From cdca875b63d37bf0009c5ec09e951c6043ee9e17 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=A1=D1=8B=D1=80=D1=86=D0=B5=D0=B2=20=D0=92=D0=B0=D0=B4?=
 =?UTF-8?q?=D0=B8=D0=BC=20=D0=98=D0=B3=D0=BE=D1=80=D0=B5=D0=B2=D0=B8=D1=87?=
 <syrtcevvi@gmail.com>
Date: Thu, 1 Feb 2024 10:35:10 +0300
Subject: [PATCH] Fix backoff bugs

---
 .../src/{backoff_strategy.rs => backoff.rs}   |  7 +++++-
 crates/teloxide/src/lib.rs                    |  2 +-
 .../teloxide/src/update_listeners/polling.rs  | 25 +++++++++----------
 3 files changed, 19 insertions(+), 15 deletions(-)
 rename crates/teloxide/src/{backoff_strategy.rs => backoff.rs} (50%)

diff --git a/crates/teloxide/src/backoff_strategy.rs b/crates/teloxide/src/backoff.rs
similarity index 50%
rename from crates/teloxide/src/backoff_strategy.rs
rename to crates/teloxide/src/backoff.rs
index b4541d6a..26819a1d 100644
--- a/crates/teloxide/src/backoff_strategy.rs
+++ b/crates/teloxide/src/backoff.rs
@@ -4,7 +4,12 @@ pub type BackoffStrategy = Box<dyn Send + Fn(u32) -> Duration>;
 
 /// Calculates the backoff time in seconds for exponential strategy with base 2
 ///
+/// The maximum duration is limited to a little less than half an hour (1024
+/// secs), so the successive timings are(in secs): 1, 2, 4, .., 1024, 1024, ..
+///
 /// More at: <https://en.wikipedia.org/wiki/Exponential_backoff#Exponential_backoff_algorithm>
 pub fn exponential_backoff_strategy(error_count: u32) -> Duration {
-    Duration::from_secs((1_u64 << error_count).min(30 * 60))
+    // The error_count has to be limited so as not to cause overflow: 2^10 = 1024 ~
+    // a little less than half an hour
+    Duration::from_secs(1_u64 << error_count.min(10))
 }
diff --git a/crates/teloxide/src/lib.rs b/crates/teloxide/src/lib.rs
index 2ed44c89..4535d843 100644
--- a/crates/teloxide/src/lib.rs
+++ b/crates/teloxide/src/lib.rs
@@ -135,7 +135,7 @@ pub use repls::{repl, repl_with_listener};
 #[allow(deprecated)]
 pub use repls::{commands_repl, commands_repl_with_listener};
 
-pub mod backoff_strategy;
+pub mod backoff;
 pub mod dispatching;
 pub mod error_handlers;
 pub mod prelude;
diff --git a/crates/teloxide/src/update_listeners/polling.rs b/crates/teloxide/src/update_listeners/polling.rs
index 4d7e55a9..e39ba977 100644
--- a/crates/teloxide/src/update_listeners/polling.rs
+++ b/crates/teloxide/src/update_listeners/polling.rs
@@ -15,7 +15,7 @@ use futures::{ready, stream::Stream};
 use tokio::time::{sleep, Sleep};
 
 use crate::{
-    backoff_strategy::{exponential_backoff_strategy, BackoffStrategy},
+    backoff::{exponential_backoff_strategy, BackoffStrategy},
     requests::{HasPayload, Request, Requester},
     stop::{mk_stop_token, StopFlag, StopToken},
     types::{AllowedUpdate, Update},
@@ -91,8 +91,11 @@ where
     /// reconnections caused by network errors.
     ///
     /// By default, the [`exponential_backoff_strategy`] is used.
-    pub fn backoff_strategy(self, backoff_strategy: BackoffStrategy) -> Self {
-        Self { backoff_strategy, ..self }
+    pub fn backoff_strategy(
+        self,
+        backoff_strategy: impl 'static + Send + Fn(u32) -> Duration,
+    ) -> Self {
+        Self { backoff_strategy: Box::new(backoff_strategy), ..self }
     }
 
     /// Deletes webhook if it was set up.
@@ -463,16 +466,12 @@ impl<B: Requester> Stream for PollingStream<'_, B> {
         }
         // Poll eepy future until completion, needed for backoff strategy
         else if let Some(eepy) = this.eepy.as_mut().as_pin_mut() {
-            match eepy.poll(cx) {
-                Poll::Ready(_) => {
-                    // As soon as delay is waited we increment the counter
-                    *this.error_count = this.error_count.saturating_add(1);
-                    log::trace!("current error count: {}", *this.error_count);
-                    log::trace!("backoff delay completed");
-                    this.eepy.set(None);
-                }
-                Poll::Pending => return Poll::Pending,
-            }
+            ready!(eepy.poll(cx));
+            // As soon as delay is waited we increment the counter
+            *this.error_count = this.error_count.saturating_add(1);
+            log::trace!("current error count: {}", *this.error_count);
+            log::trace!("backoff delay completed");
+            this.eepy.as_mut().set(None);
         }
 
         let (offset, limit, timeout) = match (this.stopping, this.drop_pending_updates) {