Adds support for custom flashloan fees #360
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fastlane_bot/config/constants.py
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| # should be in the form of {network: fee * 1e6} | ||
| "ethereum": 0, | ||
| "coinbase_base": 0, | ||
| "fantom": 300, # Flashloans come with a 0.03% Fee from Beethoven X (Balancer fork) |
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Why represent percentage like that?
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Is this not a standard approach in the industry, to specify in PPM? In any case, just following what we did in the simulator, and as well how Uniswap does it, etc. Happy to change if there is a more preferred method.
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- It is not standard, but an implementation-decision (typically per DEX).
- Unless this is related to something the you need to process before passing as input to a contract function or after receiving as output from a contract function, there is no reason for you to use this resolution to begin with; the only reason for it being used onchain, is the lack of non-integer-arithmetic support, which is obviously not an issue in offchain scripts.
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In this case, what is your preferred implementation approach / alternative?
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Why not just use 0.0003 (i.e., multiply by that value wherever needed)?
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I'd go with the most obvious - either 0.0003 # 0.03% or 0.03 # %
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This has been updated.
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An important note to make here is that Mike's original decision to use a PPM factor, was actually a good one in the sense of avoiding floating-point calculations as much as possible (i.e., the calculation would subsequently turn into amount * fee // 1e6, which is purely integer-arithmetic).
But not critical at this point, especially after he's already changed that.
fastlane_bot/helpers/routehandler.py
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| @@ -529,7 +530,7 @@ def _get_flashloan_platform_id(self, tkn: str) -> int: | |||
| else: | |||
| return 7 | |||
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| def _get_flashloan_struct(self, trade_instructions_objects: List[TradeInstruction]) -> List: | |||
| def _get_flashloan_struct(self, trade_instructions_objects: List[TradeInstruction]) -> Tuple[List, int]: | |||
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where do you actually return the fee? I can't find where you add the fee to the Tuple
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Should be corrected now.
…com/bancorprotocol/fastlane-bot into 346-add-handling-of-flashloan-fee-1
| @@ -964,14 +969,17 @@ def _handle_trade_instructions( | |||
| # Get the flashloan token | |||
| fl_token = calculated_trade_instructions[0].tknin_address | |||
| fl_token_symbol = calculated_trade_instructions[0].tknin_symbol | |||
| flashloan_amount = int(calculated_trade_instructions[0].amtin_wei) | |||
| flashloan_fee = FLASHLOAN_FEE_MAP.get(self.ConfigObj.NETWORK, 0) | |||
| flashloan_fee_amt = int(flashloan_fee * flashloan_amount) | |||
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In the initialization of FLASHLOAN_FEE_MAP, you are using a percentage value of 0.03% (at least by the comment next to it), i.e., a value between 0 and 100.
But the calculation in the line above implies that you are using a normalized value (between 0 and 1).
So either change the map to consist of normalized values, or add in this line a division by 100.
fastlane_bot/config/constants.py
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| # should be in the form of {network: fee * 1e6} | ||
| "ethereum": 0, | ||
| "coinbase_base": 0, | ||
| "fantom": 0.03 # % |
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My previous comment assumes that 0.03 here stands for 0.03%.
Handles issue 346