other_ errors will be bubbled up in the function's [`Result`].
81 * # Pruning stale channel updates
83 * Stale updates are pruned when a full monitor is written. The old monitor is first read, and if
84 * that succeeds, updates in the range between the old and new monitors are deleted. The `lazy`
85 * flag is used on the [`KVStore::remove`] method, so there are no guarantees that the deletions
86 * will complete. However, stale updates are not a problem for data integrity, since updates are
87 * only read that are higher than the stored [`ChannelMonitor`]'s `update_id`.
89 * If you have many stale updates stored (such as after a crash with pending lazy deletes), and
90 * would like to get rid of them, consider using the
91 * [`MonitorUpdatingPersister::cleanup_stale_updates`] function.
93 public class MonitorUpdatingPersister : CommonBase {
94 internal MonitorUpdatingPersister(object _dummy, long ptr) : base(ptr) { }
95 ~MonitorUpdatingPersister() {
96 if (ptr != 0) { bindings.MonitorUpdatingPersister_free(ptr); }
100 * Constructs a new [`MonitorUpdatingPersister`].
102 * The `maximum_pending_updates` parameter controls how many updates may be stored before a
103 * [`MonitorUpdatingPersister`] consolidates updates by writing a full monitor. Note that
104 * consolidation will frequently occur with fewer updates than what you set here; this number
105 * is merely the maximum that may be stored. When setting this value, consider that for higher
106 * values of `maximum_pending_updates`:
108 * - [`MonitorUpdatingPersister`] will tend to write more [`ChannelMonitorUpdate`]s than
109 * [`ChannelMonitor`]s, approaching one [`ChannelMonitor`] write for every
110 * `maximum_pending_updates` [`ChannelMonitorUpdate`]s.
111 * - [`MonitorUpdatingPersister`] will issue deletes differently. Lazy deletes will come in
112 * \"waves\" for each [`ChannelMonitor`] write. A larger `maximum_pending_updates` means bigger,
113 * less frequent \"waves.\"
114 * - [`MonitorUpdatingPersister`] will potentially have more listing to do if you need to run
115 * [`MonitorUpdatingPersister::cleanup_stale_updates`].
117 public static MonitorUpdatingPersister of(org.ldk.structs.KVStore kv_store, org.ldk.structs.Logger logger, long maximum_pending_updates, org.ldk.structs.EntropySource entropy_source, org.ldk.structs.SignerProvider signer_provider) {
118 long ret = bindings.MonitorUpdatingPersister_new(kv_store.ptr, logger.ptr, maximum_pending_updates, entropy_source.ptr, signer_provider.ptr);
119 GC.KeepAlive(kv_store);
120 GC.KeepAlive(logger);
121 GC.KeepAlive(maximum_pending_updates);
122 GC.KeepAlive(entropy_source);
123 GC.KeepAlive(signer_provider);
124 if (ret >= 0 && ret <= 4096) { return null; }
125 org.ldk.structs.MonitorUpdatingPersister ret_hu_conv = null; if (ret < 0 || ret > 4096) { ret_hu_conv = new org.ldk.structs.MonitorUpdatingPersister(null, ret); }
126 if (ret_hu_conv != null) { ret_hu_conv.ptrs_to.AddLast(ret_hu_conv); };
127 if (ret_hu_conv != null) { ret_hu_conv.ptrs_to.AddLast(kv_store); };
128 if (ret_hu_conv != null) { ret_hu_conv.ptrs_to.AddLast(logger); };
129 if (ret_hu_conv != null) { ret_hu_conv.ptrs_to.AddLast(entropy_source); };
130 if (ret_hu_conv != null) { ret_hu_conv.ptrs_to.AddLast(signer_provider); };
135 * Reads all stored channel monitors, along with any stored updates for them.
137 * It is extremely important that your [`KVStore::read`] implementation uses the
138 * [`io::ErrorKind::NotFound`] variant correctly. For more information, please see the
139 * documentation for [`MonitorUpdatingPersister`].
