solana 0.18.0-pre1

//! The `replay_stage` replays transactions broadcast by the leader.

use crate::bank_forks::BankForks;
use crate::blocktree::{Blocktree, BlocktreeError};
use crate::blocktree_processor;
use crate::cluster_info::ClusterInfo;
use crate::consensus::{StakeLockout, Tower};
use crate::entry::{Entry, EntrySlice};
use crate::leader_schedule_cache::LeaderScheduleCache;
use crate::packet::BlobError;
use crate::poh_recorder::PohRecorder;
use crate::result::{Error, Result};
use crate::rpc_subscriptions::RpcSubscriptions;
use crate::service::Service;
use crate::snapshot_package::SnapshotPackageSender;
use solana_metrics::{datapoint_warn, inc_new_counter_info};
use solana_runtime::bank::Bank;
use solana_sdk::hash::Hash;
use solana_sdk::pubkey::Pubkey;
use solana_sdk::signature::KeypairUtil;
use solana_sdk::timing::{self, duration_as_ms};
use solana_sdk::transaction::Transaction;
use solana_vote_api::vote_instruction;
use std::collections::HashMap;
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::mpsc::{channel, Receiver, RecvTimeoutError, Sender};
use std::sync::{Arc, Mutex, RwLock};
use std::thread::{self, Builder, JoinHandle};
use std::time::Duration;
use std::time::Instant;

pub const MAX_ENTRY_RECV_PER_ITER: usize = 512;

// Implement a destructor for the ReplayStage thread to signal it exited
// even on panics
struct Finalizer {
    exit_sender: Arc<AtomicBool>,
}

impl Finalizer {
    fn new(exit_sender: Arc<AtomicBool>) -> Self {
        Finalizer { exit_sender }
    }
}

// Implement a destructor for Finalizer.
impl Drop for Finalizer {
    fn drop(&mut self) {
        self.exit_sender.clone().store(true, Ordering::Relaxed);
    }
}

pub struct ReplayStage {
    t_replay: JoinHandle<Result<()>>,
    t_lockouts: JoinHandle<()>,
}

#[derive(Default)]
struct ForkProgress {
    last_entry: Hash,
    num_blobs: usize,
    started_ms: u64,
    is_dead: bool,
}
impl ForkProgress {
    pub fn new(last_entry: Hash) -> Self {
        Self {
            last_entry,
            num_blobs: 0,
            started_ms: timing::timestamp(),
            is_dead: false,
        }
    }
}

impl ReplayStage {
    #[allow(
        clippy::new_ret_no_self,
        clippy::too_many_arguments,
        clippy::type_complexity
    )]
    pub fn new<T>(
        my_pubkey: &Pubkey,
        vote_account: &Pubkey,
        voting_keypair: Option<&Arc<T>>,
        blocktree: Arc<Blocktree>,
        bank_forks: &Arc<RwLock<BankForks>>,
        cluster_info: Arc<RwLock<ClusterInfo>>,
        exit: &Arc<AtomicBool>,
        ledger_signal_receiver: Receiver<bool>,
        subscriptions: &Arc<RpcSubscriptions>,
        poh_recorder: &Arc<Mutex<PohRecorder>>,
        leader_schedule_cache: &Arc<LeaderScheduleCache>,
        slot_full_senders: Vec<Sender<(u64, Pubkey)>>,
        snapshot_package_sender: Option<SnapshotPackageSender>,
    ) -> (Self, Receiver<Vec<Arc<Bank>>>)
    where
        T: 'static + KeypairUtil + Send + Sync,
    {
        let (root_bank_sender, root_bank_receiver) = channel();
        trace!("replay stage");
        let exit_ = exit.clone();
        let subscriptions = subscriptions.clone();
        let bank_forks = bank_forks.clone();
        let poh_recorder = poh_recorder.clone();
        let my_pubkey = *my_pubkey;
        let mut tower = Tower::new(&my_pubkey, &vote_account, &bank_forks.read().unwrap());
        // Start the replay stage loop
        let leader_schedule_cache = leader_schedule_cache.clone();
        let vote_account = *vote_account;
        let voting_keypair = voting_keypair.cloned();

        let (lockouts_sender, t_lockouts) = aggregate_stake_lockouts(exit);

        let t_replay = Builder::new()
            .name("solana-replay-stage".to_string())
            .spawn(move || {
                let _exit = Finalizer::new(exit_.clone());
                let mut progress = HashMap::new();
                let mut current_leader = None;

                loop {
                    let now = Instant::now();
                    // Stop getting entries if we get exit signal
                    if exit_.load(Ordering::Relaxed) {
                        break;
                    }

                    Self::generate_new_bank_forks(
                        &blocktree,
                        &mut bank_forks.write().unwrap(),
                        &leader_schedule_cache,
                    );

                    let mut tpu_has_bank = poh_recorder.lock().unwrap().has_bank();

                    let did_complete_bank = Self::replay_active_banks(
                        &blocktree,
                        &bank_forks,
                        &my_pubkey,
                        &mut progress,
                        &slot_full_senders,
                    );

                    let votable = Self::generate_votable_banks(&bank_forks, &tower, &mut progress);

                    if let Some((_, bank, lockouts, total_staked)) = votable.into_iter().last() {
                        subscriptions.notify_subscribers(bank.slot(), &bank_forks);

