@hyperlane-xyz/core/dependencies/@eth-optimism-contracts-0.6.0/packages/contracts/docs/CanonicalTransactionChain.md

Core solidity contracts for Hyperlane

# CanonicalTransactionChain



> CanonicalTransactionChain



*The Canonical Transaction Chain (CTC) contract is an append-only log of transactions which must be applied to the rollup state. It defines the ordering of rollup transactions by writing them to the 'CTC:batches' instance of the Chain Storage Container. The CTC also allows any account to 'enqueue' an L2 transaction, which will require that the Sequencer will eventually append it to the rollup state.*

## Methods

### MAX_ROLLUP_TX_SIZE

```solidity
function MAX_ROLLUP_TX_SIZE() external view returns (uint256)
```






#### Returns

| Name | Type | Description |
|---|---|---|
| _0 | uint256 | undefined

### MIN_ROLLUP_TX_GAS

```solidity
function MIN_ROLLUP_TX_GAS() external view returns (uint256)
```






#### Returns

| Name | Type | Description |
|---|---|---|
| _0 | uint256 | undefined

### appendSequencerBatch

```solidity
function appendSequencerBatch() external nonpayable
```

Allows the sequencer to append a batch of transactions.

*This function uses a custom encoding scheme for efficiency reasons. .param _shouldStartAtElement Specific batch we expect to start appending to. .param _totalElementsToAppend Total number of batch elements we expect to append. .param _contexts Array of batch contexts. .param _transactionDataFields Array of raw transaction data.*


### batches

```solidity
function batches() external view returns (contract IChainStorageContainer)
```

Accesses the batch storage container.




#### Returns

| Name | Type | Description |
|---|---|---|
| _0 | contract IChainStorageContainer | Reference to the batch storage container.

### enqueue

```solidity
function enqueue(address _target, uint256 _gasLimit, bytes _data) external nonpayable
```

Adds a transaction to the queue.



#### Parameters

| Name | Type | Description |
|---|---|---|
| _target | address | Target L2 contract to send the transaction to.
| _gasLimit | uint256 | Gas limit for the enqueued L2 transaction.
| _data | bytes | Transaction data.

### enqueueGasCost

```solidity
function enqueueGasCost() external view returns (uint256)
```






#### Returns

| Name | Type | Description |
|---|---|---|
| _0 | uint256 | undefined

### enqueueL2GasPrepaid

```solidity
function enqueueL2GasPrepaid() external view returns (uint256)
```






#### Returns

| Name | Type | Description |
|---|---|---|
| _0 | uint256 | undefined

### getLastBlockNumber

```solidity
function getLastBlockNumber() external view returns (uint40)
```

Returns the blocknumber of the last transaction.




#### Returns

| Name | Type | Description |
|---|---|---|
| _0 | uint40 | Blocknumber for the last transaction.

### getLastTimestamp

```solidity
function getLastTimestamp() external view returns (uint40)
```

Returns the timestamp of the last transaction.




#### Returns

| Name | Type | Description |
|---|---|---|
| _0 | uint40 | Timestamp for the last transaction.

### getNextQueueIndex

```solidity
function getNextQueueIndex() external view returns (uint40)
```

Returns the index of the next element to be enqueued.




#### Returns

| Name | Type | Description |
|---|---|---|
| _0 | uint40 | Index for the next queue element.

### getNumPendingQueueElements

```solidity
function getNumPendingQueueElements() external view returns (uint40)
```

Get the number of queue elements which have not yet been included.




#### Returns

| Name | Type | Description |
|---|---|---|
| _0 | uint40 | Number of pending queue elements.

### getQueueElement

```solidity
function getQueueElement(uint256 _index) external view returns (struct Lib_OVMCodec.QueueElement _element)
```

Gets the queue element at a particular index.



#### Parameters

| Name | Type | Description |
|---|---|---|
| _index | uint256 | Index of the queue element to access.

#### Returns

| Name | Type | Description |
|---|---|---|
| _element | Lib_OVMCodec.QueueElement | Queue element at the given index.

### getQueueLength

```solidity
function getQueueLength() external view returns (uint40)
```

Retrieves the length of the queue, including both pending and canonical transactions.




#### Returns

| Name | Type | Description |
|---|---|---|
| _0 | uint40 | Length of the queue.

