object: Polish API for Metadata

README.md

@@ -11,7 +11,9 @@ OpenDAL is in **alpha** stage and has been early adopted by [databend](https://g
 ```rust
 use anyhow::Result;
 use futures::AsyncReadExt;
+use futures::StreamExt;
 use opendal::services::fs;
+use opendal::ObjectMode;
 use opendal::Operator;
 
 #[tokio::main]
@@ -38,6 +40,16 @@ async fn main() -> Result<()> {
     let meta = o.metadata().await?;
     assert_eq!(meta.content_length(), 13);
 
+    // List current dir.
+    let mut obs = op.objects("").map(|o| o.expect("list object"));
+    while let Some(o) = obs.next().await {
+        let meta = o.metadata().await?;
+        if meta.path().contains("test_file") {
+            let mode = meta.mode();
+            assert!(mode.contains(ObjectMode::FILE));
+        }
+    }
+
     // Delete file.
     o.delete().await?;
 

examples/basic.rs

@@ -40,15 +40,15 @@ async fn main() -> Result<()> {
 
     // Get file's Metadata
     let meta = o.metadata().await?;
-    assert_eq!(meta.content_length(), Some(13));
+    assert_eq!(meta.content_length(), 13);
 
     // List current dir.
     let mut obs = op.objects("").map(|o| o.expect("list object"));
     let mut found = false;
     while let Some(o) = obs.next().await {
         let meta = o.metadata().await?;
         if meta.path().contains("test_file") {
-            let mode = meta.mode().expect("object mode");
+            let mode = meta.mode();
             assert!(mode.contains(ObjectMode::FILE));
 
             found = true

src/io.rs

@@ -127,12 +127,7 @@ impl AsyncSeek for Reader {
     ) -> Poll<std::io::Result<u64>> {
         if let ReadState::Seeking(future) = &mut self.state {
             match ready!(Pin::new(future).poll(cx)) {
-                Ok(meta) => {
-                    self.total_size = Some(
-                        meta.content_length()
-                            .expect("object doesn't have content length"),
-                    )
-                }
+                Ok(meta) => self.total_size = Some(meta.content_length()),
                 Err(e) => return Poll::Ready(Err(io::Error::from(e))),
             }
         }

src/object.rs

@@ -126,17 +126,21 @@ impl Metadata {
         self
     }
 
-    pub fn mode(&self) -> Option<ObjectMode> {
-        self.mode
+    pub fn mode(&self) -> ObjectMode {
+        debug_assert!(self.mode.is_some(), "mode must exist");
+
+        self.mode.unwrap_or_default()
     }
 
     pub(crate) fn set_mode(&mut self, mode: ObjectMode) -> &mut Self {
         self.mode = Some(mode);
         self
     }
 
-    pub fn content_length(&self) -> Option<u64> {
-        self.content_length
+    pub fn content_length(&self) -> u64 {
+        debug_assert!(self.content_length.is_some(), "content length must exist");
+
+        self.content_length.unwrap_or_default()
     }
 
     pub(crate) fn set_content_length(&mut self, content_length: u64) -> &mut Self {

tests/behavior/behavior.rs

@@ -67,7 +67,7 @@ impl BehaviorTest {
 
         // Step 3: Stat this file
         let meta = self.op.object(&path).metadata().await?;
-        assert_eq!(meta.content_length().unwrap(), size as u64, "stat file");
+        assert_eq!(meta.content_length(), size as u64, "stat file");
 
         // Step 4: Read this file's content
         // Step 4.1: Read the whole file.
@@ -103,7 +103,7 @@ impl BehaviorTest {
         while let Some(o) = obs.next().await {
             let meta = o.metadata().await?;
             if meta.path() == path {
-                let mode = meta.mode().expect("object mode");
+                let mode = meta.mode();
                 assert!(
                     mode.contains(ObjectMode::FILE),
                     "expected: {:?}, actual: {:?}",