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在交易执行期间，我们正在计算我们“燃烧了多少气体”和“使用了多少气体”。为什么我们必须单独跟踪这些计数器？

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2 回答 2

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  • 使用的气体包括燃烧的气体，所以gas_used >= gas_burnt，总是；
  • 当收取任何费用时，它同时计入gas_burnt和gas_used;
  • 当合约执行跨合约调用并X在该调用中附加一定量的 gas 时，X计入gas_used但不计入gas_burnt。gas_used这是和之间差异的唯一来源gas_burnt。如果智能合约在完成执行之前失败，则不会执行任何跨合约调用（或由合约创建的交易）并退还附加的 gas；
  • 根据前面的要点，当合约失败时gas_used - gas_burnt会被退还给账户，而gas_burnt会永远丢失（因为gas_burnt对应于实际花费验证者一些计算工作的费用）。
于 2019-12-02T20:40:45.300 回答
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在写这个答案时，@MaksymZavershynskyi 也回答了。

他的回答应该被认为是权威的，而我的回答是一个猜测。

看看源代码让我觉得

  • gas_used是生产性存储和计算的成本（完成不会失败的工作）
  • gas_burnt是非生产性传输、存储和计算的成本（从 A 点到 B 点获取数据，尝试执行功能但在执行过程中失败或导致错误等）

这是一堆带有源代码链接的片段，给我留下了这样的印象

从nearcore/runtime/runtime/src/lib.rs

fn generate_refund_receipts(
    &self,
    receipt: &Receipt,
    action_receipt: &ActionReceipt,
    result: &mut ActionResult,
) -> Result<(), RuntimeError> {
    /// ... snip ...
    let gas_refund = if result.result.is_err() {
        safe_add_gas(prepaid_gas, exec_gas)? - result.gas_burnt
    } else {
        safe_add_gas(prepaid_gas, exec_gas)? - result.gas_used
    };
    /// ... snip ...
}

资源

从nearcore/runtime/runtime/src/actions.rs

pub(crate) fn action_function_call(
    state_update: &mut TrieUpdate,
    apply_state: &ApplyState,
    account: &mut Option<Account>,
    receipt: &Receipt,
    action_receipt: &ActionReceipt,
    promise_results: &[PromiseResult],
    result: &mut ActionResult,
    account_id: &AccountId,
    function_call: &FunctionCallAction,
    action_hash: &CryptoHash,
    config: &RuntimeConfig,
    is_last_action: bool,
) -> Result<(), StorageError> {
    /// ... snip ...
    if let Some(outcome) = outcome {
        result.gas_burnt += outcome.burnt_gas;
        result.gas_burnt_for_function_call += outcome.burnt_gas;
        // Runtime in `generate_refund_receipts` takes care of using proper value for refunds.
        // It uses `gas_used` for success and `gas_burnt` for failures. So it's not an issue to
        // return a real `gas_used` instead of the `gas_burnt` into `ActionResult` for
        // `FunctionCall`s.
        result.gas_used += outcome.used_gas;
        result.logs.extend(outcome.logs.into_iter());
    }
    /// ... snip ...
}

资源

从nearcore/core/primitives/src/types.rs

pub struct ChunkExtra {
  /// ... snip ...

  /// Actually how much gas were used.
  pub gas_used: Gas

/// ... snip ...
}

资源

从nearcore/core/primitives/src/sharding.rs

pub struct ShardChunkHeaderInner {
  /// ... snip ...

  /// Gas used in this chunk.
  pub gas_used: Gas,

  /// ... snip ...
}

资源

从nearcore/runtime/runtime/src/config.rs

/// ... snip ...

pub fn tx_cost(
    config: &RuntimeFeesConfig,
    transaction: &Transaction,
    gas_price: Balance,
    sender_is_receiver: bool,
) -> Result<(Gas, Gas, Balance), IntegerOverflowError> {
    let mut gas_burnt: Gas = config.action_receipt_creation_config.send_fee(sender_is_receiver);
    gas_burnt = safe_add_gas(
        gas_burnt,
        total_send_fees(&config, sender_is_receiver, &transaction.actions)?,
    )?;
    let mut gas_used = safe_add_gas(gas_burnt, config.action_receipt_creation_config.exec_fee())?;
    gas_used = safe_add_gas(gas_used, total_exec_fees(&config, &transaction.actions)?)?;
    gas_used = safe_add_gas(gas_used, total_prepaid_gas(&transaction.actions)?)?;
    let mut total_cost = safe_gas_to_balance(gas_price, gas_used)?;
    total_cost = safe_add_balance(total_cost, total_deposit(&transaction.actions)?)?;
    Ok((gas_burnt, gas_used, total_cost))
}
/// ... snip ...


/// Total sum of gas that would need to be burnt before we start executing the given actions.
pub fn total_exec_fees(
    config: &RuntimeFeesConfig,
    actions: &[Action],
) -> Result<Gas, IntegerOverflowError> {
  /// ... snip ...
}

/// Get the total sum of deposits for given actions.
pub fn total_deposit(
    actions: &[Action]
) -> Result<Balance, IntegerOverflowError> {
  /// ... snip ...
}

/// Get the total sum of prepaid gas for given actions.
pub fn total_prepaid_gas(
    actions: &[Action]
) -> Result<Gas, IntegerOverflowError> {
  /// ... snip ...
}

资源

于 2019-12-02T20:49:50.757 回答