Node syncing - how to check?

[boltpl81]

Hi there,

How can I check if node is in syncing state? I'm using my own node, and it's getting out of sync from time to time - I can see it geth logs. I would like to avoid any rpc calls during this time.

[zemse]

There is an RPC method called eth_syncing docs.

const result = await provider.send('eth_syncing')

A very basic example of how this could be achieved (I have not tested this code).

class JsonRpcProviderModified extends JsonRpcProvider {
  // override the call method
  async call(...args) {
    await waitUntilSynced();
    return await super.call(...args)
  }
 
  async waitUntilSynced() {
    while(1) {
      const syncing = this.send('eth_syncing');
      if (syncing === false) break
    }
  }
}

This might cause performance issues since it will check node is synced or not for every call, so you might want to implement some caching here so that node is synced or not is checked less often.

[boltpl81]

Thanks man, this would do the trick probably :)
I will do the second part differently. I'm listening for each block, so I can call once per each block and decide if I want to query RPC or not. So this check will be included in "on block"

[zemse]

If the node is syncing then the block number will be increasing with great speed, and on('block') is designed to work with synced nodes, I'm not sure how it will work in syncing case, you can try, but I expect a lot of callbacks.