massa_pos_exports/

pos_final_state.rs

use crate::{
    CycleInfo, CycleInfoDeserializer, CycleInfoSerializer, DeferredCreditDeserializer,
    DeferredCreditSerializer, DeferredCredits, PoSChanges, PoSConfig, PosError, PosResult,
    ProductionStats, SelectorController,
};
use bitvec::vec::BitVec;
use massa_db_exports::{
    DBBatch, MassaDirection, MassaIteratorMode, ShareableMassaDBController,
    CYCLE_HISTORY_DESER_ERROR, CYCLE_HISTORY_PREFIX, CYCLE_HISTORY_SER_ERROR,
    DEFERRED_CREDITS_DESER_ERROR, DEFERRED_CREDITS_PREFIX, DEFERRED_CREDITS_SER_ERROR, STATE_CF,
};
use massa_hash::{Hash, HashXof, HASH_XOF_SIZE_BYTES};
use massa_ledger_exports::LedgerController;
use massa_models::{
    address::Address, amount::Amount, config::LEDGER_ENTRY_BASE_COST, prehash::PreHashMap,
    slot::Slot,
};
use massa_serialization::{
    buf_to_array_ctr, DeserializeError, Deserializer, Serializer, U64VarIntSerializer,
};
use nom::AsBytes;
use std::{
    collections::{BTreeMap, VecDeque},
    ops::{
        Bound::{Excluded, Included, Unbounded},
        RangeBounds,
    },
    path::PathBuf,
};
use tracing::{debug, warn};

// General cycle info idents
const COMPLETE_IDENT: u8 = 0u8;
const RNG_SEED_IDENT: u8 = 1u8;
const FINAL_STATE_HASH_SNAPSHOT_IDENT: u8 = 2u8;
const ROLL_COUNT_IDENT: u8 = 3u8;
const PROD_STATS_IDENT: u8 = 4u8;

// Production stats idents
const PROD_STATS_FAIL_IDENT: u8 = 0u8;
const PROD_STATS_SUCCESS_IDENT: u8 = 1u8;

/// Complete key formatting macro
#[macro_export]
macro_rules! complete_key {
    ($cycle_prefix:expr) => {
        [&$cycle_prefix[..], &[COMPLETE_IDENT]].concat()
    };
}

/// Rng seed key formatting macro
#[macro_export]
macro_rules! rng_seed_key {
    ($cycle_prefix:expr) => {
        [&$cycle_prefix[..], &[RNG_SEED_IDENT]].concat()
    };
}

/// Final state hash snapshot key formatting macro
#[macro_export]
macro_rules! final_state_hash_snapshot_key {
    ($cycle_prefix:expr) => {
        [&$cycle_prefix[..], &[FINAL_STATE_HASH_SNAPSHOT_IDENT]].concat()
    };
}

/// Roll count key prefix macro
#[macro_export]
macro_rules! roll_count_prefix {
    ($cycle_prefix:expr) => {
        [&$cycle_prefix[..], &[ROLL_COUNT_IDENT]].concat()
    };
}

/// Roll count key formatting macro
#[macro_export]
macro_rules! roll_count_key {
    ($cycle_prefix:expr, $addr:expr) => {
        [
            &$cycle_prefix[..],
            &[ROLL_COUNT_IDENT],
            &$addr.to_prefixed_bytes()[..],
        ]
        .concat()
    };
}

/// Production stats prefix macro
#[macro_export]
macro_rules! prod_stats_prefix {
    ($cycle_prefix:expr) => {
        [&$cycle_prefix[..], &[PROD_STATS_IDENT]].concat()
    };
}

/// Production stats fail key formatting macro
#[macro_export]
macro_rules! prod_stats_fail_key {
    ($cycle_prefix:expr, $addr:expr) => {
        [
            &$cycle_prefix[..],
            &[PROD_STATS_IDENT],
            &$addr.to_prefixed_bytes()[..],
            &[PROD_STATS_FAIL_IDENT],
        ]
        .concat()
    };
}

/// Production stats success key formatting macro
#[macro_export]
macro_rules! prod_stats_success_key {
    ($cycle_prefix:expr, $addr:expr) => {
        [
            &$cycle_prefix[..],
            &[PROD_STATS_IDENT],
            &$addr.to_prefixed_bytes()[..],
            &[PROD_STATS_SUCCESS_IDENT],
        ]
        .concat()
    };
}

/// Deferred credits key formatting macro
#[macro_export]
macro_rules! deferred_credits_key {
    ($id:expr) => {
        [&DEFERRED_CREDITS_PREFIX.as_bytes(), &$id[..]].concat()
    };
}

#[derive(Clone)]
/// Final state of PoS
pub struct PoSFinalState {
    /// proof-of-stake configuration
    pub config: PoSConfig,
    /// Access to the RocksDB database
    pub db: ShareableMassaDBController,
    /// contiguous cycle history, back = newest
    pub cycle_history_cache: VecDeque<(u64, bool)>,
    /// rng_seed cache to get rng_seed for the current cycle
    pub rng_seed_cache: Option<(u64, BitVec<u8>)>,
    /// selector controller
    pub selector: Box<dyn SelectorController>,
    /// initial rolls, used for negative cycle look back
    pub initial_rolls: BTreeMap<Address, u64>,
    /// initial seeds, used for negative cycle look back (cycles -2, -1 in that order)
    pub initial_seeds: Vec<Hash>,
    /// inner deferred credits serializer (one slot's credits)
    pub credits_serializer: DeferredCreditSerializer,
    /// inner deferred credits deserializer (one slot's credits)
    pub credits_deserializer: DeferredCreditDeserializer,
    /// cycle info serializer
    pub cycle_info_serializer: CycleInfoSerializer,
    /// cycle info deserializer
    pub cycle_info_deserializer: CycleInfoDeserializer,
}

impl PoSFinalState {
    /// Number of slots (and thus RNG seed bits) in a full cycle.
    fn slots_per_cycle(&self) -> usize {
        self.config
            .periods_per_cycle
            .saturating_mul(self.config.thread_count as u64)
            .try_into()
            .expect("slots_per_cycle overflow")
    }

    /// create a new `PoSFinalState`
    pub fn new(
        config: PoSConfig,
        initial_seed_string: &str,
        initial_rolls_path: &PathBuf,
        selector: Box<dyn SelectorController>,
        db: ShareableMassaDBController,
    ) -> Result<Self, PosError> {
        // load get initial rolls from file
        let initial_rolls = serde_json::from_str::<BTreeMap<Address, u64>>(
            &std::fs::read_to_string(initial_rolls_path).map_err(|err| {
                PosError::RollsFileLoadingError(format!("error while deserializing: {}", err))
            })?,
        )
        .map_err(|err| PosError::RollsFileLoadingError(format!("error opening file: {}", err)))?;

        // Seeds used as the initial seeds for negative cycles (-2 and -1 respectively)
        let init_seed = Hash::compute_from(initial_seed_string.as_bytes());
        let initial_seeds = vec![Hash::compute_from(init_seed.to_bytes()), init_seed];

        let cycle_info_deserializer =
            CycleInfoDeserializer::new(config.max_rolls_length, config.max_production_stats_length);

        let pos_state = Self {
            config: config.clone(),
            db,
            cycle_history_cache: Default::default(),
            rng_seed_cache: None,
            selector,
            initial_rolls,
            initial_seeds,
            credits_serializer: DeferredCreditSerializer::new(),
            credits_deserializer: DeferredCreditDeserializer::new(config.max_credit_length),
            cycle_info_serializer: CycleInfoSerializer::new(),
            cycle_info_deserializer,
        };

        Ok(pos_state)
    }

    /// Try load initial deferred credits from file
    ///
    /// Credits that would fail at execution time (same rules as `transfer_coins` when
    /// crediting with `from_addr = None`) are skipped:
    /// * non-existing SC address
    /// * non-existing user address with `amount` below the ledger entry base cost
    pub fn load_initial_deferred_credits(
        &mut self,
        batch: &mut DBBatch,
        ledger: &dyn LedgerController,
    ) -> Result<(), PosError> {
        let Some(initial_deferred_credits_path) = &self.config.initial_deferred_credits_path else {
            return Ok(());
        };

        use serde::Deserialize;
        #[derive(Deserialize)]
        struct AddressInitialDeferredCredits {
            slot: Slot,
            amount: Amount,
        }

        let initial_deferred_credits =
            serde_json::from_str::<PreHashMap<Address, Vec<AddressInitialDeferredCredits>>>(
                &std::fs::read_to_string(initial_deferred_credits_path).map_err(|err| {
                    PosError::DeferredCreditsFileLoadingError(format!(
                        "error while deserializing initial deferred credits file {}: {}",
                        initial_deferred_credits_path.display(),
                        err
                    ))
                })?,
            )
            .map_err(|err| {
                PosError::DeferredCreditsFileLoadingError(format!(
                    "error loading initial deferred credits file {}: {}",
                    initial_deferred_credits_path.display(),
                    err
                ))
            })?;

        for (address, deferred_credits) in initial_deferred_credits {
            let address_is_sc = matches!(address, Address::SC(..));
            let address_exists = ledger.entry_exists(&address);
            for AddressInitialDeferredCredits { slot, amount } in deferred_credits {
                if address_is_sc {
                    warn!(
                        "deferred credits for address {} with amount {} will not execute because it is a SC address",
                        address, amount
                    );
                } else if !address_exists && amount < LEDGER_ENTRY_BASE_COST {
                    warn!(
                        "deferred credits for address {} with amount {} will likely not execute because the address does not exist in the ledger and the amount is below the ledger entry base cost",
                        address, amount
                    );
                }

                // Note that we still put the deferred credits in the database even if they are likely to fail at execution time.
                // It's for instance possible the address is created before the execution slot of the deferred credits.
                self.put_deferred_credits_entry(&slot, &address, &amount, batch);
            }
        }

        Ok(())
    }

    /// After bootstrap or load from disk, recompute the caches
    pub fn recompute_pos_state_caches(&mut self) {
        self.cycle_history_cache = self.get_cycle_history_cycles().into();

        if let Some((cycle, _)) = self.cycle_history_cache.back() {
            self.rng_seed_cache = self
                .get_cycle_history_rng_seed(*cycle)
                .map(|rng_seed| (*cycle, rng_seed));
        } else {
            self.rng_seed_cache = None;
        }
    }

