storage: don't return errors from MVCC scans

src/sql/engine/local.rs

@@ -205,7 +205,7 @@ impl<E: storage::Engine> super::Transaction for Transaction<E> {
  let table = self.must_get_table(table)?;
  Ok(Box::new(
  self.txn
- .scan_prefix(&KeyPrefix::Row((&table.name).into()).encode())?
+ .scan_prefix(&KeyPrefix::Row((&table.name).into()).encode())
  .iter()
  .map(|r| r.and_then(|(_, v)| Row::decode(&v)))
  .filter_map(move |r| match r {
@@ -235,7 +235,7 @@ impl<E: storage::Engine> super::Transaction for Transaction<E> {
  self.txn
  .scan_prefix(
  &KeyPrefix::Index((&table.name).into(), (&column.name).into()).encode(),
- )?
+ )
  .iter()
  .map(|r| -> Result<(Value, HashSet<Value>)> {
  let (k, v) = r?;
@@ -314,7 +314,7 @@ impl<E: storage::Engine> Catalog for Transaction<E> {
 
  fn list_tables(&self) -> Result<Vec<Table>> {
  self.txn
- .scan_prefix(&KeyPrefix::Table.encode())?
+ .scan_prefix(&KeyPrefix::Table.encode())
  .iter()
  .map(|r| r.and_then(|(_, v)| Table::decode(&v)))
  .collect()

src/storage/mvcc.rs

@@ -565,7 +565,7 @@ impl<E: Engine> Transaction<E> {
 
  /// Returns an iterator over the latest visible key/value pairs at the
  /// transaction's version.
- pub fn scan<R: RangeBounds<Vec<u8>>>(&self, range: R) -> Result<Scan<E>> {
+ pub fn scan<R: RangeBounds<Vec<u8>>>(&self, range: R) -> Scan<E> {
  let start = match range.start_bound() {
  Bound::Excluded(k) => Bound::Excluded(Key::Version(k.into(), u64::MAX).encode()),
  Bound::Included(k) => Bound::Included(Key::Version(k.into(), 0).encode()),
@@ -576,17 +576,19 @@ impl<E: Engine> Transaction<E> {
  Bound::Included(k) => Bound::Included(Key::Version(k.into(), u64::MAX).encode()),
  Bound::Unbounded => Bound::Excluded(KeyPrefix::Unversioned.encode()),
  };
- Ok(Scan::new(self.engine.lock()?, self.state(), start, end))
+ let engine = self.engine.lock().expect("mutex failed");
+ Scan::new(engine, self.state(), start, end)
  }
 
  /// Scans keys under a given prefix.
- pub fn scan_prefix(&self, prefix: &[u8]) -> Result<Scan<E>> {
+ pub fn scan_prefix(&self, prefix: &[u8]) -> Scan<E> {
  // Normally, KeyPrefix::Version will only match all versions of the
  // exact given key. We want all keys maching the prefix, so we chop off
  // the KeyCode byte slice terminator 0x0000 at the end.
  let mut prefix = KeyPrefix::Version(prefix.into()).encode();
  prefix.truncate(prefix.len() - 2);
- Ok(Scan::new_prefix(self.engine.lock()?, self.state(), prefix))
+ let engine = self.engine.lock().expect("mutex error");
+ Scan::new_prefix(engine, self.state(), prefix)
  }
 }
 
@@ -960,7 +962,7 @@ pub mod tests {
  )?;
  args.reject_rest()?;
 
- let mut scan = txn.scan(range)?;
+ let mut scan = txn.scan(range);
  let kvs: Vec<_> = match reverse {
  false => scan.iter().collect::<crate::error::Result<_>>()?,
  true => scan.iter().rev().collect::<crate::error::Result<_>>()?,
@@ -979,7 +981,7 @@ pub mod tests {
  let reverse = args.lookup_parse("reverse")?.unwrap_or(false);
  args.reject_rest()?;
 
- let mut scan = txn.scan_prefix(&prefix)?;
+ let mut scan = txn.scan_prefix(&prefix);
  let kvs: Vec<_> = match reverse {
  false => scan.iter().collect::<crate::error::Result<_>>()?,
  true => scan.iter().rev().collect::<crate::error::Result<_>>()?,