feat: add empty task handler for hard_link_or_copy (#310)

Signed-off-by: Gaius <gaius.qi@gmail.com>

dragonfly-client-storage/src/content.rs

@@ -56,25 +56,41 @@ impl Content {
     // hard_link_or_copy_task hard links or copies the task content to the destination.
     pub async fn hard_link_or_copy_task(
         &self,
-        task_id: &str,
+        task: super::metadata::Task,
         to: &Path,
         range: Option<Range>,
     ) -> Result<()> {
         // Copy the task content to the destination by range
         // if the range is specified.
         if let Some(range) = range {
-            self.copy_task_by_range(task_id, to, range).await?;
+            // If the range length is 0, no need to copy. Need to open the file to
+            // ensure the file exists.
+            if range.length == 0 {
+                info!("range length is 0, no need to copy");
+                File::create(to).await?;
+                return Ok(());
+            }
+
+            self.copy_task_by_range(task.id.as_str(), to, range).await?;
             info!("copy range of task success");
             return Ok(());
         }
 
         // If the hard link fails,
         // copy the task content to the destination.
-        if let Err(err) = self.hard_link_task(task_id, to).await {
+        if let Err(err) = self.hard_link_task(task.id.as_str(), to).await {
             info!("hard link task failed: {}", err);
 
+            // If the task is empty, no need to copy. Need to open the file to
+            // ensure the file exists.
+            if task.is_empty() {
+                info!("task is empty, no need to copy");
+                File::create(to).await?;
+                return Ok(());
+            }
+
             fs::remove_file(to).await?;
-            self.copy_task(task_id, to).await?;
+            self.copy_task(task.id.as_str(), to).await?;
             info!("copy task success");
             return Ok(());
         }

dragonfly-client-storage/src/lib.rs

@@ -58,13 +58,11 @@ impl Storage {
     // hard_link_or_copy_task hard links or copies the task content to the destination.
     pub async fn hard_link_or_copy_task(
         &self,
-        task_id: &str,
+        task: metadata::Task,
         to: &Path,
         range: Option<Range>,
     ) -> Result<()> {
-        self.content
-            .hard_link_or_copy_task(task_id, to, range)
-            .await
+        self.content.hard_link_or_copy_task(task, to, range).await
     }
 
     // read_task_by_range returns the reader of the task by range.

dragonfly-client-storage/src/metadata.rs

@@ -100,6 +100,17 @@ impl Task {
         self.finished_at.is_some()
     }
 
+    // is_empty returns whether the task is empty.
+    pub fn is_empty(&self) -> bool {
+        if let Some(content_length) = self.content_length() {
+            if content_length == 0 {
+                return true;
+            }
+        }
+
+        false
+    }
+
     // content_length returns the content length of the task.
     pub fn content_length(&self) -> Option<u64> {
         match self.response_header.get(header::CONTENT_LENGTH.as_str()) {

dragonfly-client/src/grpc/dfdaemon_download.rs

@@ -274,7 +274,7 @@ impl DfdaemonDownload for DfdaemonDownloadServerHandler {
                             // Hard link or copy the task content to the destination.
                             if let Err(err) = task_manager
                                 .hard_link_or_copy(
-                                    task_id.as_str(),
+                                    task,
                                     Path::new(output_path.as_str()),
                                     download.range.clone(),
                                 )

dragonfly-client/src/task/mod.rs

@@ -165,13 +165,11 @@ impl Task {
     // hard_link_or_copy hard links or copies the task content to the destination.
     pub async fn hard_link_or_copy(
         &self,
-        task_id: &str,
+        task: metadata::Task,
         to: &Path,
         range: Option<Range>,
     ) -> ClientResult<()> {
-        self.storage
-            .hard_link_or_copy_task(task_id, to, range)
-            .await
+        self.storage.hard_link_or_copy_task(task, to, range).await
     }
 
     // download downloads a task.