                        if let Some(votable_leader) =
                            leader_schedule_cache.slot_leader_at(bank.slot(), Some(&bank))
                        {
                            Self::log_leader_change(
                                &my_pubkey,
                                bank.slot(),
                                &mut current_leader,
                                &votable_leader,
                            );
                        }

                        let next_slot = bank.slot() + 1;
                        if let Some(new_leader) =
                            leader_schedule_cache.slot_leader_at(next_slot, Some(&bank))
                        {
                            datapoint_info!(
                                "replay_stage-new_leader",
                                ("slot", next_slot, i64),
                                ("leader", new_leader.to_string(), String),
                            );
                        }

                        Self::handle_votable_bank(
                            &bank,
                            &bank_forks,
                            &mut tower,
                            &mut progress,
                            &vote_account,
                            &voting_keypair,
                            &cluster_info,
                            &blocktree,
                            &leader_schedule_cache,
                            &root_bank_sender,
                            lockouts,
                            total_staked,
                            &lockouts_sender,
                            &snapshot_package_sender,
                        )?;

                        Self::reset_poh_recorder(
                            &my_pubkey,
                            &blocktree,
                            &bank,
                            &poh_recorder,
                            &leader_schedule_cache,
                        );
                        tpu_has_bank = false;
                    }

                    if !tpu_has_bank {
                        Self::maybe_start_leader(
                            &my_pubkey,
                            &bank_forks,
                            &poh_recorder,
                            &leader_schedule_cache,
                        );

                        if let Some(bank) = poh_recorder.lock().unwrap().bank() {
                            Self::log_leader_change(
                                &my_pubkey,
                                bank.slot(),
                                &mut current_leader,
                                &my_pubkey,
                            );
                        }
                    }

                    inc_new_counter_info!(
                        "replicate_stage-duration",
                        duration_as_ms(&now.elapsed()) as usize
                    );
                    if did_complete_bank {
                        //just processed a bank, skip the signal; maybe there's more slots available
                        continue;
                    }
                    let timer = Duration::from_millis(100);
                    let result = ledger_signal_receiver.recv_timeout(timer);
                    match result {
                        Err(RecvTimeoutError::Timeout) => continue,
                        Err(_) => break,
                        Ok(_) => trace!("blocktree signal"),
                    };
                }
                Ok(())
            })
            .unwrap();
        (
            Self {
                t_replay,
                t_lockouts,
            },
            root_bank_receiver,
        )
    }

    fn log_leader_change(
        my_pubkey: &Pubkey,
        bank_slot: u64,
        current_leader: &mut Option<Pubkey>,
        new_leader: &Pubkey,
    ) {
        if let Some(ref current_leader) = current_leader {
            if current_leader != new_leader {
                let msg = if current_leader == my_pubkey {
                    ". I am no longer the leader"
                } else if new_leader == my_pubkey {
                    ". I am now the leader"
                } else {
                    ""
                };
                info!(
                    "LEADER CHANGE at slot: {} leader: {}{}",
                    bank_slot, new_leader, msg
                );
            }
        }
        current_leader.replace(new_leader.to_owned());
    }

    fn maybe_start_leader(
        my_pubkey: &Pubkey,
        bank_forks: &Arc<RwLock<BankForks>>,
        poh_recorder: &Arc<Mutex<PohRecorder>>,
        leader_schedule_cache: &Arc<LeaderScheduleCache>,
    ) {
        // all the individual calls to poh_recorder.lock() are designed to
        // increase granularity, decrease contention

        assert!(!poh_recorder.lock().unwrap().has_bank());

        let (reached_leader_tick, _grace_ticks, poh_slot, parent_slot) =
            poh_recorder.lock().unwrap().reached_leader_tick();

        if !reached_leader_tick {
            trace!("{} poh_recorder hasn't reached_leader_tick", my_pubkey);
            return;
        }
        trace!("{} reached_leader_tick", my_pubkey,);

        let parent = bank_forks
            .read()
            .unwrap()
            .get(parent_slot)
            .expect("parent_slot doesn't exist in bank forks")
            .clone();

        assert!(parent.is_frozen());

        if bank_forks.read().unwrap().get(poh_slot).is_some() {
            warn!("{} already have bank in forks at {}?", my_pubkey, poh_slot);
            return;
        }
        trace!(
            "{} poh_slot {} parent_slot {}",
            my_pubkey,
            poh_slot,
            parent_slot
        );

        if let Some(next_leader) = leader_schedule_cache.slot_leader_at(poh_slot, Some(&parent)) {
            trace!(
                "{} leader {} at poh slot: {}",
                my_pubkey,
                next_leader,
                poh_slot
            );

