From c8d01b6151f77b62494d1d0147e3f3ab268d2bab Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ond=C5=99ej=20Hru=C5=A1ka?= <ondra@ondrovo.com>
Date: Sat, 31 Oct 2020 17:55:23 +0100
Subject: [PATCH] coroutine fixes, first example

---
 crsn/src/runtime/run_thread.rs       | 16 +++++++++---
 crsn/src/runtime/run_thread/state.rs |  5 +++-
 examples/coroutines1.csn             | 38 ++++++++++++++++++++++++++++
 3 files changed, 55 insertions(+), 4 deletions(-)
 create mode 100644 examples/coroutines1.csn

diff --git a/crsn/src/runtime/run_thread.rs b/crsn/src/runtime/run_thread.rs
index 9c6d3d7..fb58990 100644
--- a/crsn/src/runtime/run_thread.rs
+++ b/crsn/src/runtime/run_thread.rs
@@ -91,6 +91,7 @@ impl RunThread {
                         loop_helper.loop_start();
                     }
                     trace!("Step {}; Status = {}", advance, self.state.cr.frame.status);
+                    let orig_pc = self.state.cr.frame.pc;
                     self.state.cr.frame.pc.advance(advance);
 
                     if let Some(dl) = self.state.cr_deadline {
@@ -100,14 +101,17 @@ impl RunThread {
                     match sched {
                         SchedSignal::Normal => {}
                         SchedSignal::Yield(None) => {
+                            trace!("yield");
                             self.state.cr.cr_state = CoroutineState::Ready;
                             want_switch = true;
                         }
                         SchedSignal::Yield(Some(value)) => {
+                            trace!("yield {}", value);
                             self.state.cr.cr_state = CoroutineState::YieldedValue(value);
                             want_switch = true;
                         }
                         SchedSignal::Sleep(time) => {
+                            trace!("sleep {:?}", time);
                             self.state.cr.cr_state = CoroutineState::Sleep { due: Instant::now() + time };
                             want_switch = true;
                         }
@@ -117,27 +121,33 @@ impl RunThread {
                             // TODO prioritize a thread that is waiting for this return value
                         }
                         SchedSignal::Join(handle) => {
+                            trace!("Join cr {:#}", handle);
                             let mut found = false;
                             'find: for (n, th) in self.state.parked.iter_mut().enumerate() {
                                 if th.handle == handle {
                                     if let CoroutineState::Finished(_) = &th.cr_state {
                                         let mut crs = mem::replace(&mut th.cr_state, CoroutineState::Ready);
                                         self.state.parked.remove(n); // delete it
+                                        found = true;
 
                                         if let CoroutineState::Finished(vals) = crs {
                                             self.state.cr.frame.set_retvals(&vals);
-                                            found = true;
                                             break 'find;
                                         } else {
                                             unreachable!();
                                         }
+                                    } else {
+                                        self.state.cr.frame.pc = orig_pc; // Retry
+                                        self.state.cr.cr_state = CoroutineState::Ready;
+                                        want_switch = true;
+                                        found = true;
                                     }
                                 }
                             }
 
                             if !found {
                                 self.state.set_flag(Flag::Invalid, true);
-                                warn!("Join with invalid thread handle!");
+                                warn!("Join with invalid thread handle {:#}!", handle);
                                 self.state.cr.frame.set_retvals(&[]);
                             }
                         }
@@ -214,7 +224,7 @@ impl RunThread {
                 let n_alive = self.state.parked.iter()
                     .filter(|p| p.cr_state.is_alive()).count();
 
-                if n_alive <= 1 {
+                if n_alive == 0 {
                     trace!("Stop task switching, no parked threads are alive");
                     self.state.cr_deadline = None;
                 }
diff --git a/crsn/src/runtime/run_thread/state.rs b/crsn/src/runtime/run_thread/state.rs
index fc4f055..5b3ffc2 100644
--- a/crsn/src/runtime/run_thread/state.rs
+++ b/crsn/src/runtime/run_thread/state.rs
@@ -82,7 +82,10 @@ impl RunState {
     /// Add a coroutine, marked as Ready, to run next
     pub fn add_coroutine(&mut self, frame : StackFrame) -> Value {
         let handle = self.thread_info.unique_handle();
-        self.parked.push_back(CoroutineContext {
+        trace!("Spawn cr {:#}", handle);
+
+        // front - so it runs ASAP
+        self.parked.push_front(CoroutineContext {
             handle,
             frame,
             call_stack: vec![],
diff --git a/examples/coroutines1.csn b/examples/coroutines1.csn
new file mode 100644
index 0000000..e550114
--- /dev/null
+++ b/examples/coroutines1.csn
@@ -0,0 +1,38 @@
+(
+    (lds @cout "main\n")
+    (msleep 500)
+    (lds @cout "main\n")
+    (msleep 500)
+
+    (lds @cout "Spawnign bg\n")
+
+    (spawn r15 bg 10)
+
+    (msleep 500)
+    (lds @cout "FG\n")
+    (msleep 500)
+    (lds @cout "FG\n")
+    (msleep 500)
+    (lds @cout "FG\n")
+
+    (msleep 1000)
+
+    (lds @cout "Wait for BG\n")
+    (join @r15)
+    (lds @cout "Joined\n")
+    (msleep 500)
+    (lds @cout "main\n")
+    (msleep 500)
+    (lds @cout "main\n")
+    (msleep 500)
+
+    (proc bg times
+        (ld r0 times)
+        (:x)
+        (msleep 500)
+        (lds @cout "***BG\n")
+        (dec r0 (nz? (j :x)))
+        (lds @cout "***BG done.\n")
+        (ret)
+    )
+)