feat: Make next_block_blob_fee functions accept an update fraction parameter

crates/consensus/src/block/header.rs

@@ -4,7 +4,7 @@ use alloy_eips::{
     calc_blob_gasprice,
     eip1559::{calc_next_block_base_fee, BaseFeeParams},
     eip1898::BlockWithParent,
-    eip4844::{self},
+    eip4844::{self, calc_blob_gasprice_with_update_fraction},
     eip7742,
     merge::ALLOWED_FUTURE_BLOCK_TIME_SECONDS,
     BlockNumHash,
@@ -214,10 +214,39 @@ impl Header {
     /// Returns `None` if `excess_blob_gas` is None.
     ///
     /// See also [Self::next_block_excess_blob_gas]
+    #[deprecated(
+        since = "0.8.1",
+        note = "Use `next_block_blob_fee_with_fraction` to account for update fractions"
+    )]
     pub fn next_block_blob_fee(&self) -> Option<u128> {
         Some(eip4844::calc_blob_gasprice(self.next_block_excess_blob_gas()?))
     }
 
+    /// Returns the blob fee for the next block according to the EIP-4844 spec,
+    /// applying the provided update fraction.
+    ///
+    /// # Arguments
+    ///
+    /// - `update_fraction`: Fraction for the fee adjustment calculation (must be between 0.0 and
+    ///   1.0).
+    ///
+    /// # Returns
+    ///
+    /// - `Some(u128)` containing the calculated blob fee if `excess_blob_gas` is `Some`.
+    /// - `None` if `excess_blob_gas` is `None`.
+    ///
+    /// # Panics
+    ///
+    /// - Panics if `update_fraction` is not within the range [0.0, 1.0].
+    pub fn next_block_blob_fee_with_fraction(&self, update_fraction: f64) -> Option<u128> {
+        if !(0.0..=1.0).contains(&update_fraction) {
+            panic!("update_fraction must be between 0.0 and 1.0");
+        }
+
+        let excess_blob_gas = self.next_block_excess_blob_gas()?;
+        Some(calc_blob_gasprice_with_update_fraction(excess_blob_gas, update_fraction))
+    }
+
     /// Calculate base fee for next block according to the EIP-1559 spec.
     ///
     /// Returns a `None` if no base fee is set, no EIP-1559 support
@@ -731,6 +760,17 @@ pub trait BlockHeader {
             txs_and_ommers_empty && withdrawals_root == EMPTY_ROOT_HASH
         })
     }
+
+    /// Returns the blob fee for the next block according to the EIP-4844 spec,
+    /// applying the provided update fraction.
+    fn next_block_blob_fee_with_fraction(&self, update_fraction: f64) -> Option<u128> {
+        if !(0.0..=1.0).contains(&update_fraction) {
+            panic!("update_fraction must be between 0.0 and 1.0");
+        }
+
+        let excess_blob_gas = self.next_block_excess_blob_gas()?;
+        Some(calc_blob_gasprice_with_update_fraction(excess_blob_gas, update_fraction))
+    }
 }
 
 impl BlockHeader for Header {

crates/eips/src/eip4844/mod.rs

@@ -140,7 +140,14 @@ pub fn calc_blob_gasprice(excess_blob_gas: u64) -> u128 {
         BLOB_GASPRICE_UPDATE_FRACTION,
     )
 }
-
+/// Calculate the blob gas price using an update fraction.
+pub fn calc_blob_gasprice_with_update_fraction(excess_blob_gas: u64, update_fraction: f64) -> u128 {
+    fake_exponential(
+        BLOB_TX_MIN_BLOB_GASPRICE,
+        (excess_blob_gas as f64 * update_fraction) as u128,
+        BLOB_GASPRICE_UPDATE_FRACTION,
+    )
+}
 /// Approximates `factor * e ** (numerator / denominator)` using Taylor expansion.
 ///
 /// This is used to calculate the blob price.