Do not enforce a a 25% increase of gas premium when replacing a message

[dd45e640b42e6da7da96faee3996ef7c]

Describe the bug
The mpool specification (https://spec.filecoin.io/#section-systems.filecoin_blockchain.message_pool) does not specify an increase of 25% on a messages gas-premium to allow a message replace to succeed. Nonetheless lotus mpool replace is enforcing it.

To Reproduce
Steps to reproduce the behavior:

1. Run lotus mpool replace ... on a random, locally created message and do not increase the gas-premium
2. See lotus demanding a 25% increase of the gas-premium

Expected behavior
To not enforce values that aren't specified and therefore not needed.

Version (run lotus version):
all

Additional context
I get the rationale behind the 25% increase - but a miner can just choose to include the old version of the message anyways - it should be up to the user to decide how much he wants to increase the gas-premium to create an incentive for the miner to include the new version of the message.

[jennijuju]

@Kubuxu i think you may have thoughts here?

[dd45e640b42e6da7da96faee3996ef7c]

lotus mpool config
{"PriorityAddrs":null,"SizeLimitHigh":30000,"SizeLimitLow":20000,"ReplaceByFeeRatio":1.25,
"PruneCooldown":60000000000,"GasLimitOverestimation":1.25}

lotus mpool config --help
NAME:
   lotus mpool config - get or set current mpool configuration

USAGE:
   lotus mpool config [command options] [new-config]

OPTIONS:
   --help, -h  show help (default: false)

[line break added for easier reading]

one can obviously change the settings here - i think. Now the question is if the ReplaceByFeeRatio":1.25 is enforced when receiving a message another peer send or not.

if it is then there should be something in the docs to document this behavior. the specs do not imply it.

[edit]
is ReplaceByFeeRatio":1.25 actually the value that is responsible for the 25% increase enforcement of the gas-premium in the replace command?

i am not sure right now if this is really just some kind of anti spam measure or if i miss something.

[hyunmoon]

Q: Is the 25% increase in GasPremium for replacing a message required by the chain or the lotus client?
A: It is required by mpool, chain doesn't know about other messages. The reason why it is there is so it makes sense to miners which message is the best (gives them highest reward).

Q: How about lifting the +25% GasPremium requirement for replacing a message? Why 25%? Can't it be 10%?
A: We took the 25% to perform Replace By Fee from Ethereum.

https://filecoinproject.slack.com/archives/C0179RNEMU4/p1605901372252300?thread_ts=1605888166.231100&cid=C0179RNEMU4
https://filecoinproject.slack.com/archives/C0179RNEMU4/p1607129594241000?thread_ts=1607103246.206400&cid=C0179RNEMU4

[dd45e640b42e6da7da96faee3996ef7c]

thanks @hyunmoon

so we just need to properly document this behavior. an alternative mpool implementation should know about that the reference implementation is setting this!

[dd45e640b42e6da7da96faee3996ef7c]

this is a very strange solution for a problem - is this solving a problem? not sure... but the argument that "eth is doing it" is weak for choosing a number. an increase by 1 attoFIL has the same effect ultimately if the argument for this is "he reason why it is there is so it makes sense to miners which message is the best (gives them highest reward)"

[edit]
it's not solving the problem - it intends to give incentives to not create the problem.

[dd45e640b42e6da7da96faee3996ef7c]

so maybe change the title of this to:

decrease the increase of gas-premium to 1 attoFIL ;)