Add batch minting with ERC2309

cblanquera commented 2 years ago

This spec provides a way to batch mint. The spec requires that the following ConsecutiveTransfer event to be defined and emitted after a batch call.

//ERC721 interface
import "@openzeppelin/contracts/token/ERC721/IERC721.sol";

/**
 * @dev Required interface of an IERC721Exchange compliant contract.
 */
interface IERC2309 is IERC721 {
  /**
   * @dev Emitted when `owner` books their `tokenId` to
   * be sold for `amount` in wei.
   */
  event ConsecutiveTransfer(
    uint256 indexed fromTokenId, 
    uint256 toTokenId, 
    address indexed fromAddress, 
    address indexed toAddress
  );
}

cblanquera commented 2 years ago

Mintpress does not encourage batch minting because we already tried. The following is a report of our findings.

ERC2309

If you are using the @openzeppelin ERC721 contract, this would require you to modify the _mint() function or create a new _silentMint(), one that doesn't emit the Transfer event (or hey maybe it was intended for both events to be emitted...). Either way since the _balances and _owners properties on the ERC721 contract is private, you would eventually need to have a modified version of this file in your project if you are looking to optimize the mint process in order to save gas.

Flexible Batch Minting

Consider the following function that allows to batch mint multiple tokens in multiple token classes.

/**
 * @dev Multiclass batch minting
 */
function batchMint(
  uint[] memory classIds, 
  uint fromTokenId,
  address recipient
) external virtual onlyOwner {
  uint length = classIds.length;

  for (uint i = 0; i < length; i++) {
    //check size
    require(!classFilled(classIds[i]), "Mintpress: Class filled.");
    //mint first and wait for errors
    _safeSilentMint(recipient, fromTokenId + i);
    //then classify it
    _classify(fromTokenId + i, classIds[i]);
    //then increment supply
    _addClassSupply(classIds[i], 1);
  }

  uint toTokenId = (fromTokenId + length) - 1;
  emit ConsecutiveTransfer(fromTokenId, toTokenId, address(0), recipient);
}

This is the gas report for batch minting 100 tokens. After the 100, it sometimes runs out of gas.

·--------------------------------|---------------------------|-------------|-----------------------------·
|      Solc version: 0.8.9       ·  Optimizer enabled: true  ·  Runs: 200  ·  Block limit: 12450000 gas  │
·································|···························|·············|······························
|  Methods                       ·              200 gwei/gas               ·       4578.47 usd/eth       │
··············|··················|·············|·············|·············|···············|··············
|  Contract   ·  Method          ·  Min        ·  Max        ·  Avg        ·  # calls      ·  usd (avg)  │
··············|··················|·············|·············|·············|···············|··············
|  Mintpress  ·  batchMint       ·     338855  ·    4816814  ·    2577835  ·            2  ·    2360.51  │
·--------------------------------|-------------|-------------|-------------|---------------|-------------·

Practical Batch Minting

Consider the following safer function that allows to batch mint multiple tokens per token class.

/**
 * @dev Multiclass batch minting
 */
function batchMint(
  uint classId, 
  uint fromTokenId,
  uint toTokenId,
  address recipient
) external virtual onlyOwner {
  require(
    fromTokenId < toTokenId, 
    "Mintpress: Invalid token range."
  );

  //check size
  uint length = (toTokenId - fromTokenId) + 1;
  uint supply = classSupply(classId);
  uint size = classSize(classId);

  require(
    size == 0 || ((supply + length) <= size), 
    "Mintpress: Batch mint exceeds class size."
  );

  for (uint tokenId = fromTokenId; tokenId <= toTokenId; tokenId++) {
    //mint first and wait for errors
    _safeSilentMint(recipient, tokenId);
    //then classify it
    _classify(tokenId, classId);
  }

  //then increment supply
  _addClassSupply(classId, length);

  emit ConsecutiveTransfer(fromTokenId, toTokenId, address(0), recipient);
}

This is the gas report for batch minting 200 tokens. After the 200, it sometimes runs out of gas.

·--------------------------------|---------------------------|-------------|-----------------------------·
|      Solc version: 0.8.9       ·  Optimizer enabled: true  ·  Runs: 200  ·  Block limit: 12450000 gas  │
·································|···························|·············|······························
|  Methods                       ·              200 gwei/gas               ·       4578.47 usd/eth       │
··············|··················|·············|·············|·············|···············|··············
|  Contract   ·  Method          ·  Min        ·  Max        ·  Avg        ·  # calls      ·  usd (avg)  │
··············|··················|·············|·············|·············|···············|··············
|  Mintpress  ·  batchMint       ·          -  ·          -  ·    9320281  ·            1  ·    8552.87  │
·--------------------------------|-------------|-------------|-------------|---------------|-------------·

Both gas reports indicates that though batch minting is a wanted idea, the implementation of it is impractical.

cblanquera commented 2 years ago

Apparent Cargo can mint 2^255 times in a single transaction.

https://docs.cargo.build/advanced-information/batch-minting-non-fungible-tokens

I tried to make a very minimal example using @openzeppilin ERC721 and _silentMint() but I can't recreate those results.

Open for contributions here.

cblanquera / mintpress