Add reward caller (using transcoder-to-reward caller mapping direction)

.github/workflows/test.yaml

@@ -47,6 +47,9 @@ jobs:
           name: ${{ github.event.repository.name }}
           token: ${{ secrets.CI_CODECOV_TOKEN }}
 
+      - name: Enforce test coverage threshold
+        run: yarn test:coverage:check
+
   editorconfig:
     name: Run editorconfig checker
     runs-on: ubuntu-latest

contracts/bonding/BondingManager.sol

@@ -29,7 +29,7 @@
     // Constants
     // Occurances are replaced at compile time
     // and computed to a single value if possible by the optimizer
     uint256 constant MAX_FUTURE_ROUND = 2**256 - 1;
 
     // Time between unbonding and possible withdrawl in rounds
     uint64 public unbondingPeriod;
@@ -102,6 +102,10 @@
     // If the balance of the treasury in LPT is above this value, automatic treasury contributions will halt.
     uint256 public treasuryBalanceCeiling;
 
+    // Allow reward() calls from one pre-defined address per transcoder.
+    // @dev Since the setter is callable by any address, a mapping key does not guarantee to be a registered or active transcoder.
+    mapping(address => address) public transcoderToRewardCaller;
+
     // Check if sender is TicketBroker
     modifier onlyTicketBroker() {
         _onlyTicketBroker();
@@ -188,6 +192,16 @@
         emit ParameterUpdate("numActiveTranscoders");
     }
 
+    /**
+     * @notice Set a reward caller for a transcoder
+     * @param _rewardCaller Address of the new reward caller
+     * @dev By providing address(0) the reward caller can be unset
+     */
+    function setRewardCaller(address _rewardCaller) external whenSystemNotPaused {
+        transcoderToRewardCaller[msg.sender] = _rewardCaller;
+        emit RewardCallerSet(msg.sender, _rewardCaller);
+    }
+
     /**
      * @notice Sets commission rates as a transcoder and if the caller is not in the transcoder pool tries to add it
      * @dev Percentages are represented as numerators of fractions over MathUtils.PERC_DIVISOR
@@ -294,6 +308,15 @@
         rewardWithHint(address(0), address(0));
     }
 
+    /**
+     * @notice Mint token rewards for an active transcoder and its delegators
+     * @param _transcoder Address of the transcoder on behalf of which the reward is called
+     * @dev Only callable by trusted rewardCaller
+     */
+    function rewardForTranscoder(address _transcoder) external {
+        rewardForTranscoderWithHint(_transcoder, address(0), address(0));
+    }
+
     /**
      * @notice Update transcoder's fee pool. Only callable by the TicketBroker
      * @param _transcoder Transcoder address
@@ -863,21 +886,53 @@
      * @param _newPosPrev Address of previous transcoder in pool if the caller is in the pool
      * @param _newPosNext Address of next transcoder in pool if the caller is in the pool
      */
-    function rewardWithHint(address _newPosPrev, address _newPosNext)
-        public
-        whenSystemNotPaused
-        currentRoundInitialized
-        autoCheckpoint(msg.sender)
-    {
+    function rewardWithHint(address _newPosPrev, address _newPosNext) public {
+        _rewardWithHint(msg.sender, _newPosPrev, _newPosNext);
+    }
+
+    /**
+     * @notice Mint token rewards for an active transcoder and its delegators and update the transcoder pool using an optional list hint if needed
+     * @dev If the `_transcoder` is in the transcoder pool, the caller can provide an optional hint for its insertion position in the
+     * pool via the `_newPosPrev` and `_newPosNext` params. A linear search will be executed starting at the hint to find the correct position.
+     * In the best case, the hint is the correct position so no search is executed. See SortedDoublyLL.sol for details on list hints
+     * @dev Only callable by trusted rewardCaller
+     * @param _transcoder Address of the transcoder on behalf of which the reward is called
+     * @param _newPosPrev Address of previous transcoder in pool if the `_transcoder` is in the pool
+     * @param _newPosNext Address of next transcoder in pool if the `_transcoder` is in the pool
+     */
+    function rewardForTranscoderWithHint(
+        address _transcoder,
+        address _newPosPrev,
+        address _newPosNext
+    ) public {
+        address rewardCaller = transcoderToRewardCaller[_transcoder];
+        require(rewardCaller == msg.sender, "caller must be a reward caller set by the transcoder");
+        _rewardWithHint(_transcoder, _newPosPrev, _newPosNext);
+    }
+
+    /**
+     * @notice Mint token rewards for an active transcoder and its delegators and update the transcoder pool using an optional list hint if needed
+     * @dev If the `_transcoder` is in the transcoder pool, the caller can provide an optional hint for its insertion position in the
+     * pool via the `_newPosPrev` and `_newPosNext` params. A linear search will be executed starting at the hint to find the correct position.
+     * In the best case, the hint is the correct position so no search is executed. See SortedDoublyLL.sol for details on list hints
+     * @param _transcoder Address of the transcoder on behalf of which the reward is called
+     * @param _newPosPrev Address of previous transcoder in pool if `_transcoder` is in the pool
+     * @param _newPosNext Address of next transcoder in pool if `_transcoder` is in the pool
+     */
+    function _rewardWithHint(
+        address _transcoder,
+        address _newPosPrev,
+        address _newPosNext
+    ) private whenSystemNotPaused currentRoundInitialized autoCheckpoint(_transcoder) {
         uint256 currentRound = roundsManager().currentRound();
 
