fix: dirty last checkpoint metadata file when enable object store cac…

…hing, GreptimeTeam#2013

src/object-store/src/layers/lru_cache.rs

@@ -19,7 +19,7 @@ use std::sync::Arc;
 use async_trait::async_trait;
 use lru::LruCache;
 use metrics::increment_counter;
-use opendal::raw::oio::{Page, Read, Reader, Write};
+use opendal::raw::oio::{Page, Read, ReadExt, Reader, Write};
 use opendal::raw::{
     Accessor, Layer, LayeredAccessor, OpAppend, OpDelete, OpList, OpRead, OpWrite, RpAppend,
     RpDelete, RpList, RpRead, RpWrite,
@@ -89,6 +89,12 @@ pub struct LruCacheAccessor<I, C> {
     lru_cache: Arc<Mutex<LruCache<String, ()>>>,
 }
 
+/// Returns true when the path of the file can be cached.
+fn can_cache(path: &str) -> bool {
+    // TODO(dennis): find a better way
+    !path.ends_with("_last_checkpoint")
+}
+
 impl<I, C> LruCacheAccessor<I, C> {
     fn cache_path(&self, path: &str, args: &OpRead) -> String {
         format!(
@@ -99,8 +105,6 @@ impl<I, C> LruCacheAccessor<I, C> {
     }
 }
 
-use opendal::raw::oio::ReadExt;
-
 #[async_trait]
 impl<I: Accessor, C: Accessor> LayeredAccessor for LruCacheAccessor<I, C> {
     type Inner = I;
@@ -117,6 +121,10 @@ impl<I: Accessor, C: Accessor> LayeredAccessor for LruCacheAccessor<I, C> {
     }
 
     async fn read(&self, path: &str, args: OpRead) -> Result<(RpRead, Self::Reader)> {
+        if !can_cache(path) {
+            return self.inner.read(path, args).await.map(to_output_reader);
+        }
+
         let path = path.to_string();
         let cache_path = self.cache_path(&path, &args);
         let lru_cache = &self.lru_cache;
@@ -218,3 +226,19 @@ impl<I: Accessor, C: Accessor> LayeredAccessor for LruCacheAccessor<I, C> {
 fn to_output_reader<R: Read + 'static>(input: (RpRead, R)) -> (RpRead, Reader) {
     (input.0, Box::new(input.1))
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_can_cache() {
+        assert!(can_cache("test"));
+        assert!(can_cache("a/b/c.parquet"));
+        assert!(can_cache("1.json"));
+        assert!(can_cache("100.checkpoint"));
+        assert!(can_cache("test/last_checkpoint"));
+        assert!(!can_cache("test/__last_checkpoint"));
+        assert!(!can_cache("a/b/c/__last_checkpoint"));
+    }
+}