Avoid eth_chainId call when creating a WebSocketProvider

[janschmutz]

Hey there,

I'm developing a wallet application as a chrome extension and noticed that a big chunk of my infura usage boils down to
eth_chainid, which I'm not actively calling. I read in another ticket that this is a internal ethers.js safety feature in case the network switches.

In my case it is impossible because we always use mainnet, so I'm wondering if it is possible to disable this feature while using the WebSocketProvider (which obviously helps me save resources elsewhere e.g. eth_blockNumber)

[ricmoo]

The WebSocketProvider should be safe to mimic the StaticJsonRpcProvider logic to not call chainId.

I’ll investigate this tomorrow. :)

[ricmoo]

Taking a quick look at the code, it looks like it should cache the chainId. I'll investigate more tomorrow, but quick check on what version of ethers are you using?

[janschmutz]

yes, thanks it is npm version 5.0.32

[ricmoo]

Can you try upgrading to 5.4.1 and checking this wasn't fixed by a change since March? I don't recall making any change that would affect this, but just to double-check. :)

[janschmutz]

Hi @ricmoo so I figured out in the end where all these eth_chainId requests come from with the websocket provider I think. Every time a new websocket provider instance is created (E.g. onclose handler is called or similar.) there is a single eth_chainId request conducted internally. In my case this happens quite often thus the number of requests. Is this necessary internally or is there a way to perhaps disable this feature?

[ricmoo]

Hi @ricmoo so I figured out in the end where all these eth_chainId requests come from with the websocket provider I think. Every time a new websocket provider instance is created (E.g. onclose handler is called or similar.) there is a single eth_chainId request conducted internally. In my case this happens quite often thus the number of requests. Is this necessary internally or is there a way to perhaps disable this feature?

This is necessary, but if you know the chainId you can pass it in as the second parameter to the WebSocketProvider connector, or even passing in the .getNetwork() promise should work, like:

// Replace the current provider, but re-use the network lookup
websocket = new WebSocket(websocket.connection.url, websocket.getNetwork());

Does that make sense?

[janschmutz]

totally, thanks that solved the issue for me!

[ricmoo]

Moving to discussion in case someone else has a similar question in the future. :)

[janschmutz]

Ahh @ricmoo looks like I was a little early, the infura requests just came in with some time delay.
So just setting the network initially did not solve the issue for me I'm still getting the eth_chainid every time a new provider instance is created.

provider = new ethers.providers.WebSocketProvider(infuraUrl, {
    name: 'mainnet',
    chainId: 1,
 })

If I understand your code example correctly above you suggest just replacing the underlying websocket and not creating a new provider instance?

this.provider._websocket = new WebSocket(chromeSocket.connection.url, chromeSocket.getNetwork())

this is not possible because the property is marked readonly here I think. Did I misunderstand you ?

[ChrisLahaye]

This would only work for JsonRpcProvider not WebSocketProvider, that one always calls detectNetwork().