chore: improve ImmutableDB error handling (#426)

Co-authored-by: Steven Johnson <stevenj@users.noreply.github.com>

pallas-hardano/src/storage/immutable/chunk.rs

@@ -15,52 +15,59 @@ pub type SecondaryEntry = super::secondary::Entry;
 pub struct Reader {
     inner: BufReader<File>,
     index: SecondaryIndex,
-    current: Option<Result<SecondaryEntry, std::io::Error>>,
-    next: Option<Result<SecondaryEntry, std::io::Error>>,
+    current: Option<Result<SecondaryEntry, secondary::Error>>,
+    next: Option<Result<SecondaryEntry, secondary::Error>>,
+}
+
+#[derive(thiserror::Error, Debug)]
+pub enum Error {
+    #[error("Cannot open chunk file, error: {0}")]
+    CannotOpenChunkFile(std::io::Error),
+    #[error("Cannot read block, error: {0}")]
+    CannotReadBlock(std::io::Error),
+    #[error(transparent)]
+    SecondaryIndexError(secondary::Error),
 }
 
 impl Reader {
-    fn open(mut index: SecondaryIndex, chunks: File) -> Result<Self, std::io::Error> {
+    fn open(mut index: SecondaryIndex, chunks: File) -> Self {
         let inner = BufReader::new(chunks);
 
         let current = index.next();
         let next = index.next();
 
-        Ok(Self {
+        Self {
             inner,
             index,
             current,
             next,
-        })
+        }
     }
 
-    fn read_middle_block(
-        file: &mut BufReader<File>,
-        next_offset: u64,
-    ) -> Result<Vec<u8>, std::io::Error> {
-        let start = file.stream_position()?;
+    fn read_middle_block(file: &mut BufReader<File>, next_offset: u64) -> Result<Vec<u8>, Error> {
+        let start = file.stream_position().map_err(Error::CannotReadBlock)?;
         let delta = next_offset - start;
         trace!(start, delta, "reading chunk middle block");
 
         let mut buf = vec![0u8; delta as usize];
-        file.read_exact(&mut buf)?;
+        file.read_exact(&mut buf).map_err(Error::CannotReadBlock)?;
 
         Ok(buf)
     }
 
-    fn read_last_block(file: &mut BufReader<File>) -> Result<Vec<u8>, std::io::Error> {
-        let start = file.stream_position()?;
+    fn read_last_block(file: &mut BufReader<File>) -> Result<Vec<u8>, Error> {
+        let start = file.stream_position().map_err(Error::CannotReadBlock)?;
         trace!(start, "reading chunk last block");
 
         let mut buf = vec![];
-        file.read_to_end(&mut buf)?;
+        file.read_to_end(&mut buf).map_err(Error::CannotReadBlock)?;
 
         Ok(buf)
     }
 }
 
 impl Iterator for Reader {
-    type Item = Result<Vec<u8>, std::io::Error>;
+    type Item = Result<Vec<u8>, Error>;
 
     fn next(&mut self) -> Option<Self::Item> {
         match (self.current.take(), self.next.take()) {
@@ -69,7 +76,7 @@ impl Iterator for Reader {
                 self.current = None;
                 self.next = None;
 
-                Some(Err(next))
+                Some(Err(Error::SecondaryIndexError(next)))
             }
             (Some(_), Some(Ok(next))) => {
                 let block = Self::read_middle_block(&mut self.inner, next.block_offset);
@@ -91,18 +98,12 @@ impl Iterator for Reader {
     }
 }
 
-pub fn read_blocks(dir: &Path, name: &str) -> Result<Reader, std::io::Error> {
-    let primary = dir.join(name).with_extension("primary");
-    let primary = std::fs::File::open(primary)?;
-    let primary = immutable::primary::Reader::open(primary)?;
-
-    let secondary = dir.join(name).with_extension("secondary");
-    let secondary = std::fs::File::open(secondary)?;
-    let secondary = secondary::Reader::open(primary, secondary)?;
+pub fn read_blocks(dir: &Path, name: &str) -> Result<Reader, Error> {
+    let secondary = secondary::read_entries(dir, name).map_err(Error::SecondaryIndexError)?;
 
     let chunk = dir.join(name).with_extension("chunk");
-    let chunk = std::fs::File::open(chunk)?;
-    Reader::open(secondary, chunk)
+    let chunk = std::fs::File::open(chunk).map_err(Error::CannotOpenChunkFile)?;
+    Ok(Reader::open(secondary, chunk))
 }
 