    /// Ensures every complete cycle has the persisted fields required for selector feeding.
    ///
    /// A cycle marked complete must have an RNG seed and a non-empty
    /// `final_state_hash_snapshot`. Used after load/bootstrap and during DB validation so
    /// malformed history fails fast instead of panicking later in `feed_selector`.
    pub fn validate_selector_history(&self) -> PosResult<()> {
        for (cycle, complete) in self.get_cycle_history_cycles() {
            if !complete {
                continue;
            }
            if self.get_cycle_history_rng_seed(cycle).is_none() {
                return Err(PosError::ContainerInconsistency(format!(
                    "complete cycle {} is missing RNG seed required for selector feeding",
                    cycle
                )));
            }
            if self
                .get_cycle_history_final_state_hash_snapshot(cycle)
                .is_none()
            {
                return Err(PosError::ContainerInconsistency(format!(
                    "complete cycle {} is missing final state hash snapshot required for selector feeding",
                    cycle
                )));
            }
        }
        Ok(())
    }

    /// Reset the state of the PoS final state
    ///
    /// USED ONLY FOR BOOTSTRAP
    pub fn reset(&mut self) {
        let mut db = self.db.write();
        db.delete_prefix(CYCLE_HISTORY_PREFIX, STATE_CF, None);
        db.delete_prefix(DEFERRED_CREDITS_PREFIX, STATE_CF, None);
        self.cycle_history_cache = Default::default();
        self.rng_seed_cache = None;
    }

    /// Create the initial cycle based off the initial rolls.
    ///
    /// This should be called only if bootstrap did not happen.
    pub fn create_initial_cycle(&mut self, batch: &mut DBBatch) {
        let mut rng_seed = BitVec::with_capacity(self.slots_per_cycle());
        rng_seed.extend(vec![false; self.config.thread_count as usize]);

        self.put_new_cycle_info(
            &CycleInfo::new(
                0,
                false,
                self.initial_rolls.clone(),
                rng_seed,
                PreHashMap::default(),
            ),
            batch,
        );
    }

    /// Create a cycle based off of another cycle_info.
    ///
    /// Used for downtime interpolation, when restarting from a snapshot.
    /// Roll counts are always carried over from `last_cycle_info`.
    ///
    /// `rng_seed` and `production_stats` are kept only when continuing the same
    /// incomplete cycle (`last_cycle_info.cycle` matches the target cycle and
    /// `first_slot` is not the first slot of that cycle). Otherwise the seed
    /// starts fresh and `production_stats` are empty, so interpolated future
    /// cycles do not inherit stale production results from the snapshot.
    ///
    /// In all cases, `rng_seed` is then extended with `false` bits for every
    /// interpolated slot in `[first_slot, last_slot]`.
    pub fn create_new_cycle_from_last(
        &mut self,
        last_cycle_info: &CycleInfo,
        first_slot: Slot,
        last_slot: Slot,
        batch: &mut DBBatch,
    ) -> Result<(), PosError> {
        let cycle = last_slot.get_cycle(self.config.periods_per_cycle);

        // Keep seed/stats only when filling the gap in the same incomplete cycle.
        // Require both same cycle id and a non-first first_slot (defense in depth:
        // callers may reuse a snapshot CycleInfo across several target cycles).
        let continuing_same_cycle = last_cycle_info.cycle == cycle
            && !first_slot.is_first_of_cycle(self.config.periods_per_cycle);

        let (mut rng_seed, production_stats) = if continuing_same_cycle {
            (
                last_cycle_info.rng_seed.clone(),
                last_cycle_info.production_stats.clone(),
            )
        } else {
            (
                BitVec::with_capacity(self.slots_per_cycle()),
                PreHashMap::default(),
            )
        };

        let num_slots = match last_slot.slots_since(&first_slot, self.config.thread_count) {
            Ok(slots_since) => slots_since.saturating_add(1),
            // if first_slot is greater than last_slot, we have nothing to do
            Err(_) => return Ok(()),
        };

        let slots_per_cycle = self.slots_per_cycle();
        // Existing seed (e.g. genesis thread_count padding) may already cover some of
        // the interpolated range. Cap so we never exceed a full cycle.
        if rng_seed.len() > slots_per_cycle {
            return Err(PosError::ContainerInconsistency(format!(
                "RNG seed for cycle {} exceeds slots_per_cycle: {} > {}",
                cycle,
                rng_seed.len(),
                slots_per_cycle
            )));
        }
        // Pad downtime slots; not the same as leaving the seed empty.
        let to_add = (num_slots as usize).min(slots_per_cycle.saturating_sub(rng_seed.len()));
        rng_seed.extend(vec![false; to_add]);

        let complete =
            last_slot.is_last_of_cycle(self.config.periods_per_cycle, self.config.thread_count);
        if rng_seed.len() > slots_per_cycle || (complete && rng_seed.len() != slots_per_cycle) {
            return Err(PosError::ContainerInconsistency(format!(
                "invalid RNG seed length {} for cycle {} (slots_per_cycle {}, complete={})",
                rng_seed.len(),
                cycle,
                slots_per_cycle,
                complete
            )));
        }

        self.put_new_cycle_info(
            &CycleInfo::new(
                cycle,
                complete,
                last_cycle_info.roll_counts.clone(),
                rng_seed,
                production_stats,
            ),
            batch,
        );

        Ok(())
    }

    /// Deletes a given cycle from RocksDB
    pub fn delete_cycle_info(&mut self, cycle: u64, batch: &mut DBBatch) {
        let db = self.db.read();

        let prefix = self.cycle_history_cycle_prefix(cycle);

        for (serialized_key, _) in db.prefix_iterator_cf(STATE_CF, &prefix) {
            if !serialized_key.starts_with(prefix.as_bytes()) {
                break;
            }
            db.delete_key(batch, serialized_key.to_vec());
        }
    }

    /// Sends the current draw inputs (initial or bootstrapped) to the selector.
    /// Waits for the initial draws to be performed.
    pub fn compute_initial_draws(&mut self) -> PosResult<()> {
        // Reject incomplete selector inputs before recomputing draws from history.
        self.validate_selector_history()?;

        // if cycle_history starts at a cycle that is strictly higher than 0, do not feed cycles 0, 1 to selector
        let history_starts_late = self
            .cycle_history_cache
            .front()
            .map(|c_info| c_info.0 > 0)
            .unwrap_or(false);

        let mut max_cycle = None;

        // feed cycles 0, 1 to selector if necessary
        if !history_starts_late {
            for draw_cycle in 0u64..=1 {
                self.feed_selector(draw_cycle)?;
                max_cycle = Some(draw_cycle);
            }
        }

        // feed cycles available from history
        for (idx, hist_item) in self.cycle_history_cache.iter().enumerate() {
            if !hist_item.1 {
                break;
            }
            if history_starts_late && idx == 0 {
                // If the history starts late, the first RNG seed cannot be used to draw
                // because the roll distribution which should be provided by the previous element is absent.
                continue;
            }
            let draw_cycle = hist_item.0.checked_add(2).ok_or_else(|| {
                PosError::OverflowError("cycle overflow in give_selector_controller".into())
            })?;
            self.feed_selector(draw_cycle)?;
            max_cycle = Some(draw_cycle);
        }

        // wait for all fed cycles to be drawn
        if let Some(wait_cycle) = max_cycle {
            self.selector.as_mut().wait_for_draws(wait_cycle)?;
        }
        Ok(())
    }

    /// Technical specification of `apply_changes_to_batch`:
    ///
    /// set `self.last_final_slot` = C
    /// if cycle C is absent from `self.cycle_history_cache`:
    ///     `push` a new empty `CycleInfo` on disk and reflect in `self.cycle_history_cache` and set its cycle = C
    ///     `pop_front` from `cycle_history_cache` until front() represents cycle C-4 or later (not C-3 because we might need older endorsement draws on the limit between 2 cycles)
    ///     delete the removed cycles from disk
    /// for the cycle C entry in the db:
    ///     extend `seed_bits` with `changes.seed_bits`
    ///     extend `roll_counts` with `changes.roll_changes`
    ///         delete all entries from `roll_counts` for which the roll count is zero
    ///     add each element of `changes.production_stats` to the cycle's `production_stats`
    /// for each `changes.deferred_credits` targeting cycle Ct:
    ///     overwrite `self.deferred_credits` entries of cycle Ct in `cycle_history` with the ones from change
    ///         remove entries for which Amount = 0
    /// if slot S was the last of cycle C:
    ///     set complete=true for cycle C in the history
    ///     compute the seed hash and notifies the `PoSDrawer` for cycle `C+3`
    ///
    pub fn apply_changes_to_batch(
        &mut self,
        changes: PoSChanges,
        slot: Slot,
        feed_selector: bool,
        batch: &mut DBBatch,
    ) -> PosResult<()> {
        let slots_per_cycle = self.slots_per_cycle();

        // compute the current cycle from the given slot
        let cycle = slot.get_cycle(self.config.periods_per_cycle);

        // if cycle C is absent from self.cycle_history:
        // push a new empty CycleInfo at the back of self.cycle_history and set its cycle = C
        // pop_front from cycle_history until front() represents cycle C-4 or later
        // (not C-3 because we might need older endorsement draws on the limit between 2 cycles)
        if let Some(info) = self.cycle_history_cache.back() {
            if cycle == info.0 && !info.1 {
                // extend the last incomplete cycle
            } else if info.0.checked_add(1) == Some(cycle) && info.1 {
                // the previous cycle is complete, push a new incomplete/empty one to extend
                // By now `_finalize` should already have written its final_state_hash_snapshot.
                // Catch a missing snapshot here (first slot of the new cycle) instead of waiting
                // until feed_selector needs it as a lookback (~1 cycle later).
                if self
                    .get_cycle_history_final_state_hash_snapshot(info.0)
                    .is_none()
                {
                    return Err(PosError::ContainerInconsistency(format!(
                        "complete cycle {} is missing final state hash snapshot before starting cycle {}",
                        info.0, cycle
                    )));
                }

                let roll_counts = self.get_all_roll_counts(info.0);
                self.put_new_cycle_info(
                    &CycleInfo::new(
                        cycle,
                        false,
                        roll_counts,
                        BitVec::with_capacity(slots_per_cycle),
                        PreHashMap::default(),
                    ),
                    batch,
                );
                while self.cycle_history_cache.len() > self.config.cycle_history_length {
                    if let Some((old_cycle, _)) = self.cycle_history_cache.pop_front() {
                        self.delete_cycle_info(old_cycle, batch);
                    }
                }
            } else {
                return Err(PosError::OverflowError(
                    "invalid cycle sequence in PoS final state".into(),
                ));
            }
        } else {
            return Err(PosError::ContainerInconsistency(
                "PoS history should never be empty here".into(),
            ));
        }

        let complete: bool =
            slot.is_last_of_cycle(self.config.periods_per_cycle, self.config.thread_count);

