Refactors is_masp_new_epoch

crates/core/src/masp.rs

@@ -80,6 +80,17 @@ impl MaspEpoch {
         Some(Self(self.0.checked_sub(1)?))
     }
 
+    /// Check if the given epoch is also a new masp epoch based on the
+    /// multiplier provided
+    pub fn is_masp_new_epoch(epoch: Epoch, masp_epoch_multiplier: u64) -> bool {
+        matches!(
+            Self::from_epoch(epoch, masp_epoch_multiplier)
+                .0
+                .checked_rem(masp_epoch_multiplier),
+            Some(Epoch(0))
+        )
+    }
+
     /// Initialize a new masp epoch from the provided one
     #[cfg(any(test, feature = "testing"))]
     pub fn new(epoch: u64) -> Self {

crates/namada/src/ledger/native_vp/masp.rs

@@ -355,7 +355,7 @@ where
             )?
             .ok_or_else(|| {
                 Error::NativeVpError(native_vp::Error::SimpleMessage(
-                    "Could not deserialize masp epoch multiplier",
+                    "Missing expected masp epoch multiplier parameter",
                 ))
             })?;
         let masp_epoch = MaspEpoch::from_epoch(

crates/node/src/shell/finalize_block.rs

@@ -67,7 +67,7 @@ where
 
         // Begin the new block and check if a new epoch has begun
         let (height, new_epoch) = self.update_state(req.header);
-        let is_masp_new_epoch = self.state.is_masp_new_epoch(new_epoch);
+        let is_masp_new_epoch = self.state.is_masp_new_epoch(new_epoch)?;
 
         let (current_epoch, _gas) = self.state.in_mem().get_current_epoch();
         let update_for_tendermint = matches!(

crates/sdk/src/queries/shell.rs

@@ -339,7 +339,7 @@ where
         )?
         .ok_or_else(|| {
             namada_storage::Error::new_const(
-                "Could not deserialize masp epoch multiplier",
+                "Missing expected masp epoch multiplier parameter",
             )
         })?;
     Ok(MaspEpoch::from_epoch(epoch, masp_epoch_multiplier))

crates/state/src/wl_state.rs

@@ -5,6 +5,7 @@ use namada_core::address::Address;
 use namada_core::arith::checked;
 use namada_core::borsh::BorshSerializeExt;
 use namada_core::chain::ChainId;
+use namada_core::masp::MaspEpoch;
 use namada_core::storage;
 use namada_core::time::DateTimeUtc;
 use namada_events::{EmitEvents, EventToEmit};
@@ -190,23 +191,31 @@ where
     }
 
     /// Returns `true` if a new masp epoch has begun
-    pub fn is_masp_new_epoch(&self, is_new_epoch: bool) -> bool {
-        // FIXME: read from protocol param
-        // FIXME: need a function to convert from epoch to masp epoch?
+    pub fn is_masp_new_epoch(&self, is_new_epoch: bool) -> StorageResult<bool> {
+        let masp_epoch_multiplier = self
+            .read::<u64>(
+                &namada_parameters::storage::get_masp_epoch_multiplier_key(),
+            )?
+            .ok_or_else(|| {
+                namada_storage::Error::new_const(
+                    "Missing expected masp epoch multiplier parameter",
+                )
+            })?;
         let masp_new_epoch = is_new_epoch
-            && checked!(u64::from(self.in_mem.block.epoch) % 4)
-                .expect("Masp epoch multiplier cannot be 0")
-                == 0;
+            && MaspEpoch::is_masp_new_epoch(
+                self.in_mem.block.epoch,
+                masp_epoch_multiplier,
+            );
 
         if masp_new_epoch {
-            tracing::info!(
-                "Began a new masp epoch {}",
-                checked!(u64::from(self.in_mem.block.epoch) / 4)
-                    .expect("Masp epoch multiplier cannot be 0")
+            let masp_epoch = MaspEpoch::from_epoch(
+                self.in_mem.block.epoch,
+                masp_epoch_multiplier,
             );
+            tracing::info!("Began a new masp epoch {masp_epoch}");
         }
 
-        masp_new_epoch
+        Ok(masp_new_epoch)
     }
 
     /// Commit the current block's write log to the storage and commit the block