Overview

This issue has been discovered during development of FIP-21 Staking and requires a consideration and decision on best path forward.

The Issue

Requirements

Staking requirements state that:

• When user unstakes tokens, those tokens are locked for a period of 7 days.

• User can unstake any amount less than what they originally staked.

• User can stake/unstake from an account which has Mainnet or FIP-6 locks.

7 day lock technical approach

The technical approach to deliver the 7 day unstake lock is to rely on FIP-6 functionality which is defined by:

• Total locked amount

• Percentage unlocked at any given period

• Example

  • Locked amount: 100

  • Periods

    • Period 1

      • Duration: 10 days

      • Percent: 50.000%

    • Period 2

      • Duration: 20 days

      • Percent: 50.000%

  • Result

    • 50 tokens will unlock after 10 days

    • 50 tokens will unlock after 20 days

When user unstakes an amount the FIP-6 locks are supposed to be adjusted to insert a new unlock period. To continue the above example, if the user of the above account staked 100 tokens and now unstakes 10, their FIP-6 locks would be adapted as follows:

• Locked amount: 110

• Periods

  • Period 0

    • Duration: 7 days

    • Percent: 9.09090909090909…

  • Period 1

    • Duration: 10 days

    • Percent: 45.45454545454545…

  • Period 2

    • Duration: 20 days

    • Percent: 45.45454545454545…

However FIP-6 percent precision is decimals, so each period will have to be rounded as follows:

• 9.09090909090909 becomes 9.091

• 45.45454545454545 becomes 45.455

Which when added equal to 100.001%

We initially thought this could be solved by adjusting the “slack” of Period 0 in the above example like this:

• Period 0

  • Duration: 7 days

  • Percent: 9.090

• Period 1

  • Duration: 10 days

  • Percent: 45.455

• Period 2

  • Duration: 20 days

  • Percent: 45.455

• Result

  • 9.999 tokens will unlock after 7 days

  • 50.0005 tokens will unlock after 10 days

  • 50.0005 tokens will unlock after 20 days

However, after additional consideration this approach appears undesirable because:

• It causes undesired differences in token amounts, which may be hard to explain to users.

• In extreme cases it can lead to undesired behavior, when the user may be rounded down. For example:

  • User got 50,000,000 FIO tokens locked via FIP-6 locks for 1 year

  • They now stake 10,000 FIO

  • They now want to unstake 250 FIO

  • Since 250 is 0.0004999% it will get rounded to 0%, and even if the “slack” logic above was in place the user would unstake 500 FIO

Solutions