            // I guess I missed my slot
            if next_leader != *my_pubkey {
                return;
            }

            datapoint_info!(
                "replay_stage-new_leader",
                ("slot", poh_slot, i64),
                ("leader", next_leader.to_string(), String),
            );

            let tpu_bank = bank_forks
                .write()
                .unwrap()
                .insert(Bank::new_from_parent(&parent, my_pubkey, poh_slot));

            poh_recorder.lock().unwrap().set_bank(&tpu_bank);
        } else {
            error!("{} No next leader found", my_pubkey);
        }
    }

    // Returns Some(result) if the `result` is a fatal error, which is an error that will cause a
    // bank to be marked as dead/corrupted
    fn is_replay_result_fatal(result: &Result<()>) -> bool {
        match result {
            Err(Error::TransactionError(e)) => {
                // Transactions withand transaction errors mean this fork is bogus
                let tx_error = Err(e.clone());
                !Bank::can_commit(&tx_error)
            }
            Err(Error::BlobError(BlobError::VerificationFailed)) => true,
            Err(Error::BlocktreeError(BlocktreeError::InvalidBlobData(_))) => true,
            _ => false,
        }
    }

    // Returns the replay result and the number of replayed transactions
    fn replay_blocktree_into_bank(
        bank: &Bank,
        blocktree: &Blocktree,
        progress: &mut HashMap<u64, ForkProgress>,
    ) -> (Result<()>, usize) {
        let mut tx_count = 0;
        let result =
            Self::load_blocktree_entries(bank, blocktree, progress).and_then(|(entries, num)| {
                tx_count += entries.iter().map(|e| e.transactions.len()).sum::<usize>();
                Self::replay_entries_into_bank(bank, entries, progress, num)
            });

        if Self::is_replay_result_fatal(&result) {
            warn!(
                "Fatal replay result in slot: {}, result: {:?}",
                bank.slot(),
                result
            );
            Self::mark_dead_slot(bank.slot(), blocktree, progress);
        }

        (result, tx_count)
    }

    fn mark_dead_slot(slot: u64, blocktree: &Blocktree, progress: &mut HashMap<u64, ForkProgress>) {
        // Remove from progress map so we no longer try to replay this bank
        let mut progress_entry = progress
            .get_mut(&slot)
            .expect("Progress entry must exist after call to replay_entries_into_bank()");
        progress_entry.is_dead = true;
        blocktree
            .set_dead_slot(slot)
            .expect("Failed to mark slot as dead in blocktree");
    }

    #[allow(clippy::too_many_arguments)]
    fn handle_votable_bank<T>(
        bank: &Arc<Bank>,
        bank_forks: &Arc<RwLock<BankForks>>,
        tower: &mut Tower,
        progress: &mut HashMap<u64, ForkProgress>,
        vote_account: &Pubkey,
        voting_keypair: &Option<Arc<T>>,
        cluster_info: &Arc<RwLock<ClusterInfo>>,
        blocktree: &Arc<Blocktree>,
        leader_schedule_cache: &Arc<LeaderScheduleCache>,
        root_bank_sender: &Sender<Vec<Arc<Bank>>>,
        lockouts: HashMap<u64, StakeLockout>,
        total_staked: u64,
        lockouts_sender: &Sender<LockoutAggregationData>,
        snapshot_package_sender: &Option<SnapshotPackageSender>,
    ) -> Result<()>
    where
        T: 'static + KeypairUtil + Send + Sync,
    {
        trace!("handle votable bank {}", bank.slot());
        if let Some(new_root) = tower.record_vote(bank.slot(), bank.hash()) {
            // get the root bank before squash
            let root_bank = bank_forks
                .read()
                .unwrap()
                .get(new_root)
                .expect("Root bank doesn't exist")
                .clone();
            let mut rooted_banks = root_bank.parents();
            rooted_banks.push(root_bank);
            let rooted_slots: Vec<_> = rooted_banks.iter().map(|bank| bank.slot()).collect();
            blocktree
                .set_roots(&rooted_slots)
                .expect("Ledger set roots failed");
            // Set root first in leader schedule_cache before bank_forks because bank_forks.root
            // is consumed by repair_service to update gossip, so we don't want to get blobs for
            // repair on gossip before we update leader schedule, otherwise they may get dropped.
            leader_schedule_cache.set_root(rooted_banks.last().unwrap());
            bank_forks
                .write()
                .unwrap()
                .set_root(new_root, snapshot_package_sender);
            Self::handle_new_root(&bank_forks, progress);
            trace!("new root {}", new_root);
            if let Err(e) = root_bank_sender.send(rooted_banks) {
                trace!("root_bank_sender failed: {:?}", e);
                Err(e)?;
            }
        }
        Self::update_confidence_cache(bank_forks, tower, lockouts, total_staked, lockouts_sender);

        if let Some(ref voting_keypair) = voting_keypair {
            let node_keypair = cluster_info.read().unwrap().keypair.clone();

