### Timing Attacks { #timing-attacks }

But what's a "timing attack"?

Let's imagine some attackers are trying to guess the username and password.

And they send a request with a username `johndoe` and a password `love123`.

Then the Python code in your application would be equivalent to something like:

```Python
if "johndoe" == "stanleyjobson" and "love123" == "swordfish":

time scanning up to a sixteenth of the namespace. Object versions marked `PENDING` or `FAILED` are re-queued for replication.

Replication speed depends on the cluster load, number of objects in the object store as well as storage speed. In addition, any bandwidth limits set via `mc admin bucket remote add` could also contribute to replication speed. The number of workers used for replication defaults to 100. Based on network bandwidth and system load, the number of workers used in replication...

Returning any error will also cancel the stream remotely.

CAREFUL: When utilizing two-way communication, it is important to ensure that the remote handler is not blocked on a send.
If the remote handler is blocked on a send, and the client is trying to send without the remote receiving,
the operation would become deadlocked if the channels are full.

### Typed handlers

        new LineProcessor<Integer>() {
          int seen;

          @Override
          public boolean processLine(String line) {
            seen++;
            sb.append(line);
            return seen < 2;
          }

          @Override
          public Integer getResult() {
            return seen;
          }
        };

        new LineProcessor<Integer>() {
          int seen;

          @Override
          public boolean processLine(String line) {
            seen++;
            sb.append(line);
            return seen < 2;
          }

          @Override
          public Integer getResult() {
            return seen;
          }
        };

Then, the browser will send an HTTP `OPTIONS` request to the `:80`-backend, and if the backend sends the appropriate headers authorizing the communication from this different origin (`http://localhost:8080`) then the `:8080`-browser will let the JavaScript in the frontend send its request to the `:80`-backend.

To achieve this, the `:80`-backend must have a list of "allowed origins".

///

## Returning a custom `Response` { #returning-a-custom-response }

The example above shows all the parts you need, but it's not very useful yet, as you could have just returned the `item` directly, and **FastAPI** would put it in a `JSONResponse` for you, converting it to a `dict`, etc. All that by default.

Now, let's see how you could use that to return a custom response.

# Async Tests { #async-tests }

You have already seen how to test your **FastAPI** applications using the provided `TestClient`. Up to now, you have only seen how to write synchronous tests, without using `async` functions.

Start by forking the MinIO GitHub repository, make changes in a branch and then send a pull request. We encourage pull requests to discuss code changes. Here are the steps in details:

### Setup your MinIO GitHub Repository

Fork [MinIO upstream](https://github.com/minio/minio/fork) source repository to your own personal repository. Copy the URL of your MinIO fork (you will need it for the `git clone` command below).

```sh

        withModule<RemoveXmlApisRule>("xalan:xalan")
        withModule<RemoveXmlApisRule>("jaxen:jaxen")

        // We only need "failureaccess" of Guava's dependencies
        applyRule<KeepDependenciesByNameRule>("com.google.guava:guava", setOf("failureaccess"))

        // We only need a few utility classes of this module
        applyRule<DependencyRemovalByNameRule>("jcifs:jcifs", setOf("servlet-api"))