### getTotalBatches

```solidity
function getTotalBatches() external view returns (uint256 _totalBatches)
```

Retrieves the total number of batches submitted.




#### Returns

| Name | Type | Description |
|---|---|---|
| _totalBatches | uint256 | Total submitted batches.

### getTotalElements

```solidity
function getTotalElements() external view returns (uint256 _totalElements)
```

Retrieves the total number of elements submitted.




#### Returns

| Name | Type | Description |
|---|---|---|
| _totalElements | uint256 | Total submitted elements.

### l2GasDiscountDivisor

```solidity
function l2GasDiscountDivisor() external view returns (uint256)
```






#### Returns

| Name | Type | Description |
|---|---|---|
| _0 | uint256 | undefined

### libAddressManager

```solidity
function libAddressManager() external view returns (contract Lib_AddressManager)
```






#### Returns

| Name | Type | Description |
|---|---|---|
| _0 | contract Lib_AddressManager | undefined

### maxTransactionGasLimit

```solidity
function maxTransactionGasLimit() external view returns (uint256)
```






#### Returns

| Name | Type | Description |
|---|---|---|
| _0 | uint256 | undefined

### resolve

```solidity
function resolve(string _name) external view returns (address)
```

Resolves the address associated with a given name.



#### Parameters

| Name | Type | Description |
|---|---|---|
| _name | string | Name to resolve an address for.

#### Returns

| Name | Type | Description |
|---|---|---|
| _0 | address | Address associated with the given name.

### setGasParams

```solidity
function setGasParams(uint256 _l2GasDiscountDivisor, uint256 _enqueueGasCost) external nonpayable
```

Allows the Burn Admin to update the parameters which determine the amount of gas to burn. The value of enqueueL2GasPrepaid is immediately updated as well.



#### Parameters

| Name | Type | Description |
|---|---|---|
| _l2GasDiscountDivisor | uint256 | The ratio of the cost of L1 gas to the cost of L2 gas
| _enqueueGasCost | uint256 | The approximate cost of calling the enqueue function



## Events

### L2GasParamsUpdated

```solidity
event L2GasParamsUpdated(uint256 l2GasDiscountDivisor, uint256 enqueueGasCost, uint256 enqueueL2GasPrepaid)
```





#### Parameters

| Name | Type | Description |
|---|---|---|
| l2GasDiscountDivisor  | uint256 | undefined |
| enqueueGasCost  | uint256 | undefined |
| enqueueL2GasPrepaid  | uint256 | undefined |

### QueueBatchAppended

```solidity
event QueueBatchAppended(uint256 _startingQueueIndex, uint256 _numQueueElements, uint256 _totalElements)
```





#### Parameters

| Name | Type | Description |
|---|---|---|
| _startingQueueIndex  | uint256 | undefined |
| _numQueueElements  | uint256 | undefined |
| _totalElements  | uint256 | undefined |

### SequencerBatchAppended

```solidity
event SequencerBatchAppended(uint256 _startingQueueIndex, uint256 _numQueueElements, uint256 _totalElements)
```





#### Parameters

| Name | Type | Description |
|---|---|---|
| _startingQueueIndex  | uint256 | undefined |
| _numQueueElements  | uint256 | undefined |
| _totalElements  | uint256 | undefined |

### TransactionBatchAppended

```solidity
event TransactionBatchAppended(uint256 indexed _batchIndex, bytes32 _batchRoot, uint256 _batchSize, uint256 _prevTotalElements, bytes _extraData)
```





#### Parameters

| Name | Type | Description |
|---|---|---|
| _batchIndex `indexed` | uint256 | undefined |
| _batchRoot  | bytes32 | undefined |
| _batchSize  | uint256 | undefined |
| _prevTotalElements  | uint256 | undefined |
| _extraData  | bytes | undefined |

### TransactionEnqueued

```solidity
event TransactionEnqueued(address indexed _l1TxOrigin, address indexed _target, uint256 _gasLimit, bytes _data, uint256 indexed _queueIndex, uint256 _timestamp)
```





#### Parameters

| Name | Type | Description |
|---|---|---|
| _l1TxOrigin `indexed` | address | undefined |
| _target `indexed` | address | undefined |
| _gasLimit  | uint256 | undefined |
| _data  | bytes | undefined |
| _queueIndex `indexed` | uint256 | undefined |
| _timestamp  | uint256 | undefined |