            // Send our last few votes along with the new one
            let vote_ix = vote_instruction::vote(
                &vote_account,
                &voting_keypair.pubkey(),
                tower.recent_votes(),
            );

            let mut vote_tx =
                Transaction::new_with_payer(vec![vote_ix], Some(&node_keypair.pubkey()));

            let blockhash = bank.last_blockhash();
            vote_tx.partial_sign(&[node_keypair.as_ref()], blockhash);
            vote_tx.partial_sign(&[voting_keypair.as_ref()], blockhash);
            cluster_info.write().unwrap().push_vote(vote_tx);
        }
        Ok(())
    }

    fn update_confidence_cache(
        bank_forks: &Arc<RwLock<BankForks>>,
        tower: &Tower,
        lockouts: HashMap<u64, StakeLockout>,
        total_staked: u64,
        lockouts_sender: &Sender<LockoutAggregationData>,
    ) {
        {
            let mut bank_forks = bank_forks.write().unwrap();
            for (fork, stake_lockout) in lockouts.iter() {
                if tower.root().is_none() || *fork >= tower.root().unwrap() {
                    bank_forks.cache_fork_confidence(
                        *fork,
                        stake_lockout.stake(),
                        total_staked,
                        stake_lockout.lockout(),
                    );
                }
            }
        }

        let bank_forks_clone = bank_forks.clone();
        let root = tower.root();

        if let Err(e) = lockouts_sender.send((lockouts, root, bank_forks_clone)) {
            trace!("lockouts_sender failed: {:?}", e);
        }
    }

    fn reset_poh_recorder(
        my_pubkey: &Pubkey,
        blocktree: &Blocktree,
        bank: &Arc<Bank>,
        poh_recorder: &Arc<Mutex<PohRecorder>>,
        leader_schedule_cache: &Arc<LeaderScheduleCache>,
    ) {
        let next_leader_slot =
            leader_schedule_cache.next_leader_slot(&my_pubkey, bank.slot(), &bank, Some(blocktree));
        poh_recorder
            .lock()
            .unwrap()
            .reset(bank.last_blockhash(), bank.slot(), next_leader_slot);

        let next_leader_msg = if let Some(next_leader_slot) = next_leader_slot {
            format!("My next leader slot is {}", next_leader_slot.0)
        } else {
            "I am not in the leader schedule yet".to_owned()
        };

        info!(
            "{} voted and reset PoH at tick height {}. {}",
            my_pubkey,
            bank.tick_height(),
            next_leader_msg,
        );
    }

    fn replay_active_banks(
        blocktree: &Arc<Blocktree>,
        bank_forks: &Arc<RwLock<BankForks>>,
        my_pubkey: &Pubkey,
        progress: &mut HashMap<u64, ForkProgress>,
        slot_full_senders: &[Sender<(u64, Pubkey)>],
    ) -> bool {
        let mut did_complete_bank = false;
        let mut tx_count = 0;
        let active_banks = bank_forks.read().unwrap().active_banks();
        trace!("active banks {:?}", active_banks);

        for bank_slot in &active_banks {
            // If the fork was marked as dead, don't replay it
            if progress.get(bank_slot).map(|p| p.is_dead).unwrap_or(false) {
                continue;
            }

            let bank = bank_forks.read().unwrap().get(*bank_slot).unwrap().clone();
            if bank.collector_id() != my_pubkey {
                let (replay_result, replay_tx_count) =
                    Self::replay_blocktree_into_bank(&bank, &blocktree, progress);
                tx_count += replay_tx_count;
                if Self::is_replay_result_fatal(&replay_result) {
                    trace!("replay_result_fatal slot {}", bank_slot);
                    // If the bank was corrupted, don't try to run the below logic to check if the
                    // bank is completed
                    continue;
                }
            }
            assert_eq!(*bank_slot, bank.slot());
            if bank.tick_height() == bank.max_tick_height() {
                did_complete_bank = true;
                Self::process_completed_bank(my_pubkey, bank, slot_full_senders);
            } else {
                trace!(
                    "bank {} not completed tick_height: {}, max_tick_height: {}",
                    bank.slot(),
                    bank.tick_height(),
                    bank.max_tick_height()
                );
            }
        }
        inc_new_counter_info!("replay_stage-replay_transactions", tx_count);
        did_complete_bank
    }

    #[allow(clippy::type_complexity)]
    fn generate_votable_banks(
        bank_forks: &Arc<RwLock<BankForks>>,
        tower: &Tower,
        progress: &mut HashMap<u64, ForkProgress>,
    ) -> Vec<(u128, Arc<Bank>, HashMap<u64, StakeLockout>, u64)> {
        let tower_start = Instant::now();
        // Tower voting
        let descendants = bank_forks.read().unwrap().descendants();
        let ancestors = bank_forks.read().unwrap().ancestors();
        let frozen_banks = bank_forks.read().unwrap().frozen_banks();

