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reentrancy mutex gas optimization #1155

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Merged
merged 2 commits into from
Aug 6, 2018
Merged

reentrancy mutex gas optimization #1155

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aef43e0
reentrancy mutex gas optimization
yaronvel Aug 5, 2018
1662fa7
1) uint => uint256 2) ++ to += 1
yaronvel Aug 6, 2018
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19 changes: 5 additions & 14 deletions contracts/ReentrancyGuard.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -9,17 +9,8 @@ pragma solidity ^0.4.24;
*/
contract ReentrancyGuard {

/// @dev Constant for unlocked guard state - non-zero to prevent extra gas costs.
/// See: https://github.com/OpenZeppelin/openzeppelin-solidity/issues/1056
uint private constant REENTRANCY_GUARD_FREE = 1;

/// @dev Constant for locked guard state
uint private constant REENTRANCY_GUARD_LOCKED = 2;

/**
* @dev We use a single lock for the whole contract.
*/
uint private reentrancyLock = REENTRANCY_GUARD_FREE;
/// @dev counter to allow mutex lock with only one SSTORE operation
uint256 private guardCounter = 1;

/**
* @dev Prevents a contract from calling itself, directly or indirectly.
Expand All @@ -30,10 +21,10 @@ contract ReentrancyGuard {
* wrapper marked as `nonReentrant`.
*/
modifier nonReentrant() {
require(reentrancyLock == REENTRANCY_GUARD_FREE);
reentrancyLock = REENTRANCY_GUARD_LOCKED;
guardCounter += 1;
uint256 localCounter = guardCounter;
_;
reentrancyLock = REENTRANCY_GUARD_FREE;
require(localCounter == guardCounter);
}

}