minor package and README updates

README.md

@@ -3,6 +3,8 @@
 simple event-based model over core Python utilities like `ThreadPoolExecutor` to
 facilitate reactivity and manage concurrent responses.
 
+![High-level execution flow diagram](docs/_static/execlib.png)
+
 There are a few top-level classes exposed by the package:
 
 - **Router**: Central event routing object. Routers facilitate route registration,
@@ -17,3 +19,20 @@ There are a few top-level classes exposed by the package:
   iNotify to dynamically respond to file events.
 - **Server**: Long-running process manager for listeners and optional live-reloading via
   HTTP. Interfaces with listener `start()` and `shutdown()` for graceful interruption.
+
+# Install
+```sh
+pip install execlib
+```
+
+# Development
+
+## Documentation
+```sh
+pip install execlib[docs]
+```
+
+## Testing
+```sh
+pip install execlib[tests]
+```

execlib/router.py

@@ -860,14 +860,15 @@ class Router[E: Event]:
 
         # manually track and cancel pending futures b/c `.shutdown(cancel_futures=True)`
         # is misleading, and will cause an outer `as_completed` loop to hang
-        for future in tqdm(
-            list(self._active_futures),
-            desc=color_text(
-                f'Cancelling {len(self._active_futures)} pending futures...',
-                Fore.BLACK, Back.RED),
-            colour='red',
-        ):
-            future.cancel()
+        if self._active_futures:
+            for future in tqdm(
+                list(self._active_futures),
+                desc=color_text(
+                    f'Cancelling {len(self._active_futures)} pending futures...',
+                    Fore.BLACK, Back.RED),
+                colour='red',
+            ):
+                future.cancel()
 
         if self._thread_pool_2 is not None:
             # cancel pending futures (i.e., those not started)

pyproject.toml

@@ -43,6 +43,7 @@ docs = [
     "furo",
     "myst-parser",
 ]
+jupyter = ["ipykernel"]
 
 [project.urls]
 Homepage = "https://doc.olog.io/execlib"