Change storage layout to allow mapping

.gitmodules

@@ -4,9 +4,6 @@
 [submodule "lib/openzeppelin-contracts"]
 	path = lib/openzeppelin-contracts
 	url = https://github.com/OpenZeppelin/openzeppelin-contracts
-[submodule "lib/block-hash-pusher"]
-	path = lib/block-hash-pusher
-	url = https://github.com/Offchainlabs/block-hash-pusher
 [submodule "lib/scroll-contracts"]
 	path = lib/scroll-contracts
 	url = https://github.com/scroll-tech/scroll-contracts

foundry.lock

@@ -1,7 +1,4 @@
 {
-  "lib/block-hash-pusher": {
-    "rev": "085872efb820563b9c50d85732457147523fbe67"
-  },
   "lib/forge-std": {
     "rev": "8bbcf6e3f8f62f419e5429a0bd89331c85c37824"
   },

remappings.txt

@@ -3,6 +3,5 @@ forge-std/=lib/forge-std/src/
 @openzeppelin/contracts/=lib/openzeppelin-contracts/contracts/
 @eth-optimism/=node_modules/@eth-optimism/
 @arbitrum/nitro-contracts/=node_modules/@arbitrum/nitro-contracts
-block-hash-pusher/=lib/block-hash-pusher/
 @scroll-tech/scroll-contracts/=lib/scroll-contracts/src/
 @linea-contracts/=lib/linea-monorepo/contracts/src/

snapshots/verifyBroadcastMessage.json

@@ -1,9 +1,9 @@
 {
-  "EthereumToOptimism": "1642608",
-  "EthereumToTaikoL2": "1055627",
+  "EthereumToOptimism": "1639195",
+  "EthereumToTaikoL2": "1052214",
   "LineaL2ToEthereum": "2551776",
-  "ScrollL2ToEthereum": "1363077",
-  "ScrollToOptimism": "1349825",
-  "TaikoL2ToEthereum": "1025690",
+  "ScrollL2ToEthereum": "1361940",
+  "ScrollToOptimism": "1348688",
+  "TaikoL2ToEthereum": "1022277",
   "ZkSyncL2ToEthereum": "125479"
 }

src/contracts/block-hash-pusher/BaseBuffer.sol

@@ -19,22 +19,14 @@ abstract contract BaseBuffer is IBuffer {
     /// @dev The block number of the newest block in the buffer.
     uint256 private _newestBlockNumber;
 
-    struct BufferSlot {
-        uint256 blockNumber;
-        bytes32 blockHash;
-    }
+    /// @dev Mapping of block numbers to block hashes.
+    mapping(uint256 blockNumber => bytes32 blockHash) private _blockHashes;
 
-    BufferSlot[_BUFFER_SIZE] private _buffer;
+    uint256[_BUFFER_SIZE] private _blockNumberBuffer;
 
     /// @inheritdoc IBuffer
     function parentChainBlockHash(uint256 parentChainBlockNumber) external view returns (bytes32) {
-        BufferSlot storage s = _buffer[parentChainBlockNumber % _BUFFER_SIZE];
-
-        if (s.blockNumber != parentChainBlockNumber) {
-            revert UnknownParentChainBlockHash(parentChainBlockNumber);
-        }
-
-        bytes32 blockHash = s.blockHash;
+        bytes32 blockHash = _blockHashes[parentChainBlockNumber];
         if (blockHash == 0) {
             revert UnknownParentChainBlockHash(parentChainBlockNumber);
         }
@@ -54,19 +46,22 @@ abstract contract BaseBuffer is IBuffer {
             revert EmptyBlockHashes();
         }
 
-        // write the hashes to the buffer, evicting old hashes as necessary
+        // write the hashes to both the mapping and circular buffer
         for (uint256 i = 0; i < blockHashesLength; i++) {
             uint256 blockNumber = firstBlockNumber + i;
             uint256 bufferIndex = blockNumber % _BUFFER_SIZE;
+            uint256 existingBlockNumber = _blockNumberBuffer[bufferIndex];
 
