Fix calculation of per-second used counts in throttling

This is not the cause of throttling issues that I was having, but
something I think is a bug from reading the code.

`history` is a deque that is kept sorted by the timestamp: old entries
are popped from the front, and new entries are pushed to the back. To
calculate `used` and `requests_sent.per_sec[chat]`, we want to count
entries from the past second, so the newest ones, so from the back.

For `take_while` to work as expected, it needs to be called on the
reverse iterator, as the regular iterator is front-to-back. Otherwise
`take_while` can finish early due to entries that are up to a minute
old.

CHANGELOG.md

@@ -33,6 +33,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Now `InlineQueryResultsButton` serializes properly ([issue 1181](https://github.com/teloxide/teloxide/issues/1181))
 - Now `ThreadId` is able to serialize in multipart requests ([PR 1179](https://github.com/teloxide/teloxide/pull/1179))
 - Now stack does not overflow on dispatch ([issue 1154](https://github.com/teloxide/teloxide/issues/1154))
+- Fixed calculation of per-second limits in the `Throttle` adaptor ([PR 1212](https://github.com/teloxide/teloxide/pull/1212))
 
 ## 0.13.0 - 2024-08-16
 

crates/teloxide-core/src/adaptors/throttle/worker.rs

@@ -213,7 +213,7 @@ pub(super) async fn worker<B>(
 
         // as truncates which is ok since in case of truncation it would always be >=
         // limits.overall_s
-        let used = history.iter().take_while(|(_, time)| time > &sec_back).count() as u32;
+        let used = history.iter().rev().take_while(|(_, time)| time > &sec_back).count() as u32;
         let mut allowed = limits.messages_per_sec_overall.saturating_sub(used);
 
         if allowed == 0 {
@@ -222,7 +222,7 @@ pub(super) async fn worker<B>(
             continue;
         }
 
-        for (chat, _) in history.iter().take_while(|(_, time)| time > &sec_back) {
+        for (chat, _) in history.iter().rev().take_while(|(_, time)| time > &sec_back) {
             *requests_sent.per_sec.entry(*chat).or_insert(0) += 1;
         }