feat: set custom exit period on contract initialization

README.md

@@ -1,10 +1,5 @@
 # Plasma Contracts
 
-**IMPORTANT NOTICE** / **TODO**:
-This implementation includes a brute-force shortening of the exit periods, see [here](https://github.com/omisego/plasma-contracts/blob/master/contracts/RootChain.sol#L36).
-This will be made configurable on contract deployment and should be _much longer_ for any secure deployment.
-**DO NOT DEPLOY TO MAINNET**
-
 Root chain contracts for Plasma MVP, work in progress.
 
 ## Contents

contracts/RootChain.sol

@@ -32,17 +32,16 @@ contract RootChain {
     /*
      * Storage
      */
-
-    // NOTE: this is the "middle" period. Exit period for fresh utxos we'll double that while IFE phase is half that
-    // TODO: this is a value sensible only for testing and demo purposes, **DO NOT DEPLOY TO MAINNET**
-    uint256 constant public MIN_EXIT_PERIOD = 4 minutes;
     uint256 constant public CHILD_BLOCK_INTERVAL = 1000;
 
     // WARNING: These placeholder bond values are entirely arbitrary.
     uint256 public standardExitBond = 31415926535 wei;
     uint256 public inFlightExitBond = 31415926535 wei;
     uint256 public piggybackBond = 31415926535 wei;
 
+    // NOTE: this is the "middle" period. Exit period for fresh utxos we'll double that while IFE phase is half that
+    uint256 public minExitPeriod;
+
     address public operator;
 
     uint256 public nextChildBlock;
@@ -175,13 +174,18 @@ contract RootChain {
      * Public functions
      */
 
-    // @dev Required to be called before any operations on the contract
-    //      Split from `constructor` to fit into block gas limit
-    function init()
+    /**
+     * @dev Required to be called before any operations on the contract
+     * Split from `constructor` to fit into block gas limit
+     * @param _minExitPeriod standard exit period in seconds
+     */
+    function init(uint256 _minExitPeriod)
         public
     {
       _initOperator();
 
+      minExitPeriod = _minExitPeriod;
+
       nextChildBlock = CHILD_BLOCK_INTERVAL;
       nextDepositBlock = 1;
 
@@ -904,11 +908,11 @@ contract RootChain {
     {
         uint256 blknum = _outputId.getBlknum();
         if (blknum % CHILD_BLOCK_INTERVAL == 0) {
-            return Math.max(blocks[blknum].timestamp + (MIN_EXIT_PERIOD * 2), block.timestamp + MIN_EXIT_PERIOD);
+            return Math.max(blocks[blknum].timestamp + (minExitPeriod * 2), block.timestamp + minExitPeriod);
         }
         else {
             // High priority exit for the deposit.
-            return block.timestamp + MIN_EXIT_PERIOD;
+            return block.timestamp + minExitPeriod;
         }
     }
 
@@ -922,7 +926,7 @@ contract RootChain {
         view
         returns (uint256)
     {
-        return ((block.timestamp + (2 * MIN_EXIT_PERIOD)) << 192) | _feeExitId;
+        return ((block.timestamp + (2 * minExitPeriod)) << 192) | _feeExitId;
     }
 
 
@@ -998,7 +1002,7 @@ contract RootChain {
         view
         returns (uint256)
     {
-        uint256 periodTime = MIN_EXIT_PERIOD / 2;
+        uint256 periodTime = minExitPeriod / 2;
         return ((block.timestamp - clearFlag(_inFlightExit.exitStartTimestamp)) / periodTime) + 1;
     }
 

plasma_core/constants.py

@@ -54,6 +54,5 @@
 WEEK = 60 * 60 * 24 * 7
 DAY = 60 * 60 * 24
 
-# TODO: this is dictated by the hard-coded constant in RootChain.sol for now. After parametrized, it could be used for
-#       suitable test contract instantiation and can even be shorter.
+# used for suitable test contract instantiation
 MIN_EXIT_PERIOD = 4 * MINUTE

tests/conftest.py

@@ -11,6 +11,7 @@
 from solc import link_code
 
 
+EXIT_PERIOD = 4 * 60  # 4 minutes
 GAS_LIMIT = 8000000
 START_GAS = GAS_LIMIT - 1000000
 config_metropolis['BLOCK_GAS_LIMIT'] = GAS_LIMIT
@@ -68,12 +69,16 @@ def create_contract(path, args=(), sender=ethtester.k0, libraries=dict()):
 
 @pytest.fixture
 def root_chain(ethtester, get_contract):
+    return initialized_contract(ethtester, get_contract, EXIT_PERIOD)
+
+
+def initialized_contract(ethtester, get_contract, exit_period):
     pql = get_contract('PriorityQueueLib')
     pqf = get_contract('PriorityQueueFactory', libraries={'PriorityQueueLib': pql.address})
     ethtester.chain.mine()
     contract = get_contract('RootChain', libraries={'PriorityQueueFactory': pqf.address})
     ethtester.chain.mine()
-    contract.init(sender=ethtester.k0)
+    contract.init(exit_period, sender=ethtester.k0)
     ethtester.chain.mine()
     return contract
 
@@ -90,6 +95,16 @@ def testlang(root_chain, ethtester):
     return TestingLanguage(root_chain, ethtester)
 
 
+@pytest.fixture
+def root_chain_short_exit_period(ethtester, get_contract):
+    return initialized_contract(ethtester, get_contract, 0)
+
+
+@pytest.fixture
+def testlang_root_chain_short_exit_period(root_chain_short_exit_period, ethtester):
+    return TestingLanguage(root_chain_short_exit_period, ethtester)
+
+
 @pytest.fixture
 def utxo(testlang):
     return testlang.create_utxo()

tests/contracts/root_chain/test_init.py

@@ -2,10 +2,27 @@
 from ethereum.tools.tester import TransactionFailed
 
 
+EXIT_PERIOD = 4 * 60
+
+
+@pytest.fixture
+def utxo(testlang_root_chain_short_exit_period):
+    return testlang_root_chain_short_exit_period.create_utxo()
+
+
 def test_cant_ever_init_twice(ethtester, root_chain):
     ethtester.chain.mine()
     with pytest.raises(TransactionFailed):
-        root_chain.init(sender=ethtester.k0)
+        root_chain.init(EXIT_PERIOD, sender=ethtester.k0)
+
+
+def test_exit_period_setting_has_effect(testlang_root_chain_short_exit_period):
+    owner = testlang_root_chain_short_exit_period.accounts[0]
+    deposit_id = testlang_root_chain_short_exit_period.deposit(owner, 100)
+
+    spend_id = testlang_root_chain_short_exit_period.spend_utxo([deposit_id], [owner.key])
+
+    testlang_root_chain_short_exit_period.start_in_flight_exit(spend_id)
 
     with pytest.raises(TransactionFailed):
-        root_chain.init(sender=ethtester.k1)
+        testlang_root_chain_short_exit_period.piggyback_in_flight_exit_input(spend_id, 0, owner.key)