-            BufferSlot storage bufferSlot = _buffer[bufferIndex];
-            if (blockNumber <= bufferSlot.blockNumber) {
-                // noop
+            if (blockNumber <= existingBlockNumber) {
                 continue;
             }
 
-            bufferSlot.blockNumber = blockNumber;
-            bufferSlot.blockHash = blockHashes[i];
+            if (existingBlockNumber != 0) {
+                _blockHashes[existingBlockNumber] = 0;
+            }
+
+            _blockHashes[blockNumber] = blockHashes[i];
+            _blockNumberBuffer[bufferIndex] = blockNumber;
         }
 
         uint256 lastBlockNumber = firstBlockNumber + blockHashesLength - 1;

src/contracts/provers/arbitrum/ChildToParentProver.sol

@@ -3,7 +3,7 @@ pragma solidity 0.8.30;
 
 import {ProverUtils} from "../../libraries/ProverUtils.sol";
 import {IStateProver} from "../../interfaces/IStateProver.sol";
-import {IBuffer} from "block-hash-pusher/contracts/interfaces/IBuffer.sol";
+import {IBuffer} from "../../block-hash-pusher/interfaces/IBuffer.sol";
 import {SlotDerivation} from "@openzeppelin/contracts/utils/SlotDerivation.sol";
 
 /// @notice Arbitrum implementation of a child to parent IStateProver.

src/contracts/provers/linea/ChildToParentProver.sol

@@ -3,7 +3,7 @@ pragma solidity 0.8.30;
 
 import {ProverUtils} from "../../libraries/ProverUtils.sol";
 import {IStateProver} from "../../interfaces/IStateProver.sol";
-import {IBuffer} from "block-hash-pusher/contracts/interfaces/IBuffer.sol";
+import {IBuffer} from "../../block-hash-pusher/interfaces/IBuffer.sol";
 import {SlotDerivation} from "@openzeppelin/contracts/utils/SlotDerivation.sol";
 
 /// @notice Linea implementation of a child to parent IStateProver.
@@ -14,7 +14,7 @@ contract ChildToParentProver is IStateProver {
     address public immutable blockHashBuffer;
     /// @dev Storage slot the buffer contract uses to store block hashes.
     ///      See https://github.com/openintentsframework/broadcaster/blob/main/src/contracts/block-hash-pusher/BaseBuffer.sol
-    uint256 public constant blockHashMappingSlot = 51;
+    uint256 public constant blockHashMappingSlot = 1;
 
     /// @dev The chain ID of the home chain (child chain).
     uint256 public immutable homeChainId;

src/contracts/provers/scroll/ChildToParentProver.sol

@@ -3,7 +3,7 @@ pragma solidity 0.8.30;
 
 import {ProverUtils} from "../../libraries/ProverUtils.sol";
 import {IStateProver} from "../../interfaces/IStateProver.sol";
-import {IBuffer} from "block-hash-pusher/contracts/interfaces/IBuffer.sol";
+import {IBuffer} from "../../block-hash-pusher/interfaces/IBuffer.sol";
 import {SlotDerivation} from "@openzeppelin/contracts/utils/SlotDerivation.sol";
 
 /// @notice Scroll implementation of a child to parent IStateProver.
@@ -15,7 +15,7 @@ contract ChildToParentProver is IStateProver {
     address public immutable blockHashBuffer;
     /// @dev Storage slot the buffer contract uses to store block hashes.
     ///      https://github.com/openintentsframework/broadcaster/blob/main/src/contracts/block-hash-pusher/BaseBuffer.sol
-    uint256 public constant blockHashMappingSlot = 51;
+    uint256 public constant blockHashMappingSlot = 1;
 
     /// @dev The chain ID of the home chain (child chain).
     uint256 public immutable homeChainId;

src/contracts/provers/zksync/ChildToParentProver.sol

@@ -3,7 +3,7 @@ pragma solidity 0.8.30;
 
 import {ProverUtils} from "../../libraries/ProverUtils.sol";
 import {IStateProver} from "../../interfaces/IStateProver.sol";
-import {IBuffer} from "block-hash-pusher/contracts/interfaces/IBuffer.sol";
+import {IBuffer} from "../../block-hash-pusher/interfaces/IBuffer.sol";
 import {SlotDerivation} from "@openzeppelin/contracts/utils/SlotDerivation.sol";
 
