-/// An event indicating on-chain activity to watch for pertaining to a channel.
-pub enum WatchEvent {
- /// Watch for a transaction with `txid` and having an output with `script_pubkey` as a spending
- /// condition.
- WatchTransaction {
- /// Identifier of the transaction.
- txid: Txid,
-
- /// Spending condition for an output of the transaction.
- script_pubkey: Script,
- },
- /// Watch for spends of a transaction output identified by `outpoint` having `script_pubkey` as
- /// the spending condition.
- WatchOutput {
- /// Identifier for the output.
- outpoint: OutPoint,
-
- /// Spending condition for the output.
- script_pubkey: Script,
+/// The `Filter` trait defines behavior for indicating chain activity of interest pertaining to
+/// channels.
+///
+/// This is useful in order to have a [`Watch`] implementation convey to a chain source which
+/// transactions to be notified of. Notification may take the form of pre-filtering blocks or, in
+/// the case of [BIP 157]/[BIP 158], only fetching a block if the compact filter matches. If
+/// receiving full blocks from a chain source, any further filtering is unnecessary.
+///
+/// After an output has been registered, subsequent block retrievals from the chain source must not
+/// exclude any transactions matching the new criteria nor any in-block descendants of such
+/// transactions.
+///
+/// Note that use as part of a [`Watch`] implementation involves reentrancy. Therefore, the `Filter`
+/// should not block on I/O. Implementations should instead queue the newly monitored data to be
+/// processed later. Then, in order to block until the data has been processed, any `Watch`
+/// invocation that has called the `Filter` must return [`TemporaryFailure`].
+///
+/// [`Watch`]: trait.Watch.html
+/// [`TemporaryFailure`]: channelmonitor/enum.ChannelMonitorUpdateErr.html#variant.TemporaryFailure
+/// [BIP 157]: https://github.com/bitcoin/bips/blob/master/bip-0157.mediawiki
+/// [BIP 158]: https://github.com/bitcoin/bips/blob/master/bip-0158.mediawiki
+pub trait Filter: Send + Sync {
+ /// Registers interest in a transaction with `txid` and having an output with `script_pubkey` as
+ /// a spending condition.
+ fn register_tx(&self, txid: &Txid, script_pubkey: &Script);
+
+ /// Registers interest in spends of a transaction output identified by `outpoint` having
+ /// `script_pubkey` as the spending condition.
+ fn register_output(&self, outpoint: &OutPoint, script_pubkey: &Script);
+}
+
+impl<T: Listen> Listen for std::ops::Deref<Target = T> {
+ fn block_connected(&self, block: &Block, height: u32) {
+ (**self).block_connected(block, height);
+ }
+
+ fn block_disconnected(&self, header: &BlockHeader, height: u32) {
+ (**self).block_disconnected(header, height);
+ }
+}
+
+impl<T: std::ops::Deref, U: std::ops::Deref> Listen for (T, U)
+where
+ T::Target: Listen,
+ U::Target: Listen,
+{
+ fn block_connected(&self, block: &Block, height: u32) {
+ self.0.block_connected(block, height);
+ self.1.block_connected(block, height);
+ }
+
+ fn block_disconnected(&self, header: &BlockHeader, height: u32) {
+ self.0.block_disconnected(header, height);
+ self.1.block_disconnected(header, height);