 #[cfg(test)]

pallas-hardano/src/storage/immutable/mod.rs

@@ -6,7 +6,6 @@ use std::{
 
 use pallas_traverse::MultiEraBlock;
 use tap::Tap;
-use thiserror::Error;
 use tracing::debug;
 
 pub mod chunk;
@@ -17,13 +16,18 @@ pub mod secondary;
 // `network`.
 pub type Point = pallas_network::miniprotocols::Point;
 
-#[derive(Debug, Error, PartialEq, Eq)]
+#[derive(thiserror::Error, Debug)]
 pub enum Error {
     #[error("Cannot find block by the provided point: {0:?}")]
     CannotFindBlock(Point),
-
     #[error("Origin block is missing, provided truncated chain data")]
     OriginMissing,
+    #[error("Cannot read directory, error: {0}")]
+    CannotReadDir(std::io::Error),
+    #[error("Cannot decode block, error: {0}")]
+    CannotDecodeBlock(pallas_traverse::Error),
+    #[error(transparent)]
+    ChunkReadError(chunk::Error),
 }
 
 /// Performs a binary search of the given sorted chunks in descending order
@@ -39,8 +43,8 @@ pub enum Error {
 fn chunk_binary_search<ChunkT, PointT>(
     chunks: &[ChunkT],
     point: &PointT,
-    cmp: impl Fn(&ChunkT, &PointT) -> Result<Ordering, Box<dyn std::error::Error>>,
-) -> Result<Option<usize>, Box<dyn std::error::Error>> {
+    cmp: impl Fn(&ChunkT, &PointT) -> Result<Ordering, Error>,
+) -> Result<Option<usize>, Error> {
     let mut size = chunks.len();
     let mut left = 0;
     let mut right: usize = size;
@@ -75,12 +79,12 @@ fn iterate_till_point(
     iter: impl Iterator<Item = FallibleBlock>,
     slot: u64,
     block_hash: &[u8],
-) -> Result<impl Iterator<Item = FallibleBlock>, Box<dyn std::error::Error>> {
+) -> Result<impl Iterator<Item = FallibleBlock>, Error> {
     let mut iter = iter.peekable();
     match iter.peek() {
         Some(Ok(block_data)) => {
             let mut block_data = block_data.clone();
-            let mut block = MultiEraBlock::decode(&block_data)?;
+            let mut block = MultiEraBlock::decode(&block_data).map_err(Error::CannotDecodeBlock)?;
 
             while block.slot() < slot {
                 iter.next();
@@ -88,7 +92,8 @@ fn iterate_till_point(
                 match iter.peek() {
                     Some(Ok(data)) => {
                         block_data.clone_from(data);
-                        block = MultiEraBlock::decode(&block_data)?;
+                        block =
+                            MultiEraBlock::decode(&block_data).map_err(Error::CannotDecodeBlock)?;
                     }
                     Some(Err(_)) | None => return Ok(iter),
                 }
@@ -104,8 +109,9 @@ fn iterate_till_point(
     }
 }
 
-fn build_stack_of_chunk_names(dir: &Path) -> Result<ChunkNameSack, std::io::Error> {
-    let mut chunks = std::fs::read_dir(dir)?
+fn build_stack_of_chunk_names(dir: &Path) -> Result<ChunkNameSack, Error> {
+    let mut chunks = std::fs::read_dir(dir)
+        .map_err(Error::CannotReadDir)?
         .map_while(|e| e.ok())
         .filter(|e| {
             e.path()
@@ -135,7 +141,7 @@ pub type ChunkNameSack = Vec<ChunkName>;
 pub struct ChunkReaders(PathBuf, ChunkNameSack);
 
 impl Iterator for ChunkReaders {
-    type Item = Result<chunk::Reader, std::io::Error>;
+    type Item = Result<chunk::Reader, chunk::Error>;
 
     fn next(&mut self) -> Option<Self::Item> {
         self.1
@@ -145,9 +151,9 @@ impl Iterator for ChunkReaders {
     }
 }
 
-pub type FallibleBlock = Result<Block, std::io::Error>;
+pub type FallibleBlock = Result<Block, chunk::Error>;
 