 /// @notice ZkSync implementation of a child to parent IStateProver.
@@ -15,7 +15,7 @@ contract ChildToParentProver is IStateProver {
     address public immutable blockHashBuffer;
     /// @dev Storage slot the buffer contract uses to store block hashes.
     ///      See https://github.com/openintentsframework/broadcaster/blob/main/src/contracts/block-hash-pusher/BaseBuffer.sol
-    uint256 public constant blockHashMappingSlot = 51;
+    uint256 public constant blockHashMappingSlot = 1;
 
     /// @dev The chain ID of the home chain (child chain).
     uint256 public immutable homeChainId;

test/Receiver.ethereum.t.sol

@@ -10,7 +10,7 @@ import {IOutbox} from "@arbitrum/nitro-contracts/src/bridge/IOutbox.sol";
 import {IStateProverPointer} from "../src/contracts/interfaces/IStateProverPointer.sol";
 import {STATE_PROVER_POINTER_SLOT} from "../src/contracts/StateProverPointer.sol";
 import {BlockHeaders} from "./utils/BlockHeaders.sol";
-import {IBuffer} from "block-hash-pusher/contracts/interfaces/IBuffer.sol";
+import {IBuffer} from "../src/contracts/block-hash-pusher/interfaces/IBuffer.sol";
 import {BufferMock} from "./mocks/BufferMock.sol";
 
 import {ChildToParentProver as ArbChildToParentProver} from "../src/contracts/provers/arbitrum/ChildToParentProver.sol";

test/Receiver.t.sol

@@ -10,7 +10,7 @@ import {IOutbox} from "@arbitrum/nitro-contracts/src/bridge/IOutbox.sol";
 import {IStateProverPointer} from "../src/contracts/interfaces/IStateProverPointer.sol";
 import {STATE_PROVER_POINTER_SLOT} from "../src/contracts/StateProverPointer.sol";
 import {BlockHeaders} from "./utils/BlockHeaders.sol";
-import {IBuffer} from "block-hash-pusher/contracts/interfaces/IBuffer.sol";
+import {IBuffer} from "../src/contracts/block-hash-pusher/interfaces/IBuffer.sol";
 import {BufferMock} from "./mocks/BufferMock.sol";
 
 import {ChildToParentProver as ArbChildToParentProver} from "../src/contracts/provers/arbitrum/ChildToParentProver.sol";

test/mocks/BufferMock.sol

@@ -1,12 +1,12 @@
 // SPDX-License-Identifier: MIT
 pragma solidity ^0.8.27;
 
-import {IBuffer} from "block-hash-pusher/contracts/interfaces/IBuffer.sol";
+import {IBuffer} from "../../src/contracts/block-hash-pusher/interfaces/IBuffer.sol";
 
 contract BufferMock is IBuffer {
     mapping(uint256 => bytes32) public parentChainBlockHash;
 
-    uint64 public newestBlockNumber;
+    uint256 public newestBlockNumber;
 
     function receiveHashes(uint256 firstBlockNumber, bytes32[] memory blockHashes) external {
         for (uint256 i = 0; i < blockHashes.length; i++) {
@@ -16,30 +16,8 @@ contract BufferMock is IBuffer {
         newestBlockNumber = uint64(firstBlockNumber + blockHashes.length - 1);
     }
 
