feat: Add executor in OpXxx and Operator

core/src/lib.rs

@@ -153,7 +153,7 @@ mod tests {
     /// unexpected struct/enum size change.
     #[test]
     fn assert_size() {
-        assert_eq!(24, size_of::<Operator>());
+        assert_eq!(40, size_of::<Operator>());
         assert_eq!(256, size_of::<Entry>());
         assert_eq!(232, size_of::<Metadata>());
         assert_eq!(1, size_of::<EntryMode>());

core/src/raw/ops.rs

@@ -306,6 +306,7 @@ pub struct OpRead {
     override_cache_control: Option<String>,
     override_content_disposition: Option<String>,
     version: Option<String>,
+    executor: Option<Executor>,
 }
 
 impl OpRead {
@@ -380,6 +381,31 @@ impl OpRead {
     pub fn version(&self) -> Option<&str> {
         self.version.as_deref()
     }
+
+    /// Set the executor of the option
+    pub fn with_executor(mut self, executor: Executor) -> Self {
+        self.executor = Some(executor);
+        self
+    }
+
+    /// Merge given executor into option.
+    ///
+    /// If executor has already been set, this will do nothing.
+    /// Otherwise, this will set the given executor.
+    pub(crate) fn merge_executor(self, executor: Option<Executor>) -> Self {
+        if self.executor.is_some() {
+            return self;
+        }
+        if let Some(exec) = executor {
+            return self.with_executor(exec);
+        }
+        self
+    }
+
+    /// Get executor from option
+    pub fn executor(&self) -> Option<&Executor> {
+        self.executor.as_ref()
+    }
 }
 
 /// Args for reader operation.
@@ -550,10 +576,10 @@ pub struct OpWrite {
     append: bool,
     chunk: Option<usize>,
     concurrent: usize,
-
     content_type: Option<String>,
     content_disposition: Option<String>,
     cache_control: Option<String>,
+    executor: Option<Executor>,
 }
 
 impl OpWrite {
@@ -647,6 +673,31 @@ impl OpWrite {
         self.concurrent = concurrent;
         self
     }
+
+    /// Get the executor from option
+    pub fn executor(&self) -> Option<&Executor> {
+        self.executor.as_ref()
+    }
+
+    /// Set the executor of the option
+    pub fn with_executor(mut self, executor: Executor) -> Self {
+        self.executor = Some(executor);
+        self
+    }
+
+    /// Merge given executor into option.
+    ///
+    /// If executor has already been set, this will do nothing.
+    /// Otherwise, this will set the given executor.
+    pub(crate) fn merge_executor(self, executor: Option<Executor>) -> Self {
+        if self.executor.is_some() {
+            return self;
+        }
+        if let Some(exec) = executor {
+            return self.with_executor(exec);
+        }
+        self
+    }
 }
 
 /// Args for `copy` operation.

core/src/types/execute/api.rs

@@ -24,7 +24,7 @@ use std::pin::Pin;
 use std::task::{Context, Poll};
 
 /// Execute trait is used to execute task in background.
-pub trait Execute: 'static {
+pub trait Execute: Send + Sync + 'static {
     /// Execute async task in background.
     ///
     /// # Behavior
@@ -34,6 +34,15 @@ pub trait Execute: 'static {
     fn execute(&self, f: BoxedStaticFuture<()>) -> Result<()>;
 }
 
+impl Execute for () {
+    fn execute(&self, _: BoxedStaticFuture<()>) -> Result<()> {
+        Err(Error::new(
+            ErrorKind::Unexpected,
+            "no executor has been set",
+        ))
+    }
+}
+
 /// Task is generated by Executor that represents an executing task.
 ///
 /// Users can fetch the results by calling `poll` or `.await` on this task.

core/src/types/execute/executor.rs

@@ -19,6 +19,7 @@ use super::*;
 use crate::raw::MaybeSend;
 use crate::*;
 use futures::FutureExt;
+use std::fmt::{Debug, Formatter};
 use std::future::Future;
 use std::sync::Arc;
 
@@ -29,11 +30,17 @@ use std::sync::Arc;
 ///
 /// Executor will run futures in background and return a [`Task`] as handle to the future. Users
 /// can call `task.await` to wait for the future to complete or drop the `Task` to cancel it.
+#[derive(Clone)]
 pub struct Executor {
     executor: Arc<dyn Execute>,
 }
 
-#[cfg(feature = "executors-tokio")]
+impl Debug for Executor {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "Executor")
+    }
+}
+
 impl Default for Executor {
     fn default() -> Self {
         Self::new()
@@ -43,10 +50,17 @@ impl Default for Executor {
 impl Executor {
     /// Create a default executor.
     ///
-    /// The default executor is enabled by feature flags.
-    #[cfg(feature = "executors-tokio")]
+    /// The default executor is enabled by feature flags. If no feature flags enabled, the default
+    /// executor will always return error if users try to perform concurrent tasks.
     pub fn new() -> Self {
-        Self::with(executors::TokioExecutor::default())
+        #[cfg(feature = "executors-tokio")]
+        {
+            Self::with(executors::TokioExecutor::default())
+        }
+        #[cfg(not(feature = "executors-tokio"))]
+        {
+            Self::with(())
+        }
     }
 
