Events
======

Events allow you to capture metrics on your application’s HTTP calls. Use events to monitor:

 * The size and frequency of the HTTP calls your application makes. If you’re making too many calls, or your calls are too large, you should know about it!
 * The performance of these calls on the underlying network. If the network’s performance isn’t sufficient, you need to either improve the network or use less of it.

### EventListener

## Install `websockets` { #install-websockets }

Make sure you create a [virtual environment](../virtual-environments.md){.internal-link target=_blank}, activate it, and install `websockets` (a Python library that makes it easy to use the "WebSocket" protocol):

<div class="termy">

```console
$ pip install websockets

---> 100%
```

</div>

But I'll show you how to improve that next. 🤓

## Custom Operation IDs and Better Method Names { #custom-operation-ids-and-better-method-names }

You can **modify** the way these operation IDs are **generated** to make them simpler and have **simpler method names** in the clients.

		ttl:       ttl,
		size:      size,
		evictList: NewList[K, V](),
		items:     make(map[K]*Entry[K, V]),
		onEvict:   onEvict,
		done:      make(chan struct{}),
	}

	// initialize the buckets
	res.buckets = make([]bucket[K, V], numBuckets)
	for i := 0; i < numBuckets; i++ {
		res.buckets[i] = bucket[K, V]{entries: make(map[K]*Entry[K, V])}
	}

    OkHttp used _get_ and _set_ prefixes sporadically which make the API
    inconsistent and awkward to explore.

 *  **OkHttpClient now implements the new `Call.Factory` interface.** This
    interface will make your code easier to test. When you test code that makes
    HTTP requests, you can use this interface to replace the real `OkHttpClient`
    with your own mocks or fakes.

`OAuth2PasswordBearer` makes **FastAPI** know that it is a security scheme. So it is added that way to OpenAPI.

But `OAuth2PasswordRequestForm` is just a class dependency that you could have written yourself, or you could have declared `Form` parameters directly.

But as it's a common use case, it is provided by **FastAPI** directly, just to make it easier.

///

### Use the form data { #use-the-form-data }

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does not provide legal services or legal advice. Distribution of
Creative Commons public licenses does not create a lawyer-client or
other relationship. Creative Commons makes its licenses and related
information available on an "as-is" basis. Creative Commons gives no
warranties regarding its licenses, any material licensed under their
terms and conditions, or any related information. Creative Commons

   */
  @Throws(IOException::class)
  fun authenticate(
    route: Route?,
    response: Response,
  ): Request?

  companion object {
    /** An authenticator that knows no credentials and makes no attempt to authenticate. */
    @JvmField
    val NONE: Authenticator = AuthenticatorNone()

    private class AuthenticatorNone : Authenticator {
      override fun authenticate(
        route: Route?,

			// since Linux 4.11.
			_ = syscall.SetsockoptInt(fd, syscall.IPPROTO_TCP, unix.TCP_FASTOPEN_CONNECT, 1)

			// Enable TCP quick ACK, John Nagle says
			// "Set TCP_QUICKACK. If you find a case where that makes things worse, let me know."
			_ = syscall.SetsockoptInt(fd, syscall.IPPROTO_TCP, unix.TCP_QUICKACK, 1)

			/// Enable keep-alive
			{
				_ = unix.SetsockoptInt(fd, unix.SOL_SOCKET, unix.SO_KEEPALIVE, 1)

### Retrieving Container ID

To use Docker commands on a specific container, you need to know the `Container ID` for that container. To get the `Container ID`, run

```sh
docker ps -a
```

`-a` flag makes sure you get all the containers (Created, Running, Exited). Then identify the `Container ID` from the output.

### Starting and Stopping Containers