SX Flash Loans ⚡️ - EOSIO Smart Contract

简体 | en

Borrow any amount of liquidity instantly for near-zero fees & no collateral.

SHA256 Checksum

Local

$ eosio-cpp flash.sx.cpp -I include
$ shasum -a 256 flash.sx.wasm
c5c951f95c9fa420e68471e9372078313f03a7e5324eb3dd4bc02f15201509e1  flash.sx.wasm

EOS Mainnet

$ cleos -u https://api.eosn.io get code flash.sx
code hash: c5c951f95c9fa420e68471e9372078313f03a7e5324eb3dd4bc02f15201509e1

Table of Content

• Concept
• Examples
• ACTION borrow
• ACTION callback
• STATIC calculate_fee
• TABLE settings
• TABLE state

Concept

1. account calls borrow action from flash.sx with a desired quantity.
   • contract gets initial balance of asset.
   • contract sends quantity to account.
2. account recieves notifications via on_notify and/or callback of incoming transfer.
   • account is free to use received quantity for any purposes.
   • account returns loan back to contract.
3. contract gets final balance of asset
   • contract throws an error if initial balance is lower than final balance.

🙏 Inspired by EOS Titan flashloans smart contract design.

Examples

• basic.cpp
• callback.cpp

ACTION borrow

Account requests to borrow quantity

• authority: any

params

• {name} receiver - receiver of flash loan
• {extended_asset} amount - flash loan request amount
• {string} [memo=""] - (optional) transfer memo
• {name} [notifier=""] - (optional) notify accounts after transfer has been sent

Example 1

const asset quantity = asset{10000, symbol{"EOS", 4}};
const name contract = "eosio.token"_n;

sx::flash::borrow_action borrow( "flash.sx"_n, { get_self(), "active"_n });
borrow.send( get_self(), extended_asset{quantity, contract}, "my memo", "notifyme" );

Example 2

$ cleos push action flash.sx borrow '["myaccount", ["1.0000 EOS", "eosio.token"], "my memo", "notifyme"]' -p myaccount

ACTION callback

Notifies recipient account via callback action after transfer has been sent from borrow action

• authority: get_self()

params

• {name} code - flash loan contract
• {name} receiver - receiver of flash loan
• {extended_asset} amount - flash loan request amount
• {asset} fee - flash loan fee
• {string} [memo=""] - used for outgoing transfer
• {name} [notifier=""] - callback notifier account

Example

[[eosio::on_notify("flash.sx::callback")]]
void callback( const name code, const name receiver, const extended_asset amount, const asset fee, const string memo, const name notifier )
{
    eosio::token::transfer_action transfer( amount.contract, { receiver, "active"_n });
    transfer.send( receiver, code, amount.quantity + fee, memo );
}

STATIC calculate_fee

Calculate processing fee

params

• {name} code - flash loan code
• {asset} quantity - quantity input

example

const asset quantity = asset{10000, symbol{"EOS", 4}}; // 1.0000 EOS
const asset fee = sx::flash::calculate_fee( "flash.sx"_n, quantity );
// => 0.0002 EOS

TABLE settings

• {uint8_t} fee - processing fee (bips 1/100 of 1%)

example

{
    "fee": 2
}

TABLE state

• {name} contract - contract name
• {asset} balance - balance amount

example

{
    "contract": "eosio.token",
    "balance": "1.0000 EOS"
}