141 public Result_CVec_C2Tuple_ThirtyTwoBytesChannelMonitorZZIOErrorZ read_all_channel_monitors_with_updates(org.ldk.structs.BroadcasterInterface broadcaster, org.ldk.structs.FeeEstimator fee_estimator) {
142 long ret = bindings.MonitorUpdatingPersister_read_all_channel_monitors_with_updates(this.ptr, broadcaster.ptr, fee_estimator.ptr);
144 GC.KeepAlive(broadcaster);
145 GC.KeepAlive(fee_estimator);
146 if (ret >= 0 && ret <= 4096) { return null; }
147 Result_CVec_C2Tuple_ThirtyTwoBytesChannelMonitorZZIOErrorZ ret_hu_conv = Result_CVec_C2Tuple_ThirtyTwoBytesChannelMonitorZZIOErrorZ.constr_from_ptr(ret);
148 if (this != null) { this.ptrs_to.AddLast(broadcaster); };
149 if (this != null) { this.ptrs_to.AddLast(fee_estimator); };
154 * Read a single channel monitor, along with any stored updates for it.
156 * It is extremely important that your [`KVStore::read`] implementation uses the
157 * [`io::ErrorKind::NotFound`] variant correctly. For more information, please see the
158 * documentation for [`MonitorUpdatingPersister`].
160 * For `monitor_key`, channel storage keys be the channel's transaction ID and index, or
161 * [`OutPoint`], with an underscore `_` between them. For example, given:
163 * - Transaction ID: `deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef`
166 * The correct `monitor_key` would be:
167 * `deadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeefdeadbeef_1`
169 * Loading a large number of monitors will be faster if done in parallel. You can use this
170 * function to accomplish this. Take care to limit the number of parallel readers.
172 public Result_C2Tuple_ThirtyTwoBytesChannelMonitorZIOErrorZ read_channel_monitor_with_updates(org.ldk.structs.BroadcasterInterface broadcaster, org.ldk.structs.FeeEstimator fee_estimator, string monitor_key) {
173 long ret = bindings.MonitorUpdatingPersister_read_channel_monitor_with_updates(this.ptr, broadcaster.ptr, fee_estimator.ptr, InternalUtils.encodeString(monitor_key));
175 GC.KeepAlive(broadcaster);
176 GC.KeepAlive(fee_estimator);
177 GC.KeepAlive(monitor_key);
178 if (ret >= 0 && ret <= 4096) { return null; }
179 Result_C2Tuple_ThirtyTwoBytesChannelMonitorZIOErrorZ ret_hu_conv = Result_C2Tuple_ThirtyTwoBytesChannelMonitorZIOErrorZ.constr_from_ptr(ret);
180 if (this != null) { this.ptrs_to.AddLast(broadcaster); };
181 if (this != null) { this.ptrs_to.AddLast(fee_estimator); };
186 * Cleans up stale updates for all monitors.
188 * This function works by first listing all monitors, and then for each of them, listing all
189 * updates. The updates that have an `update_id` less than or equal to than the stored monitor
190 * are deleted. The deletion can either be lazy or non-lazy based on the `lazy` flag; this will
191 * be passed to [`KVStore::remove`].
193 public Result_NoneIOErrorZ cleanup_stale_updates(bool lazy) {
194 long ret = bindings.MonitorUpdatingPersister_cleanup_stale_updates(this.ptr, lazy);
197 if (ret >= 0 && ret <= 4096) { return null; }
198 Result_NoneIOErrorZ ret_hu_conv = Result_NoneIOErrorZ.constr_from_ptr(ret);
203 * Constructs a new Persist which calls the relevant methods on this_arg.
204 * This copies the `inner` pointer in this_arg and thus the returned Persist must be freed before this_arg is
206 public Persist as_Persist() {
207 long ret = bindings.MonitorUpdatingPersister_as_Persist(this.ptr);
209 if (ret >= 0 && ret <= 4096) { return null; }
210 Persist ret_hu_conv = new Persist(null, ret);
211 if (ret_hu_conv != null) { ret_hu_conv.ptrs_to.AddLast(this); };