Detect and notify when deserializable shreds are available (#11816)

* Add logic to check for complete data ranges

* Add RPC signature notification

Co-authored-by: Carl <carl@solana.com>

core/src/completed_data_sets_service.rs

@@ -0,0 +1,82 @@
+use crate::rpc_subscriptions::RpcSubscriptions;
+use crossbeam_channel::{Receiver, RecvTimeoutError, Sender};
+use solana_ledger::blockstore::{Blockstore, CompletedDataSetInfo};
+use solana_sdk::signature::Signature;
+use std::{
+    sync::{
+        atomic::{AtomicBool, Ordering},
+        Arc,
+    },
+    thread::{self, Builder, JoinHandle},
+    time::Duration,
+};
+
+pub type CompletedDataSetsReceiver = Receiver<Vec<CompletedDataSetInfo>>;
+pub type CompletedDataSetsSender = Sender<Vec<CompletedDataSetInfo>>;
+
+pub struct CompletedDataSetsService {
+    thread_hdl: JoinHandle<()>,
+}
+
+impl CompletedDataSetsService {
+    pub fn new(
+        completed_sets_receiver: CompletedDataSetsReceiver,
+        blockstore: Arc<Blockstore>,
+        rpc_subscriptions: Arc<RpcSubscriptions>,
+        exit: &Arc<AtomicBool>,
+    ) -> Self {
+        let exit = exit.clone();
+        let thread_hdl = Builder::new()
+            .name("completed-data-set-service".to_string())
+            .spawn(move || loop {
+                if exit.load(Ordering::Relaxed) {
+                    break;
+                }
+                if let Err(RecvTimeoutError::Disconnected) = Self::recv_completed_data_sets(
+                    &completed_sets_receiver,
+                    &blockstore,
+                    &rpc_subscriptions,
+                ) {
+                    break;
+                }
+            })
+            .unwrap();
+        Self { thread_hdl }
+    }
+
+    fn recv_completed_data_sets(
+        completed_sets_receiver: &CompletedDataSetsReceiver,
+        blockstore: &Blockstore,
+        rpc_subscriptions: &RpcSubscriptions,
+    ) -> Result<(), RecvTimeoutError> {
+        let completed_data_sets = completed_sets_receiver.recv_timeout(Duration::from_secs(1))?;
+        for completed_set_info in std::iter::once(completed_data_sets)
+            .chain(completed_sets_receiver.try_iter())
+            .flatten()
+        {
+            let CompletedDataSetInfo {
+                slot,
+                start_index,
+                end_index,
+            } = completed_set_info;
+            match blockstore.get_entries_in_data_block(slot, start_index, end_index, None) {
+                Ok(entries) => {
+                    let transactions = entries
+                        .into_iter()
+                        .flat_map(|e| e.transactions.into_iter().map(|t| t.signatures[0]))
+                        .collect::<Vec<Signature>>();
+                    if !transactions.is_empty() {
+                        rpc_subscriptions.notify_signatures_received((slot, transactions));
+                    }
+                }
+                Err(e) => warn!("completed-data-set-service deserialize error: {:?}", e),
+            }
+        }
+
+        Ok(())
+    }
+
+    pub fn join(self) -> thread::Result<()> {
+        self.thread_hdl.join()
+    }
+}