        // OPTIM: we could avoid reading the previous seed bits with a cache or with an update function
        // Validate selector inputs before marking the cycle complete so a malformed seed cannot
        // leave `complete=true` in the in-memory cache when we return an error.
        let mut rng_seed = self.get_cycle_history_rng_seed(cycle).ok_or_else(|| {
            PosError::ContainerInconsistency(format!("missing RNG seed for cycle {}", cycle))
        })?;
        // Reject already-corrupt or overflowing seed state before mutating caches/batch.
        if rng_seed.len() > slots_per_cycle {
            return Err(PosError::ContainerInconsistency(format!(
                "RNG seed for cycle {} exceeds slots_per_cycle: {} > {}",
                cycle,
                rng_seed.len(),
                slots_per_cycle
            )));
        }
        rng_seed.extend(changes.seed_bits);
        if rng_seed.len() > slots_per_cycle || (complete && rng_seed.len() != slots_per_cycle) {
            return Err(PosError::ContainerInconsistency(format!(
                "cycle {} RNG seed length {} invalid (slots_per_cycle {}, complete={})",
                cycle,
                rng_seed.len(),
                slots_per_cycle,
                complete
            )));
        }

        self.put_cycle_history_complete(cycle, complete, batch);
        self.put_cycle_history_rng_seed(cycle, rng_seed, batch);

        // extend roll counts
        for (addr, roll_count) in changes.roll_changes {
            self.put_cycle_history_address_entry(cycle, &addr, Some(&roll_count), None, batch);
        }

        // extend production stats
        for (addr, stats) in changes.production_stats {
            if let Some(prev_production_stats) = self.get_production_stats_for_address(cycle, &addr)
            {
                let mut new_production_stats = prev_production_stats;
                new_production_stats.extend(&stats);
                self.put_cycle_history_address_entry(
                    cycle,
                    &addr,
                    None,
                    Some(&new_production_stats),
                    batch,
                );
            } else {
                self.put_cycle_history_address_entry(cycle, &addr, None, Some(&stats), batch);
            }
        }

        // extend deferred_credits with changes.deferred_credits and remove zeros
        for (slot, credits) in changes.deferred_credits.credits.iter() {
            for (address, amount) in credits.iter() {
                self.put_deferred_credits_entry(slot, address, amount, batch);
            }
        }

        // feed the cycle if it is complete
        // notify the PoSDrawer about the newly ready draw data
        // to draw cycle + 2, we use the rng data from cycle - 1 and the seed from cycle
        debug!(
            "After slot {} PoS cycle list is {:?}",
            slot, self.cycle_history_cache
        );
        if complete && feed_selector {
            self.feed_selector(cycle.checked_add(2).ok_or_else(|| {
                PosError::OverflowError("cycle overflow when feeding selector".into())
            })?)
        } else {
            Ok(())
        }
    }

    /// Feeds the selector targeting a given draw cycle
    pub fn feed_selector(&self, draw_cycle: u64) -> PosResult<()> {
        // get roll lookback

        let (lookback_rolls, lookback_state_hash) = match draw_cycle.checked_sub(3) {
            // looking back in history
            Some(c) => {
                let index = self
                    .get_cycle_index(c)
                    .ok_or(PosError::CycleUnavailable(c))?;
                let cycle_info = &self.cycle_history_cache[index];
                if !cycle_info.1 {
                    return Err(PosError::CycleUnfinished(c));
                }
                // take the final_state_hash_snapshot at cycle - 3
                // it will later be combined with rng_seed from cycle - 2 to determine the selection seed
                // do this here to avoid a potential attacker manipulating the selections
                let state_hash = self
                    .get_cycle_history_final_state_hash_snapshot(cycle_info.0)
                    .ok_or_else(|| {
                        PosError::ContainerInconsistency(format!(
                            "complete cycle {} is missing final state hash snapshot required for selector feeding",
                            c
                        ))
                    })?;
                (self.get_all_roll_counts(cycle_info.0), Some(state_hash))
            }
            // looking back to negative cycles
            None => (self.initial_rolls.clone(), None),
        };

        // get seed lookback
        let lookback_seed = match draw_cycle.checked_sub(2) {
            // looking back in history
            Some(c) => {
                let index = self
                    .get_cycle_index(c)
                    .ok_or(PosError::CycleUnavailable(c))?;
                let cycle_info = &self.cycle_history_cache[index];
                if !cycle_info.1 {
                    return Err(PosError::CycleUnfinished(c));
                }
                let u64_ser = U64VarIntSerializer::new();
                let mut seed = Vec::new();
                u64_ser.serialize(&c, &mut seed).unwrap();
                let rng_seed = self
                    .get_cycle_history_rng_seed(cycle_info.0)
                    .ok_or_else(|| {
                        PosError::ContainerInconsistency(format!(
                            "complete cycle {} is missing RNG seed required for selector feeding",
                            c
                        ))
                    })?;
                seed.extend(rng_seed.into_vec());
                if let Some(lookback_state_hash) = lookback_state_hash {
                    seed.extend(lookback_state_hash.to_bytes());
                }
                Hash::compute_from(&seed)
            }
            // looking back to negative cycles
            None => self.initial_seeds[draw_cycle as usize],
        };

        // feed selector
        self.selector
            .as_ref()
            .feed_cycle(draw_cycle, lookback_rolls, lookback_seed)
    }

    /// Feeds the selector targeting a given draw cycle
    pub fn feed_cycle_state_hash(
        &self,
        cycle: u64,
        final_state_hash: HashXof<HASH_XOF_SIZE_BYTES>,
    ) {
        if self.get_cycle_index(cycle).is_some() {
            let mut batch = DBBatch::new();
            self.put_cycle_history_final_state_hash_snapshot(
                cycle,
                Some(final_state_hash),
                &mut batch,
            );

            self.db.write().write_batch(batch, Default::default(), None);
        } else {
            panic!("cycle {} should be contained here", cycle);
        }
    }
}

// RocksDB getters
impl PoSFinalState {
    /// Retrieves the amount of rolls a given address has at the latest cycle
    pub fn get_rolls_for(&self, addr: &Address) -> u64 {
        self.cycle_history_cache
            .back()
            .and_then(|info| {
                let cycle = info.0;
                let db = self.db.read();

                let key = roll_count_key!(self.cycle_history_cycle_prefix(cycle), addr);

                if let Some(serialized_value) =
                    db.get_cf(STATE_CF, key).expect(CYCLE_HISTORY_DESER_ERROR)
                {
                    let (_, amount) = self
                        .cycle_info_deserializer
                        .rolls_deser
                        .u64_deserializer
                        .deserialize::<DeserializeError>(&serialized_value)
                        .expect(CYCLE_HISTORY_DESER_ERROR);

                    Some(amount)
                } else {
                    None
                }
            })
            .unwrap_or_default()
    }

    /// Retrieves the amount of rolls a given address has at a given cycle - 3
    /// if cycle - 3 does not exist, values from initial rolls are returned
    pub fn get_address_active_rolls(&self, addr: &Address, cycle: u64) -> Option<u64> {
        match cycle.checked_sub(3) {
            Some(lookback_cycle) => {
                let key = roll_count_key!(self.cycle_history_cycle_prefix(lookback_cycle), addr);
                let db = self.db.read();
                if let Some(serialized_value) =
                    db.get_cf(STATE_CF, key).expect(CYCLE_HISTORY_DESER_ERROR)
                {
                    let (_, amount) = self
                        .cycle_info_deserializer
                        .rolls_deser
                        .u64_deserializer
                        .deserialize::<DeserializeError>(&serialized_value)
                        .expect(CYCLE_HISTORY_DESER_ERROR);

                    Some(amount)
                } else {
                    None
                }
            }
            None => self.initial_rolls.get(addr).cloned(),
        }
    }

    /// Gets all active rolls for a given cycle - 3, use self.initial_rolls if cycle - 3 does not exist
    pub fn get_all_active_rolls(&self, cycle: u64) -> BTreeMap<Address, u64> {
        match cycle.checked_sub(3) {
            Some(lookback_cycle) => {
                // get rolls
                self.get_all_roll_counts(lookback_cycle)
            }
            None => self.initial_rolls.clone(),
        }
    }

