Transaction fees and dust values

[jsalatas]

TransactionOutput::getMinNonDustValue()

defines "the minimum value for this output to be considered "not dust"" as

(Transaction::REFERENCE_DEFAULT_MIN_TX_FEE * 3) * (33 + 148)

where (33 + 148) is the size of the transaction's output in bytes and requires an input of 148 bytes as seen at
TransactionOutput::getMinNonDustValue(Coin)

Faircoin's current blockchain parameters define a Transaction fee equal to 0.008 FAIR.

Question 1: Does it refer to Transaction::REFERENCE_DEFAULT_MIN_TX_FEE or to Transaction::DEFAULT_TX_FEE ???

The blockchain parameters also define a Dust threshold equal also to 0.008 FAIR which I guess refers to Transaction::MIN_NONDUST_OUTPUT. Right?

Question 2: I am not sure how is this connected to the TransactionOutput::getMinNonDustValue() above. In bitcoin branch Transaction::MIN_NONDUST_OUTPUT and the output of TransactionOutput::getMinNonDustValue() are about the same. In faircoin's branch I fail to see how are these related. :\

[jsalatas]

ping? :)

[jsalatas]

ping? :\

[jsalatas]

last ping :)

[TonyFord]

Question 1:
REFERENCE_DEFAULT_MIN_TX_FEE means the minimum fee that will treat as fee in Bitcoin. If the fee is lower then it will treat equal as no fee.
DEFAULT_TX_FEE means the fee where the chance is high that the transaction will confirmed in a couple of blocks.

In FairCoin we don't have the fee competition. So both values are the same. But the reference to REFERENCE_DEFAULT_MIN_TX_FEE make more sense because in FairCoin higher fees will also accepted but lower fees not.

MIN_NONDUST_OUTPUT, here I have found a good explanation in the bitcoinj
https://github.com/bitcoinj/bitcoinj/blob/25f36872d5284ad2a1c4372972e38855de35798d/core/src/main/java/org/bitcoinj/core/TransactionOutput.java

In my opinion it is the same calculation as the fee. So I would remove the .multiply(3)
return getMinNonDustValue(Transaction.REFERENCE_DEFAULT_MIN_TX_FEE);
That means that the lowest NonDustValue is the same as the fee.

Question 2:
Transaction::MIN_NONDUST_OUTPUT is depreciated, see this commit in bitcoinj
bitcoinj@6035608#diff-25a7d8851e54b470509e6fc28323aa8b

https://github.com/bitcoinj/bitcoinj/blob/master/core/src/main/java/org/bitcoinj/core/Transaction.java#L126

In my opinion the value should be ( minimum tx size * 0.008 / 1000 ) = 192 * 0.008 / 1000 = 153600satFAIR

I have used 192bytes in the calculation because I have found this size in the faircoin blockchain single tx.

[jsalatas]

DEFAULT_TX_FEE means the fee where the chance is high that the transaction will confirmed in a couple of blocks.

So this doesn't apply to PoC algorithm. Right? As any transaction in the block is confirmed and there is no way to have a fork in the blockchain, because CVNs always need to agree before posting the block.

I have used 192bytes in the calculation because I have found this size in the faircoin blockchain single tx.

FYI: There are some clients that calculate different fees than others. I have posted in telegram some examples of such blocks in the past. So we may need to describe exactly how the fees should be calculated.

[TonyFord]

I have found this in the faircoin sources.

https://github.com/faircoin/faircoin/blob/master/src/primitives/transaction.h#L138

size_t nSize = GetSerializeSize(SER_DISK,0)+148u;
return 3*minRelayTxFee.GetFee(nSize);

the GetFee method is defined here
https://github.com/faircoin/faircoin/blob/master/src/amount.cpp#L20

the GetSerializeSize here
https://github.com/faircoin/faircoin/blob/master/src/serialize.h

3*800000*(148 + 34)/1000=436800

This would be the same ratio as in bitcoin ( dust/fee 546/1000 )

[jsalatas]

Nice! That might be something!

Thanks again! :)