refactor: wrap the fetching-task with the semaphoreHEADmain

That is, do that instead of wrapping the code inside 'fetch'.

The current approach conveys more pithily what our intention is - that
'fetch' is the entirety of the asynchronous task we want to "rate
limit".

1 files changed, 11 insertions, 3 deletions

diff --git a/main.py b/main.py
index cf647ff..44662b2 100644
--- a/main.py
+++ b/main.py
@@ -33,7 +33,7 @@ def get_urls(filename: str, limit: int | None = None) -> list[str]:
         return urls
 
 
-async def fetch(session: aiohttp.ClientSession, url: str, semaphore: asyncio.Semaphore) -> str:
+async def fetch(session: aiohttp.ClientSession, url: str) -> str:
     """Fetch a URL under the given SESSION.
 
     Use SEMAPHORE to limit the number of tasks that can make an HTTP
@@ -45,7 +45,7 @@ async def fetch(session: aiohttp.ClientSession, url: str, semaphore: asyncio.Sem
     """
 
     try:
-        async with semaphore, session.get(url) as response:
+        async with session.get(url) as response:
             print(".", end="", flush=True)
             if response.ok:
                 return "😁"
@@ -73,7 +73,15 @@ async def ping(urls: list[str], max_concurrency: int) -> list[str]:
         asyncio.TaskGroup() as tg,
     ):
         semaphore = asyncio.Semaphore(max_concurrency)
-        tasks = [tg.create_task(fetch(session, url, semaphore)) for url in urls]
+        tasks: list[asyncio.Task[str]] = []
+
+        for url in urls:
+            # Wrap the fetch-call with the semaphore.
+            async def rate_limited():
+                async with semaphore:
+                    return await fetch(session, url)
+
+            tasks.append(tg.create_task(rate_limited()))
 
     return [t.result() for t in tasks]