    /// Retrieves every deferred credit in a slot range
    /// Warning: this can be quite slow if there is tons of Deferred credits (e.g. just after genesis) to fetch
    ///          so there is an option to filter by an address to improve the speed (cf json rpc api get_addresses)
    pub fn get_deferred_credits_range<R>(
        &self,
        range: R,
        addr_filter: Option<&Address>,
    ) -> DeferredCredits
    where
        R: RangeBounds<Slot>,
    {
        let db = self.db.read();

        let mut deferred_credits = DeferredCredits::new();

        let mut start_key_buffer = Vec::new();
        start_key_buffer.extend_from_slice(DEFERRED_CREDITS_PREFIX.as_bytes());

        match range.start_bound() {
            Included(slot) => {
                start_key_buffer.extend_from_slice(&slot.to_bytes_key());
            }
            Excluded(slot) => {
                start_key_buffer.extend_from_slice(
                    &slot
                        .get_next_slot(self.config.thread_count)
                        .expect(DEFERRED_CREDITS_SER_ERROR)
                        .to_bytes_key(),
                );
            }
            Unbounded => {}
        };

        let iterator_cf = db
            .iterator_cf(
                STATE_CF,
                MassaIteratorMode::From(&start_key_buffer, MassaDirection::Forward),
            )
            .take_while(|(k, _)| k.starts_with(DEFERRED_CREDITS_PREFIX.as_bytes()));

        for (serialized_key, serialized_value) in iterator_cf {
            // deserialize the slot
            let rest_key = &serialized_key[DEFERRED_CREDITS_PREFIX.len()..];
            let (rest_key, slot) = buf_to_array_ctr(rest_key, Slot::from_bytes_key)
                .expect(DEFERRED_CREDITS_DESER_ERROR);

            if !range.contains(&slot) {
                break;
            }

            let (_, address) = self
                .credits_deserializer
                .address_deserializer
                .deserialize::<DeserializeError>(rest_key)
                .expect(DEFERRED_CREDITS_DESER_ERROR);

            if let Some(addr_filter_value) = &addr_filter {
                if &&address != addr_filter_value {
                    continue;
                }
            }

            let (_, amount) = self
                .credits_deserializer
                .amount_deserializer
                .deserialize::<DeserializeError>(&serialized_value)
                .expect(DEFERRED_CREDITS_DESER_ERROR);

            deferred_credits.insert(slot, address, amount);
        }

        deferred_credits
    }

    /// Gets the index of a cycle in history
    pub fn get_cycle_index(&self, cycle: u64) -> Option<usize> {
        let first_cycle = match self.cycle_history_cache.front() {
            Some(c) => c.0,
            None => return None, // history empty
        };
        if cycle < first_cycle {
            return None; // in the past
        }
        let index: usize = match (cycle - first_cycle).try_into() {
            Ok(v) => v,
            Err(_) => return None, // usize overflow
        };
        if index >= self.cycle_history_cache.len() {
            return None; // in the future
        }
        Some(index)
    }

    /// Get all the roll counts for a given cycle
    pub fn get_all_roll_counts(&self, cycle: u64) -> BTreeMap<Address, u64> {
        let db = self.db.read();

        if self.get_cycle_index(cycle).is_none() {
            panic!("Cycle {} not in history", cycle)
        }

        let mut roll_counts: BTreeMap<Address, u64> = BTreeMap::new();
        let prefix = roll_count_prefix!(self.cycle_history_cycle_prefix(cycle));
        for (serialized_key, serialized_value) in db.prefix_iterator_cf(STATE_CF, &prefix) {
            if !serialized_key.starts_with(prefix.as_bytes()) {
                break;
            }

            // deserialize the cycle
            let rest_key = &serialized_key[CYCLE_HISTORY_PREFIX.len()..];
            let (rest_key, _cycle) = buf_to_array_ctr(rest_key, |v| u64::from_be_bytes(*v))
                .expect(CYCLE_HISTORY_DESER_ERROR);

            let (_, address) = self
                .cycle_info_deserializer
                .rolls_deser
                .address_deserializer
                .deserialize::<DeserializeError>(&rest_key[1..])
                .expect(CYCLE_HISTORY_DESER_ERROR);

            let (_, amount) = self
                .cycle_info_deserializer
                .rolls_deser
                .u64_deserializer
                .deserialize::<DeserializeError>(&serialized_value)
                .expect(CYCLE_HISTORY_DESER_ERROR);

            roll_counts.insert(address, amount);
        }

        roll_counts
    }

    /// Retrieves the productions statistics for all addresses on a given cycle
    pub fn get_all_production_stats(
        &self,
        cycle: u64,
    ) -> Option<PreHashMap<Address, ProductionStats>> {
        self.get_cycle_index(cycle)
            .map(|idx| self.get_all_production_stats_private(self.cycle_history_cache[idx].0))
    }

    /// Retrieves the productions statistics for all addresses on a given cycle
    fn get_all_production_stats_private(&self, cycle: u64) -> PreHashMap<Address, ProductionStats> {
        let db = self.db.read();

        let mut production_stats: PreHashMap<Address, ProductionStats> = PreHashMap::default();
        let mut cur_production_stat = ProductionStats::default();
        let mut cur_address = None;

        let prefix = prod_stats_prefix!(self.cycle_history_cycle_prefix(cycle));
        for (serialized_key, serialized_value) in db.prefix_iterator_cf(STATE_CF, &prefix) {
            if !serialized_key.starts_with(prefix.as_bytes()) {
                break;
            }

            // deserialize the cycle
            let rest_key = &serialized_key[CYCLE_HISTORY_PREFIX.len()..];
            let (rest_key, _cycle) = buf_to_array_ctr(rest_key, |v| u64::from_be_bytes(*v))
                .expect(CYCLE_HISTORY_DESER_ERROR);

            let (rest_key, address) = self
                .cycle_info_deserializer
                .production_stats_deser
                .address_deserializer
                .deserialize::<DeserializeError>(&rest_key[1..])
                .expect(CYCLE_HISTORY_DESER_ERROR);

            if cur_address != Some(address) {
                cur_address = Some(address);
                cur_production_stat = ProductionStats::default();
            }

            let (_, value) = self
                .cycle_info_deserializer
                .production_stats_deser
                .u64_deserializer
                .deserialize::<DeserializeError>(&serialized_value)
                .expect(CYCLE_HISTORY_DESER_ERROR);

            if rest_key.len() == 1 && rest_key[0] == PROD_STATS_FAIL_IDENT {
                cur_production_stat.block_failure_count = value;
            } else if rest_key.len() == 1 && rest_key[0] == PROD_STATS_SUCCESS_IDENT {
                cur_production_stat.block_success_count = value;
            } else {
                panic!("{}", CYCLE_HISTORY_DESER_ERROR);
            }

            production_stats.insert(address, cur_production_stat);
        }

        production_stats
    }

    /// Getter for the rng_seed of a given cycle, prioritizing the cache and querying the database as fallback.
    fn get_cycle_history_rng_seed(&self, cycle: u64) -> Option<BitVec<u8>> {
        if let Some((cached_cycle, rng_seed)) = &self.rng_seed_cache {
            if *cached_cycle == cycle {
                return Some(rng_seed.clone());
            }
        }

        let serialized_rng_seed = self
            .db
            .read()
            .get_cf(
                STATE_CF,
                rng_seed_key!(self.cycle_history_cycle_prefix(cycle)),
            )
            .expect(CYCLE_HISTORY_DESER_ERROR);
        let serialized_rng_seed = serialized_rng_seed?;

        let (_, rng_seed) = self
            .cycle_info_deserializer
            .bitvec_deser
            .deserialize::<DeserializeError>(&serialized_rng_seed)
            .expect(CYCLE_HISTORY_DESER_ERROR);

        Some(rng_seed)
    }

    /// Getter for the final_state_hash_snapshot of a given cycle.
    ///
    /// Returns `None` if the RocksDB key is absent or if the stored value is `None`.
    fn get_cycle_history_final_state_hash_snapshot(
        &self,
        cycle: u64,
    ) -> Option<HashXof<HASH_XOF_SIZE_BYTES>> {
        let db = self.db.read();

        let serialized_state_hash = db
            .get_cf(
                STATE_CF,
                final_state_hash_snapshot_key!(self.cycle_history_cycle_prefix(cycle)),
            )
            .expect(CYCLE_HISTORY_DESER_ERROR)?;
        let (_, state_hash) = self
            .cycle_info_deserializer
            .opt_hash_deser
            .deserialize::<DeserializeError>(&serialized_state_hash)
            .expect(CYCLE_HISTORY_DESER_ERROR);
        state_hash
    }

    /// Used to recompute the cycle cache from the disk.
    ///
    fn get_cycle_history_cycles(&self) -> Vec<(u64, bool)> {
        let mut found_cycles: Vec<u64> = Vec::new();

        {
            let db = self.db.read();

            while let Some((serialized_key, _)) = match found_cycles.last() {
                Some(prev_cycle) => db
                    .iterator_cf(
                        STATE_CF,
                        MassaIteratorMode::From(
                            &self.cycle_history_cycle_prefix(prev_cycle.saturating_add(1)),
                            MassaDirection::Forward,
                        ),
                    )
                    .next(),
                None => db
                    .iterator_cf(
                        STATE_CF,
                        MassaIteratorMode::From(
                            CYCLE_HISTORY_PREFIX.as_bytes(),
                            MassaDirection::Forward,
                        ),
                    )
                    .next(),
            } {
                if !serialized_key.starts_with(CYCLE_HISTORY_PREFIX.as_bytes()) {
                    break;
                }

                // deserialize the cycle
                let rest_key = &serialized_key[CYCLE_HISTORY_PREFIX.len()..];
                let (_rest_key, cycle) = buf_to_array_ctr(rest_key, |v| u64::from_be_bytes(*v))
                    .expect(CYCLE_HISTORY_DESER_ERROR);

                found_cycles.push(cycle);
            }
        }

        found_cycles
            .into_iter()
            .map(|cycle| (cycle, self.is_cycle_complete(cycle).unwrap_or(false)))
            .collect()
    }

    /// Queries a given cycle info in the database
    pub fn get_cycle_info(&self, cycle: u64) -> Option<CycleInfo> {
        // TODO improve performance by not taking a lock and re-searching the key at every element

        let complete = self.is_cycle_complete(cycle)?;
        let rng_seed = self.get_cycle_history_rng_seed(cycle)?;
        let final_state_hash_snapshot = self.get_cycle_history_final_state_hash_snapshot(cycle);

        let roll_counts = self.get_all_roll_counts(cycle);

        let production_stats = self.get_all_production_stats(cycle).unwrap_or_default();

        let mut cycle_info =
            CycleInfo::new(cycle, complete, roll_counts, rng_seed, production_stats);
        cycle_info.final_state_hash_snapshot = final_state_hash_snapshot;
        Some(cycle_info)
    }

    /// Gets the deferred credits for a given address that will be credited at a given slot
    pub fn get_address_credits_for_slot(&self, addr: &Address, slot: &Slot) -> Option<Amount> {
        let db = self.db.read();

        let mut serialized_key = Vec::new();
        serialized_key.extend_from_slice(&slot.to_bytes_key());
        self.credits_serializer
            .address_ser
            .serialize(addr, &mut serialized_key)
            .expect(DEFERRED_CREDITS_SER_ERROR);

        match db.get_cf(STATE_CF, deferred_credits_key!(serialized_key)) {
            Ok(Some(serialized_amount)) => {
                let (_, amount) = self
                    .credits_deserializer
                    .amount_deserializer
                    .deserialize::<DeserializeError>(&serialized_amount)
                    .expect(DEFERRED_CREDITS_DESER_ERROR);
                Some(amount)
            }
            _ => None,
        }
    }

