Consider removal of batch.js

[miohtama]

Expected behavior

Some old code was pointed out by a contributed on Gitter channel:

https://github.com/ethereum/web3.js/blob/a5e832fc20088cf4c4e916bc0ec3107ceb4428d0/packages/web3-core-requestmanager/src/batch.js

This is for doing multiple API calls parallel from 2015.

Actual behavior

Modern JavaScript has similar functionality with Promise.all and some other Promise resolvers. Just make all your API calls as promises and then wait for all of these Promises to resolve once.

I would suggest deprecating this code and then removing it in the next major release.

Here is also an alternative if you want to have the responses, e.g. the call return values, recorded on an object:

https://stackoverflow.com/questions/29292921/how-to-use-promise-all-with-an-object-as-input/51722274#51722274

[DeepalUsyD]

just figured that batch.add has a callback. So I believe this shouldn't be an issue. Besides, batch.add and batch.execute can be used to send a batch of transactions to a blockchain, so I think it's important that it remains in subsequent releases.

[GregTheGreek]

Do you mind linking the gitter conversation if possible? Found it.

Hmm, yes I think we could probably remove this all together.

[DeepalUsyD]

Do you mind linking the gitter conversation if possible? Found it.

Hmm, yes I think we could probably remove this all together.

Hi,
I am the person who raised this on Gitter. I am wondering, could you please consider not removing this? batch.add and batch.execute has been useful so far for me.

[GregTheGreek]

@DeepalUsyD Would require some further discussions. But looking at it, I can't imagine why you would need this over Promise.all or similar?

[DeepalUsyD]

@GregTheGreek
I am not sure if I am correct. But I see a difference in batch requests and Promise.all
e.g.

let promises =  [];
  for (let i = 0; i < 9000; i++) {
    promises.push(web3.eth.sendTransaction({
      from: "0x8fd0c5f80785d7d13c49d0ca8c88d2fb0803690b",
      to: toAccount,
      value: weiVal
    }));
  }

  return Promise.all(promises);
}

Returns promises for all the pushed transactions but the transactions are pushed in a loop, one after the other. Not as a batch in one go.
In contrast batch.add creates a batch first and executes the created batch. Doesn't push tx one after the other like promise.push:

for (i = 0; i < 3000; i++) {
        batch.add(web3.eth.sendTransaction({
            from: account-address1,
            to: account-address2,
            value: i
        }))
    }
    batch.execute();

I think creating a batch first and executing it later may come in handy. Anyway, I do believe, batch.js does require more explanation in the documentation.

Edit by @GregTheGreek: I formatted the code blocks for readability.

[GregTheGreek]

Ah you know what, you are right. I completely forgot that json-rpc supports a batch method.

I think we can close this, batch.js is here to stay. that being said, adding documentation around this is needed. Will be opening a relevant issue :)