Runtime, output format, docs

storey/flow.py

@@ -1438,7 +1438,30 @@ def set_table(self, key, table):
         self._tables[key] = table
 
 
+class _ParallelExecutionRunnableResult:
+    def __init__(self, data, runtime):
+        self.data = data
+        self.runtime = runtime
+
+
 class ParallelExecutionRunnable:
+    """
+    Runnable to be run by a ParallelExecution step. Subclasses must assign execution_mechanism with one of:
+    * "multiprocessing" – To run in a separate process. This is appropriate for CPU or GPU intensive tasks as they
+        would otherwise block the main process by holding Python's Global Interpreter Lock (GIL).
+    * "threading" – To run in a separate thread. This is appropriate for blocking I/O tasks, as they would otherwise
+        block the main event loop thread.
+    * "asyncio" – To run in an asyncio task. This is appropriate for I/O tasks that use asyncio, allowing the event
+        loop to continue running while waiting for a response.
+    * "naive" – To run in the main event loop. This is appropriate only for trivial computation and/or file I/O. It
+        means that the runnable will not actually be run in parallel to anything else.
+
+    Subclasses must also override the run() method with user code that handles the event and returns a result.
+
+    Subclasses may optionally override the init() method if the user's implementation of run() requires prior
+    initialization.
+    """
+
     execution_mechanism = None
 
     def __init__(self, name):
@@ -1452,6 +1475,18 @@ def init(self):
     def run(self, event):
         return event
 
+    def _run(self, event):
+        start = time.monotonic()
+        data = self.run(event)
+        end = time.monotonic()
+        return _ParallelExecutionRunnableResult(data, end - start)
+
+    async def _async_run(self, event):
+        start = time.monotonic()
+        data = await self.run(event)
+        end = time.monotonic()
+        return _ParallelExecutionRunnableResult(data, end - start)
+
 
 class ParallelExecution(Flow):
     """
@@ -1516,16 +1551,16 @@ async def _do(self, event):
                     raise ValueError(f"select_runnables() returned more than one outlet named '{runnable.name}'")
                 runnables_encountered.add(id(runnable))
                 if runnable.execution_mechanism == "asyncio":
-                    future = asyncio.get_running_loop().create_task(runnable.run(event))
+                    future = asyncio.get_running_loop().create_task(runnable._async_run(event))
                 elif runnable.execution_mechanism == "naive":
                     future = asyncio.get_running_loop().create_future()
-                    future.set_result(runnable.run(event))
+                    future.set_result(runnable._run(event))
                 else:
                     executor = self._executors[runnable.execution_mechanism]
-                    future = asyncio.get_running_loop().run_in_executor(executor, runnable.run, event)
+                    future = asyncio.get_running_loop().run_in_executor(executor, runnable._run, event)
                 futures.append(future)
-            results = await asyncio.gather(*futures)
-            event.body = {"inputs": event.body, "outputs": {}}
+            results: list[_ParallelExecutionRunnableResult] = await asyncio.gather(*futures)
+            event.body = {"input": event.body, "results": {}}
             for index, result in enumerate(results):
-                event.body["outputs"][self.runnables[index].name] = result
+                event.body["results"][self.runnables[index].name] = {"runtime": result.runtime, "output": result.data}
             return await self._do_downstream(event)

tests/test_flow.py

@@ -4809,13 +4809,15 @@ def select_runnables(self, event):
     controller = source.run()
     controller.emit(0)
     controller.terminate()
-    result = controller.await_termination()
+    termination_result = controller.await_termination()
     end = time.monotonic()
 
     assert end - start < 6
-    assert result == [
-        {
-            "inputs": 0,
-            "outputs": {"busy1": 1, "busy2": 1, "sleep1": 1, "sleep2": 1, "asleep1": 1, "asleep2": 1, "naive": 1},
-        }
-    ]
+    termination_result = termination_result[0]
+    assert termination_result.keys() == {"input", "results"}
+    assert termination_result["input"] == 0
+    results = termination_result["results"]
+    assert results.keys() == {"busy1", "busy2", "sleep1", "sleep2", "asleep1", "asleep2", "naive"}
+    for result in results.values():
+        assert result["output"] == 1
+        assert 1 < result["runtime"] < 2