Fix a post-request crasher when we try to do sandbox reuse

examples/game-of-life.py

@@ -15,17 +15,19 @@
 app = Flask(__name__)
 
 
-# Board width and height. We assume a square board for now.
-# 45 crashes. Viceroy will pass us no more than 1936 bytes of the board. (Or
-# maybe the entire URL gets truncated at 1965b.) If you change this, change the
-# f"{i:010000b}" format string below to be the new value squared.
+# Board width and height. We assume a square board for now. If you change this,
+# change the f"{i:010000b}" format string below to be the new value squared.
 WIDTH = HEIGHT = 50
 
 
 def decompressed_board(compressed: str) -> str:
     """Decompress the board representation sent from JS, returning a B&W board
     string ("10011011"...).
 
+    Viceroy will pass us no more than 1936 bytes of the board. (Or maybe the
+    entire URL gets truncated at 1965b.) This overcomes that (for the board
+    sizes we're interested in).
+
     :arg compressed: A urlsafe_b64encode()d representation of the bit-packed
         black-and-white board. (We don't need color info in order to compute the
         next board.)
@@ -41,9 +43,8 @@ def decompressed_board(compressed: str) -> str:
 
 @app.route("/board/<compressed_board>")
 def board(compressed_board: str):
-    """Return the next frame of the Game Of Life, given the current one. If a ""
-    board is given, return a new random board.
-    """
+    """Return the next frame of the Game Of Life, given the current one. If "none"
+    is given instead, return a new random board."""
     cells = decompressed_board(compressed_board)
 
     # Random board on start:

fastly_compute/wsgi.py

@@ -208,6 +208,8 @@ def handle(self, request: Any, body: Any) -> None:
                     # Something went wrong.
                     raise
             else:
+                if not result:
+                    break
                 request, body = result
                 serve_wsgi_request(
                     request,

tests/test_app.py → tests/test_bottle_example.py

@@ -1,9 +1,9 @@
-"""Tests for the Fastly Compute Python service (app.wasm functionality)."""
-
 from fastly_compute.testing import ViceroyTestBase
 
 
-class TestFastlyComputeApp(ViceroyTestBase):
+class TestBottleApp(ViceroyTestBase):
+    """Tests for the Bottle framework example"""
+
     def test_hello_endpoint(self):
         """Test the hello endpoint returns expected content."""
         response = self.get("/hello/test")

tests/test_flask_example.py

@@ -1,10 +1,10 @@
-"""Tests for the Flask example application."""
+"""Tests for the Flask example application"""
 
 from fastly_compute.testing import ViceroyTestBase
 
 
 class TestFlaskApp(ViceroyTestBase):
-    """Integration tests for the Flask example application."""
+    """Integration tests for the Flask example application"""
 
     WASM_FILE = "build/flask-app.composed.wasm"
 

tests/test_game_of_life_example.py

@@ -0,0 +1,50 @@
+import re
+from time import sleep
+
+from fastly_compute.testing import ViceroyTestBase
+
+
+class TestGameOfLife(ViceroyTestBase):
+    """Integration tests for the Game Of Life example"""
+
+    WASM_FILE = "build/game-of-life.composed.wasm"
+
+    def test_root(self):
+        """Show that the page full of JS at least loads."""
+        response = self.get("/")
+        assert response.status_code == 200
+        assert "async function startAnimation" in response.text
+
+    def test_random_board(self):
+        """Show that random boards are generated for the first frame."""
+        response = self.get("/board/none")
+        assert response.status_code == 200
+        assert re.match(r"[01]+", response.text)
+
+    def test_evolved_board(self):
+        """Show that a new board is correctly computed from an old one."""
+        response = self.get(
+            "/board/AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAcAAAAAAAAAAAAAAAAEAAAAAAABAAAAAHAAQAAAAAAAAAAAAAAAcAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAQAAAAAAAKAAAAAAAEgAAAAAAAwAADAAAAAAAN6AAAAAACscAAAAAAoOAGAAAAGACBgAAAAAAgAAAAAAAgAAAAAAAsAAAAAAAIAwAAAAAAgSAAAAAAAEgAAAAAAAwAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAHAAAAAAAAQAAAAAAAOADAAAAAAAAwAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=="
+        )
+        assert response.status_code == 200
+        assert (
+            response.text
+            == "0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000100000000000001210000000000000000000000000000000002000000000000000000000000000000000000000000000000010000000000010000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000202000000000000000000000000000000000000000000000020020000000000000000000000000000000000000000000000022000000000000000000010010000000000000000000000000000000000000000000231000300110000000000000000000000000000000000000003030001100020000000000000000000000000000000000000020300000200100000000033000000000000000000000000000032000000100000000000330000000000000000000000000000000000000000100000000000000000000000000000000000000000000000120000000000000000000000000000000000000000000000000220000000000000000000000000000000000000000000000001100000022000000000000000000000000000000000000000000000002002000000000000000000000000000000000000000000000020020000000000000000000000000000000000000000000000022000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000000000000000000000000003200000000000000000000000000000000000000000000000100000000000000000000000000000000000000000000000000232000000000003300000000000000000000000000000000000100000000000033000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
+        )
+
+    def test_reuse_sandboxes(self):
+        """Make sure attempting to issue multiple requests to a single sandbox doesn't crash.
+
+        This does not test whether a single sandbox actually served multiple
+        requests, though it tries to provoke that. Still, 2 sandboxes could have
+        served 1 request each.
+        """
+        response = self.get("/board/none")
+        assert response.status_code == 200
+        response = self.get("/board/none")
+        assert response.status_code == 200
+
+        # Reports about crashers in the post-response code come *after* the
+        # request has succeeded. And it seems to take awhile to show up.
+        sleep(0.5)  # .3 is not enough.
+        assert "WebAssembly trapped" not in "\n".join(self.server.output_lines)