     /// Create a new executor with given execute impl.

core/src/types/operator/operator.rs

@@ -67,6 +67,8 @@ pub struct Operator {
 
     // limit is usually the maximum size of data that operator will handle in one operation
     limit: usize,
+    /// The default executor that used to run futures in background.
+    default_executor: Option<Executor>,
 }
 
 /// # Operator basic API.
@@ -81,7 +83,11 @@ impl Operator {
             .full_capability()
             .batch_max_operations
             .unwrap_or(1000);
-        Self { accessor, limit }
+        Self {
+            accessor,
+            limit,
+            default_executor: None,
+        }
     }
 
     pub(super) fn into_inner(self) -> Accessor {
@@ -103,6 +109,18 @@ impl Operator {
         op
     }
 
+    /// Get the default executor.
+    pub fn default_executor(&self) -> Option<Executor> {
+        self.default_executor.clone()
+    }
+
+    /// Specify the default executor.
+    pub fn with_default_executor(&self, executor: Executor) -> Self {
+        let mut op = self.clone();
+        op.default_executor = Some(executor);
+        op
+    }
+
     /// Get information of underlying accessor.
     ///
     /// # Examples
@@ -537,7 +555,10 @@ impl Operator {
         OperatorFuture::new(
             self.inner().clone(),
             path,
-            (OpRead::default(), OpReader::default()),
+            (
+                OpRead::default().merge_executor(self.default_executor.clone()),
+                OpReader::default(),
+            ),
             |inner, path, (args, options)| async move {
                 if !validate_path(&path, EntryMode::FILE) {
                     return Err(
@@ -647,7 +668,10 @@ impl Operator {
         OperatorFuture::new(
             self.inner().clone(),
             path,
-            (OpRead::default(), OpReader::default()),
+            (
+                OpRead::default().merge_executor(self.default_executor.clone()),
+                OpReader::default(),
+            ),
             |inner, path, (args, options)| async move {
                 if !validate_path(&path, EntryMode::FILE) {
                     return Err(
@@ -1052,7 +1076,7 @@ impl Operator {
         OperatorFuture::new(
             self.inner().clone(),
             path,
-            OpWrite::default(),
+            OpWrite::default().merge_executor(self.default_executor.clone()),
             |inner, path, args| async move {
                 if !validate_path(&path, EntryMode::FILE) {
                     return Err(
@@ -1196,7 +1220,10 @@ impl Operator {
         OperatorFuture::new(
             self.inner().clone(),
             path,
-            (OpWrite::default(), bs),
+            (
+                OpWrite::default().merge_executor(self.default_executor.clone()),
+                bs,
+            ),
             |inner, path, (args, bs)| async move {
                 if !validate_path(&path, EntryMode::FILE) {
                     return Err(

core/src/types/operator/operator_futures.rs

@@ -217,6 +217,11 @@ impl<F: Future<Output = Result<Buffer>>> FutureRead<F> {
         self.map(|(args, op_reader)| (args.with_version(v), op_reader))
     }
 
+    /// Set the executor for this operation.
+    pub fn executor(self, executor: Executor) -> Self {
+        self.map(|(args, op_reader)| (args.with_executor(executor), op_reader))
+    }
+
     /// Set the range header for this operation.
     pub fn range(self, range: impl RangeBounds<u64>) -> Self {
         self.map(|(args, op_reader)| (args, op_reader.with_range(range.into())))
@@ -312,6 +317,11 @@ impl<F: Future<Output = Result<()>>> FutureWrite<F> {
     pub fn content_disposition(self, v: &str) -> Self {
         self.map(|(args, bs)| (args.with_content_disposition(v), bs))
     }
+
+    /// Set the executor for this operation.
+    pub fn executor(self, executor: Executor) -> Self {
+        self.map(|(args, bs)| (args.with_executor(executor), bs))
+    }
 }
 
 /// Future that generated by [`Operator::writer_with`].
@@ -369,6 +379,11 @@ impl<F: Future<Output = Result<Writer>>> FutureWriter<F> {
     pub fn content_disposition(self, v: &str) -> Self {
         self.map(|args| args.with_content_disposition(v))
     }
+
+    /// Set the executor for this operation.
+    pub fn executor(self, executor: Executor) -> Self {
+        self.map(|args| args.with_executor(executor))
+    }
 }
 
 /// Future that generated by [`Operator::delete_with`].