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Purpose

The purpose of the pause rule is to allow developers to pause the entirety of an application for maintenance, security or any other reason. Pausing the application means that no transfer of tokens is allowed at any level (with the few exceptions listed in the Evaluation Exceptions section below).

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Scope

This rule works at the application level which means that all tokens in the app will have no choice but to comply with this rule when active.

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Data Structure

A pause rule is composed of 2 components:
  • Pause Start (uint64): The timestamp where the pause rule starts.
  • Pause Stop (uint64): The timestamp where the pause rule ends.
struct PauseRule {
    uint64 pauseStart;
    uint64 pauseStop;
}
see PauseRule

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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 protocol’s rule processor retrieves all the pause rules stored in the data contract of the appManager.
  2. The processor loops through all these pause rules, and evaluates if current timestamp is greater or equal to pauseStart and less than pauseStop. If the condition is true for at least one rule, then the transaction reverts.
see ApplicationPauseProcessorFacet -> checkPauseRules

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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 a 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 ApplicationPaused(uint256 started, uint256 ends);
The selector for this error is 0x33385551.

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Create Function

Adding a pause rule is done through the function: 
function addPauseRule(uint256 _pauseStart, uint256 _pauseStop) external onlyRole(RULE_ADMIN_ROLE);
see AppManager

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Parameters:

  • _pauseStart (uint256): the Unix timestamp for the start of the paused period.
  • _pauseStop (uint256): the Unix timestamp for the end of the paused period.
The add function will return the protocol ID of the rule. This add function will also delete automatically any pause rule where the pauseStop timestamp is less than current timestamp since this means that the rule has expired. There is a default limit of 15 pause rules per application to avoid too much gas consumption during transactions. 
uint8 constant MAX_RULES = 15;

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Parameter Optionality:

There are no options for the parameters of 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:
  • The amount of rules won’t be greater than MAX_RULES.
  • pauseStop timestamp is greater than pauseStart.
  • pauseStart timestamp is greater than current timestamp.
see PauseRule
It is worth noting that this rule is special in the sense that it is not stored in the protocol but in the AppManager data contracts. Therefore, this rule doesn’t have an ID like the other rules. This fact also makes this rule unreachable by other applications.
see ProtocolApplicationHandler

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Other Functions:

  • In AppManager:
    • Function to remove a rule: 
      function removePauseRule(
                uint256 _pauseStart,
                uint256 _pauseStop
            )
            external
            onlyRole(RULE_ADMIN_ROLE);
    • Function to activate/deactivate the rule: 
      function activatePauseRuleCheck(bool _on) external onlyRole(RULE_ADMIN_ROLE);
    • Function to get all rules: 
      function getPauseRules() external view returns (PauseRule[] memory);
    • Function to clean expired rules: 
      function cleanOutdatedRules() external;

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Return Data

This rule doesn’t return any data.

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Data Recorded

This rule doesn’t require of any data to be recorded.

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Events

  • event AD1467_PauseRuleEvent(uint256 indexed pauseStart, uint256 indexed pauseStop, bool indexed add): emitted when:
    • A pause rule has been added. In this case, the add field of the event will be true.
    • A pause rule has been removed. In this case, the add field of the event will be false.

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Dependencies

This rule has no dependencies.