Support dynamic CKB fee rate when send CKB transactions.

[yangby-cryptape]

References

• A suboptimal implementation.

  I have been suggestion, that to use the median fee rate which is fetched through the CKB RPC method get_fee_rate_statistics as the dynamic CKB fee rate to send CKB transactions.

  But after few days test, I found some issues of this implementation.

  If someone sent a large-fee transaction, even all blocks are nearly empty, 1000 is enough, the dynamic fee rate API will still return a large number.

  A better solution is required.

[EthanYuan]

• link feat: add estimate_fee_rate rpc nervosnetwork/ckb#4465

[Flouse]

Some thoughts about the implementation of a dynamic fee rate feature for the SPV updater:

Requirements

1. The SPV updater should automatically adjust the fee rate based on current network congestion.
2. Include options for service maintainers to set minimum and maximum fee thresholds.
3. Provide logging for fee adjustments made by the updater.
4. Ensure compatibility with existing transaction processing workflows.

References

• ckb 0.120.0 (29456f5 2024-12-11) introduced an optional fee estimator with multiple algorithms to enhance transaction fee calculations.
  • feat: (experimental) optional fee estimator with different algorithms nervosnetwork/ckb#4477 by @yangby-cryptape