add is_current for metadata

(cherry picked from commit 39bb79d)

core/src/services/oss/backend.rs

@@ -521,8 +521,11 @@ impl Access for OssBackend {
                 let headers = resp.headers();
                 let mut meta = self.core.parse_metadata(path, resp.headers())?;
 
+                // If version id exists, set the version; otherwise, mark as the current version.
                 if let Some(v) = parse_header_to_str(headers, "x-oss-version-id")? {
                     meta.set_version(v);
+                } else {
+                    meta.set_is_current(true);
                 }
 
                 Ok(RpStat::new(meta))

core/src/services/oss/lister.rs

@@ -102,6 +102,7 @@ impl oio::PageList for OssLister {
             }
 
             let mut meta = Metadata::new(EntryMode::from_path(&path));
+            meta.set_is_current(true);
             meta.set_etag(&object.etag);
             meta.set_content_md5(object.etag.trim_matches('"'));
             meta.set_content_length(object.size);

core/src/services/s3/backend.rs

@@ -1016,8 +1016,11 @@ impl Access for S3Backend {
                     meta.with_user_metadata(user_meta);
                 }
 
+                // If version id exists, set the version; otherwise, mark as the current version.
                 if let Some(v) = parse_header_to_str(headers, "x-amz-version-id")? {
                     meta.set_version(v);
+                } else {
+                    meta.set_is_current(true);
                 }
 
                 Ok(RpStat::new(meta))

core/src/services/s3/lister.rs

@@ -124,7 +124,7 @@ impl oio::PageList for S3Lister {
             }
 
             let mut meta = Metadata::new(EntryMode::from_path(&path));
-
+            meta.set_is_current(true);
             if let Some(etag) = &object.etag {
                 meta.set_etag(etag);
                 meta.set_content_md5(etag.trim_matches('"'));
@@ -239,6 +239,7 @@ impl oio::PageList for S3ObjectVersionsLister {
 
             let mut meta = Metadata::new(EntryMode::from_path(&path));
             meta.set_version(&version_object.version_id);
+            meta.set_is_current(version_object.is_latest);
             meta.set_content_length(version_object.size);
             meta.set_last_modified(parse_datetime_from_rfc3339(
                 version_object.last_modified.as_str(),

core/src/types/metadata.rs

@@ -43,6 +43,7 @@ pub struct Metadata {
     etag: Option<String>,
     last_modified: Option<DateTime<Utc>>,
     version: Option<String>,
+    is_current: Option<bool>,
 
     user_metadata: Option<HashMap<String, String>>,
 }
@@ -64,6 +65,7 @@ impl Metadata {
             content_disposition: None,
             version: None,
             user_metadata: None,
+            is_current: None,
         }
     }
 
@@ -404,6 +406,27 @@ impl Metadata {
         self
     }
 
+    /// Is_current of this entry.
+    /// 
+    /// Is_current is a boolean that can be used to identify 
+    /// if the version of this entry is the latest version.
+    pub fn is_current(&self) -> Option<bool> {
+        self.is_current
+    }
+
+    /// Set is_current of this entry.
+    /// 
+    /// For HeadObject without version_id, we will set it to Some(true).
+    /// 
+    /// For HeadObject with version_id, we will set it to None.
+    /// 
+    /// For ListObjects, we will set all keys to Some(ture)
+    /// 
+    /// For ListObjectVersions, we will decide the value based on IsLatest.
+    pub fn set_is_current(&mut self, is_current:bool)  {
+        self.is_current = Some(is_current);
+    }
+
     /// User defined metadata of this entry
     ///
     /// The prefix of the user defined metadata key(for example: in oss, it's x-oss-meta-)