finish week 1 day 6

Signed-off-by: Alex Chi Z <iskyzh@gmail.com>

mini-lsm-starter/src/compact.rs

@@ -140,4 +140,27 @@ impl LsmStorageInner {
         }
         Ok(None)
     }
+
+    fn trigger_flush(&self) -> Result<()> {
+        Ok(())
+    }
+
+    pub(crate) fn spawn_flush_thread(
+        self: &Arc<Self>,
+        rx: crossbeam_channel::Receiver<()>,
+    ) -> Result<Option<std::thread::JoinHandle<()>>> {
+        let this = self.clone();
+        let handle = std::thread::spawn(move || {
+            let ticker = crossbeam_channel::tick(Duration::from_millis(50));
+            loop {
+                crossbeam_channel::select! {
+                    recv(ticker) -> _ => if let Err(e) = this.trigger_flush() {
+                        eprintln!("flush failed: {}", e);
+                    },
+                    recv(rx) -> _ => return
+                }
+            }
+        });
+        return Ok(Some(handle));
+    }
 }