fix(cardano-blockchain-types): Fork type

Signed-off-by: bkioshn <[email protected]>

Author: bkioshn

rust/cardano-blockchain-types/src/fork.rs

@@ -0,0 +1,41 @@
+//! Fork count is a counter that is incremented every time there is a roll-back in
+//! live-chain It is used to help followers determine how far to roll-back to
+//! resynchronize without storing full block history. The fork count starts at 1 for live
+//! blocks and increments if the live chain tip is purged due to a detected fork, but it
+//! does not track the exact number of forks reported by peers.
+//!
+//! Note: This fork terminology is different from fork in blockchain.
+
+use crate::conversion::from_saturating;
+
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
+/// Counter that is incremented every time there is a roll-back in live-chain
+pub struct Fork(u64);
+
+impl Fork {
+    /// Convert an `<T>` to Fork. (saturate if out of range.)
+    pub fn from_saturating<
+        T: Copy
+            + TryInto<u64>
+            + std::ops::Sub<Output = T>
+            + std::cmp::PartialOrd<T>
+            + num_traits::identities::Zero,
+    >(
+        value: T,
+    ) -> Self {
+        let value: u64 = from_saturating(value);
+        Self(value)
+    }
+}
+
+impl From<u64> for Fork {
+    fn from(value: u64) -> Self {
+        Self(value)
+    }
+}
+
+impl From<Fork> for u64 {
+    fn from(val: Fork) -> Self {
+        val.0
+    }
+}

rust/cardano-blockchain-types/src/lib.rs

@@ -2,6 +2,7 @@
 
 mod auxdata;
 pub mod conversion;
+mod fork;
 pub mod hashes;
 mod multi_era_block_data;
 mod network;

rust/cardano-blockchain-types/src/multi_era_block_data.rs

@@ -18,6 +18,7 @@ use crate::{
     auxdata::{
         block::BlockAuxData, metadatum_label::MetadatumLabel, metadatum_value::MetadatumValue,
     },
+    fork::Fork,
     network::Network,
     point::Point,
     txn_index::TxnIndex,
@@ -80,7 +81,7 @@ pub struct MultiEraBlock {
     /// It starts at 1 for live blocks, and is only incremented if the live-chain tip is
     /// purged because of a detected fork based on data received from the peer node.
     /// It does NOT count the strict number of forks reported by the peer node.
-    fork: u64,
+    fork: Fork,
     /// The Immutable decoded data about the block itself.
     inner: Arc<MultiEraBlockInner>,
 }
@@ -92,7 +93,7 @@ impl MultiEraBlock {
     ///
     /// If the given bytes cannot be decoded as a multi-era block, an error is returned.
     fn new_block(
-        chain: Network, raw_data: Vec<u8>, previous: &Point, fork: u64,
+        chain: Network, raw_data: Vec<u8>, previous: &Point, fork: Fork,
     ) -> anyhow::Result<Self> {
         let builder = SelfReferencedMultiEraBlockTryBuilder {
             raw_data,
@@ -155,13 +156,13 @@ impl MultiEraBlock {
     ///
     /// If the given bytes cannot be decoded as a multi-era block, an error is returned.
     pub fn new(
-        chain: Network, raw_data: Vec<u8>, previous: &Point, fork: u64,
+        chain: Network, raw_data: Vec<u8>, previous: &Point, fork: Fork,
     ) -> anyhow::Result<Self> {
         MultiEraBlock::new_block(chain, raw_data, previous, fork)
     }
 
     /// Remake the block on a new fork.
-    pub fn set_fork(&mut self, fork: u64) {
+    pub fn set_fork(&mut self, fork: Fork) {
         self.fork = fork;
     }
 
@@ -212,7 +213,7 @@ impl MultiEraBlock {
     /// `true` if the block is immutable, `false` otherwise.
     #[must_use]
     pub fn immutable(&self) -> bool {
-        self.fork == 0
+        self.fork == 0.into()
     }
 
     /// What fork is the block from.
@@ -226,7 +227,7 @@ impl MultiEraBlock {
     /// # Returns
     /// The fork the block was found on.
     #[must_use]
-    pub fn fork(&self) -> u64 {
+    pub fn fork(&self) -> Fork {
         self.fork
     }
 
@@ -288,7 +289,7 @@ impl Display for MultiEraBlock {
         let fork = if self.immutable() {
             "Immutable".to_string()
         } else {
-            format!("Fork: {fork}")
+            format!("Fork: {fork:?}")
         };
 
         let block_era = match block {
@@ -452,8 +453,12 @@ pub(crate) mod tests {
                     .into(),
             );
 
-            let block =
-                MultiEraBlock::new(Network::Preprod, test_block.raw.clone(), &previous_point, 1);
+            let block = MultiEraBlock::new(
+                Network::Preprod,
+                test_block.raw.clone(),
+                &previous_point,
+                1.into(),
+            );
 
             assert!(block.is_err());
         }
@@ -471,8 +476,12 @@ pub(crate) mod tests {
             let previous_point =
                 Point::new((pallas_block.slot() - 1).into(), vec![0; 32].try_into()?);
 
-            let block =
-                MultiEraBlock::new(Network::Preprod, test_block.raw.clone(), &previous_point, 1);
+            let block = MultiEraBlock::new(
+                Network::Preprod,
+                test_block.raw.clone(),
+                &previous_point,
+                1.into(),
+            );
 
             assert!(block.is_err());
         }
@@ -496,8 +505,12 @@ pub(crate) mod tests {
                     .into(),
             );
 
-            let block =
-                MultiEraBlock::new(Network::Preprod, test_block.raw.clone(), &previous_point, 1)?;
+            let block = MultiEraBlock::new(
+                Network::Preprod,
+                test_block.raw.clone(),
+                &previous_point,
+                1.into(),
+            )?;
 
             assert_eq!(block.decode().hash(), pallas_block.hash());
         }
@@ -523,7 +536,7 @@ pub(crate) mod tests {
                     })
                     .expect("cannot create point");
 
-                MultiEraBlock::new(Network::Preprod, block.clone(), &prev_point, 1)
+                MultiEraBlock::new(Network::Preprod, block.clone(), &prev_point, 1.into())
                     .expect("cannot create multi-era block")
             })
             .collect()
@@ -720,7 +733,7 @@ pub(crate) mod tests {
                 Network::Preprod,
                 test_block.raw.clone(),
                 &test_block.previous,
-                1,
+                1.into(),
             );
 
             assert!(block.is_ok());