[examples/hackernews] Add button to simulate activity.

Add a special API end point that simulate series of 1 to 20 upvotes to
a random post every second.

Author: Lucas Hosseini

examples/hackernews/web_service/app.py

@@ -2,6 +2,8 @@
 import secrets
 import psycopg2
 import requests
+import random
+import time
 
 REACTIVE_SERVICE_URL = "http://reactive_cache:8081/v1"
 
@@ -250,3 +252,24 @@ def deupvote_post(post_id):
 @app.get("/healthcheck")
 def healthcheck():
     return "ok", 200
+
+
+@app.post("/simulate_activity")
+def simulate_activity():
+    with get_db() as db:
+        with db.cursor() as cur:
+            cur.execute("SELECT id FROM posts")
+            post_ids = [x[0] for x in cur.fetchall()]
+
+            for i in range(1000):
+                post_id = random.choice(post_ids)
+                for j in range(random.randrange(20)):
+                    user_id = random.randint(0, 1000)
+                    cur.execute(
+                        "INSERT INTO upvotes(user_id, post_id) VALUES (%s, %s)",
+                        (user_id, post_id),
+                    )
+                    db.commit()
+                time.sleep(1)
+
+    return "ok", 200

examples/hackernews/www/src/App.tsx

@@ -203,6 +203,14 @@ function Feed(props: { posts: Post[]; session: Session | null }) {
     );
   }
 
+  function simulateActivity() {
+    void fetch("/api/simulate_activity", { method: "POST" }).catch(
+      (err: unknown) => {
+        console.error(err);
+      },
+    );
+  }
+
   return (
     <>
       <Header session={session} />
@@ -233,6 +241,14 @@ function Feed(props: { posts: Post[]; session: Session | null }) {
           ))}
         </ol>
       </div>
+      <button
+        onClick={(e) => {
+          e.preventDefault();
+          simulateActivity();
+        }}
+      >
+        Simulate activity
+      </button>
     </>
   );
 }