feat(protocol): implemented partial and more fair block proposal rewa…

…rds (#14888) Co-authored-by: Daniel Wang <[email protected]> Co-authored-by: Daniel Wang <[email protected]>
taikoxyz · Oct 6, 2023 · 4c78ddb · 4c78ddb
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Showing 6 changed files with 54 additions and 19 deletions.
diff --git a/packages/protocol/contracts/L1/TaikoData.sol b/packages/protocol/contracts/L1/TaikoData.sol
@@ -37,8 +37,9 @@ library TaikoData {
         uint24 blockMaxTxListBytes;
         // Amount of token to reward to the first block propsoed in each L1
         // block.
-        uint256 proposerRewardPerSecond;
-        uint256 proposerRewardMax;
+        uint128 proposerRewardPerL1Block;
+        uint128 proposerRewardMax;
+        uint8 proposerRewardPoolPctg;
         // ---------------------------------------------------------------------
         // Group 3: Proof related configs
         // ---------------------------------------------------------------------
@@ -172,6 +173,11 @@ library TaikoData {
         uint64 lastVerifiedBlockId;
     }
 
+    struct SlotC {
+        uint128 accumulatedReward;
+        uint64 lastProposedHeight;
+    }
+
     /// @dev Struct holding the state variables for the {TaikoL1} contract.
     struct State {
         // Ring buffer for proposed blocks and a some recent verified blocks.
@@ -192,6 +198,7 @@ library TaikoData {
         mapping(address account => uint256 balance) tokenBalances;
         SlotA slotA; // slot 6
         SlotB slotB; // slot 7
-        uint256[143] __gap;
+        SlotC slotC; // slot 8
+        uint256[142] __gap;
     }
 }
diff --git a/packages/protocol/contracts/L1/TaikoL1.sol b/packages/protocol/contracts/L1/TaikoL1.sol
@@ -317,8 +317,10 @@ contract TaikoL1 is
             blockMaxGasLimit: 8_000_000,
             blockFeeBaseGas: 20_000,
             blockMaxTxListBytes: 120_000,
-            proposerRewardPerSecond: 25e16, // 0.25 Taiko token
+            proposerRewardPerL1Block: 3e18, // 0.25 Taiko token * 12s = 3 TKO
             proposerRewardMax: 32e18, // 32 Taiko token
+            proposerRewardPoolPctg: 30, // means that 30% of the accumulated
+                // reward is given to the next proposer
             livenessBond: 10_240e18,
             ethDepositRingBufferSize: 1024,
             ethDepositMinCountPerBlock: 8,

diff --git a/packages/protocol/contracts/L1/libs/LibProposing.sol b/packages/protocol/contracts/L1/libs/LibProposing.sol
@@ -99,27 +99,46 @@ library LibProposing {
 
         // The block reward doesn't undergo automatic halving; instead, we
         // depend on Taiko DAO to make necessary adjustments to the rewards.
-        uint256 reward;
+        uint128 reward;
 
-        if (config.proposerRewardPerSecond > 0 && config.proposerRewardMax > 0)
-        {
-            // Unchecked is safe as block.timestamp is always greater than
-            // block.proposedAt (proposed in the past)
+        // Reward block proposers with Taiko tokens to encourage chain adoption
+        // and ensure liveness.
+        // Rewards are issued only if `proposerRewardPerL1Block` and
+        // `proposerRewardMax` are set to nonzero values in the configuration.
+        if (config.proposerRewardPerL1Block != 0) {
             unchecked {
-                uint256 blockTime = block.timestamp
-                    - state.blocks[(b.numBlocks - 1) % config.blockRingBufferSize]
-                        .proposedAt;
-
-                if (blockTime > 0) {
-                    reward = (config.proposerRewardPerSecond * blockTime).min(
-                        config.proposerRewardMax
+                // Mint additional tokens into the reward pool as L1 block
+                // numbers increase, to incentivize future proposers.
+                if (
+                    state.slotC.lastProposedHeight != 0
+                        && state.slotC.lastProposedHeight < block.number
+                ) {
+                    uint256 extraRewardMinted = (
+                        block.number - state.slotC.lastProposedHeight
+                    ) * config.proposerRewardPerL1Block;
+
+                    // Reward pool is capped to `proposerRewardMax`
+                    state.slotC.accumulatedReward = uint128(
+                        (extraRewardMinted + state.slotC.accumulatedReward).min(
+                            config.proposerRewardMax
+                        )
                     );
+                }
+
+                if (state.slotC.accumulatedReward != 0) {
+                    // The current proposer receives a fixed percentage of the
+                    // reward pool.
+                    reward = state.slotC.accumulatedReward / 100
+                        * config.proposerRewardPoolPctg;
+
+                    state.slotC.accumulatedReward -= reward;
 
                     // Reward must be minted
                     LibTaikoToken.creditToken(
                         state, resolver, msg.sender, reward, true
                     );
                 }
+                state.slotC.lastProposedHeight = uint64(block.number);
             }
         }
 

diff --git a/packages/protocol/contracts/L1/libs/LibVerifying.sol b/packages/protocol/contracts/L1/libs/LibVerifying.sol
@@ -50,7 +50,7 @@ library LibVerifying {
                 || config.blockMaxGasLimit == 0 || config.blockMaxTxListBytes == 0
                 || config.blockMaxTxListBytes > 128 * 1024 //blob up to 128K
                 || config.livenessBond == 0
-                || config.livenessBond < 10 * config.proposerRewardPerSecond
+                || config.livenessBond < 10 * config.proposerRewardPerL1Block
                 || config.ethDepositRingBufferSize <= 1
                 || config.ethDepositMinCountPerBlock == 0
                 || config.ethDepositMaxCountPerBlock
@@ -64,6 +64,13 @@ library LibVerifying {
                     >= type(uint96).max / config.ethDepositMaxCountPerBlock
         ) revert L1_INVALID_CONFIG();
 
+        if (config.proposerRewardPerL1Block != 0) {
+            if (
+                config.proposerRewardMax == 0
+                    || config.proposerRewardPoolPctg == 0
+            ) revert L1_INVALID_CONFIG();
+        }
+
         // Init state
         state.slotA.genesisHeight = uint64(block.number);
         state.slotA.genesisTimestamp = uint64(block.timestamp);

diff --git a/packages/protocol/test/L1/TaikoL1.t.sol b/packages/protocol/test/L1/TaikoL1.t.sol
@@ -25,7 +25,7 @@ contract TaikoL1_NoCooldown is TaikoL1 {
         config.blockMaxProposals = 10;
         config.blockRingBufferSize = 12;
         config.livenessBond = 1e18; // 1 Taiko token
-        config.proposerRewardPerSecond = 1e15; // 0.001 Taiko token
+        config.proposerRewardPerL1Block = 1e15; // 0.001 Taiko token
     }
 }
 

diff --git a/packages/protocol/test/L1/TaikoL1LibProvingWithTiers.t.sol b/packages/protocol/test/L1/TaikoL1LibProvingWithTiers.t.sol
@@ -30,7 +30,7 @@ contract TaikoL1Tiers is TaikoL1 {
         config.blockMaxProposals = 10;
         config.blockRingBufferSize = 12;
         config.livenessBond = 1e18; // 1 Taiko token
-        config.proposerRewardPerSecond = 1e15; // 0.001 Taiko token
+        config.proposerRewardPerL1Block = 1e15; // 0.001 Taiko token
     }
 }