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indexedlog: index: stop iteration if an error is encountered

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Summary:
Without this change, code doing `index.get(...).values().collect()` might
end up with an infinite loop.

Reviewed By: DurhamG

Differential Revision: D8156510

fbshipit-source-id: 5497aa354de7d49cfc4308a025856608ce981a1e
This commit is contained in:
Jun Wu 2018-06-04 23:50:28 -07:00 committed by Facebook Github Bot
parent 798e55d53d
commit c65612acc9
1 changed files with 16 additions and 3 deletions
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19
lib/indexedlog/src/index.rs
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@ -260,7 +260,7 @@ trait TypedOffsetMethods: Sized {
// Implement traits for typed offset structs.
macro_rules! impl_offset {
($type: ident, $type_int: expr, $name: expr) => {
($type:ident, $type_int:expr, $name:expr) => {
impl TypedOffsetMethods for $type {
#[inline]
fn type_int() -> u8 {
@ -497,13 +497,14 @@ impl LeafOffset {
pub struct LeafValueIter<'a> {
index: &'a Index,
offset: LinkOffset,
errored: bool,
}
impl<'a> Iterator for LeafValueIter<'a> {
type Item = io::Result<u64>;
fn next(&mut self) -> Option<Self::Item> {
if self.offset.is_null() {
if self.offset.is_null() || self.errored {
None
} else {
match self.offset.value_and_next(self.index) {
@ -511,7 +512,10 @@ impl<'a> Iterator for LeafValueIter<'a> {
self.offset = next;
Some(Ok(value))
}
Err(e) => Some(Err(e)),
Err(e) => {
self.errored = true;
Some(Err(e))
}
}
}
}
@ -521,6 +525,7 @@ impl LinkOffset {
/// Iterating through values referred by this linked list.
pub fn values<'a>(self, index: &'a Index) -> LeafValueIter<'a> {
LeafValueIter {
errored: false,
index,
offset: self,
}
@ -2099,6 +2104,14 @@ mod tests {
// Empty linked list
assert_eq!(index.get(&[1]).unwrap().values(&index).count(), 0);
// In case error happens, the iteration still stops.
index.insert(&[], 5).expect("insert");
index.dirty_links[0].next_link_offset = LinkOffset(Offset(1000));
// Note: `collect` can return `io::Result<Vec<u64>>`. But that does not exercises the
// infinite loop avoidance logic since `collect` stops iteration at the first error.
let list_errored: Vec<io::Result<u64>> = index.get(&[]).unwrap().values(&index).collect();
assert!(list_errored[list_errored.len() - 1].is_err());
}
#[test]