-        require(isActiveTranscoder(msg.sender), "caller must be an active transcoder");
+        require(isActiveTranscoder(_transcoder), "transcoder must be active");
         require(
-            transcoders[msg.sender].lastRewardRound != currentRound,
+            transcoders[_transcoder].lastRewardRound != currentRound,
             "caller has already called reward for the current round"
         );
 
-        Transcoder storage t = transcoders[msg.sender];
+        Transcoder storage t = transcoders[_transcoder];
         EarningsPool.Data storage earningsPool = t.earningsPoolPerRound[currentRound];
 
         // Set last round that transcoder called reward
@@ -910,17 +965,17 @@
 
             mtr.trustedTransferTokens(trsry, treasuryRewards);
 
-            emit TreasuryReward(msg.sender, trsry, treasuryRewards);
+            emit TreasuryReward(_transcoder, trsry, treasuryRewards);
         }
 
         uint256 transcoderRewards = totalRewardTokens.sub(treasuryRewards);
 
-        updateTranscoderWithRewards(msg.sender, transcoderRewards, currentRound, _newPosPrev, _newPosNext);
+        updateTranscoderWithRewards(_transcoder, transcoderRewards, currentRound, _newPosPrev, _newPosNext);
 
         // Set last round that transcoder called reward
         t.lastRewardRound = currentRound;
 
-        emit Reward(msg.sender, transcoderRewards);
+        emit Reward(_transcoder, transcoderRewards);
     }
 
     /**

contracts/bonding/IBondingManager.sol

@@ -44,6 +44,7 @@ interface IBondingManager {
         uint256 startRound,
         uint256 endRound
     );
+    event RewardCallerSet(address indexed transcoder, address indexed rewardCaller);
 
     // Deprecated events
     // These event signatures can be used to construct the appropriate topic hashes to filter for past logs corresponding
@@ -71,6 +72,20 @@ interface IBondingManager {
 
     function setCurrentRoundTotalActiveStake() external;
 
+    function setRewardCaller(address _rewardCaller) external;
+
+    function reward() external;
+
+    function rewardWithHint(address _newPosPrev, address _newPosNext) external;
+
+    function rewardForTranscoder(address _transcoder) external;
+
+    function rewardForTranscoderWithHint(
+        address _transcoder,
+        address _newPosPrev,
+        address _newPosNext
+    ) external;
+
     // Public functions
     function getTranscoderPoolSize() external view returns (uint256);
 

package.json

@@ -21,6 +21,7 @@
     "clean": "rm -rf cache artifacts typechain",
     "compile": "npx hardhat compile",
     "test:coverage": "npx hardhat coverage",
+    "test:coverage:check": "npx istanbul check-coverage ./coverage.json --statements 100 --branches 100 --functions 100 --lines 100",
     "test": "npx hardhat test",
     "test:unit": "npx hardhat test test/unit/*.*",
     "test:integration": "npx hardhat test test/integration/**",

test/unit/BondingManager.js

@@ -5532,7 +5532,7 @@ describe("BondingManager", () => {
         it("should fail if caller is not a transcoder", async () => {
             await expect(
                 bondingManager.connect(nonTranscoder).reward()
-            ).to.be.revertedWith("caller must be an active transcoder")
+            ).to.be.revertedWith("transcoder must be active")
         })
 
         it("should fail if caller is registered but not an active transcoder yet in the current round", async () => {
@@ -5542,7 +5542,7 @@ describe("BondingManager", () => {
             )
             await expect(
                 bondingManager.connect(transcoder).reward()
-            ).to.be.revertedWith("caller must be an active transcoder")
+            ).to.be.revertedWith("transcoder must be active")
         })
 
