Do not leak an internal grenad Error

milli/src/documents/mod.rs

@@ -7,7 +7,7 @@ use std::io;
 use bimap::BiHashMap;
 pub use builder::DocumentsBatchBuilder;
 use obkv::KvReader;
-pub use reader::{DocumentsBatchCursor, DocumentsBatchReader};
+pub use reader::{DocumentsBatchCursor, DocumentsBatchCursorError, DocumentsBatchReader};
 use serde::{Deserialize, Serialize};
 
 use crate::error::{FieldIdMapMissingEntry, InternalError};

milli/src/documents/reader.rs

@@ -1,5 +1,5 @@
 use std::convert::TryInto;
-use std::io;
+use std::{error, fmt, io};
 
 use obkv::KvReader;
 
@@ -79,7 +79,9 @@ impl<R> DocumentsBatchCursor<R> {
 impl<R: io::Read + io::Seek> DocumentsBatchCursor<R> {
     /// Returns the next document, starting from the first one. Subsequent calls to
     /// `next_document` advance the document reader until all the documents have been read.
-    pub fn next_document(&mut self) -> Result<Option<KvReader<FieldId>>, grenad::Error> {
+    pub fn next_document(
+        &mut self,
+    ) -> Result<Option<KvReader<FieldId>>, DocumentsBatchCursorError> {
         match self.cursor.move_on_next()? {
             Some((key, value)) if key != DOCUMENTS_BATCH_INDEX_KEY => {
                 Ok(Some(KvReader::new(value)))
@@ -88,3 +90,29 @@ impl<R: io::Read + io::Seek> DocumentsBatchCursor<R> {
         }
     }
 }
+
+/// The possible error thrown by the `DocumentsBatchCursor` when iterating on the documents.
+#[derive(Debug)]
+pub struct DocumentsBatchCursorError {
+    inner: grenad::Error,
+}
+
+impl From<grenad::Error> for DocumentsBatchCursorError {
+    fn from(error: grenad::Error) -> DocumentsBatchCursorError {
+        DocumentsBatchCursorError { inner: error }
+    }
+}
+
+impl Into<grenad::Error> for DocumentsBatchCursorError {
+    fn into(self) -> grenad::Error {
+        self.inner
+    }
+}
+
+impl error::Error for DocumentsBatchCursorError {}
+
+impl fmt::Display for DocumentsBatchCursorError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        self.inner.fmt(f)
+    }
+}

milli/src/error.rs

@@ -7,6 +7,7 @@ use rayon::ThreadPoolBuildError;
 use serde_json::Value;
 use thiserror::Error;
 
+use crate::documents::DocumentsBatchCursorError;
 use crate::{CriterionError, DocumentId, FieldId, Object, SortError};
 
 pub fn is_reserved_keyword(keyword: &str) -> bool {
@@ -209,6 +210,12 @@ where
     }
 }
 
+impl From<DocumentsBatchCursorError> for Error {
+    fn from(error: DocumentsBatchCursorError) -> Error {
+        Error::from(Into::<grenad::Error>::into(error))
+    }
+}
+
 impl From<Infallible> for Error {
     fn from(_error: Infallible) -> Error {
         unreachable!()