-pub fn read_blocks(dir: &Path) -> Result<impl Iterator<Item = FallibleBlock>, std::io::Error> {
+pub fn read_blocks(dir: &Path) -> Result<impl Iterator<Item = FallibleBlock>, Error> {
     let names = build_stack_of_chunk_names(dir)?;
 
     let iter = ChunkReaders(dir.to_owned(), names)
@@ -166,8 +172,9 @@ pub fn read_blocks(dir: &Path) -> Result<impl Iterator<Item = FallibleBlock>, st
 ///   genesis block.
 /// * `Error::CannotFindBlock` - If the specific block indicated by the `Point`
 ///   value is not found.
-/// * `std::io::Error` - If an I/O error occurs.
-/// * `pallas_traverse::Error` - If the block cannot be decoded.
+/// * `Error::CannotReadDir` - If the directory cannot be read.
+/// * `Error::ChunkReadError` - Chunk read error.
+/// * `Error::CannotDecodeBlock` - If the block cannot be decoded.
 ///
 /// # Example
 ///
@@ -204,7 +211,7 @@ pub fn read_blocks(dir: &Path) -> Result<impl Iterator<Item = FallibleBlock>, st
 pub fn read_blocks_from_point(
     dir: &Path,
     point: Point,
-) -> Result<Box<dyn Iterator<Item = FallibleBlock> + Send + Sync>, Box<dyn std::error::Error>> {
+) -> Result<Box<dyn Iterator<Item = FallibleBlock> + Send + Sync>, Error> {
     let names = build_stack_of_chunk_names(dir)?;
 
     match point {
@@ -218,7 +225,8 @@ pub fn read_blocks_from_point(
             // check the first block
             match iter.peek() {
                 Some(Ok(block_data)) => {
-                    let block = MultiEraBlock::decode(block_data)?;
+                    let block =
+                        MultiEraBlock::decode(block_data).map_err(Error::CannotDecodeBlock)?;
                     // check that the first block is genesis
                     if block.slot() == 0 && block.number() == 0 {
                         Ok(Box::new(iter))
@@ -236,13 +244,15 @@ pub fn read_blocks_from_point(
             // and compares block's slot with provided slot number
             let cmp = {
                 |chunk_name: &String, point: &u64| {
-                    let mut blocks = chunk::read_blocks(dir, chunk_name)?;
+                    let mut blocks =
+                        chunk::read_blocks(dir, chunk_name).map_err(Error::ChunkReadError)?;
 
                     // Try to read the first block from the chunk
                     if let Some(block_data) = blocks.next() {
-                        let block_data = block_data?;
+                        let block_data = block_data.map_err(Error::ChunkReadError)?;
 
-                        let block = MultiEraBlock::decode(&block_data)?;
+                        let block =
+                            MultiEraBlock::decode(&block_data).map_err(Error::CannotDecodeBlock)?;
                         Ok(block.slot().cmp(point))
                     } else {
                         Ok(Ordering::Greater)
@@ -254,9 +264,10 @@ pub fn read_blocks_from_point(
             // index.
             let names = chunk_binary_search(&names, &slot, cmp)?
                 .map(|chunk_index| names[..chunk_index + 1].to_vec())
-                .ok_or::<Box<dyn std::error::Error>>(
-                    Error::CannotFindBlock(Point::Specific(slot, block_hash.clone())).into(),
-                )?;
+                .ok_or(Error::CannotFindBlock(Point::Specific(
+                    slot,
+                    block_hash.clone(),
+                )))?;
 
             let iter = ChunkReaders(dir.to_owned(), names.clone())
                 .map_while(Result::ok)
@@ -277,8 +288,9 @@ pub fn read_blocks_from_point(
 ///
 /// # Errors
 ///
-/// * `std::io::Error` - If an I/O error occurs.
-/// * `pallas_traverse::Error` - If the block cannot be decoded.
+/// * `Error::CannotReadDir` - If the directory cannot be read.
+/// * `Error::ChunkReadError` - Chunk read error.
+/// * `Error::CannotDecodeBlock` - If the block cannot be decoded.
 ///
 /// # Example
 ///
@@ -303,19 +315,21 @@ pub fn read_blocks_from_point(
 ///     Ok(())
 /// }
 /// ```
-pub fn get_tip(dir: &Path) -> Result<Option<Point>, Box<dyn std::error::Error>> {
+pub fn get_tip(dir: &Path) -> Result<Option<Point>, Error> {
     match build_stack_of_chunk_names(dir)?.into_iter().next() {
         Some(name) => {
             let tip_point = ChunkReaders(dir.to_owned(), vec![name])
                 .map_while(Result::ok)
                 .flatten()
                 .last()
-                .transpose()?
+                .transpose()
+                .map_err(Error::ChunkReadError)?
                 .map(|tip_data| {
                     MultiEraBlock::decode(&tip_data)
                         .map(|block| Point::Specific(block.slot(), block.hash().to_vec()))
                 })
-                .transpose()?;
+                .transpose()
+                .map_err(Error::CannotDecodeBlock)?;
             Ok(tip_point)
         }
         None => Ok(None),
@@ -511,25 +525,21 @@ mod tests {
         assert_eq!(Point::Specific(block.slot(), block.hash().to_vec()), point);
 
