diff --git a/.changeset/quiet-seals-destroy.md b/.changeset/quiet-seals-destroy.md
new file mode 100644
index 0000000000000000000000000000000000000000..feb236197121895bfa5f509359a478060f46808c
--- /dev/null
+++ b/.changeset/quiet-seals-destroy.md
@@ -0,0 +1,5 @@
+---
+'@eth-optimism/contracts': minor
+---
+
+Reduce CTC gas costs by storing only a blockhash.
diff --git a/packages/contracts/contracts/L1/rollup/CanonicalTransactionChain.sol b/packages/contracts/contracts/L1/rollup/CanonicalTransactionChain.sol
index 68aa91a7b19608a969e8199e7ce433e4a556ddf7..83f89f01cab4504683231c7ffa4dbbbf47668831 100644
--- a/packages/contracts/contracts/L1/rollup/CanonicalTransactionChain.sol
+++ b/packages/contracts/contracts/L1/rollup/CanonicalTransactionChain.sol
@@ -358,9 +358,6 @@ contract CanonicalTransactionChain is ICanonicalTransactionChain, Lib_AddressRes
IChainStorageContainer queueRef = queue();
uint40 queueLength = _getQueueLength(queueRef);
- // Each leaf index corresponds to a tx, either sequenced or enqueued.
- uint32 leafIndex = 0;
-
// Counter for number of sequencer transactions appended so far.
uint32 numSequencerTransactions = 0;
@@ -380,7 +377,12 @@ contract CanonicalTransactionChain is ICanonicalTransactionChain, Lib_AddressRes
// Now process any subsequent queue transactions.
nextQueueIndex += uint40(curContext.numSubsequentQueueTransactions);
+
}
+ require(
+ nextQueueIndex <= queueLength,
+ "Attempted to append more elements than are available in the queue."
+ );
// Generate the required metadata that we need to append this batch
uint40 numQueuedTransactions = totalElementsToAppend - numSequencerTransactions;
@@ -590,96 +592,6 @@ contract CanonicalTransactionChain is ICanonicalTransactionChain, Lib_AddressRes
return uint40(_queueRef.length() / 2);
}
- /**
- * Retrieves the hash of a sequencer element.
- * @param _context Batch context for the given element.
- * @param _nextTransactionPtr Pointer to the next transaction in the calldata.
- * @param _txDataLength Length of the transaction item.
- * @return Hash of the sequencer element.
- */
- function _getSequencerLeafHash(
- BatchContext memory _context,
- uint256 _nextTransactionPtr,
- uint256 _txDataLength,
- bytes memory _hashMemory
- )
- internal
- pure
- returns (
- bytes32
- )
- {
- // Only allocate more memory if we didn't reserve enough to begin with.
- if (BYTES_TILL_TX_DATA + _txDataLength > _hashMemory.length) {
- _hashMemory = new bytes(BYTES_TILL_TX_DATA + _txDataLength);
- }
-
- uint256 ctxTimestamp = _context.timestamp;
- uint256 ctxBlockNumber = _context.blockNumber;
-
- bytes32 leafHash;
- assembly {
- let chainElementStart := add(_hashMemory, 0x20)
-
- // Set the first byte equal to `1` to indicate this is a sequencer chain element.
- // This distinguishes sequencer ChainElements from queue ChainElements because
- // all queue ChainElements are ABI encoded and the first byte of ABI encoded
- // elements is always zero
- mstore8(chainElementStart, 1)
-
- mstore(add(chainElementStart, 1), ctxTimestamp)
- mstore(add(chainElementStart, 33), ctxBlockNumber)
- // solhint-disable-next-line max-line-length
- calldatacopy(add(chainElementStart, BYTES_TILL_TX_DATA), add(_nextTransactionPtr, 3), _txDataLength)
-
- leafHash := keccak256(chainElementStart, add(BYTES_TILL_TX_DATA, _txDataLength))
- }
-
- return leafHash;
- }
-
- /**
- * Retrieves the hash of a sequencer element.
- * @param _txChainElement The chain element which is hashed to calculate the leaf.
- * @return Hash of the sequencer element.
- */
- function _getSequencerLeafHash(
- Lib_OVMCodec.TransactionChainElement memory _txChainElement
- )
- internal
- view
- returns(
- bytes32
- )
- {
- bytes memory txData = _txChainElement.txData;
- uint256 txDataLength = _txChainElement.txData.length;
-
- bytes memory chainElement = new bytes(BYTES_TILL_TX_DATA + txDataLength);
- uint256 ctxTimestamp = _txChainElement.timestamp;
- uint256 ctxBlockNumber = _txChainElement.blockNumber;
-
- bytes32 leafHash;
- assembly {
- let chainElementStart := add(chainElement, 0x20)
-
- // Set the first byte equal to `1` to indicate this is a sequencer chain element.
- // This distinguishes sequencer ChainElements from queue ChainElements because
- // all queue ChainElements are ABI encoded and the first byte of ABI encoded
- // elements is always zero
- mstore8(chainElementStart, 1)
-
- mstore(add(chainElementStart, 1), ctxTimestamp)
- mstore(add(chainElementStart, 33), ctxBlockNumber)
- // solhint-disable-next-line max-line-length
- pop(staticcall(gas(), 0x04, add(txData, 0x20), txDataLength, add(chainElementStart, BYTES_TILL_TX_DATA), txDataLength))
-
- leafHash := keccak256(chainElementStart, add(BYTES_TILL_TX_DATA, txDataLength))
- }
-
- return leafHash;
- }
-
/**
* Inserts a batch into the chain of batches.
* @param _transactionRoot Root of the transaction tree for this batch.
diff --git a/packages/contracts/test/contracts/L1/rollup/CanonicalTransactionChain.spec.ts b/packages/contracts/test/contracts/L1/rollup/CanonicalTransactionChain.spec.ts
index 1ca440070ce702c3304c9594b4f17d7c04aacb0b..7dcae164275e37bae085803a7d661eb4e22a5a4f 100644
--- a/packages/contracts/test/contracts/L1/rollup/CanonicalTransactionChain.spec.ts
+++ b/packages/contracts/test/contracts/L1/rollup/CanonicalTransactionChain.spec.ts
@@ -420,6 +420,26 @@ describe('CanonicalTransactionChain', () => {
)
})
+ it('should revert if attempting to append more elements than are available in the queue.', async () => {
+ await expect(
+ appendSequencerBatch(CanonicalTransactionChain, {
+ transactions: ['0x1234'],
+ contexts: [
+ {
+ numSequencedTransactions: 1,
+ numSubsequentQueueTransactions: 1,
+ timestamp: 0,
+ blockNumber: 0,
+ },
+ ],
+ shouldStartAtElement: 0,
+ totalElementsToAppend: 2,
+ })
+ ).to.be.revertedWith(
+ 'Attempted to append more elements than are available in the queue.'
+ )
+ })
+
it('should revert if not called by the sequencer', async () => {
await expect(
appendSequencerBatch(CanonicalTransactionChain.connect(signer), {