Subject: Re: [bitcoin-dev] Trying to patch Core ZMQ "rawtx" topic to only publish unconfirmed transactions: How?

From: Ali Sherief <[email-masked]>
Date: Mon, 29 Nov 2021 14:13:37 +0000

Theoretically that would be the desired outcome for me but this change is going to be implemented as part of a casino which must display the status of new deposits that are made, even when they are unconfirmed to now. Hence why I need to receive the unconfirmed messages.

- Ali Sherief

On Mon, Nov 29, 2021 at 5:10 PM, LORD HIS EXCELLENCY JAMES HRMH <[email-masked]> wrote:

> Wasn't this already not a problem because you can check if it was confirmed? The transaction is not finalised in the mempool it is just speculation of a transaction, so it makes sense to emit when the transaction is confirmed. Just already check..
>
>> It appears that the ZeroMQ topic I'm listening to, "rawtx", not only
>> emits a raw transaction when it appears on the mempool, but once it's
>> already confirmed too.
>
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> From: bitcoin-dev <[email-masked]> on behalf of 0xB10C via bitcoin-dev <[email-masked]>
> Sent: Monday, 29 November 2021 8:32 PM
> To: Ali Sherief <[email-masked]>; Bitcoin Protocol Discussion <[email-masked]>
> Subject: Re: [bitcoin-dev] Trying to patch Core ZMQ "rawtx" topic to only publish unconfirmed transactions: How?
>
> Hi Ali,
>
> I've run into this multiple times myself. I've opened a draft PR [0]
> adding a rawmempooltx publisher.
>
> You're right. In zmq/zmqnotificationinterface.cpp the
> CZMQNotificationInterface is notified about TransactionAddedToMempool.
> Currently, this calls NotifyTransaction() (the publisher with the rawtx
> topic) and NotifyTransactionAcceptance() (the publisher with the
> sequence topic)[1]. I've added a call to a new
> NotifyMempoolTransaction() function (the publisher with the rawmempooltx
> topic).
>
> I'd find a mempool transaction publisher with both the raw transaction
> and transaction fee useful too. However, this requires changes to the
> chain notifications in interfaces/chain.h.
>
> [0]: https://github.com/bitcoin/bitcoin/pull/23624
> [1]:
> https://github.com/bitcoin/bitcoin/pull/23624/files#diff-ac4b2d3a8de2c4dd41ad9d75505ea6ce4dc87a476710a9ebee8acf9bebf5cca2L146-L148
>
> Best,
> 0xB10C
>
> On 11/26/21 5:56 PM, Ali Sherief via bitcoin-dev wrote:
>>
>> This has also been posted on Bitcointalk
>> forum: https://bitcointalk.org/index.php?topic=5373341.msg58539261#msg58539261
>> <https://bitcointalk.org/index.php?topic=5373341.msg58539261#msg58539261> I
>> have republished it here hoping someone more knowledgeable can post
>> some insight about this.
>> ----
>> It appears that the ZeroMQ topic I'm listening to, "rawtx", not only
>> emits a raw transaction when it appears on the mempool, but once it's
>> already confirmed too.
>>
>> This messes with my software, causing it to add txids, addresses, etc.
>> a second time inside arrays (this means that the same transaction is
>> received twice in total).
>>
>> Array de-duping is not a viable solution long-term (because the array
>> will quickly grow to be big eventually and then this has to happen
>> every time a new element is added), so I'm trying to nip the problem
>> from the source by instructing Core to only publish unconfirmed
>> bitcoin transactions.
>>
>> According to
>> https://bitcoin.stackexchange.com/questions/52848/is-it-possible-to-configure-the-bitcoin-daemon-to-only-broadcast-unconfirmed-tra
>> <https://bitcoin.stackexchange.com/questions/52848/is-it-possible-to-configure-the-bitcoin-daemon-to-only-broadcast-unconfirmed-tra>
>> , it is not possible to configure this from a configuration or
>> command-line option. The source code must directly be edited. But
>> since the codebase has changed greatly, the proposed solution no
>> longer works.
>>
>> ----
>>
>> So basically, I know that something inside
>> src/zmq/zmqnotificationinterface.cpp needs to be patched, but I'm not
>> sure which function, or how to do it. Because I only need unconfirmed
>> transactions to be published on ZeroMQ rawtx and not confirmed ones,
>> it's one of the following functions that I need to patch for my own build:
>>
>> CZMQNotificationInterface::TransactionRemovedFromMempool
>> void CZMQNotificationInterface::BlockDisconnected
>>
>> Both of these call NotifyTransaction() method which I assume fires a
>> message on "rawtx" channel.
>>
>> In the Stack Exchange question I linked above, Jonas Schnelli
>> suggested adding an `if (!pblock)` check, but that was several years
>> ago and the function he was referencing no longer exists.
>>
>> But I still wonder if the pblock check is still applicable in the
>> present day (i.e. if it's indicating a block the transaction is inside).
>>
>> - Ali Sherief
>>
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