refactor(chain): use BlockTree as header chain implementation

Author: rustaceanrob

src/chain/chain.rs

@@ -13,7 +13,6 @@ pub(crate) enum HeaderSyncError {
     MiscalculatedDifficulty,
     InvalidBits,
     FloatingHeaders,
-    LessWorkFork,
     DbError,
 }
 
@@ -43,9 +42,6 @@ impl Display for HeaderSyncError {
                 f,
                 "the peer sent us a chain that does not connect to any header of ours."
             ),
-            HeaderSyncError::LessWorkFork => {
-                write!(f, "a peer sent us a fork with less work than our chain.")
-            }
             HeaderSyncError::DbError => write!(f, "the database could not load a fork."),
             HeaderSyncError::InvalidBits => write!(
                 f,

src/chain/error.rs

@@ -9,6 +9,8 @@ use bitcoin::{
 
 use super::IndexedHeader;
 
+const LOCATOR_INDEX: &[u32] = &[1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024];
+
 #[derive(Debug, Clone, Copy, Hash, PartialEq, Eq, PartialOrd, Ord)]
 pub(crate) struct Height(u32);
 
@@ -28,7 +30,8 @@ impl Height {
         Self(self.0 + 1)
     }
 
-    fn checked_sub(&self, other: Height) -> Option<Self> {
+    fn checked_sub(&self, other: impl Into<Height>) -> Option<Self> {
+        let other = other.into();
         let height_sub_checked = self.0.checked_sub(other.0);
         height_sub_checked.map(Self)
     }
@@ -132,7 +135,7 @@ pub struct BlockTree {
 
 #[allow(unused)]
 impl BlockTree {
-    pub fn new(tip: impl Into<Tip>, network: Network) -> Self {
+    pub(crate) fn new(tip: impl Into<Tip>, network: Network) -> Self {
         let tip = tip.into();
         Self {
             canonical_hashes: BTreeMap::new(),
@@ -143,7 +146,7 @@ impl BlockTree {
         }
     }
 
-    pub fn from_genesis(network: Network) -> Self {
+    pub(crate) fn from_genesis(network: Network) -> Self {
         let genesis = genesis_block(network);
         let height = Height::new(0);
         let hash = genesis.block_hash();
@@ -164,7 +167,7 @@ impl BlockTree {
         }
     }
 
-    pub fn from_header(height: impl Into<Height>, header: Header, network: Network) -> Self {
+    pub(crate) fn from_header(height: impl Into<Height>, header: Header, network: Network) -> Self {
         let height = height.into();
         let hash = header.block_hash();
         let tip = Tip {
@@ -184,7 +187,7 @@ impl BlockTree {
         }
     }
 
-    fn accept_header(&mut self, new_header: Header) -> AcceptHeaderChanges {
+    pub(crate) fn accept_header(&mut self, new_header: Header) -> AcceptHeaderChanges {
         let new_hash = new_header.block_hash();
         let prev_hash = new_header.prev_blockhash;
 
@@ -391,6 +394,9 @@ impl BlockTree {
 
     pub(crate) fn block_hash_at_height(&self, height: impl Into<Height>) -> Option<BlockHash> {
         let height = height.into();
+        if self.active_tip.height.eq(&height) {
+            return Some(self.active_tip.hash);
+        }
         self.canonical_hashes.get(&height).copied()
     }
 
@@ -408,6 +414,14 @@ impl BlockTree {
         self.active_tip.height.to_u32()
     }
 
+    pub(crate) fn contains(&self, hash: BlockHash) -> bool {
+        self.headers.contains_key(&hash) || self.active_tip.hash.eq(&hash)
+    }
+
+    pub(crate) fn tip_hash(&self) -> BlockHash {
+        self.active_tip.hash
+    }
+
     pub(crate) fn filter_hash(&self, block_hash: BlockHash) -> Option<FilterHash> {
         self.headers.get(&block_hash)?.filter_hash
     }
@@ -418,6 +432,26 @@ impl BlockTree {
         self.headers.get(hash)?.filter_hash
     }
 
+    pub(crate) fn locators(&self) -> Vec<BlockHash> {
+        let mut locators = Vec::new();
+        locators.push(self.active_tip.hash);
+        for locator in LOCATOR_INDEX {
+            let height = self.active_tip.height.checked_sub(*locator);
+            match height {
+                Some(height) => match self.block_hash_at_height(height) {
+                    Some(hash) => locators.push(hash),
+                    None => return locators.into_iter().rev().collect(),
+                },
+                None => return locators.into_iter().rev().collect(),
+            }
+        }
+        locators.into_iter().rev().collect()
+    }
+
+    pub(crate) fn internally_cached_headers(&self) -> usize {
+        self.headers.len()
+    }
+
     pub(crate) fn iter(&self) -> BlockTreeIterator {
         BlockTreeIterator {
             block_tree: self,

src/chain/graph.rs

@@ -1,5 +1,3 @@
-use std::ops::RangeFrom;
-
 use bitcoin::{block::Header, params::Params, Target};
 
 use crate::impl_sourceless_error;
@@ -64,18 +62,6 @@ impl HeadersBatch {
             .expect("headers have at least one element by construction")
     }
 
-    pub(crate) fn len(&self) -> usize {
-        self.batch.len()
-    }
-
-    pub(crate) fn get(&self, index: usize) -> Option<&Header> {
-        self.batch.get(index)
-    }
-
-    pub(crate) fn get_slice(&self, index: RangeFrom<usize>) -> Option<&[Header]> {
-        self.batch.get(index)
-    }
-
     pub(crate) fn inner(&self) -> &[Header] {
         &self.batch
     }