Reward validator when marking missing proof (#209)

Author: 2-towns

configuration/configuration.js

@@ -7,6 +7,7 @@ const DEFAULT_CONFIGURATION = {
     repairRewardPercentage: 10,
     maxNumberOfSlashes: 2,
     slashPercentage: 20,
+    validatorRewardPercentage: 20, // percentage of the slashed amount going to the validators
   },
   proofs: {
     // period has to be less than downtime * blocktime

contracts/Configuration.sol

@@ -14,6 +14,7 @@ struct CollateralConfig {
   uint8 repairRewardPercentage;
   uint8 maxNumberOfSlashes; // frees slot when the number of slashing reaches this value
   uint8 slashPercentage; // percentage of the collateral that is slashed
+  uint8 validatorRewardPercentage; // percentage of the slashed amount going to the validators
 }
 
 struct ProofConfig {

contracts/FuzzMarketplace.sol

@@ -9,7 +9,7 @@ contract FuzzMarketplace is Marketplace {
   constructor()
     Marketplace(
       MarketplaceConfig(
-        CollateralConfig(10, 5, 10),
+        CollateralConfig(10, 5, 10, 20),
         ProofConfig(10, 5, 64, "", 67),
         SlotReservationsConfig(20)
       ),

contracts/Marketplace.sol

@@ -334,10 +334,14 @@ contract Marketplace is SlotReservations, Proofs, StateRetrieval, Endian {
     Slot storage slot = _slots[slotId];
     Request storage request = _requests[slot.requestId];
 
-    // TODO: Reward for validator that calls this function
-
     uint256 slashedAmount = (request.ask.collateralPerSlot() *
       _config.collateral.slashPercentage) / 100;
+
+    uint256 validatorRewardAmount = (slashedAmount *
+      _config.collateral.validatorRewardPercentage) / 100;
+    _marketplaceTotals.sent += validatorRewardAmount;
+    assert(_token.transfer(msg.sender, validatorRewardAmount));
+
     slot.currentCollateral -= slashedAmount;
     if (missingProofs(slotId) >= _config.collateral.maxNumberOfSlashes) {
       // When the number of slashings is at or above the allowed amount,

test/Marketplace.test.js

@@ -106,7 +106,8 @@ describe("Marketplace", function () {
     host2,
     host3,
     hostRewardRecipient,
-    hostCollateralRecipient
+    hostCollateralRecipient,
+    validatorRecipient
   let request
   let slot
 
@@ -123,6 +124,7 @@ describe("Marketplace", function () {
       host3,
       hostRewardRecipient,
       hostCollateralRecipient,
+      validatorRecipient,
     ] = await ethers.getSigners()
     host = host1
 
@@ -136,6 +138,7 @@ describe("Marketplace", function () {
       host3,
       hostRewardRecipient,
       hostCollateralRecipient,
+      validatorRecipient,
     ]) {
       await token.mint(account.address, ACCOUNT_STARTING_BALANCE)
     }
@@ -1384,6 +1387,36 @@ describe("Marketplace", function () {
           )
         )
       })
+
+      it("rewards validator when marking proof as missing", async function () {
+        const id = slotId(slot)
+        const { slashCriterion, slashPercentage, validatorRewardPercentage } =
+          config.collateral
+        await marketplace.reserveSlot(slot.request, slot.index)
+        await marketplace.fillSlot(slot.request, slot.index, proof)
+
+        switchAccount(validatorRecipient)
+
+        const startBalance = await token.balanceOf(validatorRecipient.address)
+
+        await waitUntilProofIsRequired(id)
+        let missedPeriod = periodOf(await currentTime())
+        await advanceTimeForNextBlock(period + 1)
+        await marketplace.markProofAsMissing(id, missedPeriod)
+
+        const endBalance = await token.balanceOf(validatorRecipient.address)
+
+        const collateral = collateralPerSlot(request)
+        const slashedAmount = (collateral * slashPercentage) / 100
+
+        const expectedReward = Math.round(
+          (slashedAmount * validatorRewardPercentage) / 100
+        )
+
+        expect(endBalance.toNumber()).to.equal(
+          startBalance.toNumber() + expectedReward
+        )
+      })
     })
 
     it("frees slot when collateral slashed below minimum threshold", async function () {

test/examples.js

@@ -7,6 +7,7 @@ const exampleConfiguration = () => ({
     repairRewardPercentage: 10,
     maxNumberOfSlashes: 5,
     slashPercentage: 10,
+    validatorRewardPercentage: 20,
   },
   proofs: {
     period: 10,