DBC: Changelog for Rate Limiter and 99% Fee

Changelog for Program

dynamic_bonding_curve [0.1.3]

Added

• Allow partner to configure another mode for base fee, called rate limiter. When the mode is enabled, fee slope will increase if user buy with a higher quote amount. The rate limiter mode is only available if collect fee mode is in quote token only, and when user buys the token (not sell). Rate limiter doesn't allow user to send multiple swap instructions (or CPI) to the same pool in 1 transaction.

Breaking Changes

• Maximum cliff_fee_numerator has been bumped up from 50% (5000 bps / 500_000_000) to 99% (9900 bps / 990_000_000)
• If is_rate_limiter_applied, then swap instruction will need to submit instruction_sysvar_account in remaining_accounts, otherwise transaction will fail.
• swap_quote function will need to account for the rate limiter math calculation and 99% max fee. Math formulas can be found in here.

Changes

• base_fee parameters in pool_config has been updated to first_factor, second_factor, third_factor

• Updated fee_scheduler_mode to base_fee_mode to account for rate limiter base fee mode

  • 0 = Fee Scheduler - Linear
  • 1 = Fee Scheduler - Exponential
  • 2 = Rate Limiter

  Old Structure

  base_fee = {
      cliff_fee_numerator: BN
      number_of_period: number
      period_frequency: BN
      reduction_factor: BN
      fee_scheduler_mode: FeeSchedulerMode // 0 or 1
  }
  

  New Structure:

  base_fee = {
      cliff_fee_numerator: BN
      first_factor: number // feeScheduler: numberOfPeriod, rateLimiter: feeIncrementBps
      second_factor: BN // feeScheduler: periodFrequency, rateLimiter: maxLimiterDuration
      third_factor: BN // feeScheduler: reductionFactor, rateLimiter: referenceAmount
      base_fee_mode: BaseFeeMode // 0, 1, or 2
  }
  

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