    /// Gets the production stats for a given address
    pub fn get_production_stats_for_address(
        &self,
        cycle: u64,
        address: &Address,
    ) -> Option<ProductionStats> {
        let db = self.db.read();

        let prefix = self.cycle_history_cycle_prefix(cycle);

        let query = vec![
            (STATE_CF, prod_stats_fail_key!(prefix, *address)),
            (STATE_CF, prod_stats_success_key!(prefix, *address)),
        ];

        let results = db.multi_get_cf(query);

        match (results.first(), results.get(1)) {
            (Some(Ok(Some(serialized_fail))), Some(Ok(Some(serialized_success)))) => {
                let (_, fail) = self
                    .cycle_info_deserializer
                    .production_stats_deser
                    .u64_deserializer
                    .deserialize::<DeserializeError>(serialized_fail)
                    .expect(CYCLE_HISTORY_DESER_ERROR);
                let (_, success) = self
                    .cycle_info_deserializer
                    .production_stats_deser
                    .u64_deserializer
                    .deserialize::<DeserializeError>(serialized_success)
                    .expect(CYCLE_HISTORY_DESER_ERROR);

                Some(ProductionStats {
                    block_success_count: success,
                    block_failure_count: fail,
                })
            }
            _ => None,
        }
    }

    /// Check if a cycle is complete (all slots finalized)
    pub fn is_cycle_complete(&self, cycle: u64) -> Option<bool> {
        let key = complete_key!(self.cycle_history_cycle_prefix(cycle));
        let res = self.db.read().get_cf(STATE_CF, key);
        match res {
            Ok(Some(complete_value)) => Some(complete_value.first() == Some(&1)),
            Ok(None) => None,
            Err(err) => {
                panic!(
                    "Error while checking if cycle {} is complete: {}",
                    cycle, err
                );
            }
        }
    }
}

// RocksDB setters
impl PoSFinalState {
    /// Helper function to put a new CycleInfo to RocksDB, and update the cycle_history cache
    pub fn put_new_cycle_info(&mut self, cycle_info: &CycleInfo, batch: &mut DBBatch) {
        self.put_cycle_history_complete(cycle_info.cycle, cycle_info.complete, batch);
        self.put_cycle_history_rng_seed(cycle_info.cycle, cycle_info.rng_seed.clone(), batch);
        self.put_cycle_history_final_state_hash_snapshot(
            cycle_info.cycle,
            cycle_info.final_state_hash_snapshot,
            batch,
        );
        for (address, roll) in cycle_info.roll_counts.iter() {
            self.put_cycle_history_address_entry(
                cycle_info.cycle,
                address,
                Some(roll),
                None,
                batch,
            );
        }
        for (address, prod_stats) in cycle_info.production_stats.iter() {
            self.put_cycle_history_address_entry(
                cycle_info.cycle,
                address,
                None,
                Some(prod_stats),
                batch,
            );
        }
        self.cycle_history_cache
            .push_back((cycle_info.cycle, cycle_info.complete));
    }

    /// Helper function to put a the complete flag for a given cycle
    fn put_cycle_history_complete(&mut self, cycle: u64, value: bool, batch: &mut DBBatch) {
        let db = self.db.read();

        let prefix = self.cycle_history_cycle_prefix(cycle);

        let serialized_value = if value { &[1] } else { &[0] };

        db.put_or_update_entry_value(batch, complete_key!(prefix), serialized_value);

        if let Some(index) = self.get_cycle_index(cycle) {
            self.cycle_history_cache[index].1 = value;
        }
    }

    /// Helper function to put a the final_state_hash_snapshot for a given cycle
    fn put_cycle_history_final_state_hash_snapshot(
        &self,
        cycle: u64,
        value: Option<HashXof<HASH_XOF_SIZE_BYTES>>,
        batch: &mut DBBatch,
    ) {
        let db = self.db.read();

        let prefix = self.cycle_history_cycle_prefix(cycle);

        let mut serialized_value = Vec::new();
        self.cycle_info_serializer
            .opt_hash_ser
            .serialize(&value, &mut serialized_value)
            .expect(CYCLE_HISTORY_SER_ERROR);

        db.put_or_update_entry_value(
            batch,
            final_state_hash_snapshot_key!(prefix),
            &serialized_value,
        );
    }

    /// Helper function to put a the rng_seed for a given cycle
    fn put_cycle_history_rng_seed(&mut self, cycle: u64, value: BitVec<u8>, batch: &mut DBBatch) {
        let db = self.db.read();

        let prefix = self.cycle_history_cycle_prefix(cycle);

        let mut serialized_value = Vec::new();
        self.cycle_info_serializer
            .bitvec_ser
            .serialize(&value, &mut serialized_value)
            .expect(CYCLE_HISTORY_SER_ERROR);

        self.rng_seed_cache = Some((cycle, value.clone()));

        db.put_or_update_entry_value(batch, rng_seed_key!(prefix), &serialized_value);
    }

    /// Internal function to put an entry for a given address in the cycle history
    fn put_cycle_history_address_entry(
        &self,
        cycle: u64,
        address: &Address,
        roll_count: Option<&u64>,
        production_stats: Option<&ProductionStats>,
        batch: &mut DBBatch,
    ) {
        let db = self.db.read();

        let prefix = self.cycle_history_cycle_prefix(cycle);

        // Roll count
        if let Some(0) = roll_count {
            db.delete_key(batch, roll_count_key!(prefix, address));
        } else if let Some(roll_count) = roll_count {
            let mut serialized_roll_count = Vec::new();
            self.cycle_info_serializer
                .u64_ser
                .serialize(roll_count, &mut serialized_roll_count)
                .expect(CYCLE_HISTORY_SER_ERROR);
            db.put_or_update_entry_value(
                batch,
                roll_count_key!(prefix, address),
                &serialized_roll_count,
            );
        }

        // Production stats
        if let Some(production_stats) = production_stats {
            let mut serialized_prod_stats_fail = Vec::new();
            self.cycle_info_serializer
                .u64_ser
                .serialize(
                    &production_stats.block_failure_count,
                    &mut serialized_prod_stats_fail,
                )
                .expect(CYCLE_HISTORY_SER_ERROR);
            db.put_or_update_entry_value(
                batch,
                prod_stats_fail_key!(prefix, address),
                &serialized_prod_stats_fail,
            );

            // Production stats success
            let mut serialized_prod_stats_success = Vec::new();
            self.cycle_info_serializer
                .u64_ser
                .serialize(
                    &production_stats.block_success_count,
                    &mut serialized_prod_stats_success,
                )
                .expect(CYCLE_HISTORY_SER_ERROR);
            db.put_or_update_entry_value(
                batch,
                prod_stats_success_key!(prefix, address),
                &serialized_prod_stats_success,
            );
        }
    }

    /// Internal function to put an entry
    pub fn put_deferred_credits_entry(
        &self,
        slot: &Slot,
        address: &Address,
        amount: &Amount,
        batch: &mut DBBatch,
    ) {
        let db = self.db.read();

        let mut serialized_key = Vec::new();
        serialized_key.extend_from_slice(&slot.to_bytes_key());
        self.credits_serializer
            .address_ser
            .serialize(address, &mut serialized_key)
            .expect(DEFERRED_CREDITS_SER_ERROR);

        if amount.is_zero() {
            db.delete_key(batch, deferred_credits_key!(serialized_key));
        } else {
            let mut serialized_amount = Vec::new();
            self.credits_serializer
                .amount_ser
                .serialize(amount, &mut serialized_amount)
                .expect(DEFERRED_CREDITS_SER_ERROR);

            db.put_or_update_entry_value(
                batch,
                deferred_credits_key!(serialized_key),
                &serialized_amount,
            );
        }
    }
}

/// Helpers for key and value management
impl PoSFinalState {
    /// Helper function to construct the key prefix associated with a given cycle
    fn cycle_history_cycle_prefix(&self, cycle: u64) -> Vec<u8> {
        let mut serialized_key = Vec::new();
        serialized_key.extend_from_slice(CYCLE_HISTORY_PREFIX.as_bytes());
        serialized_key.extend_from_slice(&cycle.to_be_bytes());
        serialized_key
    }

    /// Deserializes the key and value, useful after bootstrap
    pub fn is_cycle_history_key_value_valid(
        &self,
        serialized_key: &[u8],
        serialized_value: &[u8],
    ) -> bool {
        if !serialized_key.starts_with(CYCLE_HISTORY_PREFIX.as_bytes()) {
            return false;
        }

        // deserialize the cycle
        let rest_key = &serialized_key[CYCLE_HISTORY_PREFIX.len()..];
        let Some((rest_key, cycle)) = buf_to_array_ctr(rest_key, |v| u64::from_be_bytes(*v)) else {
            return false;
        };

        if rest_key.is_empty() {
            return false;
        }

        let slots_per_cycle = self.slots_per_cycle();

