Keep socket alive for a configured time

Currently, if the ClientOption lazy is true, the websocket is closed as soon as there are no pending operations.

This adds a lot of overhead in case you have an application that is often sending queries or mutations since the client needs to re-establish the socket for every query/mutation.

It would be great if we could add a new keepalive parameter to ClientOptions that would control how long the socket should remain open after the last subscription has completed.

For instance:

export interface ClientOptions {
...
  /**
   * How long the client should wait, after the last query/mutation/subscription is completed, before closing the socket.
   *
   * @default 0 * 1000 (0 seconds)
   */
  keepalive?: number;
...
}

[enisdenjo]

Another enhancement I would like to suggest is to accept connectionParams to be a Promise or async function. I can open a separate enhancement request for this if you agree.

I agree! Please open another issue just for the sake of clarity and documentation.

[enisdenjo]

A recipe would be a way, however… I spoke too soon.

@rpastro has actually a great point! I changed my mind, this would be indeed nice to have. Am already cooking up some code for this - bare with me. 😄