add start_newPendingTransactions_loop

[waelsy123]

This change is 

Support for new pending transactions pubsub #2672

[WIP]
do we have a notification Channel to subscribe for when new pending transaction? so far I'm using the new_block_hashes channel

[Conflux-Dev]

Can one of the admins verify this patch?

[peilun-conflux]

ok to test

[peilun-conflux]

There is no such a channel, and that's probably why newPendingTransactions was not supported in the first place.

One possible choice is to create a new channel for this and push successfully inserted transaction hashes in TransactionPool::insert_new_transactions(). And we also need to filter out transaction spaces for RPCs. I'm not quite sure if this exactly meet the definition of new pending transactions pubsub though.

[waelsy123]

@peilun-conflux I just created a new channel new_pending_transactions and notified subscribers with new hashes inserted in the queue. what do you think about that?

[peilun-conflux]

Reviewed 2 of 2 files at r2, all commit messages.
Reviewable status: all files reviewed, 2 unresolved discussions (waiting on @waelsy123)

---

client/src/rpc/impls/eth_pubsub.rs line 117 at r2 (raw file):

        let fut = async move {
            while let Some(new_tx) = receiver.recv().await {
                debug!("new_pending_transactions_loop: {:?}", new_tx);

Since transactions can be received very fast, it's better to remove this or change it to trace!.

---

client/src/rpc/impls/eth_pubsub.rs line 292 at r2 (raw file):

    // notify each subscriber about new pending transaction `hash` concurrently
    fn notify_new_pending_transaction(&self, hash: H256) {

Same about the log level here.

[peilun-conflux]

@peilun-conflux I just created a new channel new_pending_transactions and notified subscribers with new hashes inserted in the queue. what do you think about that?

Looks good to me.

BTW, you need to run ./cargo_fmt.sh --install to format the code so it can pass the CI check. After installing the (very old) hardcoded cargo version for the first time, running ./cargo_fmt.sh should be enough later.

[waelsy123]

@peilun-conflux thank you for the feedback!
I just used trace for better logs level,

regarding the formating, seems like rustup doesn't support my m1 mac arch, I'm getting this error:

%  ./cargo_fmt.sh --install                         
info: syncing channel updates for 'nightly-2019-07-03-aarch64-apple-darwin'
info: latest update on 2019-07-03, rust version 1.37.0-nightly (0beb2ba16 2019-07-02)
error: target 'aarch64-apple-darwin' not found in channel.  Perhaps check https://doc.rust-lang.org/nightly/rustc/platform-support.html for available targets

it's worth to mention I'm using rustup 1.26.0 (5af9b9484 2023-04-05)

I'm curious why do we use hardcoded nightly-2019-07-03 ?

[CRossel87a]

There are already flashbots working in the mempool of Conflux. Is a beta version out?

[Pana]

@waelsy123 can you fix the conflict issue?