         it("should fail if caller already called reward during the current round", async () => {
@@ -6158,6 +6158,130 @@ describe("BondingManager", () => {
                 atCeilingTest("when above limit", 1500)
             })
         })
+
+        describe("reward delegation", () => {
+            const transcoderRewards = 1000
+
+            it("should allow a transcoder to call reward even if RewardCaller is set", async () => {
+                const setRewardCallerTx = bondingManager
+                    .connect(transcoder)
+                    .setRewardCaller(nonTranscoder.address)
+                await expect(setRewardCallerTx)
+                    .to.emit(bondingManager, "RewardCallerSet")
+                    .withArgs(transcoder.address, nonTranscoder.address)
+
+                const rewardTx = bondingManager.connect(transcoder).reward()
+                await expect(rewardTx)
+                    .to.emit(bondingManager, "Reward")
+                    .withArgs(transcoder.address, transcoderRewards)
+
+                await fixture.roundsManager.setMockUint256(
+                    functionSig("currentRound()"),
+                    currentRound + 3
+                )
+
+                const unsetRewardCallerTx = bondingManager
+                    .connect(transcoder)
+                    .setRewardCaller(ZERO_ADDRESS)
+                await expect(unsetRewardCallerTx)
+                    .to.emit(bondingManager, "RewardCallerSet")
+                    .withArgs(transcoder.address, ZERO_ADDRESS)
+
+                const rewardTx2 = bondingManager.connect(transcoder).reward()
+                await expect(rewardTx2)
+                    .to.emit(bondingManager, "Reward")
+                    .withArgs(transcoder.address, transcoderRewards)
+            })
+
+            it("should allow a RewardCaller to call reward", async () => {
+                const setRewardCallerTx = bondingManager
+                    .connect(transcoder)
+                    .setRewardCaller(nonTranscoder.address)
+                await expect(setRewardCallerTx)
+                    .to.emit(bondingManager, "RewardCallerSet")
+                    .withArgs(transcoder.address, nonTranscoder.address)
+
+                const rewardTx = bondingManager
+                    .connect(nonTranscoder)
+                    .rewardForTranscoder(transcoder.address)
+                await expect(rewardTx)
+                    .to.emit(bondingManager, "Reward")
+                    .withArgs(transcoder.address, transcoderRewards)
+
+                await fixture.roundsManager.setMockUint256(
+                    functionSig("currentRound()"),
+                    currentRound + 3
+                )
+
+                const unsetRewardCallerTx = bondingManager
+                    .connect(transcoder)
+                    .setRewardCaller(ZERO_ADDRESS)
+                await expect(unsetRewardCallerTx)
+                    .to.emit(bondingManager, "RewardCallerSet")
+                    .withArgs(transcoder.address, ZERO_ADDRESS)
+
+                const rewardTx2 = bondingManager
+                    .connect(nonTranscoder)
+                    .rewardForTranscoder(transcoder.address)
+                await expect(rewardTx2).to.be.revertedWith(
+                    "caller must be a reward caller set by the transcoder"
+                )
+            })
+
+            it("should fail if system is paused", async () => {
+                await bondingManager
+                    .connect(transcoder)
+                    .setRewardCaller(nonTranscoder.address)
+
+                await fixture.controller.pause()
+                const setRewardCallerTx = bondingManager
+                    .connect(transcoder)
+                    .setRewardCaller(nonTranscoder.address)
+                await expect(setRewardCallerTx).to.be.revertedWith(
+                    "system is paused"
+                )
+
+                const rewardTx = bondingManager
+                    .connect(nonTranscoder)
+                    .rewardForTranscoder(transcoder.address)
+                await expect(rewardTx).to.be.revertedWith("system is paused")
+            })
+
+            it("should fail if current round is not initialized", async () => {
+                await bondingManager
+                    .connect(transcoder)
+                    .setRewardCaller(nonTranscoder.address)
+                await fixture.roundsManager.setMockBool(
+                    functionSig("currentRoundInitialized()"),
+                    false
+                )
+                const rewardTx = bondingManager
+                    .connect(nonTranscoder)
+                    .rewardForTranscoder(transcoder.address)
+                await expect(rewardTx).to.be.revertedWith(
+                    "current round is not initialized"
+                )
+            })
+
+            it("should always checkpoint the reward recipient, not the RewardCaller", async () => {
+                await bondingManager
+                    .connect(transcoder)
+                    .setRewardCaller(nonTranscoder.address)
+                const rewardCallerTx = await bondingManager
+                    .connect(nonTranscoder)
+                    .rewardForTranscoder(transcoder.address)
+
+                await expectCheckpoints(fixture, rewardCallerTx, {
+                    account: transcoder.address,
+                    startRound: currentRound + 2,
+                    bondedAmount: 1000,
+                    delegateAddress: transcoder.address,
+                    delegatedAmount: 2000,
+                    lastClaimRound: currentRound,
+                    lastRewardRound: currentRound + 1
+                })
+            })
+        })
     })
 
     describe("updateTranscoderWithFees", () => {