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Document and clarify vesting logic

This commit is contained in:
Jorge Izquierdo 2017-04-24 12:57:56 +02:00
parent 133ee16055
commit 1c16008c99
1 changed files with 45 additions and 21 deletions
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66
contracts/MiniMeIrrevocableVestedToken.sol
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@ -23,6 +23,7 @@ import "zeppelin/SafeMath.sol";
// More complex cloning could account for past vesting calendars.
contract MiniMeIrrevocableVestedToken is MiniMeToken, SafeMath {
// Keep the struct at 2 sstores (1 slot for value + 64 * 3 (dates) + 20 (address) = 2 slots (2nd slot is 212 bytes, lower than 256))
struct TokenGrant {
address granter;
uint256 value;
@ -54,7 +55,6 @@ contract MiniMeIrrevocableVestedToken is MiniMeToken, SafeMath {
function transfer(address _to, uint _value)
canTransfer(msg.sender, _value)
returns (bool success) {
return super.transfer(_to, _value);
}
@ -80,15 +80,10 @@ contract MiniMeIrrevocableVestedToken is MiniMeToken, SafeMath {
uint64 _cliff,
uint64 _vesting) {
if (_cliff < _start) {
throw;
}
if (_vesting < _start) {
throw;
}
if (_vesting < _cliff) {
throw;
}
// Check start, cliff and vesting are properly order to ensure correct functionality of the formula.
if (_cliff < _start) throw;
if (_vesting < _start) throw;
if (_vesting < _cliff) throw;
if (disabledGrants[_to]) throw; // If the receiver has explicitely blocked receiving grants, throw.
if (grants[_to].length > 20) throw; // To prevent a user being spammed and have his balance locked (out of gas attack when calculating vesting).
@ -99,10 +94,12 @@ contract MiniMeIrrevocableVestedToken is MiniMeToken, SafeMath {
if (!transfer(_to, _value)) throw;
}
// @dev Not allow token grants
function revokeTokenGrant(address _holder, uint _grantId) {
throw;
}
//
function tokenGrantsCount(address _holder) constant returns (uint index) {
return grants[_holder].length;
}
@ -134,30 +131,55 @@ contract MiniMeIrrevocableVestedToken is MiniMeToken, SafeMath {
uint256 time,
uint256 start,
uint256 cliff,
uint256 vesting) internal constant returns (uint256 vestedTokens)
uint256 vesting) internal constant returns (uint256)
{
if (time < cliff) {
return 0;
}
// Shortcuts for before cliff and after vesting cases.
if (time < cliff) return 0;
if (time >= vesting) return tokens;
if (time >= vesting) {
return tokens;
}
// Cliff tokens is the part of the tokens that gets unlocked after the cliff.
// Interpolated in function of the relation of vesting and cliff time.
uint256 cliffTokens = safeDiv(safeMul(tokens, safeSub(cliff, start)), safeSub(vesting, start));
vestedTokens = cliffTokens;
// Actual order of operations is changed to divide the biggest numbers because
// of the lack of floating point types
// cliffTokens = tokens * (cliff - start) / (vesting - start)
uint256 cliffTokens = safeDiv(
safeMul(
tokens,
safeSub(cliff, start)
),
safeSub(vesting, start)
);
// Vesting tokens is the part of the token grant that wasn't part of the cliff tokens
// vestingTokens = tokens - cliffTokens
uint256 vestingTokens = safeSub(tokens, cliffTokens);
vestedTokens = safeAdd(vestedTokens, safeDiv(safeMul(vestingTokens, safeSub(time, cliff)), safeSub(vesting, cliff)));
// Vested vesting tokens is the part of the vesting tokens that are already vested
// vestedVestingTokens = vestingTokens * (time - cliff) / (vesting - cliff)
uint256 vestedVestingTokens = safeDiv(
safeMul(
vestingTokens,
safeSub(time, cliff)
),
safeSub(vesting, cliff)
);
// cliff tokens + vestedVestingToken
return safeAdd(cliffTokens, vestedVestingTokens);
}
function nonVestedTokens(TokenGrant grant, uint64 time) internal constant returns (uint256) {
// Of all the tokens of the grant, how many of them are not vested?
// grantValue - vestedTokens
return safeSub(grant.value, vestedTokens(grant, time));
}
// @dev The date in which all tokens are transferable for the holder
// Useful for displaying purposes (not used in any logic calculations)
function lastTokenIsTransferableDate(address holder) constant public returns (uint64 date) {
date = uint64(now);
uint256 grantIndex = grants[holder].length;
@ -170,13 +192,15 @@ contract MiniMeIrrevocableVestedToken is MiniMeToken, SafeMath {
function transferableTokens(address holder, uint64 time) constant public returns (uint256) {
uint256 grantIndex = grants[holder].length;
if (grantIndex == 0) return balanceOf(holder);
if (grantIndex == 0) return balanceOf(holder); // shortcut for holder without grants
// Iterate through all the grants the holder has, and add all non-vested tokens
uint256 nonVested = 0;
for (uint256 i = 0; i < grantIndex; i++) {
nonVested = safeAdd(nonVested, nonVestedTokens(grants[holder][i], time));
}
// Balance - totalNonVested is the amount of tokens a holder can transfer at any given time
return safeSub(balanceOf(holder), nonVested);
}
}