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Purpose

The purpose of the token-min-tx-size rule is to prevent micro-trades or dust trades within an ecosystem. A developer can set the minimum number of tokens required per transfer to prevent these types of trades.

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Scope

This rule works at a token level. It must be activated and configured for each desired token in the corresponding token handler.

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Data Structure

A token-min-tx-size rule is composed of 1 component:
  • minSize (uint256): minimum number of tokens that must be transferred for each transaction.
    /// ******** Token Minimum Transfer Rules ********
    struct TokenMinTxSize {
        uint256 minSize;
    }
see RuleDataInterfaces
The token-min-tx-size rules are stored in a mapping indexed by ruleId(uint32) in order of creation: 
   /// ******** Minimum Transaction ********
   struct TokenMinTxSizeS {
       mapping(uint32 => INonTaggedRules.TokenMinTxSize) tokenMinTxSizeRules;
       uint32 tokenMinTxSizeIndex; /// increments every time someone adds a rule
   }
see IRuleStorage

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Configuration and Enabling/Disabling

  • This rule can only be configured in the protocol by a rule administrator.
  • This rule can only be set in the asset handler by a rule administrator.
  • This rule can only be activated/deactivated in the asset handler by a rule administrator.
  • This rule can only be updated in the asset handler by a rule administrator.

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Rule Evaluation

The rule will be evaluated with the following logic:
  1. The handler determines if the rule is active from the supplied action. If not, processing does not continue past this step.
  2. The processor receives the ID of the token-min-tx-size rule set in the token handler.
  3. The processor receives the amount of tokens from the handler.
  4. The processor evaluates the amount against the rule minSize and reverts if the amount less than the rule minimum.
  5. If it’s a non-custodial style Buy
    1. When the Sell action is also active, checks steps 1-4 for from address.
  6. If it’s a non-custodial style Sell
    1. When the Buy action is also active, checks steps 1-4 for to address.
The list of available actions rules can be applied to can be found at ACTION_TYPES
see ERC20RuleProcessorFacet -> checkTokenMinTxSize

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Evaluation Exceptions

  • This rule doesn’t apply when a treasuryAccount address is in either the from or the to side of the transaction. This doesn’t necessarily mean that if an treasury account is the one executing the transaction it will bypass the rule, unless the aforementioned condition is true.

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Revert Message

The rule processor will revert with the following error if the rule check fails: 
error UnderMinTxSize();
The selector for this error is 0x7a78c901.

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Create Function

Adding a token-min-tx-size rule is done through the function: 
function addTokenMinTxSize(
    address _appManagerAddr,
    uint256 _minSize
) external ruleAdministratorOnly(_appManagerAddr) returns (uint32);
see RuleDataFacet
The add function will return the protocol ID of the rule.

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Parameters:

  • _appManagerAddr (address): The address of the application manager to verify that the caller has Rule administrator privileges.
  • _minSize (uint256): Minimum number of tokens for the transaction.

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Parameter Optionality:

There is no parameter optionality for this rule.

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Parameter Validation:

The following validation will be carried out by the add function in order to ensure that these parameters are valid and make sense:
  • _appManagerAddr is not the zero address.
  • _minSize is greater than 0.
see RuleDataFacet

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Other Functions:

  • In Protocol Rule Processor:
    • Function to get a rule by its ID: 
      function getTokenMinTxSize(
            uint32 _index
        )
        external
        view
        returns
        (NonTaggedRules.TokenMinTxSize memory);
    • Function to get current amount of rules in the protocol: 
      function getTotalTokenMinTxSize() public view returns (uint32);
  • In Protocol Rule Processor:
    • Function that evaluates the rule: 
      function checkTokenMinTxSize(
            uint32 _ruleId,
            uint256 _amountToTransfer
        )
        external
        view;
  • in Asset Handler:
    • Function to set and activate at the same time the rule for the supplied actions in an asset handler: 
      function setTokenMinTxSizeId(ActionTypes[] calldata _actions, uint32 _ruleId) external ruleAdministratorOnly(appManagerAddress);
    • Function to activate/deactivate the rule for the supplied actions actions in an asset handler: 
      function activateTokenMinTxSize(ActionTypes[] calldata _action, bool _on) external ruleAdministratorOnly(appManagerAddress);
    • Function to know the activation state of the rule for the supplied action in an asset handler: 
      function isTokenMinTxSizeActive(ActionTypes _action) external view returns (bool);
    • Function to get the rule Id for the supplied action from an asset handler: 
      function getTokenMinTxSizeId(ActionTypes _action) external view returns (uint32);

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Return Data

This rule does not return any data.

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Data Recorded

This rule does not require any data to be recorded.

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Events

  • event AD1467_ProtocolRuleCreated(bytes32 indexed ruleType, uint32 indexed ruleId, bytes32[] extraTags):
    • Emitted when: the rule has been created in the protocol.
    • Parameters:
      • ruleType: “TOKEN_MIN_TX_SIZE”.
      • ruleId: the index of the rule created in the protocol by rule type.
      • extraTags: an empty array.
  • event AD1467_ApplicationHandlerActionApplied(bytes32 indexed ruleType, ActionTypes action, uint32 indexed ruleId):
    • Emitted when: rule has been applied in an asset handler.
    • parameters:
      • ruleType: “TOKEN_MIN_TX_SIZE”.
      • action: the protocol action the rule is being applied to.
      • ruleId: the index of the rule created in the protocol by rule type.
  • event AD1467_ApplicationHandlerActionActivated(bytes32 indexed ruleType, ActionTypes actions, uint256 indexed ruleId)
    • Emitted when: A Token Min Transaction Size rule has been activated in an asset handler:
    • Parameters:
      • ruleType: “TOKEN_MIN_TX_SIZE”.
      • actions: the protocol actions for which the rule is being activated.
      • ruleId: a placeholder of 0 will be passed for ruleId
  • event AD1467_ApplicationHandlerActionDeactivated(bytes32 indexed ruleType, ActionTypes actions, uint256 indexed ruleId)
    • Emitted when: A Token Min Transaction Size rule has been deactivated in an asset handler:
    • Parameters:
      • ruleType: “TOKEN_MIN_TX_SIZE”.
      • actions: the protocol actions for which the rule is being deactivated.
      • ruleId: a placeholder of 0 will be passed for ruleId

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Dependencies

  • This rule has no dependencies.