        trace!("frozen_banks {}", frozen_banks.len());
        let mut votable: Vec<(u128, Arc<Bank>, HashMap<u64, StakeLockout>, u64)> = frozen_banks
            .values()
            .filter(|b| {
                let is_votable = b.is_votable();
                trace!("bank is votable: {} {}", b.slot(), is_votable);
                is_votable
            })
            .filter(|b| {
                let has_voted = tower.has_voted(b.slot());
                trace!("bank has_voted: {} {}", b.slot(), has_voted);
                !has_voted
            })
            .filter(|b| {
                let is_locked_out = tower.is_locked_out(b.slot(), &descendants);
                trace!("bank is is_locked_out: {} {}", b.slot(), is_locked_out);
                !is_locked_out
            })
            .map(|bank| {
                (
                    bank,
                    tower.collect_vote_lockouts(
                        bank.slot(),
                        bank.vote_accounts().into_iter(),
                        &ancestors,
                    ),
                )
            })
            .filter(|(b, (stake_lockouts, total_staked))| {
                let vote_threshold =
                    tower.check_vote_stake_threshold(b.slot(), &stake_lockouts, *total_staked);
                Self::confirm_forks(tower, &stake_lockouts, *total_staked, progress, bank_forks);
                debug!("bank vote_threshold: {} {}", b.slot(), vote_threshold);
                vote_threshold
            })
            .map(|(b, (stake_lockouts, total_staked))| {
                (
                    tower.calculate_weight(&stake_lockouts),
                    b.clone(),
                    stake_lockouts,
                    total_staked,
                )
            })
            .collect();

        votable.sort_by_key(|b| b.0);
        let ms = timing::duration_as_ms(&tower_start.elapsed());

        trace!("votable_banks {}", votable.len());
        if !votable.is_empty() {
            let weights: Vec<u128> = votable.iter().map(|x| x.0).collect();
            info!(
                "@{:?} tower duration: {:?} len: {} weights: {:?}",
                timing::timestamp(),
                ms,
                votable.len(),
                weights
            );
        }
        inc_new_counter_info!("replay_stage-tower_duration", ms as usize);

        votable
    }

    fn confirm_forks(
        tower: &Tower,
        stake_lockouts: &HashMap<u64, StakeLockout>,
        total_staked: u64,
        progress: &mut HashMap<u64, ForkProgress>,
        bank_forks: &Arc<RwLock<BankForks>>,
    ) {
        progress.retain(|slot, prog| {
            let duration = timing::timestamp() - prog.started_ms;
            if tower.is_slot_confirmed(*slot, stake_lockouts, total_staked)
                && bank_forks
                    .read()
                    .unwrap()
                    .get(*slot)
                    .map(|s| s.is_frozen())
                    .unwrap_or(true)
            {
                info!("validator fork confirmed {} {}ms", *slot, duration);
                datapoint_warn!("validator-confirmation", ("duration_ms", duration, i64));
                false
            } else {
                debug!(
                    "validator fork not confirmed {} {}ms {:?}",
                    *slot,
                    duration,
                    stake_lockouts.get(slot)
                );
                true
            }
        });
    }

    fn load_blocktree_entries(
        bank: &Bank,
        blocktree: &Blocktree,
        progress: &mut HashMap<u64, ForkProgress>,
    ) -> Result<(Vec<Entry>, usize)> {
        let bank_slot = bank.slot();
        let bank_progress = &mut progress
            .entry(bank_slot)
            .or_insert_with(|| ForkProgress::new(bank.last_blockhash()));
        blocktree.get_slot_entries_with_blob_count(bank_slot, bank_progress.num_blobs as u64, None)
    }

    fn replay_entries_into_bank(
        bank: &Bank,
        entries: Vec<Entry>,
        progress: &mut HashMap<u64, ForkProgress>,
        num: usize,
    ) -> Result<()> {
        let bank_progress = &mut progress
            .entry(bank.slot())
            .or_insert_with(|| ForkProgress::new(bank.last_blockhash()));
        let result = Self::verify_and_process_entries(&bank, &entries, &bank_progress.last_entry);
        bank_progress.num_blobs += num;
        if let Some(last_entry) = entries.last() {
            bank_progress.last_entry = last_entry.hash;
        }

        result
    }

    pub fn verify_and_process_entries(
        bank: &Bank,
        entries: &[Entry],
        last_entry: &Hash,
    ) -> Result<()> {
        if !entries.verify(last_entry) {
            trace!(
                "entry verification failed {} {} {} {}",
                entries.len(),
                bank.tick_height(),
                last_entry,
                bank.last_blockhash()
            );

            datapoint_error!(
                "replay-stage-entry_verification_failure",
                ("slot", bank.slot(), i64),
                ("last_entry", last_entry.to_string(), String),
            );
            return Err(Error::BlobError(BlobError::VerificationFailed));
        }
        blocktree_processor::process_entries(bank, entries)?;