         // Try to read an origin block
-        assert_eq!(
+        assert!(matches!(
             read_blocks_from_point(Path::new("../test_data"), Point::Origin)
                 .err()
-                .unwrap()
-                .downcast::<super::Error>()
                 .unwrap(),
-            Box::new(super::Error::OriginMissing)
-        );
+            super::Error::OriginMissing
+        ));
 
         // Try to read from a non existing point
         let point = Point::Specific(0, vec![]);
-        assert_eq!(
+        assert!(matches!(
             read_blocks_from_point(Path::new("../test_data"), point.clone())
                 .err()
-                .unwrap()
-                .downcast::<super::Error>()
                 .unwrap(),
-            Box::new(super::Error::CannotFindBlock(point))
-        );
+            super::Error::CannotFindBlock(_)
+        ));
     }
 
     fn read_full_snapshot(path: &Path) {

pallas-hardano/src/storage/immutable/primary.rs

@@ -11,6 +11,14 @@ binary_layout::define_layout!(layout, BigEndian, {
 pub type RelativeSlot = u32;
 pub type SecondaryOffset = u32;
 
+#[derive(thiserror::Error, Debug)]
+pub enum Error {
+    #[error("Version missing, cannot read version from primary index file, error: {0}")]
+    VersionMissing(std::io::Error),
+    #[error("Cannot read offset from primary index file, error: {0}")]
+    CannotReadPrimaryIndex(std::io::Error),
+}
+
 #[derive(Debug)]
 pub enum Entry {
     Empty(RelativeSlot),
@@ -30,20 +38,22 @@ pub struct Reader {
     inner: BufReader<File>,
     version: u8,
     last_slot: Option<RelativeSlot>,
-    last_offset: Option<Result<SecondaryOffset, std::io::Error>>,
-    next_offset: Option<Result<SecondaryOffset, std::io::Error>>,
+    last_offset: Option<Result<SecondaryOffset, Error>>,
+    next_offset: Option<Result<SecondaryOffset, Error>>,
 }
 
 impl Reader {
-    fn read_version(inner: &mut BufReader<File>) -> Result<u8, std::io::Error> {
-        let mut buf = vec![0u8; 1];
-        inner.read_exact(&mut buf)?;
-        let version = buf.first().unwrap();
+    fn read_version(inner: &mut BufReader<File>) -> Result<u8, Error> {
+        let mut buf = [0u8; 1];
+        inner
+            .read_exact(&mut buf)
+            .map_err(|e| Error::VersionMissing(e))?;
+        let version = buf[0];
 
-        Ok(*version)
+        Ok(version)
     }
 
-    pub fn open(file: File) -> Result<Self, std::io::Error> {
+    pub fn open(file: File) -> Result<Self, Error> {
         let mut inner = BufReader::new(file);
         let version = Reader::read_version(&mut inner)?;
 
@@ -63,7 +73,7 @@ impl Reader {
         self.version
     }
 
-    pub fn next_occupied(&mut self) -> Option<Result<Entry, std::io::Error>> {
+    pub fn next_occupied(&mut self) -> Option<Result<Entry, Error>> {
         loop {
             let next = self.next();
 
@@ -78,12 +88,12 @@ impl Reader {
         }
     }
 
-    fn read_offset(file: &mut BufReader<File>) -> Option<Result<SecondaryOffset, std::io::Error>> {
+    fn read_offset(file: &mut BufReader<File>) -> Option<Result<SecondaryOffset, Error>> {
         let mut buf = vec![0u8; layout::SIZE.unwrap()];
 
         match file.read_exact(&mut buf) {
             Err(err) if err.kind() == std::io::ErrorKind::UnexpectedEof => None,
-            Err(err) => Some(Err(err)),
+            Err(err) => Some(Err(Error::CannotReadPrimaryIndex(err))),
             Ok(_) => {
                 let view = layout::View::new(&buf);
                 let offset = view.secondary_offset().read();
@@ -94,7 +104,7 @@ impl Reader {
 }
 
 impl Iterator for Reader {
-    type Item = Result<Entry, std::io::Error>;
+    type Item = Result<Entry, Error>;
 
     fn next(&mut self) -> Option<Self::Item> {
         match (self.last_offset.take(), self.next_offset.take()) {

pallas-hardano/src/storage/immutable/secondary.rs

@@ -18,6 +18,18 @@ binary_layout::define_layout!(layout, BigEndian, {
     block_or_ebb: [u8; 8],
 });
 
