From d78bf379fb85c0264c9971a26724f8b933a234ee Mon Sep 17 00:00:00 2001
From: Alex Auvolat <alex@adnab.me>
Date: Tue, 1 Mar 2022 14:55:37 +0100
Subject: [PATCH] Fix resync queue to not drop items

---
 src/model/block.rs | 37 +++++++++++++++++++++----------------
 1 file changed, 21 insertions(+), 16 deletions(-)

diff --git a/src/model/block.rs b/src/model/block.rs
index f0814eda..8329bb6f 100644
--- a/src/model/block.rs
+++ b/src/model/block.rs
@@ -562,9 +562,12 @@ impl BlockManager {
 	}
 
 	async fn resync_iter(&self, must_exit: &mut watch::Receiver<bool>) -> Result<bool, Error> {
-		if let Some((time_bytes, hash_bytes)) = self.resync_queue.pop_min()? {
+		if let Some(first_pair_res) = self.resync_queue.iter().next() {
+			let (time_bytes, hash_bytes) = first_pair_res?;
+
 			let time_msec = u64::from_be_bytes(time_bytes[0..8].try_into().unwrap());
 			let now = now_msec();
+
 			if now >= time_msec {
 				let hash = Hash::try_from(&hash_bytes[..]).unwrap();
 
@@ -575,6 +578,9 @@ impl BlockManager {
 						// don't do resync and return early, but still
 						// make sure the item is still in queue at expected time
 						self.put_to_resync_at(&hash, ec.next_try())?;
+						// ec.next_try() > now >= time_msec, so this remove
+						// is not removing the one we added just above
+						self.resync_queue.remove(time_bytes)?;
 						return Ok(false);
 					}
 				}
@@ -605,20 +611,25 @@ impl BlockManager {
 					warn!("Error when resyncing {:?}: {}", hash, e);
 
 					let err_counter = match self.resync_errors.get(hash.as_slice())? {
-						Some(ec) => ErrorCounter::decode(ec).add1(),
-						None => ErrorCounter::new(),
+						Some(ec) => ErrorCounter::decode(ec).add1(now + 1),
+						None => ErrorCounter::new(now + 1),
 					};
 
-					self.put_to_resync_at(&hash, err_counter.next_try())?;
 					self.resync_errors
 						.insert(hash.as_slice(), err_counter.encode())?;
+
+					self.put_to_resync_at(&hash, err_counter.next_try())?;
+					// err_counter.next_try() >= now + 1 > now,
+					// the entry we remove from the queue is not
+					// the entry we inserted with put_to_resync_at
+					self.resync_queue.remove(time_bytes)?;
 				} else {
 					self.resync_errors.remove(hash.as_slice())?;
+					self.resync_queue.remove(time_bytes)?;
 				}
 
 				Ok(true)
 			} else {
-				self.resync_queue.insert(time_bytes, hash_bytes)?;
 				let delay = tokio::time::sleep(Duration::from_millis(time_msec - now));
 				select! {
 					_ = delay.fuse() => {},
@@ -1044,19 +1055,13 @@ struct ErrorCounter {
 	last_try: u64,
 }
 
-impl Default for ErrorCounter {
-	fn default() -> Self {
+impl ErrorCounter {
+	fn new(now: u64) -> Self {
 		Self {
 			errors: 1,
-			last_try: now_msec(),
+			last_try: now,
 		}
 	}
-}
-
-impl ErrorCounter {
-	fn new() -> Self {
-		Self::default()
-	}
 
 	fn decode(data: sled::IVec) -> Self {
 		Self {
@@ -1072,10 +1077,10 @@ impl ErrorCounter {
 		.concat()
 	}
 
-	fn add1(self) -> Self {
+	fn add1(self, now: u64) -> Self {
 		Self {
 			errors: self.errors + 1,
-			last_try: now_msec(),
+			last_try: now,
 		}
 	}