        match rest_key[0] {
            COMPLETE_IDENT => {
                if rest_key.len() != 1 {
                    return false;
                }
                if serialized_value.len() != 1 {
                    return false;
                }
                if serialized_value[0] > 1 {
                    return false;
                }
                // A completed cycle must have an RNG seed of exactly slots_per_cycle bits.
                if serialized_value[0] == 1 {
                    let prefix = self.cycle_history_cycle_prefix(cycle);
                    let Ok(Some(serialized_rng_seed)) =
                        self.db.read().get_cf(STATE_CF, rng_seed_key!(prefix))
                    else {
                        return false;
                    };
                    let Ok((rest, rng_seed)) =
                        self.cycle_info_deserializer
                            .bitvec_deser
                            .deserialize::<DeserializeError>(&serialized_rng_seed)
                    else {
                        return false;
                    };
                    if !rest.is_empty() || rng_seed.len() != slots_per_cycle {
                        return false;
                    }
                }
            }
            RNG_SEED_IDENT => {
                if rest_key.len() != 1 {
                    return false;
                }
                let Ok((rest_key, rng_seed)) = self
                    .cycle_info_deserializer
                    .bitvec_deser
                    .deserialize::<DeserializeError>(serialized_value)
                else {
                    return false;
                };
                if !rest_key.is_empty() {
                    return false;
                }
                // Seed length must never exceed a full cycle; exact length for complete
                // cycles is enforced when validating the COMPLETE flag above.
                if rng_seed.len() > slots_per_cycle {
                    return false;
                }
            }
            FINAL_STATE_HASH_SNAPSHOT_IDENT => {
                if rest_key.len() != 1 {
                    return false;
                }
                let Ok((rest_key, _final_state_hash)) = self
                    .cycle_info_deserializer
                    .opt_hash_deser
                    .deserialize::<DeserializeError>(serialized_value)
                else {
                    return false;
                };
                if !rest_key.is_empty() {
                    return false;
                }
            }
            ROLL_COUNT_IDENT => {
                let Ok((rest_key, _addr)): std::result::Result<
                    (&[u8], Address),
                    nom::Err<massa_serialization::DeserializeError<'_>>,
                > = self
                    .cycle_info_deserializer
                    .rolls_deser
                    .address_deserializer
                    .deserialize::<DeserializeError>(&rest_key[1..])
                else {
                    return false;
                };
                if !rest_key.is_empty() {
                    return false;
                }
                let Ok((rest_key, _addr)) = self
                    .cycle_info_deserializer
                    .rolls_deser
                    .u64_deserializer
                    .deserialize::<DeserializeError>(serialized_value)
                else {
                    return false;
                };
                if !rest_key.is_empty() {
                    return false;
                }
            }
            PROD_STATS_IDENT => {
                let Ok((rest_key, _addr)): std::result::Result<
                    (&[u8], Address),
                    nom::Err<massa_serialization::DeserializeError<'_>>,
                > = self
                    .cycle_info_deserializer
                    .rolls_deser
                    .address_deserializer
                    .deserialize::<DeserializeError>(&rest_key[1..])
                else {
                    return false;
                };
                if rest_key.len() != 1 {
                    return false;
                }

                match rest_key[0] {
                    PROD_STATS_FAIL_IDENT => {
                        let Ok((rest_key, _fail)) = self
                            .cycle_info_deserializer
                            .production_stats_deser
                            .u64_deserializer
                            .deserialize::<DeserializeError>(serialized_value)
                        else {
                            return false;
                        };
                        if !rest_key.is_empty() {
                            return false;
                        }
                    }
                    PROD_STATS_SUCCESS_IDENT => {
                        let Ok((rest_key, _success)) = self
                            .cycle_info_deserializer
                            .production_stats_deser
                            .u64_deserializer
                            .deserialize::<DeserializeError>(serialized_value)
                        else {
                            return false;
                        };
                        if !rest_key.is_empty() {
                            return false;
                        }
                    }
                    _ => {
                        return false;
                    }
                }
            }
            _ => {
                return false;
            }
        }

        true
    }

    /// Deserializes the key and value, useful after bootstrap
    pub fn is_deferred_credits_key_value_valid(
        &self,
        serialized_key: &[u8],
        serialized_value: &[u8],
    ) -> bool {
        if !serialized_key.starts_with(DEFERRED_CREDITS_PREFIX.as_bytes()) {
            return false;
        }

        // deserialize the slot
        let rest_key = &serialized_key[DEFERRED_CREDITS_PREFIX.len()..];
        let Some((rest_key, _slot)) = buf_to_array_ctr(rest_key, Slot::from_bytes_key) else {
            return false;
        };

        let Ok((rest_key, _addr)): std::result::Result<
            (&[u8], Address),
            nom::Err<massa_serialization::DeserializeError<'_>>,
        > = self
            .credits_deserializer
            .address_deserializer
            .deserialize::<DeserializeError>(rest_key)
        else {
            return false;
        };
        if !rest_key.is_empty() {
            return false;
        }

        let Ok((rest_key, _amount)) = self
            .credits_deserializer
            .amount_deserializer
            .deserialize::<DeserializeError>(serialized_value)
        else {
            return false;
        };
        if !rest_key.is_empty() {
            return false;
        }

        true
    }
}

/// Helpers for testing
#[cfg(feature = "test-exports")]
impl PoSFinalState {
    /// Queries all the deferred credits in the database
    pub fn get_deferred_credits(&self) -> DeferredCredits {
        let db = self.db.read();

        let mut deferred_credits = DeferredCredits::new();

        for (serialized_key, serialized_value) in
            db.prefix_iterator_cf(STATE_CF, DEFERRED_CREDITS_PREFIX.as_bytes())
        {
            if !serialized_key.starts_with(DEFERRED_CREDITS_PREFIX.as_bytes()) {
                break;
            }

            // deserialize the slot
            let rest_key = &serialized_key[DEFERRED_CREDITS_PREFIX.len()..];
            let (rest_key, slot) = buf_to_array_ctr(rest_key, Slot::from_bytes_key)
                .expect(DEFERRED_CREDITS_DESER_ERROR);

            let (_, address) = self
                .credits_deserializer
                .address_deserializer
                .deserialize::<DeserializeError>(rest_key)
                .expect(DEFERRED_CREDITS_DESER_ERROR);

            let (_, amount) = self
                .credits_deserializer
                .amount_deserializer
                .deserialize::<DeserializeError>(&serialized_value)
                .expect(DEFERRED_CREDITS_DESER_ERROR);

            deferred_credits.insert(slot, address, amount);
        }
        deferred_credits
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    use std::collections::HashMap;
    use std::str::FromStr;
    use std::sync::Arc;

    use assert_matches::assert_matches;
    use bitvec::prelude::*;
    use parking_lot::RwLock;
    use tempfile::TempDir;

    use crate::MockSelectorController;

    use massa_db_exports::{MassaDBConfig, MassaDBController};
    use massa_db_worker::MassaDB;
    use massa_models::config::constants::{
        MAX_DEFERRED_CREDITS_LENGTH, MAX_PRODUCTION_STATS_LENGTH, MAX_ROLLS_COUNT_LENGTH,
        POS_SAVED_CYCLES,
    };
    use massa_signature::KeyPair;

    // This test checks that the initial deferred credits are loaded correctly
    #[test]
    fn test_initial_deferred_credits_loading() {
        let initial_deferred_credits_file = tempfile::NamedTempFile::new()
            .expect("could not create temporary initial deferred credits file");
        // write down some deferred credits
        let deferred_credits_file_contents = "{
            \"AU12pAcVUzsgUBJHaYSAtDKVTYnUT9NorBDjoDovMfAFTLFa16MNa\": [
                {
                    \"slot\": {\"period\": 3, \"thread\": 0},
                    \"amount\": \"5.01\"
                },
                {
                    \"slot\": {\"period\": 4, \"thread\": 1},
                    \"amount\": \"6.0\"
                },
                {
                    \"slot\": {\"period\": 255, \"thread\": 0},
                    \"amount\": \"5.01\"
                },
                {
                    \"slot\": {\"period\": 256, \"thread\": 0},
                    \"amount\": \"6.0\"
                }
            ],
            \"AU1wN8rn4SkwYSTDF3dHFY4U28KtsqKL1NnEjDZhHnHEy6cEQm53\": [
                {
                    \"slot\": {\"period\": 3, \"thread\": 0},
                    \"amount\": \"2.01\"
                }
            ]
        }";
        std::fs::write(
            initial_deferred_credits_file.path(),
            deferred_credits_file_contents.as_bytes(),
        )
        .expect("failed writing initial deferred credits file");
        let pos_config = PoSConfig {
            periods_per_cycle: 2,
            thread_count: 2,
            cycle_history_length: POS_SAVED_CYCLES,
            max_rolls_length: MAX_ROLLS_COUNT_LENGTH,
            max_production_stats_length: MAX_PRODUCTION_STATS_LENGTH,
            max_credit_length: MAX_DEFERRED_CREDITS_LENGTH,
            initial_deferred_credits_path: Some(initial_deferred_credits_file.path().to_path_buf()),
        };
        // initialize the database and pos_state
        let tempdir = tempfile::TempDir::new().expect("cannot create temp directory");
        let db_config = MassaDBConfig {
            path: tempdir.path().to_path_buf(),
            max_history_length: 10,
            max_final_state_elements_size: 100_000,
            max_versioning_elements_size: 100_000,
            thread_count: 2,
            max_ledger_backups: 10,
            enable_metrics: false,
        };
        let db = Arc::new(RwLock::new(
            Box::new(MassaDB::new(db_config)) as Box<dyn MassaDBController + 'static>
        ));
        let selector_controller = Box::new(MockSelectorController::new());
        let init_seed = Hash::compute_from(b"");
        let initial_seeds = vec![Hash::compute_from(init_seed.to_bytes()), init_seed];
        let cycle_info_deserializer = CycleInfoDeserializer::new(
            pos_config.max_rolls_length,
            pos_config.max_production_stats_length,
        );
        let mut pos_state = PoSFinalState {
            config: pos_config.clone(),
            db: db.clone(),
            cycle_history_cache: Default::default(),
            rng_seed_cache: None,
            selector: selector_controller,
            initial_rolls: Default::default(),
            initial_seeds,
            credits_serializer: DeferredCreditSerializer::new(),
            credits_deserializer: DeferredCreditDeserializer::new(pos_config.max_credit_length),
            cycle_info_serializer: CycleInfoSerializer::new(),
            cycle_info_deserializer,
        };
        let mut batch = DBBatch::new();
        // load initial deferred credits
        let mut ledger = massa_ledger_exports::MockLedgerController::new();
        ledger.expect_entry_exists().returning(|_| false);
        pos_state
            .load_initial_deferred_credits(&mut batch, &ledger)
            .expect("error while loading initial deferred credits");
        db.write().write_batch(batch, DBBatch::new(), None);
        let deferred_credits = pos_state.get_deferred_credits().credits;
        let addr1 =
            Address::from_str("AU12pAcVUzsgUBJHaYSAtDKVTYnUT9NorBDjoDovMfAFTLFa16MNa").unwrap();
        let a_a1_s3 = Amount::from_str("5.01").unwrap();
        let addr2 =
            Address::from_str("AU1wN8rn4SkwYSTDF3dHFY4U28KtsqKL1NnEjDZhHnHEy6cEQm53").unwrap();
        let a_a2_s3 = Amount::from_str("2.01").unwrap();
        let expected_credits = vec![
            (
                Slot::new(3, 0),
                vec![(addr1, a_a1_s3), (addr2, a_a2_s3)]
                    .into_iter()
                    .collect(),
            ),
            (
                Slot::new(4, 1),
                vec![(addr1, Amount::from_str("6.0").unwrap())]
                    .into_iter()
                    .collect(),
            ),
            (
                Slot::new(255, 0),
                vec![(addr1, Amount::from_str("5.01").unwrap())]
                    .into_iter()
                    .collect(),
            ),
            (
                Slot::new(256, 0),
                vec![(addr1, Amount::from_str("6.0").unwrap())]
                    .into_iter()
                    .collect(),
            ),
        ]
        .into_iter()
        .collect();
        assert_eq!(
            deferred_credits, expected_credits,
            "deferred credits not loaded correctly"
        );
        let credits_range_1 =
            pos_state.get_deferred_credits_range(Slot::new(4, 0)..Slot::new(4, 1), None);
        assert!(credits_range_1.is_empty());
        let credits_range_2 =
            pos_state.get_deferred_credits_range(Slot::new(2, 0)..Slot::new(3, 1), None);
        let expected_credits_range_2 = vec![(
            Slot::new(3, 0),
            vec![(addr1, a_a1_s3), (addr2, a_a2_s3)]
                .into_iter()
                .collect(),
        )]
        .into_iter()
        .collect();
        assert_eq!(credits_range_2.credits, expected_credits_range_2);
        let credits_range_3 =
            pos_state.get_deferred_credits_range(Slot::new(7, 0)..Slot::new(9, 5), None);
        assert!(credits_range_3.is_empty());
        let credits_range_4 =
            pos_state.get_deferred_credits_range(Slot::new(7, 0)..Slot::new(255, 1), None);