+#[derive(thiserror::Error, Debug)]
+pub enum Error {
+    #[error("Cannot open file, error: {0}")]
+    CannotOpenFile(std::io::Error),
+    #[error("Cannot read secondary index, error: {0}")]
+    CannotReadSecondaryIndex(std::io::Error),
+    #[error("Inconsistent state between primary and secondary index")]
+    InconsistentState,
+    #[error(transparent)]
+    PrimaryIndexError(primary::Error),
+}
+
 #[derive(Debug)]
 pub struct Entry {
     pub block_offset: u64,
@@ -49,32 +61,32 @@ pub type SecondaryOffset = u32;
 pub struct Reader {
     inner: BufReader<File>,
     index: PrimaryIndex,
-    current: Option<Result<primary::Entry, std::io::Error>>,
+    current: Option<Result<primary::Entry, primary::Error>>,
 }
 
 impl Reader {
-    pub fn open(mut index: PrimaryIndex, file: File) -> Result<Self, std::io::Error> {
+    pub fn open(mut index: PrimaryIndex, file: File) -> Self {
         let inner = BufReader::new(file);
 
         let current = index.next_occupied();
 
-        Ok(Self {
+        Self {
             inner,
             index,
             current,
-        })
+        }
     }
 }
 
 impl Iterator for Reader {
-    type Item = Result<Entry, std::io::Error>;
+    type Item = Result<Entry, Error>;
 
     fn next(&mut self) -> Option<Self::Item> {
         let current = match self.current.take()? {
             Ok(x) => x.offset()?,
             Err(err) => {
                 self.current = None;
-                return Some(Err(err));
+                return Some(Err(Error::PrimaryIndexError(err)));
             }
         };
 
@@ -82,7 +94,7 @@ impl Iterator for Reader {
             Ok(x) => x,
             Err(err) => {
                 self.current = None;
-                return Some(Err(err));
+                return Some(Err(Error::CannotReadSecondaryIndex(err)));
             }
         };
 
@@ -92,7 +104,7 @@ impl Iterator for Reader {
             Ok(_) => (),
             Err(err) => {
                 self.current = None;
-                return Some(Err(err));
+                return Some(Err(Error::CannotReadSecondaryIndex(err)));
             }
         }
 
@@ -107,23 +119,27 @@ impl Iterator for Reader {
 
                 Some(Ok(entry))
             }
+            Err(err) if err.kind() == std::io::ErrorKind::UnexpectedEof => {
+                self.current = None;
+                Some(Err(Error::InconsistentState))
+            }
             Err(err) => {
                 self.current = None;
-                Some(Err(err))
+                Some(Err(Error::CannotReadSecondaryIndex(err)))
             }
         }
     }
 }
 
-pub fn read_entries(dir: &Path, name: &str) -> Result<Reader, std::io::Error> {
+pub fn read_entries(dir: &Path, name: &str) -> Result<Reader, Error> {
     let primary = dir.join(name).with_extension("primary");
-    let primary = std::fs::File::open(primary)?;
-    let primary = primary::Reader::open(primary)?;
+    let primary = std::fs::File::open(primary).map_err(Error::CannotOpenFile)?;
+    let primary = primary::Reader::open(primary).map_err(Error::PrimaryIndexError)?;
 
     let secondary = dir.join(name).with_extension("secondary");
-    let secondary = std::fs::File::open(secondary)?;
+    let secondary = std::fs::File::open(secondary).map_err(Error::CannotOpenFile)?;
 
-    secondary::Reader::open(primary, secondary)
+    Ok(secondary::Reader::open(primary, secondary))
 }
 
 #[cfg(test)]
@@ -138,4 +154,14 @@ mod tests {
             entry.unwrap();
         }
     }
+
+    #[test]
+    fn can_parse_inconsistent_entries() {
+        let reader =
+            super::read_entries(Path::new("../test_data/inconsistent_indexes"), "10366").unwrap();
+
+        for entry in reader {
+            entry.unwrap();
+        }
+    }
 }