跳到主要内容

Nonce Management

在Conflux中，每个账户都有一个nonce值，表示该账户执行的交易序号。 可以使用RPC方法cfx_getNextNonce获取此值。 交易中的nonce字段用于指定执行顺序，较低的nonce值表示较早地执行。 通常情况下，可以直接将这个值作为下一次交易的nonce。

然而，在网络交易量高(拥堵)或需要快速提交交易的情况下，获取nonce值变得更为复杂。 本文将详细解释nonce更新机制以及如何在特殊情况下管理交易的nonce。

Nonce机制​

这里是一些nonce机制的细节:

  1. 在区块链上，交易的执行顺序是按照账户的nonce值从小到大的顺序执行的。
  2. Nonce 的初始值是 0，每执行一次交易，nonce 就增加 1。
  3. Nonce 不能重复使用。
  4. Nonce 不能跳过：假设一个账户的当前 nonce 是 n。 如果交易的nonce值为m，且m > n, 那么该交易不会被执行 直到所有nonce < m的交易都被执行。
  5. 通过cfx_sendRawTransaction 方法发送交易后, 不会立即执行。 你必须等待矿工先打包它。 一旦打包，它将延迟 5 个 epoch 执行。 交易执行后，账户的 nonce 将增加一。

Nonce 使用不当引起的问题​

用户在发送交易时设置 nonce 不正确可能会导致交易失败或在交易池中卡住，无法被打包和执行。 以下是一些常见的错误消息及其相应的解决方案。

由于nonce值过时而被丢弃​

如果新发送的交易的nonce小于账户的当前nonce，则该交易将被拒绝，并返回如下的错误消息：

"\"Transaction 0x0101010110 is discarded due to a too stale nonce\""

此错误表示使用的nonce 值已经过时或已被重新使用，需要更新到最新的nonce值。

交易的nonce与交易池中的交易相同​

如果交易已发送到交易池但尚未执行，再发送具有相同nonce的交易将导致如下错误消息，比如：

"Tx with the same nonce already inserted. To replace it, you need to specify a gas price > {}""

在这种情况下，你应该等待交易池中的交易被执行。 If you want to replace the transaction in the pool, you need to set a higher gas price and resend it.

有时，错误消息也可能是：

"\"tx already exist\""

处理方式与上面相同。

由于nonce值过大而被丢弃​

如果交易的nonce值过大，比用户当前nonce值大2000以上，将返回如下错误消息：

"\"Transaction 0x0101010101010101 is discarded due to in too distant future\""

解决方案: 发送交易时使用正确的nonce值。

除了nonce配置错误导致交易失败外，还会有一些其他情况。 欲了解更多详情，请参阅发送交易错误。

发送交易后无法获取交易收据​

有一种情况是，在发送交易后，在长时间内无法获取交易收据。 这通常是由于交易使用非连续的nonce值导致的。 在这种情况下，交易被卡在交易池内，等待先前交易的执行完成。

For example, if the account's current nonce is 1 and you send a transaction with nonce 5, it will be stuck in the transaction pool, waiting for transactions with nonces 1, 2, 3, and 4 to be sent and executed.

To ensure the execution of this transaction, you need to send transactions with nonces 1, 2, 3, and 4 to the transaction pool. Once these transactions are packaged, the transaction with nonce 5 will automatically be included and executed.

For more information on pending transactions, refer to Transaction Pending.

Rapid Transaction Processing through Manual Nonce Management​

In most situations, transactions are sent sequentially: sending one transaction, waiting for it to be executed, and then sending the next. In such cases, cfx_getNextNonce can be used directly to obtain the nonce for each transaction. However, this method has a slower processing time, typically averaging around 15 seconds per transaction.

For rapid transaction processing, managing nonce values manually is essential. The general steps for this approach are:

  1. Initial Nonce Retrieval: Obtain the current nonce of your account, referred to as nextNonce, before beginning the transaction process.

  2. Transaction Submission: For each transaction:

    • Use nextNonce for the transaction.
    • After transaction is successful sent to RPC nodes, increment nextNonce.
    • Record the hash and nonce of each transaction.

  3. Repeated Execution: Continue step 2 for multiple transactions.

  4. Transaction Monitoring:

    • Use cfx_getTransactionByHash and cfx_getTransactionReceipt for transaction status updates.
    • If a receipt is confirmed, stop monitoring that transaction.
    • If a transaction is dropped or reverted, resend it using the same nonce.
    • For delayed transactions, possibly due to network congestion, consider increasing gasPrice and resending them.

Additional Considerations:

  • Pending Transaction Management: Aim to keep pending transactions in the pool to a manageable number, ideally between 100-200. Exceeding this can complicate handling if transactions are delayed or reverted.

  • Sufficient Funds: Ensure the account has adequate CFX for both the transfer amount and transaction fees to prevent transaction processing delays.

  • Multiple Accounts for Increased Speed (for certain situations): Using several accounts in parellel for transactions can further enhance processing speed.

常见问题解答​

如何获得正确的nonce？​

Through the cfx_getNextNonce RPC, the next available nonce of an account can be obtained. 使用过的 nonce 值不能再次使用。 如果使用一个大于当前 nonce 值的 nonce，交易将无法被打包。

How and When Does the Nonce Value Change in Transactions?​

The nonce value in a transaction increments by 1 upon the transaction's execution, regardless of whether the transaction succeeds or fails. If you query the nonce using cfx_getNextNonce after sending a transaction, it may appear unchanged. This unchanged status occurs because the transaction is either still in the transaction pool pending inclusion in a block, or it has been included in a block but is in a 'defer' state awaiting execution.

Refer to nonce mechanism for more example.

如果您想批量发送交易，如何管理 nonce？​

当批量发送交易时，需要手动管理 nonce 值。 每次发送交易时，需要手动将 nonce 值加一。 在这种情况下，如果有一个交易失败，导致它的 nonce 没有被使用，您需要手动调整交易参数并重新发送该交易。 因此，在批量发送交易时，您需要保留所有交易的哈希值，并监控这些交易的状态。

Why doesn't the account's nonce increase immediately after transaction is packed into a block?​

The account's nonce does not increase immediately after a transaction appears on chain. Instead, the nonce increases after the transaction is packaged and executed.