add pending txn subscription support

[rlan35]

Feed promoted pending txns into the pending txn subscription channel, so all subscribed source can get the new pending txns.

[sophoah]

@rlan35 was the PR been tested ? can you attached the test logs if you did ? Also since we have type change what is the impact of our/dapp RPC usage ? do we need to any special communication regarding that change ?

[gupadhyaya]

@rlan35 was the PR been tested ? can you attached the test logs if you did ? Also since we have type change what is the impact of our/dapp RPC usage ? do we need to any special communication regarding that change ?

this should not have any regressions. the test logs are in the issue: #3881
should be ok to release.

[sophoah]

see test done on testnet here : #3881 (comment)

[sophoah]

@rlan35 not sure if normal but the test i did shows a duplicate tx each time.

node web3-Pendingtx-ws.js
0x769520008066520063131436e0eb9bdb
0xd085ab5e305a7f224aca5650f5ee0345d8a58e77729ea5205407cef15b7d6143
0xd085ab5e305a7f224aca5650f5ee0345d8a58e77729ea5205407cef15b7d6143
0x712d2f3f25692363726e352ffb377ba7592e2566cae89250afe4dd749524efa2
0x712d2f3f25692363726e352ffb377ba7592e2566cae89250afe4dd749524efa2

it's a minor issue but just wanted to let you know

[rlan35]

@rlan35 not sure if normal but the test i did shows a duplicate tx each time.

node web3-Pendingtx-ws.js
0x769520008066520063131436e0eb9bdb
0xd085ab5e305a7f224aca5650f5ee0345d8a58e77729ea5205407cef15b7d6143
0xd085ab5e305a7f224aca5650f5ee0345d8a58e77729ea5205407cef15b7d6143
0x712d2f3f25692363726e352ffb377ba7592e2566cae89250afe4dd749524efa2
0x712d2f3f25692363726e352ffb377ba7592e2566cae89250afe4dd749524efa2

it's a minor issue but just wanted to let you know

@gupadhyaya is this normal, did you notice this in your local testing?

[damiensgit]

Just a note that whilst pending txes worked on my local build as above, it appears that getting the transaction for the hash always returns nil rather than the tx struct data (on go-etherum client) e.g.

tx, is_pending, _ := client.TransactionByHash(context.Background(), transactionHash)

is_pending is true but tx is always nil

On other evm chains, this works as expected, and a quick test in etherjs shows the same issues so it's not a go issue- eth_gettransaction rpc method isn't able to get the tx details for the hash even tho it's in the node's mempool it seems - is the a harmony limitation or a sep. bug?

[damiensgit]

A web3 exmple of my earlier comment:

const web3 = new Web3("testnet"); 
var subscription = web3.eth.subscribe("pendingTransactions", function(err, result) {
    if (!err){
        console.log(result)
    }
}).on("data", function(transaction){
    console.log(transaction)
    web3.eth.getTransaction(transaction).then(console.log);
})


0xd085ab5e305a7f224aca5650f5ee0345d8a58e77729ea5205407cef15b7d6143
null

[orlandodiaz]

Im having the same issue as damien. I also get null transaction data on pending transactions. This only happens on my private rpc node and not on the hmy public one though