        let a_a1_s255 = Amount::from_str("5.01").unwrap();
        let expected_credits_range_4 = vec![(
            Slot::new(255, 0),
            vec![(addr1, a_a1_s255)].into_iter().collect(),
        )]
        .into_iter()
        .collect();
        assert_eq!(credits_range_4.credits, expected_credits_range_4);
    }

    // This test checks that the initial rolls are loaded correctly
    #[test]
    fn test_initial_rolls_loading() {
        let initial_deferred_credits_file =
            tempfile::NamedTempFile::new().expect("could not create temporary initial rolls file");
        let initial_rolls_file_0 =
            tempfile::NamedTempFile::new().expect("could not create temporary initial rolls file");

        // write down some rolls info
        let rolls_file_contents_0 = "{}";
        std::fs::write(
            initial_rolls_file_0.path(),
            rolls_file_contents_0.as_bytes(),
        )
        .expect("failed writing initial rolls file 0");
        // write down some deferred credits
        let deferred_credits_file_contents = "{}";
        std::fs::write(
            initial_deferred_credits_file.path(),
            deferred_credits_file_contents.as_bytes(),
        )
        .expect("failed writing initial deferred credits file");

        // initialize the database
        let tempdir = tempfile::TempDir::new().expect("cannot create temp directory");
        let db_config = MassaDBConfig {
            path: tempdir.path().to_path_buf(),
            max_history_length: 10,
            max_final_state_elements_size: 100,
            max_versioning_elements_size: 100,
            thread_count: 2,
            max_ledger_backups: 10,
            enable_metrics: false,
        };
        let db = Arc::new(RwLock::new(
            Box::new(MassaDB::new(db_config)) as Box<dyn MassaDBController + 'static>
        ));
        let selector_controller = Box::new(MockSelectorController::new());

        let pos_config = PoSConfig {
            periods_per_cycle: 2,
            thread_count: 2,
            cycle_history_length: POS_SAVED_CYCLES,
            max_rolls_length: MAX_ROLLS_COUNT_LENGTH,
            max_production_stats_length: MAX_PRODUCTION_STATS_LENGTH,
            max_credit_length: MAX_DEFERRED_CREDITS_LENGTH,
            initial_deferred_credits_path: Some(initial_deferred_credits_file.path().to_path_buf()),
        };

        let init_seed = "";
        let pos_state_0 = PoSFinalState::new(
            pos_config.clone(),
            init_seed,
            &initial_rolls_file_0.path().to_path_buf(),
            selector_controller,
            db.clone(),
        );

        // Check ok with empty roll file
        assert!(pos_state_0.is_ok());

        // Init a invalid roll file (invalid content)
        let initial_rolls_file_1 =
            tempfile::NamedTempFile::new().expect("could not create temporary initial rolls file");
        let data_1 = HashMap::from([("foo", "bar")]);
        let rolls_file_contents_1 = serde_json::to_string(&data_1).unwrap();
        // println!("rolls_file_contents_1: {}", rolls_file_contents_1);
        std::fs::write(
            initial_rolls_file_1.path(),
            rolls_file_contents_1.as_bytes(),
        )
        .expect("failed writing initial rolls file 1");
        let selector_controller = Box::new(MockSelectorController::new());

        let pos_state_1 = PoSFinalState::new(
            pos_config.clone(),
            init_seed,
            &initial_rolls_file_1.path().to_path_buf(),
            selector_controller,
            db.clone(),
        );

        // Check ko
        assert!(pos_state_1.is_err());

        // Now check with valid data

        let addr1_ = "AU12pAcVUzsgUBJHaYSAtDKVTYnUT9NorBDjoDovMfAFTLFa16MNa";
        let addr1 = Address::from_str(addr1_).unwrap();
        let roll1: u64 = 5;
        let addr2_ = "AU1wN8rn4SkwYSTDF3dHFY4U28KtsqKL1NnEjDZhHnHEy6cEQm53";
        let addr2 = Address::from_str(addr2_).unwrap();
        let roll2: u64 = 65529;

        let initial_rolls_file_2 =
            tempfile::NamedTempFile::new().expect("could not create temporary initial rolls file");
        let data_2 = HashMap::from([(addr1_, roll1), (addr2_, roll2)]);
        let rolls_file_contents_2 = serde_json::to_string(&data_2).unwrap();
        std::fs::write(
            initial_rolls_file_2.path(),
            rolls_file_contents_2.as_bytes(),
        )
        .expect("failed writing initial rolls file 2");
        let selector_controller = Box::new(MockSelectorController::new());

        let mut pos_state_2 = PoSFinalState::new(
            pos_config,
            init_seed,
            &initial_rolls_file_2.path().to_path_buf(),
            selector_controller,
            db.clone(),
        )
        .unwrap();

        assert_eq!(pos_state_2.initial_rolls.get(&addr1), Some(&roll1));
        assert_eq!(pos_state_2.initial_rolls.get(&addr2), Some(&roll2));
        // Note: get_address_active_rolls (if not cycle -3) uses initial_rolls
        assert_eq!(pos_state_2.get_address_active_rolls(&addr1, 0), Some(roll1));
        // Note: get_all_active_rolls (if not cycle -3) uses initial_rolls
        assert_eq!(
            pos_state_2.get_all_active_rolls(0).get(&addr1),
            Some(&roll1)
        );
        assert_eq!(
            pos_state_2.get_all_active_rolls(0).get(&addr2),
            Some(&roll2)
        );

        // Simulate some cycle with address 1 + decrease rolls and address 2 + increase rolls
        let roll_counts_c0 = BTreeMap::from([(addr1, roll1), (addr2, roll2)]);
        let roll_a1_c1 = roll1.checked_sub(1).unwrap();
        let roll_counts_c1 =
            BTreeMap::from([(addr1, roll_a1_c1), (addr2, roll2.checked_add(1).unwrap())]);
        let roll_counts_c2 = BTreeMap::from([
            (addr1, roll1.checked_sub(2).unwrap()),
            (addr2, roll2.checked_add(2).unwrap()),
        ]);
        let roll_a1_c3 = roll1.checked_sub(3).unwrap();
        let roll_a2_c3 = roll2.checked_add(3).unwrap();
        let roll_counts_c3 = BTreeMap::from([(addr1, roll_a1_c3), (addr2, roll_a2_c3)]);
        let roll_a1_c4 = roll1.checked_sub(4).unwrap();
        let roll_a2_c4 = roll2.checked_add(4).unwrap();
        let roll_counts_c4 = BTreeMap::from([(addr1, roll_a1_c4), (addr2, roll_a2_c4)]);
        let cycle_info_0 = CycleInfo::new(
            0,
            Default::default(),
            roll_counts_c0,
            Default::default(),
            Default::default(),
        );
        let cycle_info_1 = CycleInfo {
            cycle: 1,
            roll_counts: roll_counts_c1.clone(),
            ..cycle_info_0.clone()
        };
        let cycle_info_2 = CycleInfo {
            cycle: 2,
            roll_counts: roll_counts_c2,
            ..cycle_info_0.clone()
        };
        let cycle_info_3 = CycleInfo {
            cycle: 3,
            roll_counts: roll_counts_c3,
            ..cycle_info_0.clone()
        };
        let cycle_info_4 = CycleInfo {
            cycle: 4,
            roll_counts: roll_counts_c4,
            ..cycle_info_0.clone()
        };

        let mut batch = DBBatch::new();
        pos_state_2.put_new_cycle_info(&cycle_info_0, &mut batch);
        pos_state_2.put_new_cycle_info(&cycle_info_1, &mut batch);
        pos_state_2.put_new_cycle_info(&cycle_info_2, &mut batch);
        pos_state_2.put_new_cycle_info(&cycle_info_3, &mut batch);
        pos_state_2.put_new_cycle_info(&cycle_info_4, &mut batch);
        pos_state_2
            .db
            .write()
            .write_batch(batch, DBBatch::new(), None);

        assert_eq!(
            pos_state_2.get_address_active_rolls(&addr1, 4),
            Some(roll_a1_c1)
        );
        assert_eq!(
            pos_state_2.get_address_active_rolls(&addr1, 4 + 3 + 1),
            None
        );
        assert_eq!(pos_state_2.get_address_active_rolls(&addr1, 19), None);

        let rolls_1 = pos_state_2.get_rolls_for(&addr1);
        assert_eq!(rolls_1, roll_a1_c4);
        let rolls_2 = pos_state_2.get_rolls_for(&addr2);
        assert_eq!(rolls_2, roll_a2_c4);

        // Will fetch at cycle - 3
        let active_rolls = pos_state_2.get_all_active_rolls(4);
        assert_eq!(active_rolls, roll_counts_c1);
    }

