From c5aba7183dc7c893ad42d41d9cac19e782715533 Mon Sep 17 00:00:00 2001
From: Mathias Hall-Andersen <mathias@hall-andersen.dk>
Date: Thu, 22 Aug 2019 14:59:15 +0200
Subject: Initial version of timer framework

---
 src/timers/timer.rs | 146 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 146 insertions(+)
 create mode 100644 src/timers/timer.rs

(limited to 'src/timers/timer.rs')

diff --git a/src/timers/timer.rs b/src/timers/timer.rs
new file mode 100644
index 0000000..484a5c2
--- /dev/null
+++ b/src/timers/timer.rs
@@ -0,0 +1,146 @@
+use ferris::*;
+use spin;
+use std::collections::HashMap;
+use std::mem;
+use std::sync::atomic::{AtomicBool, AtomicU64, AtomicUsize, Ordering};
+use std::sync::{Arc, Weak};
+use std::thread;
+use std::time::{Duration, Instant};
+use std::u64;
+
+type TimerID = u64;
+type TimerKey = (u64, usize);
+type Callback = (Arc<AtomicBool>, Box<dyn Fn() -> () + Send + 'static>);
+
+const ACCURACY: Duration = Duration::from_millis(100);
+const OFFSET: Duration = Duration::from_millis(1000);
+
+struct RunnerInner {
+    keys: AtomicU64,
+    wheel: spin::Mutex<CopyWheel<TimerKey>>,
+    running: AtomicBool,
+    callback: spin::Mutex<HashMap<TimerID, Callback>>,
+}
+
+pub struct Timer {
+    pending: Arc<AtomicBool>,
+    runner: Weak<RunnerInner>,
+    id: u64,
+    cnt: AtomicUsize,
+}
+
+struct Runner(Arc<RunnerInner>, Option<thread::JoinHandle<()>>);
+
+impl Runner {
+    fn new() -> Self {
+        let inner = Arc::new(RunnerInner {
+            running: AtomicBool::new(true),
+            callback: spin::Mutex::new(HashMap::new()),
+            keys: AtomicU64::new(0),
+            wheel: spin::Mutex::new(CopyWheel::<TimerKey>::new(vec![
+                Resolution::HundredMs,
+                Resolution::Sec,
+                Resolution::Min,
+            ])),
+        });
+
+        // start runner thread
+        let handle = {
+            let inner = inner.clone();
+            thread::spawn(move || {
+                let mut next = Instant::now() + ACCURACY;
+                while inner.running.load(Ordering::Acquire) {
+                    // sleep
+                    let now = Instant::now();
+                    if next > now {
+                        thread::sleep(next - now);
+                    }
+                    next = next + ACCURACY;
+
+                    // extract expired events
+                    let expired = inner.wheel.lock().expire();
+
+                    // handle expired events
+                    for key in &expired {
+                        if let Some((pending, callback)) = inner.callback.lock().get(&key.0) {
+                            if pending.swap(false, Ordering::SeqCst) {
+                                callback();
+                            }
+                        } else {
+                            unreachable!()
+                        };
+                    }
+                }
+            })
+        };
+
+        Runner(inner, Some(handle))
+    }
+
+    pub fn timer(&self, callback: Box<dyn Fn() -> () + Send + 'static>) -> Timer {
+        let id = self.0.keys.fetch_add(1, Ordering::Relaxed);
+        let pending = Arc::new(AtomicBool::new(false));
+
+        assert!(id < u64::MAX, "wrapping of ids");
+
+        self.0
+            .callback
+            .lock()
+            .insert(id, (pending.clone(), callback));
+
+        Timer {
+            id,
+            pending: pending,
+            runner: Arc::downgrade(&self.0.clone()),
+            cnt: AtomicUsize::new(0),
+        }
+    }
+}
+
+impl Timer {
+    pub fn reset(&self, duration: Duration) {
+        if let Some(runner) = self.runner.upgrade() {
+            let mut wheel = runner.wheel.lock();
+            let cnt = self.cnt.fetch_add(1, Ordering::SeqCst);
+            self.pending.store(true, Ordering::SeqCst);
+            wheel.stop((self.id, cnt));
+            wheel.start((self.id, cnt + 1), duration - OFFSET);
+        }
+    }
+
+    pub fn start(&self, duration: Duration) {
+        if self.pending.load(Ordering::Acquire) {
+            return;
+        }
+
+        if let Some(runner) = self.runner.upgrade() {
+            let mut wheel = runner.wheel.lock();
+            if !self.pending.swap(true, Ordering::SeqCst) {
+                let cnt = self.cnt.fetch_add(1, Ordering::SeqCst);
+                wheel.start((self.id, cnt + 1), duration - OFFSET);
+            }
+        }
+    }
+
+    pub fn stop(&self) {
+        if self.pending.load(Ordering::Acquire) {
+            if let Some(runner) = self.runner.upgrade() {
+                let mut wheel = runner.wheel.lock();
+                if self.pending.swap(false, Ordering::SeqCst) {
+                    let cnt = self.cnt.load(Ordering::SeqCst);
+                    wheel.stop((self.id, cnt));
+                }
+            }
+        }
+    }
+}
+
+impl Drop for Runner {
+    fn drop(&mut self) {
+        // stop the callback thread
+        self.0.running.store(false, Ordering::SeqCst);
+        if let Some(handle) = mem::replace(&mut self.1, None) {
+            handle.join().unwrap();
+        }
+    }
+}
-- 
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