        Ok(())
    }

    fn handle_new_root(
        bank_forks: &Arc<RwLock<BankForks>>,
        progress: &mut HashMap<u64, ForkProgress>,
    ) {
        let r_bank_forks = bank_forks.read().unwrap();
        progress.retain(|k, _| r_bank_forks.get(*k).is_some());
    }

    fn process_completed_bank(
        my_pubkey: &Pubkey,
        bank: Arc<Bank>,
        slot_full_senders: &[Sender<(u64, Pubkey)>],
    ) {
        bank.freeze();
        info!("bank frozen {}", bank.slot());
        slot_full_senders.iter().for_each(|sender| {
            if let Err(e) = sender.send((bank.slot(), *bank.collector_id())) {
                trace!("{} slot_full alert failed: {:?}", my_pubkey, e);
            }
        });
    }

    fn generate_new_bank_forks(
        blocktree: &Blocktree,
        forks: &mut BankForks,
        leader_schedule_cache: &Arc<LeaderScheduleCache>,
    ) {
        // Find the next slot that chains to the old slot
        let frozen_banks = forks.frozen_banks();
        let frozen_bank_slots: Vec<u64> = frozen_banks.keys().cloned().collect();
        let next_slots = blocktree
            .get_slots_since(&frozen_bank_slots)
            .expect("Db error");
        // Filter out what we've already seen
        trace!("generate new forks {:?}", {
            let mut next_slots = next_slots.iter().collect::<Vec<_>>();
            next_slots.sort();
            next_slots
        });
        for (parent_id, children) in next_slots {
            let parent_bank = frozen_banks
                .get(&parent_id)
                .expect("missing parent in bank forks")
                .clone();
            for child_id in children {
                if forks.get(child_id).is_some() {
                    trace!("child already active or frozen {}", child_id);
                    continue;
                }
                let leader = leader_schedule_cache
                    .slot_leader_at(child_id, Some(&parent_bank))
                    .unwrap();
                info!("new fork:{} parent:{}", child_id, parent_id);
                forks.insert(Bank::new_from_parent(&parent_bank, &leader, child_id));
            }
        }
    }
}

impl Service for ReplayStage {
    type JoinReturnType = ();

    fn join(self) -> thread::Result<()> {
        self.t_lockouts.join()?;
        self.t_replay.join().map(|_| ())
    }
}

type LockoutAggregationData = (
    HashMap<u64, StakeLockout>, // lockouts
    Option<u64>,                // root
    Arc<RwLock<BankForks>>,     // bank_forks
);

fn aggregate_stake_lockouts(
    exit: &Arc<AtomicBool>,
) -> (Sender<LockoutAggregationData>, JoinHandle<()>) {
    let (lockouts_sender, lockouts_receiver): (
        Sender<LockoutAggregationData>,
        Receiver<LockoutAggregationData>,
    ) = channel();
    let exit_ = exit.clone();
    (
        lockouts_sender,
        Builder::new()
            .name("solana-aggregate-stake-lockouts".to_string())
            .spawn(move || loop {
                if exit_.load(Ordering::Relaxed) {
                    break;
                }
                if let Ok((lockouts, root, bank_forks)) = lockouts_receiver.try_recv() {
                    let ancestors = bank_forks.read().unwrap().ancestors();
                    let stake_weighted_lockouts =
                        Tower::aggregate_stake_lockouts(root, &ancestors, lockouts);
                    let mut w_bank_forks = bank_forks.write().unwrap();
                    for (fork, stake_weighted_lockout) in stake_weighted_lockouts.iter() {
                        if root.is_none() || *fork >= root.unwrap() {
                            w_bank_forks
                                .cache_stake_weighted_lockouts(*fork, *stake_weighted_lockout)
                        }
                    }
                    drop(w_bank_forks);
                }
            })
            .unwrap(),
    )
}

#[cfg(test)]
mod test {
    use super::*;
    use crate::bank_forks::Confidence;
    use crate::blocktree::get_tmp_ledger_path;
    use crate::entry;
    use crate::erasure::ErasureConfig;
    use crate::genesis_utils::{create_genesis_block, create_genesis_block_with_leader};
    use crate::packet::{Blob, BLOB_HEADER_SIZE};
    use crate::replay_stage::ReplayStage;
    use solana_runtime::genesis_utils::GenesisBlockInfo;
    use solana_sdk::hash::{hash, Hash};
    use solana_sdk::signature::{Keypair, KeypairUtil};
    use solana_sdk::system_transaction;
    use solana_sdk::transaction::TransactionError;
    use solana_vote_api::vote_state::VoteState;
    use std::fs::remove_dir_all;
    use std::sync::{Arc, RwLock};

    #[test]
    fn test_child_slots_of_same_parent() {
        let ledger_path = get_tmp_ledger_path!();
        {
            let blocktree = Arc::new(
                Blocktree::open(&ledger_path).expect("Expected to be able to open database ledger"),
            );

            let genesis_block = create_genesis_block(10_000).genesis_block;
            let bank0 = Bank::new(&genesis_block);
            let leader_schedule_cache = Arc::new(LeaderScheduleCache::new_from_bank(&bank0));
            let mut bank_forks = BankForks::new(0, bank0);
            bank_forks.working_bank().freeze();

            // Insert blob for slot 1, generate new forks, check result
            let mut blob_slot_1 = Blob::default();
            blob_slot_1.set_slot(1);
            blob_slot_1.set_parent(0);
            blob_slot_1.set_erasure_config(&ErasureConfig::default());
            blocktree.insert_data_blobs(&vec![blob_slot_1]).unwrap();
            assert!(bank_forks.get(1).is_none());
            ReplayStage::generate_new_bank_forks(
                &blocktree,
                &mut bank_forks,
                &leader_schedule_cache,
            );
            assert!(bank_forks.get(1).is_some());

