Cache block time in Blockstore (#11955)

* Add blockstore column to cache block times

* Add method to cache block time

* Add service to cache block time

* Update rpc getBlockTime to use new method, and refactor blockstore slightly

* Return block_time with confirmed block, if available

* Add measure and warning to cache-block-time

core/src/cache_block_time_service.rs

@@ -0,0 +1,76 @@
+use crossbeam_channel::{Receiver, RecvTimeoutError, Sender};
+use solana_ledger::blockstore::Blockstore;
+use solana_measure::measure::Measure;
+use solana_runtime::bank::Bank;
+use solana_sdk::timing::slot_duration_from_slots_per_year;
+use std::{
+    collections::HashMap,
+    sync::{
+        atomic::{AtomicBool, Ordering},
+        Arc,
+    },
+    thread::{self, Builder, JoinHandle},
+    time::Duration,
+};
+
+pub type CacheBlockTimeReceiver = Receiver<Arc<Bank>>;
+pub type CacheBlockTimeSender = Sender<Arc<Bank>>;
+
+pub struct CacheBlockTimeService {
+    thread_hdl: JoinHandle<()>,
+}
+
+const CACHE_BLOCK_TIME_WARNING_MS: u64 = 150;
+
+impl CacheBlockTimeService {
+    #[allow(clippy::new_ret_no_self)]
+    pub fn new(
+        cache_block_time_receiver: CacheBlockTimeReceiver,
+        blockstore: Arc<Blockstore>,
+        exit: &Arc<AtomicBool>,
+    ) -> Self {
+        let exit = exit.clone();
+        let thread_hdl = Builder::new()
+            .name("solana-cache-block-time".to_string())
+            .spawn(move || loop {
+                if exit.load(Ordering::Relaxed) {
+                    break;
+                }
+                let recv_result = cache_block_time_receiver.recv_timeout(Duration::from_secs(1));
+                match recv_result {
+                    Err(RecvTimeoutError::Disconnected) => {
+                        break;
+                    }
+                    Ok(bank) => {
+                        let mut cache_block_time_timer = Measure::start("cache_block_time_timer");
+                        Self::cache_block_time(bank, &blockstore);
+                        cache_block_time_timer.stop();
+                        if cache_block_time_timer.as_ms() > CACHE_BLOCK_TIME_WARNING_MS {
+                            warn!(
+                                "cache_block_time operation took: {}ms",
+                                cache_block_time_timer.as_ms()
+                            );
+                        }
+                    }
+                    _ => {}
+                }
+            })
+            .unwrap();
+        Self { thread_hdl }
+    }
+
+    fn cache_block_time(bank: Arc<Bank>, blockstore: &Arc<Blockstore>) {
+        let slot_duration = slot_duration_from_slots_per_year(bank.slots_per_year());
+        let epoch = bank.epoch_schedule().get_epoch(bank.slot());
+        let stakes = HashMap::new();
+        let stakes = bank.epoch_vote_accounts(epoch).unwrap_or(&stakes);
+
+        if let Err(e) = blockstore.cache_block_time(bank.slot(), slot_duration, stakes) {
+            error!("cache_block_time failed: slot {:?} {:?}", bank.slot(), e);
+        }
+    }
+
+    pub fn join(self) -> thread::Result<()> {
+        self.thread_hdl.join()
+    }
+}