Add bank drop service (#21322) (#21360)

(cherry picked from commit 0bda0c3e0c)

Co-authored-by: sakridge <sakridge@gmail.com>

core/src/drop_bank_service.rs

@@ -0,0 +1,38 @@
+use solana_measure::measure::Measure;
+use solana_runtime::bank::Bank;
+use std::{
+    sync::{mpsc::Receiver, Arc},
+    thread::{self, Builder, JoinHandle},
+};
+
+pub struct DropBankService {
+    thread_hdl: JoinHandle<()>,
+}
+
+impl DropBankService {
+    pub fn new(bank_receiver: Receiver<Vec<Arc<Bank>>>) -> Self {
+        let thread_hdl = Builder::new()
+            .name("sol-drop-b-service".to_string())
+            .spawn(move || {
+                for banks in bank_receiver.iter() {
+                    let len = banks.len();
+                    let mut dropped_banks_time = Measure::start("drop_banks");
+                    drop(banks);
+                    dropped_banks_time.stop();
+                    if dropped_banks_time.as_ms() > 10 {
+                        datapoint_info!(
+                            "handle_new_root-dropped_banks",
+                            ("elapsed_ms", dropped_banks_time.as_ms(), i64),
+                            ("len", len, i64)
+                        );
+                    }
+                }
+            })
+            .unwrap();
+        Self { thread_hdl }
+    }
+
+    pub fn join(self) -> thread::Result<()> {
+        self.thread_hdl.join()
+    }
+}