Hello I am writing a crowdsale using Zeppelin-Solidity where I need to integrate the token lock function so the ERC20 tokens can be locked for a specific period of time.
The zeppelin-solidity seems to provide Tokenvesting.sol for this purpose.
pragma solidity ^0.4.11;
import './ERC20Basic.sol';
import './SafeERC20.sol';
import '../ownership/Ownable.sol';
import '../math/Math.sol';
import '../math/SafeMath.sol';
/**
* @title TokenVesting
* @dev A token holder contract that can release its token balance gradually like a
* typical vesting scheme, with a cliff and vesting period. Optionally revocable by the
* owner.
*/
contract TokenVesting is Ownable {
using SafeMath for uint256;
using SafeERC20 for ERC20Basic;
event Released(uint256 amount);
event Revoked();
// beneficiary of tokens after they are released
address public beneficiary;
uint256 public cliff;
uint256 public start;
uint256 public duration;
bool public revocable;
mapping (address => uint256) public released;
mapping (address => bool) public revoked;
/**
* @dev Creates a vesting contract that vests its balance of any ERC20 token to the
* _beneficiary, gradually in a linear fashion until _start + _duration. By then all
* of the balance will have vested.
* @param _beneficiary address of the beneficiary to whom vested tokens are transferred
* @param _cliff duration in seconds of the cliff in which tokens will begin to vest
* @param _duration duration in seconds of the period in which the tokens will vest
* @param _revocable whether the vesting is revocable or not
*/
function TokenVesting(address _beneficiary, uint256 _start, uint256 _cliff, uint256 _duration, bool _revocable) {
require(_beneficiary != address(0));
require(_cliff <= _duration);
beneficiary = _beneficiary;
revocable = _revocable;
duration = _duration;
cliff = _start.add(_cliff);
start = _start;
}
/**
* @notice Transfers vested tokens to beneficiary.
* @param token ERC20 token which is being vested
*/
function release(ERC20Basic token) public {
uint256 unreleased = releasableAmount(token);
require(unreleased > 0);
released[token] = released[token].add(unreleased);
token.safeTransfer(beneficiary, unreleased);
Released(unreleased);
}
/**
* @notice Allows the owner to revoke the vesting. Tokens already vested
* remain in the contract, the rest are returned to the owner.
* @param token ERC20 token which is being vested
*/
function revoke(ERC20Basic token) public onlyOwner {
require(revocable);
require(!revoked[token]);
uint256 balance = token.balanceOf(this);
uint256 unreleased = releasableAmount(token);
uint256 refund = balance.sub(unreleased);
revoked[token] = true;
token.safeTransfer(owner, refund);
Revoked();
}
/**
* @dev Calculates the amount that has already vested but hasn't been released yet.
* @param token ERC20 token which is being vested
*/
function releasableAmount(ERC20Basic token) public constant returns (uint256) {
return vestedAmount(token).sub(released[token]);
}
/**
* @dev Calculates the amount that has already vested.
* @param token ERC20 token which is being vested
*/
function vestedAmount(ERC20Basic token) public constant returns (uint256) {
uint256 currentBalance = token.balanceOf(this);
uint256 totalBalance = currentBalance.add(released[token]);
if (now < cliff) {
return 0;
} else if (now >= start.add(duration) || revoked[token]) {
return totalBalance;
} else {
return totalBalance.mul(now.sub(start)).div(duration);
}
}
}
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But there are different paramters in it (start , vesting period and cliff). I am not sure how this will work
-Whether tokens are transferred to the beneficiary first and then gets lock or tokens are stored in locked contract and released later. And how vesting and cliff works. I have researched vesting and cliff on Investopedia but doesn't clarify the concept on how this will be described with respect to crowdsale(cliff, Vesting And Revoked)
