feat(backend) scheduler rewrite (deadlock for now)

backend/server/src/scheduler/tasks/async_basic.rs

@@ -0,0 +1,37 @@
+use std::{error::Error, pin::Pin, str::FromStr};
+
+use crate::{scheduler::task_func::AsyncTaskFunc, scheduler::tasks::CronTask};
+
+use chrono::{DateTime, Utc};
+use cron::Schedule;
+
+pub struct AsyncBasic {
+    schedule: Schedule,
+    func: Box<dyn AsyncTaskFunc>,
+}
+
+impl AsyncBasic {
+    pub fn new<F>(func: F, cron_expr: &str) -> Result<Self, Box<dyn Error>>
+    where
+        F: AsyncTaskFunc,
+    {
+        Ok(AsyncBasic {
+            schedule: Schedule::from_str(cron_expr)?,
+            func: Box::new(func),
+        })
+    }
+
+    pub fn to_task(self) -> Box<dyn CronTask> {
+        Box::new(self)
+    }
+}
+
+impl CronTask for AsyncBasic {
+    fn get_next_execution(&self) -> Option<DateTime<Utc>> {
+        self.schedule.upcoming(Utc).next()
+    }
+
+    fn call(&self) -> Pin<Box<(dyn Future<Output = ()> + Send)>> {
+        Box::pin((self.func)())
+    }
+}