feat: support dynamic CKB fee rate

src/cli/deploy.rs

@@ -74,7 +74,7 @@ impl Args {
             NetworkInfo::new(self.ckb.network, self.ckb.ckb_endpoint.as_str().to_owned());
         let configuration = {
             let mut tmp = TransactionBuilderConfiguration::new_with_network(network_info.clone())?;
-            tmp.fee_rate = self.ckb.fee_rate;
+            tmp.fee_rate = self.ckb.fee_rate()?;
             tmp
         };
 

src/cli/init.rs

@@ -134,7 +134,7 @@ impl Args {
             NetworkInfo::new(self.ckb.network, self.ckb.ckb_endpoint.as_str().to_owned());
         let configuration = {
             let mut tmp = TransactionBuilderConfiguration::new_with_network(network_info.clone())?;
-            tmp.fee_rate = self.ckb.fee_rate;
+            tmp.fee_rate = self.ckb.fee_rate()?;
             tmp
         };
 

src/cli/mod.rs

@@ -1,12 +1,14 @@
 //! The command line argument.
 
 use ckb_sdk::{rpc::CkbRpcClient, types::NetworkType};
-use clap::{Parser, Subcommand};
+use ckb_types::core::FeeRate;
+use clap::{Args, Parser, Subcommand};
 use clap_verbosity_flag::{InfoLevel, Verbosity};
 use url::Url;
 
 use crate::{
     components::BitcoinClient,
+    prelude::*,
     result::Result,
     utilities::{value_parsers, Key256Bits},
 };
@@ -66,11 +68,10 @@ pub struct CkbArgs {
         value_parser = value_parsers::NetworkTypeValueParser,
         default_value = "testnet"
     )]
-    pub network: NetworkType,
+    pub(crate) network: NetworkType,
 
-    /// The fee rate for CKB transactions.
-    #[arg(long = "ckb-fee-rate", default_value = "1000")]
-    pub(crate) fee_rate: u64,
+    #[command(flatten)]
+    pub(crate) fee_rate: FeeRateArgs,
 
     /// A binary file, which contains a secp256k1 private key.
     /// This private key will be used to provide all CKBytes.
@@ -92,7 +93,39 @@ pub struct CkbRoArgs {
         value_parser = value_parsers::NetworkTypeValueParser,
         default_value = "testnet"
     )]
-    pub network: NetworkType,
+    pub(crate) network: NetworkType,
+}
+
+#[derive(Args)]
+#[group(multiple = false)]
+pub struct FeeRateArgs {
+    /// The fixed fee rate for CKB transactions.
+    #[arg(
+        group = "fixed-fee-rate",
+        conflicts_with = "dynamic-fee-rate",
+        long = "ckb-fee-rate",
+        default_value = "1000"
+    )]
+    fixed_value: u64,
+
+    /// [Experimental] Enable dynamic fee rate for CKB transactions.
+    ///
+    /// The actual fee rate will be the `median` fee rate which is fetched through the CKB RPC method `get_fee_rate_statistics`.
+    ///
+    /// For security, a hard limit is required.
+    /// When the returned dynamic fee rate is larger than the hard limit, the hard limit will be used.
+    ///
+    /// ### Warning
+    ///
+    /// Users have to make sure the remote CKB node they used are trustsed.
+    ///
+    /// Ref: <https://github.com/nervosnetwork/ckb/tree/v0.114.0/rpc#method-get_fee_rate_statistics>
+    #[arg(
+        group = "dynamic-fee-rate",
+        conflicts_with = "fixed-fee-rate",
+        long = "enable-dynamic-ckb-fee-rate-with-limit"
+    )]
+    limit_for_dynamic: Option<u64>,
 }
 
 #[derive(Parser)]
@@ -160,6 +193,29 @@ impl CkbArgs {
     pub fn client(&self) -> CkbRpcClient {
         CkbRpcClient::new(self.ckb_endpoint.as_str())
     }
+
+    pub fn fee_rate(&self) -> Result<u64> {
+        let value = if let Some(limit) = self.fee_rate.limit_for_dynamic {
+            let dynamic = self.client().dynamic_fee_rate()?;
+            log::info!("CKB fee rate: {} (dynamic)", FeeRate(dynamic));
+            if dynamic > limit {
+                log::warn!(
+                    "dynamic CKB fee rate {} is too large, it seems unreasonable;\
+                    so the upper limit {} will be used",
+                    FeeRate(dynamic),
+                    FeeRate(limit)
+                );
+                limit
+            } else {
+                dynamic
+            }
+        } else {
+            let fixed = self.fee_rate.fixed_value;
+            log::info!("CKB fee rate: {} (fixed)", FeeRate(fixed));
+            fixed
+        };
+        Ok(value)
+    }
 }
 
 impl CkbRoArgs {

src/cli/serve.rs

@@ -185,7 +185,7 @@ impl Args {
             NetworkInfo::new(self.ckb.network, self.ckb.ckb_endpoint.as_str().to_owned());
         let configuration = {
             let mut tmp = TransactionBuilderConfiguration::new_with_network(network_info.clone())?;
-            tmp.fee_rate = self.ckb.fee_rate;
+            tmp.fee_rate = self.ckb.fee_rate()?;
             tmp
         };
 
@@ -357,7 +357,7 @@ impl Args {
             NetworkInfo::new(self.ckb.network, self.ckb.ckb_endpoint.as_str().to_owned());
         let configuration = {
             let mut tmp = TransactionBuilderConfiguration::new_with_network(network_info.clone())?;
-            tmp.fee_rate = self.ckb.fee_rate;
+            tmp.fee_rate = self.ckb.fee_rate()?;
             tmp
         };
 

src/components/ckb_client.rs

@@ -62,6 +62,7 @@ impl SpvInfoCell {
 }
 
 pub trait CkbRpcClientExtension {
+    fn dynamic_fee_rate(&self) -> Result<u64>;
     fn send_transaction_ext(&self, tx_json: TransactionView, dry_run: bool) -> Result<H256>;
     fn find_raw_spv_cells(&self, spv_type_script: Script) -> Result<Vec<LiveCell>>;
 
@@ -109,6 +110,17 @@ pub trait CkbRpcClientExtension {
 }
 
 impl CkbRpcClientExtension for CkbRpcClient {
+    fn dynamic_fee_rate(&self) -> Result<u64> {
+        self.get_fee_rate_statistics(None)?
+            .ok_or_else(|| {
+                let msg = "remote server replied null for \
+                    RPC method get_fee_rate_statistics(null)";
+                Error::other(msg)
+            })
+            .map(|resp| resp.median)
+            .map(Into::into)
+    }
+
     fn send_transaction_ext(&self, tx_json: TransactionView, dry_run: bool) -> Result<H256> {
         if log::log_enabled!(log::Level::Trace) {
             match serde_json::to_string_pretty(&tx_json) {
@@ -147,6 +159,8 @@ impl CkbRpcClientExtension for CkbRpcClient {
             })?
             .unpack();
 
+        log::trace!("the type script of SPV cell is {spv_type_script}");
+
         let query = CellQueryOptions::new(spv_type_script, PrimaryScriptType::Type);
         let order = Order::Desc;
         let search_key = SearchKey::from(query);