hintfile: Add height to file metadata

Depending on the client the height may also be useful along with the
hash.

Author: rustaceanrob

hintfile/src/bin/construct.rs

@@ -34,8 +34,12 @@ fn main() {
     let chainman = ChainstateManager::new(options).unwrap();
     println!("Chain state initialized");
     // Writing the chain tip allows the client to know where to stop
-    let tip = chainman.block_index_tip().block_hash().hash;
-    file.write_all(&tip).expect("file cannot be written to");
+    let tip = chainman.block_index_tip();
+    let stop_height = (tip.height() as u32).to_le_bytes();
+    file.write_all(&stop_height)
+        .expect("file cannot be written to");
+    file.write_all(&tip.block_hash().hash)
+        .expect("file cannot be written to");
 
     let genesis = chainman.block_index_genesis();
     let mut current = chainman.next_block_index(genesis).unwrap();

hintfile/src/lib.rs

@@ -47,6 +47,7 @@ pub fn read_compact_size<R: Read>(reader: &mut R) -> Result<u64, io::Error> {
 pub struct Hints {
     map: BTreeMap<BlockHeight, Vec<u64>>,
     assume_valid: BlockHash,
+    stop_height: BlockHeight,
 }
 
 impl Hints {
@@ -56,6 +57,8 @@ impl Hints {
     pub fn from_file<R: Read>(reader: &mut R) -> Self {
         let mut map = BTreeMap::new();
         let mut height = 1;
+        let mut stop_height = [0; 4];
+        reader.read_exact(&mut stop_height).expect("empty file");
         let mut assume_valid = [0; 32];
         reader.read_exact(&mut assume_valid).expect("empty file");
         while let Ok(count) = read_compact_size(reader) {
@@ -67,14 +70,23 @@ impl Hints {
             map.insert(height, offsets);
             height += 1;
         }
-        Self { map, assume_valid }
+        Self {
+            map,
+            assume_valid,
+            stop_height: BlockHeight::from_le_bytes(stop_height),
+        }
     }
 
     /// Get the last hash encoded in the hintfile.
     pub fn stop_hash(&self) -> BlockHash {
         self.assume_valid
     }
 
+    /// Get the stop height of the hint file.
+    pub fn stop_height(&self) -> BlockHeight {
+        self.stop_height
+    }
+
     /// # Panics
     ///
     /// If there are no offset present at that height, aka an overflow, or the entry has already

node/src/bin/ibd.rs

@@ -44,6 +44,7 @@ fn main() {
     let mut hintfile = File::open(hint_path).expect("invalid hintfile path");
     let hints = Arc::new(Hints::from_file(&mut hintfile));
     elapsed_time(hintfile_start_time);
+    tracing::info!("Syncing to height {}", hints.stop_height());
     let block_file_path = blocks_dir.map(PathBuf::from);
     if let Some(block_file_path) = block_file_path.as_ref() {
         std::fs::create_dir(block_file_path).expect("could not create block file directory");