Many fixes, still exceptions do not propagate properly, but tasks are cancelled when a task dies

experiment.py

@@ -10,7 +10,7 @@ What works and what does not (25th March 2020 20:35)
 - Join mechanism: V
 - Sleep mechanism: V
 - Cancellation mechanism: V
-- Exception propagation: V
+- Exception propagation: X
 - Concurrent I/O: V
 - Return values of coroutines: V
 - Scheduling tasks for future execution: V
@@ -23,6 +23,8 @@ async def countdown(n):
         while n > 0:
             print(f"Down {n}")
             n -= 1
+            if n <= 2:          # Test an exception that triggers only sometimes
+                raise ValueError
             await giambio.sleep(1)
         print("Countdown over")
         return "Count DOWN over"
@@ -44,16 +46,13 @@ async def count(stop, step=1):
 
 
 async def main():
-    try:
         print("Spawning countdown immediately, scheduling count for 4 secs from now")
         async with giambio.TaskManager(loop) as manager:
-            task = manager.spawn(countdown(4))
+            task = manager.spawn(countdown(8))
             manager.schedule(count(8, 2), 4)
-            await task.cancel()
         for task, ret in manager.values.items():
             print(f"Function '{task.coroutine.__name__}' at {hex(id(task.coroutine))} returned an object of type '{type(ret).__name__}': {repr(ret)}")
-    except:   # TODO: Fix this, see above
+
-        pass
 
 loop.start(main)
 

giambio/abstractions.py

@@ -10,7 +10,7 @@ class Result:
         self.exc = exc
 
     def __repr__(self):
-        return f"giambio.core.Result({self.val}, {self.exc})"
+        return f"giambio.core.Result({self.val}, {repr(self.exc)})"
 
 
 class Task:
@@ -19,7 +19,6 @@ class Task:
 
     def __init__(self, coroutine: types.coroutine, loop):
         self.coroutine = coroutine
-        self.status = False   # Not ran yet
         self.joined = False   # True if the task is joined
         self.result = None   # Updated when the coroutine execution ends
         self.loop = loop  # The EventLoop object that spawned the task
@@ -30,9 +29,11 @@ class Task:
     def run(self):
         """Simple abstraction layer over the coroutines ``send`` method"""
 
-        self.status = True
+        self.steps += 1
+        self.execution = "RUNNING"
         return self.coroutine.send(None)
 
+
     def __repr__(self):
         return f"giambio.core.Task({self.coroutine}, {self.status}, {self.joined}, {self.result})"
 
@@ -53,12 +54,4 @@ class Task:
         return await _join(self, silent)
 
     def get_result(self, silenced=False):
-        if self.result:
+        return self.result
-            if not silenced:
-                if self.result.exc:
-                    raise self.result.exc
-                else:
-                    return self.result.val
-            return self.result.val if self.result.val else self.result.exc
-
-

giambio/core.py

@@ -1,3 +1,4 @@
+
 import types
 from collections import deque, defaultdict
 from selectors import DefaultSelector, EVENT_READ, EVENT_WRITE
@@ -58,10 +59,13 @@ class EventLoop:
                     self.to_run.extend(self.joined.pop(self.running, ()))  # Reschedules the parent task
                 except RuntimeError:
                     self.to_run.extend(self.joined.pop(self.running, ()))   # Reschedules the parent task
-                except Exception as has_raised:
+                except CancelledError:
-                    self.to_run.extend(self.joined.pop(self.running, ()))  # Reschedules the parent task
+                    self.running.execution = "CANCELLED"
-                    self.running.result = Result(None, has_raised)  # Save the exception
+                    self.to_run.extend(self.joined.pop(self.running, ()))
-                    raise
+                except Exception as err:
+                    self.running.execution = "ERRORED"
+                    self.running.result = Result(None, err)
+                    self.to_run.extend(self.joined.pop(self.running, ()))   # Reschedules the parent task
                 except KeyboardInterrupt:
                     self.running.throw(KeyboardInterrupt)
 
@@ -139,7 +143,6 @@ class EventLoop:
     def want_cancel(self, task):
         self.to_run.extend(self.joined.pop(self.running, ()))
         self.to_run.append(self.running)   # Reschedules the parent task
-#        task.cancelled = True
         task.throw(CancelledError())
 
 
@@ -151,4 +154,4 @@ class EventLoop:
             await _want_write(sock)
         err = sock.getsockopt(SOL_SOCKET, SO_ERROR)
         if err != 0:
-            raise OSError(err, f'Connect call failed {addr}')
+            raise OSError(err, f'Connect call failed: {addr}')

giambio/util.py

@@ -15,19 +15,21 @@ class TaskManager:
         self.loop = loop   # The event loop that spawned the TaskManager
         self.silent = silent   # Make exceptions silent? (not recommended)
 
+
+    async def _cancel_and_raise(self, exc):
+        for task in self.tasks:
+            await task.cancel()
+
     async def __aenter__(self):
         return self
 
     async def __aexit__(self, type, value, traceback):
-        if type:
+        while self.tasks:
-            # TODO: Handle exceptions here
+            task = self.tasks.popleft()
-            ...
+            self.values[task] = await task.join()
-        else:
+            if task.result.exc:
-            for task in self.tasks:
+                if task.result.exc != CancelledError:
-                if not task.cancelled:
+                    await self._cancel_and_raise(task.result.exc)
-                    self.values[task] = await task.join()
-                else:
-                    self.values[task] = CancelledError()
 
     def spawn(self, coroutine: types.coroutine):
         """Schedules a task for execution, appending it to the call stack"""