            // Insert blob for slot 3, generate new forks, check result
            let mut blob_slot_2 = Blob::default();
            blob_slot_2.set_slot(2);
            blob_slot_2.set_parent(0);
            blob_slot_2.set_erasure_config(&ErasureConfig::default());
            blocktree.insert_data_blobs(&vec![blob_slot_2]).unwrap();
            assert!(bank_forks.get(2).is_none());
            ReplayStage::generate_new_bank_forks(
                &blocktree,
                &mut bank_forks,
                &leader_schedule_cache,
            );
            assert!(bank_forks.get(1).is_some());
            assert!(bank_forks.get(2).is_some());
        }

        let _ignored = remove_dir_all(&ledger_path);
    }

    #[test]
    fn test_handle_new_root() {
        let genesis_block = create_genesis_block(10_000).genesis_block;
        let bank0 = Bank::new(&genesis_block);
        let bank_forks = Arc::new(RwLock::new(BankForks::new(0, bank0)));
        let mut progress = HashMap::new();
        progress.insert(5, ForkProgress::new(Hash::default()));
        ReplayStage::handle_new_root(&bank_forks, &mut progress);
        assert!(progress.is_empty());
    }

    #[test]
    fn test_dead_fork_transaction_error() {
        let keypair1 = Keypair::new();
        let keypair2 = Keypair::new();
        let missing_keypair = Keypair::new();
        let missing_keypair2 = Keypair::new();

        let res = check_dead_fork(|blockhash| {
            entry::next_entry(
                blockhash,
                1,
                vec![
                    system_transaction::create_user_account(
                        &keypair1,
                        &keypair2.pubkey(),
                        2,
                        *blockhash,
                    ), // should be fine,
                    system_transaction::transfer(
                        &missing_keypair,
                        &missing_keypair2.pubkey(),
                        2,
                        *blockhash,
                    ), // should cause AccountNotFound error
                ],
            )
            .to_blob()
        });

        assert_matches!(
            res,
            Err(Error::TransactionError(TransactionError::AccountNotFound))
        );
    }

    #[test]
    fn test_dead_fork_entry_verification_failure() {
        let keypair1 = Keypair::new();
        let keypair2 = Keypair::new();
        let res = check_dead_fork(|blockhash| {
            let bad_hash = hash(&[2; 30]);
            entry::next_entry(
                // User wrong blockhash so that the the entry causes an entry verification failure
                &bad_hash,
                1,
                vec![system_transaction::create_user_account(
                    &keypair1,
                    &keypair2.pubkey(),
                    2,
                    *blockhash,
                )],
            )
            .to_blob()
        });

        assert_matches!(res, Err(Error::BlobError(BlobError::VerificationFailed)));
    }

    #[test]
    fn test_dead_fork_blob_deserialize_failure() {
        let keypair1 = Keypair::new();
        let keypair2 = Keypair::new();
        // Insert entry that causes blob deserialization failure

        let res = check_dead_fork(|blockhash| {
            let mut b = entry::next_entry(
                &blockhash,
                1,
                vec![system_transaction::create_user_account(
                    &keypair1,
                    &keypair2.pubkey(),
                    2,
                    *blockhash,
                )],
            )
            .to_blob();
            b.set_size(BLOB_HEADER_SIZE);
            b
        });

        assert_matches!(
            res,
            Err(Error::BlocktreeError(BlocktreeError::InvalidBlobData(_)))
        );
    }

    // Given a blob and a fatal expected error, check that replaying that blob causes causes the fork to be
    // marked as dead. Returns the error for caller to verify.
    fn check_dead_fork<F>(blob_to_insert: F) -> Result<()>
    where
        F: Fn(&Hash) -> Blob,
    {
        let ledger_path = get_tmp_ledger_path!();
        let res = {
            let blocktree = Arc::new(
                Blocktree::open(&ledger_path).expect("Expected to be able to open database ledger"),
            );
            let GenesisBlockInfo { genesis_block, .. } = create_genesis_block(1000);
            let bank0 = Arc::new(Bank::new(&genesis_block));
            let mut progress = HashMap::new();
            let last_blockhash = bank0.last_blockhash();
            progress.insert(bank0.slot(), ForkProgress::new(last_blockhash));
            let blob = blob_to_insert(&last_blockhash);
            blocktree.insert_data_blobs(&[blob]).unwrap();
            let (res, _tx_count) =
                ReplayStage::replay_blocktree_into_bank(&bank0, &blocktree, &mut progress);

            // Check that the erroring bank was marked as dead in the progress map
            assert!(progress
                .get(&bank0.slot())
                .map(|b| b.is_dead)
                .unwrap_or(false));

            // Check that the erroring bank was marked as dead in blocktree
            assert!(blocktree.is_dead(bank0.slot()));
            res
        };
        let _ignored = remove_dir_all(&ledger_path);
        res
    }

