From 6b2e179bc1fef2f91f84cdce883752162ec41466 Mon Sep 17 00:00:00 2001
From: Matt Corallo <git@bluematt.me>
Date: Mon, 12 Apr 2021 13:48:29 -0400
Subject: [PATCH] Return ChannelMonitors in a Vec, not HashMap when loading
 from disk

There's little reason for the HashMap - the ChannelMonitors are
already unique (enforced by file names), and the eventual HashMap
that users need when deserializing the `ChannelManager` is a
slightly different form (it requires no BlockHash entry).
---
 lightning-persister/src/lib.rs | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/lightning-persister/src/lib.rs b/lightning-persister/src/lib.rs
index 8effedbc..74e05d4c 100644
--- a/lightning-persister/src/lib.rs
+++ b/lightning-persister/src/lib.rs
@@ -12,7 +12,7 @@ extern crate lightning;
 extern crate bitcoin;
 extern crate libc;
 
-use bitcoin::{BlockHash, Txid};
+use bitcoin::hash_types::{BlockHash, Txid};
 use bitcoin::hashes::hex::{FromHex, ToHex};
 use crate::util::DiskWriteable;
 use lightning::chain;
@@ -24,7 +24,6 @@ use lightning::chain::transaction::OutPoint;
 use lightning::ln::channelmanager::ChannelManager;
 use lightning::util::logger::Logger;
 use lightning::util::ser::{ReadableArgs, Writeable};
-use std::collections::HashMap;
 use std::fs;
 use std::io::{Cursor, Error};
 use std::ops::Deref;
@@ -103,14 +102,14 @@ impl FilesystemPersister {
 	/// Read `ChannelMonitor`s from disk.
 	pub fn read_channelmonitors<Signer: Sign, K: Deref> (
 		&self, keys_manager: K
-	) -> Result<HashMap<OutPoint, (BlockHash, ChannelMonitor<Signer>)>, std::io::Error>
+	) -> Result<Vec<(BlockHash, ChannelMonitor<Signer>)>, std::io::Error>
 	     where K::Target: KeysInterface<Signer=Signer> + Sized
 	{
 		let path = self.path_to_monitor_data();
 		if !Path::new(&path).exists() {
-			return Ok(HashMap::new());
+			return Ok(Vec::new());
 		}
-		let mut outpoint_to_channelmonitor = HashMap::new();
+		let mut res = Vec::new();
 		for file_option in fs::read_dir(path).unwrap() {
 			let file = file_option.unwrap();
 			let owned_file_name = file.file_name();
@@ -142,10 +141,10 @@ impl FilesystemPersister {
 			let mut buffer = Cursor::new(&contents);
 			match <(BlockHash, ChannelMonitor<Signer>)>::read(&mut buffer, &*keys_manager) {
 				Ok((blockhash, channel_monitor)) => {
-					outpoint_to_channelmonitor.insert(
-						OutPoint { txid: txid.unwrap(), index: index.unwrap() },
-						(blockhash, channel_monitor),
-					);
+					if channel_monitor.get_funding_txo().0.txid != txid.unwrap() || channel_monitor.get_funding_txo().0.index != index.unwrap() {
+						return Err(std::io::Error::new(std::io::ErrorKind::InvalidData, "ChannelMonitor was stored in the wrong file"));
+					}
+					res.push((blockhash, channel_monitor));
 				}
 				Err(e) => return Err(std::io::Error::new(
 					std::io::ErrorKind::InvalidData,
@@ -153,7 +152,7 @@ impl FilesystemPersister {
 				))
 			}
 		}
-		Ok(outpoint_to_channelmonitor)
+		Ok(res)
 	}
 }
 
@@ -225,21 +224,21 @@ mod tests {
 		// Check that the persisted channel data is empty before any channels are
 		// open.
 		let mut persisted_chan_data_0 = persister_0.read_channelmonitors(nodes[0].keys_manager).unwrap();
-		assert_eq!(persisted_chan_data_0.keys().len(), 0);
+		assert_eq!(persisted_chan_data_0.len(), 0);
 		let mut persisted_chan_data_1 = persister_1.read_channelmonitors(nodes[1].keys_manager).unwrap();
-		assert_eq!(persisted_chan_data_1.keys().len(), 0);
+		assert_eq!(persisted_chan_data_1.len(), 0);
 
 		// Helper to make sure the channel is on the expected update ID.
 		macro_rules! check_persisted_data {
 			($expected_update_id: expr) => {
 				persisted_chan_data_0 = persister_0.read_channelmonitors(nodes[0].keys_manager).unwrap();
-				assert_eq!(persisted_chan_data_0.keys().len(), 1);
-				for (_, mon) in persisted_chan_data_0.values() {
+				assert_eq!(persisted_chan_data_0.len(), 1);
+				for (_, mon) in persisted_chan_data_0.iter() {
 					assert_eq!(mon.get_latest_update_id(), $expected_update_id);
 				}
 				persisted_chan_data_1 = persister_1.read_channelmonitors(nodes[1].keys_manager).unwrap();
-				assert_eq!(persisted_chan_data_1.keys().len(), 1);
-				for (_, mon) in persisted_chan_data_1.values() {
+				assert_eq!(persisted_chan_data_1.len(), 1);
+				for (_, mon) in persisted_chan_data_1.iter() {
 					assert_eq!(mon.get_latest_update_id(), $expected_update_id);
 				}
 			}
-- 
2.30.2