-    function bufferSize() external view returns (uint256) {
-        return 0;
-    }
-
-    function systemPusher() external view returns (address) {
-        return address(0);
-    }
-
-    /// @dev The aliased address of the pusher contract on the parent chain.
-    function aliasedPusher() external view returns (address) {
+    /// @dev The address of the pusher contract on the parent chain.
+    function pusher() external view returns (address) {
         return address(0);
     }
-
-    function blockHashMapping(uint256) external view returns (bytes32) {
-        return bytes32(0);
-    }
-
-    function blockNumberBuffer(uint256) external view returns (uint256) {
-        return 0;
-    }
-
-    /// @dev Whether the system address has pushed a block hash to the buffer.
-    ///      Once this is set, only the system address can push more hashes.
-    function systemHasPushed() external view returns (bool) {
-        return false;
-    }
 }

test/provers/arbitrum/ChildToParentProver.t.sol

@@ -9,7 +9,7 @@ import {ParentToChildProver} from "../../../src/contracts/provers/arbitrum/Paren
 import {IOutbox} from "@arbitrum/nitro-contracts/src/bridge/IOutbox.sol";
 import {ChildToParentProver} from "../../../src/contracts/provers/arbitrum/ChildToParentProver.sol";
 import {Bytes} from "@openzeppelin/contracts/utils/Bytes.sol";
-import {IBuffer} from "block-hash-pusher/contracts/interfaces/IBuffer.sol";
+import {IBuffer} from "../../../src/contracts/block-hash-pusher/interfaces/IBuffer.sol";
 
 import {RLP} from "@openzeppelin/contracts/utils/RLP.sol";
 import {BlockHeaders} from "../../utils/BlockHeaders.sol";

test/provers/linea/ChildToParentProver.t.sol

@@ -8,7 +8,7 @@ import {IBroadcaster} from "../../../src/contracts/interfaces/IBroadcaster.sol";
 import {IOutbox} from "@arbitrum/nitro-contracts/src/bridge/IOutbox.sol";
 import {ChildToParentProver} from "../../../src/contracts/provers/linea/ChildToParentProver.sol";
 import {Bytes} from "@openzeppelin/contracts/utils/Bytes.sol";
-import {IBuffer} from "block-hash-pusher/contracts/interfaces/IBuffer.sol";
+import {IBuffer} from "../../../src/contracts/block-hash-pusher/interfaces/IBuffer.sol";
 import {BufferMock} from "../../mocks/BufferMock.sol";
 import {RLP} from "@openzeppelin/contracts/utils/RLP.sol";
 import {BlockHeaders} from "../../utils/BlockHeaders.sol";

test/provers/scroll/ChildToParentProver.t.sol

@@ -8,7 +8,7 @@ import {IBroadcaster} from "../../../src/contracts/interfaces/IBroadcaster.sol";
 import {IOutbox} from "@arbitrum/nitro-contracts/src/bridge/IOutbox.sol";
 import {ChildToParentProver} from "../../../src/contracts/provers/scroll/ChildToParentProver.sol";
 import {Bytes} from "@openzeppelin/contracts/utils/Bytes.sol";
-import {IBuffer} from "block-hash-pusher/contracts/interfaces/IBuffer.sol";
+import {IBuffer} from "../../../src/contracts/block-hash-pusher/interfaces/IBuffer.sol";
 import {BufferMock} from "../../mocks/BufferMock.sol";
 import {RLP} from "@openzeppelin/contracts/utils/RLP.sol";
 import {BlockHeaders} from "../../utils/BlockHeaders.sol";

test/provers/zksync/ChildToParentProver.t.sol

@@ -8,7 +8,7 @@ import {IBroadcaster} from "../../../src/contracts/interfaces/IBroadcaster.sol";
 import {IOutbox} from "@arbitrum/nitro-contracts/src/bridge/IOutbox.sol";
 import {ChildToParentProver} from "../../../src/contracts/provers/zksync/ChildToParentProver.sol";
 import {Bytes} from "@openzeppelin/contracts/utils/Bytes.sol";
-import {IBuffer} from "block-hash-pusher/contracts/interfaces/IBuffer.sol";
+import {IBuffer} from "../../../src/contracts/block-hash-pusher/interfaces/IBuffer.sol";
 import {BufferMock} from "../../mocks/BufferMock.sol";
 import {RLP} from "@openzeppelin/contracts/utils/RLP.sol";
 import {BlockHeaders} from "../../utils/BlockHeaders.sol";