    #[test]
    fn test_replay_confidence_cache() {
        fn leader_vote(bank: &Arc<Bank>, pubkey: &Pubkey) {
            let mut leader_vote_account = bank.get_account(&pubkey).unwrap();
            let mut vote_state = VoteState::from(&leader_vote_account).unwrap();
            vote_state.process_slot_vote_unchecked(bank.slot());
            vote_state.to(&mut leader_vote_account).unwrap();
            bank.store_account(&pubkey, &leader_vote_account);
        }

        let (lockouts_sender, _) = aggregate_stake_lockouts(&Arc::new(AtomicBool::new(false)));

        let leader_pubkey = Pubkey::new_rand();
        let leader_lamports = 3;
        let genesis_block_info =
            create_genesis_block_with_leader(50, &leader_pubkey, leader_lamports);
        let mut genesis_block = genesis_block_info.genesis_block;
        let leader_voting_pubkey = genesis_block_info.voting_keypair.pubkey();
        genesis_block.epoch_warmup = false;
        genesis_block.ticks_per_slot = 4;
        let bank0 = Bank::new(&genesis_block);
        for _ in 1..genesis_block.ticks_per_slot {
            bank0.register_tick(&Hash::default());
        }
        bank0.freeze();
        let arc_bank0 = Arc::new(bank0);
        let bank_forks = Arc::new(RwLock::new(BankForks::new_from_banks(
            &[arc_bank0.clone()],
            vec![0],
        )));
        let pubkey = Pubkey::new_rand();
        let mut tower = Tower::new(&pubkey, &Pubkey::new_rand(), &bank_forks.read().unwrap());
        let mut progress = HashMap::new();

        leader_vote(&arc_bank0, &leader_voting_pubkey);
        let votable = ReplayStage::generate_votable_banks(&bank_forks, &tower, &mut progress);
        if let Some((_, _, lockouts, total_staked)) = votable.into_iter().last() {
            ReplayStage::update_confidence_cache(
                &bank_forks,
                &tower,
                lockouts,
                total_staked,
                &lockouts_sender,
            );
        }

        assert_eq!(
            bank_forks.read().unwrap().get_fork_confidence(0).unwrap(),
            &Confidence::new(0, 3, 2)
        );
        assert!(bank_forks.read().unwrap().get_fork_confidence(1).is_none());

        tower.record_vote(arc_bank0.slot(), arc_bank0.hash());

        let bank1 = Bank::new_from_parent(&arc_bank0, &Pubkey::default(), arc_bank0.slot() + 1);
        let _res = bank1.transfer(10, &genesis_block_info.mint_keypair, &Pubkey::new_rand());
        for _ in 0..genesis_block.ticks_per_slot {
            bank1.register_tick(&Hash::default());
        }
        bank1.freeze();
        bank_forks.write().unwrap().insert(bank1);
        let arc_bank1 = bank_forks.read().unwrap().get(1).unwrap().clone();
        leader_vote(&arc_bank1, &leader_voting_pubkey);
        let votable = ReplayStage::generate_votable_banks(&bank_forks, &tower, &mut progress);
        if let Some((_, _, lockouts, total_staked)) = votable.into_iter().last() {
            ReplayStage::update_confidence_cache(
                &bank_forks,
                &tower,
                lockouts,
                total_staked,
                &lockouts_sender,
            );
        }

        tower.record_vote(arc_bank1.slot(), arc_bank1.hash());

        let bank2 = Bank::new_from_parent(&arc_bank1, &Pubkey::default(), arc_bank1.slot() + 1);
        let _res = bank2.transfer(10, &genesis_block_info.mint_keypair, &Pubkey::new_rand());
        for _ in 0..genesis_block.ticks_per_slot {
            bank2.register_tick(&Hash::default());
        }
        bank2.freeze();
        bank_forks.write().unwrap().insert(bank2);
        let arc_bank2 = bank_forks.read().unwrap().get(2).unwrap().clone();
        leader_vote(&arc_bank2, &leader_voting_pubkey);
        let votable = ReplayStage::generate_votable_banks(&bank_forks, &tower, &mut progress);
        if let Some((_, _, lockouts, total_staked)) = votable.into_iter().last() {
            ReplayStage::update_confidence_cache(
                &bank_forks,
                &tower,
                lockouts,
                total_staked,
                &lockouts_sender,
            );
        }
        thread::sleep(Duration::from_millis(200));

        assert_eq!(
            bank_forks.read().unwrap().get_fork_confidence(0).unwrap(),
            &Confidence::new_with_stake_weighted(3, 3, 14, 60)
        );
        assert_eq!(
            bank_forks.read().unwrap().get_fork_confidence(1).unwrap(),
            &Confidence::new_with_stake_weighted(3, 3, 6, 18)
        );
        assert_eq!(
            bank_forks.read().unwrap().get_fork_confidence(2).unwrap(),
            &Confidence::new_with_stake_weighted(0, 3, 2, 0)
        );
    }
}