Changed throttling window to be properly rolling.

src/client/transport.rs

@@ -1,5 +1,6 @@
 //! An IRC transport that wraps an IRC-framed stream to provide a number of features including
 //! automatic PING replies, automatic sending of PINGs, and message rate-limiting.
+use std::collections::VecDeque;
 use std::sync::{Arc, RwLock, RwLockReadGuard};
 use std::time::{Duration, Instant};
 
@@ -21,7 +22,7 @@ where
 {
     inner: Framed<T, IrcCodec>,
     burst_timer: Timer,
-    rolling_burst_window: Sleep,
+    rolling_burst_window: VecDeque<Sleep>,
     burst_window_length: u64,
     max_burst_messages: u64,
     current_burst_messages: u64,
@@ -39,12 +40,10 @@ where
     /// Creates a new `IrcTransport` from the given IRC stream.
     pub fn new(config: &Config, inner: Framed<T, IrcCodec>) -> IrcTransport<T> {
         let timer = tokio_timer::wheel().build();
-        let burst = tokio_timer::wheel().build();
-        let burst_window = burst.sleep(Duration::from_secs(config.burst_window_length() as u64));
         IrcTransport {
             inner: inner,
-            burst_timer: burst,
-            rolling_burst_window: burst_window,
+            burst_timer: tokio_timer::wheel().build(),
+            rolling_burst_window: VecDeque::new(),
             burst_window_length: config.burst_window_length() as u64,
             max_burst_messages: config.max_messages_in_burst() as u64,
             current_burst_messages: 0,
@@ -78,6 +77,10 @@ where
         self.poll_complete()?;
         Ok(())
     }
+
+    fn rolling_burst_window_front(&mut self) -> Result<Async<()>, tokio_timer::TimerError> {
+        self.rolling_burst_window.front_mut().map(|w| w.poll()).unwrap_or(Ok(Async::NotReady))
+    }
 }
 
 impl<T> Stream for IrcTransport<T>
@@ -148,15 +151,12 @@ where
             self.close()?;
             Err(error::ErrorKind::PingTimeout.into())
         } else {
-            // Check if the last rolling window has ended.
-            match self.rolling_burst_window.poll()? {
+            // Check if the oldest message in the rolling window is discounted.
+            match self.rolling_burst_window_front()? {
                 Async::NotReady => (),
                 Async::Ready(()) => {
-                    // Since it has ended, we reset the message count and start a new window.
-                    self.current_burst_messages = 0;
-                    self.rolling_burst_window = self.burst_timer.sleep(Duration::from_secs(
-                        self.burst_window_length
-                    ));
+                    self.current_burst_messages -= 1;
+                    self.rolling_burst_window.pop_front();
                 }
             }
 
@@ -171,6 +171,9 @@ where
                 AsyncSink::NotReady(item) => Ok(AsyncSink::NotReady(item)),
                 AsyncSink::Ready => {
                     self.current_burst_messages += 1;
+                    self.rolling_burst_window.push_back(self.burst_timer.sleep(Duration::from_secs(
+                        self.burst_window_length
+                    )));
                     Ok(AsyncSink::Ready)
                 }
             }