Make `get_outputs_to_watch` return a `Vec` instead of a `HashMap`

`get_outputs_to_watch` returned a reference to an existing
`HashMap` avoiding extra clones, but there isn't a huge reason to
do so now that we have to clone to copy it out of the
`ChannelMonitor` mutex. Instead, return a `Vec` since it may be
less memory and it allows us to have a bindings C mapping for the
function.

Co-authored-by: Jeffrey Czyz <jkczyz@gmail.com>
Co-authored-by: Matt Corallo <git@bluematt.me>

diff --git a/lightning/src/chain/channelmonitor.rs b/lightning/src/chain/channelmonitor.rs
index 47ccdc16cde8e4f78f7695c6524697a23723445a..c2c791c4b172b8335c43117ff191e93320c3cddc 100644 (file)
--- a/lightning/src/chain/channelmonitor.rs
+++ b/lightning/src/chain/channelmonitor.rs
@@ -1166,16 +1166,15 @@ impl<Signer: Sign> ChannelMonitor<Signer> {
 
        /// Gets a list of txids, with their output scripts (in the order they appear in the
        /// transaction), which we must learn about spends of via block_connected().
-       ///
-       /// (C-not exported) because we have no HashMap bindings
-       pub fn get_outputs_to_watch(&self) -> HashMap<Txid, Vec<(u32, Script)>> {
-               self.inner.lock().unwrap().get_outputs_to_watch().clone()
+       pub fn get_outputs_to_watch(&self) -> Vec<(Txid, Vec<(u32, Script)>)> {
+               self.inner.lock().unwrap().get_outputs_to_watch()
+                       .iter().map(|(txid, outputs)| (*txid, outputs.clone())).collect()
        }
 
        /// Loads the funding txo and outputs to watch into the given `chain::Filter` by repeatedly
        /// calling `chain::Filter::register_output` and `chain::Filter::register_tx` until all outputs
        /// have been registered.
-       pub fn load_outputs_to_watch<F: Deref>(&self, filter: F) where F::Target: chain::Filter {
+       pub fn load_outputs_to_watch<F: Deref>(&self, filter: &F) where F::Target: chain::Filter {
                let lock = self.inner.lock().unwrap();
                filter.register_tx(&lock.get_funding_txo().0.txid, &lock.get_funding_txo().1);
                for (txid, outputs) in lock.get_outputs_to_watch().iter() {