Add newPendingRawTransactions to filter system to save bandwidth

[t-anyu]

Hey,

In use cases where client subscribes to newPendingTransactions and gets txhashes would typically re-request transaction content from the node. In public nodes or nodes that serve many simultaneous clients, this would cause some additional load.

It would be nice, and quite easy to implement another subscription of newPendingRawTransactions, which would directly send the raw transaction instead of just tx hash. Then the client can decode the raw transaction without re-requesting json'd eth_getTransactionByHash.

I think this should be easily implemented. Instead of sending tx.Hash(), a tx.MarshalBinary() would be sent to the subscription channel.

(I can do the commit if this gets green light from the maintainers)

[karalabe]

Could you provide some more details about what you're trying to use it for? We do have a few ideas in mind too, but curious about your case.

[t-anyu]

Hey,

In my case, the node that I'm hosting is mostly being used for various trading related applications. But currently working on a MEV tracking case, where we need to record all the pending transactions across multiple nodes.

I believe in most use cases that uses pending transaction filter are being used in tranding / gaming related applications. And in these cases, the exact transaction data is needed.

[amirilidan78]

it would be nice for example i want to listen on new pending transactions and check if receiver address is in my database , execute callback for my application ,but now because i have only txId and i should call 1 http per tx it would not be cool

trezor blockbook is good example it provider transaction detail on new pending transaction not just txId
https://github.com/trezor/blockbook/blob/master/docs/api.md
subscribeNewTransaction

example

{
    "id": "1",
    "data": {
        "txid": "ca32a8ea2a881ab508e3fa84f03a5ae5073bab977444bcfd5e75d6ce5d31b86f",
        "version": 2,
        "vin": [
            {
                "txid": "75eff4aaabfeaa7824337ef61ad12918ea2a8659918898330949efe9703840bf",
                "vout": 1,
                "sequence": 4294967295,
                "n": 0,
                "addresses": [
                    "bc1qunxnu8gv8ckdsvewqj809ajfyxxfkv6chak2j7"
                ],
                "isAddress": true,
                "value": "129911"
            },
            {
                "txid": "f973e88c40ea8462af2c79432a193c79247d44b24edbe44598e7fceb0361859c",
                "vout": 1,
                "sequence": 4294967295,
                "n": 1,
                "addresses": [
                    "bc1q9zexgk4r956yvskdlpvvz3y9h27e5pa424v4r5"
                ],
                "isAddress": true,
                "value": "98397"
            },
            {
                "txid": "3218619a5f858adf2471ef3eb4263ecdb041cd49f53553ce624f363838f528e2",
                "vout": 1,
                "sequence": 4294967295,
                "n": 2,
                "addresses": [
                    "bc1quc7yudz95x6m7dhh96nfpts4d6e9uxczyh5lx0"
                ],
                "isAddress": true,
                "value": "29939"
            },
            {
                "txid": "55413f9a41dd887762e8ae21917fa95ebed7bfcaabd316ff82035cae441505d8",
                "vout": 1,
                "sequence": 4294967295,
                "n": 3,
                "addresses": [
                    "bc1qww3n386xqfzzrygkq2gjv8jxl47ak8d8frwu2s"
                ],
                "isAddress": true,
                "value": "4229"
            }
        ],
        "vout": [
            {
                "value": "258804",
                "n": 0,
                "hex": "76a914cc75f99318cbeb65673396b53d9298729e558e7688ac",
                "addresses": [
                    "1Ke6BB3hJKzkPdLoYmWmBiuKbeJqpKgp8D"
                ],
                "isAddress": true
            }
        ],
        "blockHeight": 0,
        "confirmations": 0,
        "blockTime": 1654771422,
        "value": "258804",
        "valueIn": "262476",
        "fees": "3672",
        "hex": "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"
    }
}

[lmittmann]

@karalabe would you accept PRs that provide the functionality?

[karalabe]

We should review and merge the feature I guess.

[Anti83]

@lmittmann
Hi, I merged your PR into my fork, but still getting only hashes.
I am using web3 web3.eth.subscribe('pendingTransactions')
What is the right way to use it? Thanks.