    // This test checks that the recompute_pos_cache function recovers every cycle and does return correctly.
    // The test example is chosen to have the cycles overlap a power of 2, to check that the order of cycles in the DB
    // (lexicographical over bytes) is the same as the order of cycles in the cache (numerical).
    // If this is not handled properly, the node hangs as explained here: https://github.com/massalabs/massa/issues/4101
    #[test]
    fn test_pos_cache_recomputation() {
        let pos_config = PoSConfig {
            periods_per_cycle: 2,
            thread_count: 2,
            cycle_history_length: POS_SAVED_CYCLES,
            max_rolls_length: MAX_ROLLS_COUNT_LENGTH,
            max_production_stats_length: MAX_PRODUCTION_STATS_LENGTH,
            max_credit_length: MAX_DEFERRED_CREDITS_LENGTH,
            initial_deferred_credits_path: None,
        };

        // initialize the database and pos_state
        let tempdir = TempDir::new().expect("cannot create temp directory");
        let db_config = MassaDBConfig {
            path: tempdir.path().to_path_buf(),
            max_history_length: 10,
            max_final_state_elements_size: 100_000,
            max_versioning_elements_size: 100_000,
            thread_count: 2,
            max_ledger_backups: 10,
            enable_metrics: false,
        };
        let db = Arc::new(RwLock::new(
            Box::new(MassaDB::new(db_config)) as Box<dyn MassaDBController + 'static>
        ));
        let selector_controller = Box::new(MockSelectorController::new());
        let init_seed = Hash::compute_from(b"");
        let initial_seeds = vec![Hash::compute_from(init_seed.to_bytes()), init_seed];

        let cycle_info_deserializer = CycleInfoDeserializer::new(
            pos_config.max_rolls_length,
            pos_config.max_production_stats_length,
        );

        let mut pos_state = PoSFinalState {
            config: pos_config.clone(),
            db: db.clone(),
            cycle_history_cache: Default::default(),
            rng_seed_cache: None,
            selector: selector_controller,
            initial_rolls: Default::default(),
            initial_seeds,
            credits_serializer: DeferredCreditSerializer::new(),
            credits_deserializer: DeferredCreditDeserializer::new(pos_config.max_credit_length),
            cycle_info_serializer: CycleInfoSerializer::new(),
            cycle_info_deserializer,
        };

        // Populate the disk with some cycle infos
        let mut cycle_infos = Vec::new();
        for cycle in 509..516 {
            cycle_infos.push(CycleInfo::new(
                cycle,
                Default::default(),
                Default::default(),
                Default::default(),
                Default::default(),
            ));
        }

        let mut batch = DBBatch::new();
        pos_state.put_new_cycle_info(&cycle_infos[0], &mut batch);
        pos_state.put_new_cycle_info(&cycle_infos[1], &mut batch);
        pos_state.put_new_cycle_info(&cycle_infos[2], &mut batch);
        pos_state.put_new_cycle_info(&cycle_infos[3], &mut batch);
        pos_state.put_new_cycle_info(&cycle_infos[4], &mut batch);
        pos_state.put_new_cycle_info(&cycle_infos[5], &mut batch);
        pos_state.put_new_cycle_info(&cycle_infos[6], &mut batch);

        pos_state
            .db
            .write()
            .write_batch(batch, DBBatch::new(), None);

        // Recompute the cache, and assert we do not miss any data
        // We .clear() the cache explicitly, even though we do not need to, to make sure the recomputation works
        pos_state.cycle_history_cache.clear();
        pos_state.recompute_pos_state_caches();

        // Assert that the cache contains the expected cycles
        assert_eq!(
            pos_state.cycle_history_cache.len(),
            cycle_infos.len(),
            "Cycle history len does not match"
        );

        for ((cycle_from_history, _), cycle) in
            pos_state.cycle_history_cache.iter().zip(cycle_infos.iter())
        {
            assert_eq!(
                *cycle_from_history, cycle.cycle,
                "Cycle number does not match"
            );
        }
    }

    // This test aims to check that the basic workflow of apply changes to the PoS state works.
    #[test]
    fn test_pos_final_state_hash_computation() {
        let pos_config = PoSConfig {
            // slots_per_cycle = 4*2 = 8 so the seed bits accumulated below stay within bounds
            periods_per_cycle: 4,
            thread_count: 2,
            cycle_history_length: POS_SAVED_CYCLES,
            max_rolls_length: MAX_ROLLS_COUNT_LENGTH,
            max_production_stats_length: MAX_PRODUCTION_STATS_LENGTH,
            max_credit_length: MAX_DEFERRED_CREDITS_LENGTH,
            initial_deferred_credits_path: None,
        };

        // initialize the database and pos_state
        let tempdir = TempDir::new().expect("cannot create temp directory");
        let db_config = MassaDBConfig {
            path: tempdir.path().to_path_buf(),
            max_history_length: 10,
            max_final_state_elements_size: 100_000,
            max_versioning_elements_size: 100_000,
            thread_count: 2,
            max_ledger_backups: 10,
            enable_metrics: false,
        };
        let db = Arc::new(RwLock::new(
            Box::new(MassaDB::new(db_config)) as Box<dyn MassaDBController + 'static>
        ));
        let selector_controller = Box::new(MockSelectorController::new());
        let init_seed = Hash::compute_from(b"");
        let initial_seeds = vec![Hash::compute_from(init_seed.to_bytes()), init_seed];

        let cycle_info_deserializer = CycleInfoDeserializer::new(
            pos_config.max_rolls_length,
            pos_config.max_production_stats_length,
        );

        let mut pos_state = PoSFinalState {
            config: pos_config.clone(),
            db: db.clone(),
            cycle_history_cache: Default::default(),
            rng_seed_cache: None,
            selector: selector_controller,
            initial_rolls: Default::default(),
            initial_seeds,
            credits_serializer: DeferredCreditSerializer::new(),
            credits_deserializer: DeferredCreditDeserializer::new(pos_config.max_credit_length),
            cycle_info_serializer: CycleInfoSerializer::new(),
            cycle_info_deserializer,
        };

        pos_state.recompute_pos_state_caches();

        let mut batch = DBBatch::new();
        pos_state.create_initial_cycle(&mut batch);
        db.write()
            .write_batch(batch, Default::default(), Some(Slot::new(0, 0)));

        // add changes
        let addr = Address::from_public_key(&KeyPair::generate(0).unwrap().get_public_key());
        let mut roll_changes = PreHashMap::default();
        roll_changes.insert(addr, 10);
        let mut production_stats = PreHashMap::default();
        production_stats.insert(
            addr,
            ProductionStats {
                block_success_count: 4,
                block_failure_count: 0,
            },
        );
        let changes = PoSChanges {
            seed_bits: bitvec![u8, Lsb0; 0, 1],
            roll_changes: roll_changes.clone(),
            production_stats: production_stats.clone(),
            deferred_credits: DeferredCredits::new(),
        };

        let mut batch = DBBatch::new();
        pos_state
            .apply_changes_to_batch(changes, Slot::new(0, 0), false, &mut batch)
            .unwrap();
        db.write()
            .write_batch(batch, Default::default(), Some(Slot::new(0, 0)));

        // update changes once
        roll_changes.clear();
        roll_changes.insert(addr, 20);
        production_stats.clear();
        production_stats.insert(
            addr,
            ProductionStats {
                block_success_count: 4,
                block_failure_count: 6,
            },
        );
        let changes = PoSChanges {
            seed_bits: bitvec![u8, Lsb0; 1, 0],
            roll_changes: roll_changes.clone(),
            production_stats: production_stats.clone(),
            deferred_credits: DeferredCredits::new(),
        };

        let mut batch = DBBatch::new();
        pos_state
            .apply_changes_to_batch(changes, Slot::new(0, 1), false, &mut batch)
            .unwrap();
        db.write()
            .write_batch(batch, Default::default(), Some(Slot::new(0, 1)));

        // update changes twice
        roll_changes.clear();
        roll_changes.insert(addr, 0);
        production_stats.clear();
        production_stats.insert(
            addr,
            ProductionStats {
                block_success_count: 4,
                block_failure_count: 12,
            },
        );

        let changes = PoSChanges {
            seed_bits: bitvec![u8, Lsb0; 0, 1],
            roll_changes,
            production_stats,
            deferred_credits: DeferredCredits::new(),
        };

        let mut batch = DBBatch::new();
        pos_state
            .apply_changes_to_batch(changes, Slot::new(1, 0), false, &mut batch)
            .unwrap();
        db.write()
            .write_batch(batch, Default::default(), Some(Slot::new(1, 0)));

        let cycles = pos_state.get_cycle_history_cycles();
        assert_eq!(cycles.len(), 1, "wrong number of cycles");
        assert_eq!(cycles[0].0, 0, "cycle should be the 1st one");
        assert!(!cycles[0].1, "cycle should not be complete yet");

        let cycle_info_a = pos_state.get_cycle_info(0).unwrap();

        let mut prod_stats = HashMap::default();
        prod_stats.insert(
            addr,
            ProductionStats {
                block_success_count: 12,
                block_failure_count: 18,
            },
        );

        let cycle_info_b = CycleInfo::new(
            0,
            false,
            BTreeMap::default(),
            bitvec![u8, Lsb0; 0, 0, 0, 1, 1, 0, 0, 1],
            prod_stats,
        );

        assert_eq!(cycle_info_a, cycle_info_b, "cycle_info mismatch");
    }

    #[test]
    fn test_feed_selector() {
        let initial_deferred_credits_file =
            tempfile::NamedTempFile::new().expect("could not create temporary initial rolls file");

        let initial_rolls_file_0 =
            tempfile::NamedTempFile::new().expect("could not create temporary initial rolls file");

        // write down some rolls info
        let rolls_file_contents_0 = "{}";
        std::fs::write(
            initial_rolls_file_0.path(),
            rolls_file_contents_0.as_bytes(),
        )
        .expect("failed writing initial rolls file 0");

        // write down some deferred credits
        let deferred_credits_file_contents = "{}";
        std::fs::write(
            initial_deferred_credits_file.path(),
            deferred_credits_file_contents.as_bytes(),
        )
        .expect("failed writing initial deferred credits file");

        // initialize the database
        let tempdir = tempfile::TempDir::new().expect("cannot create temp directory");
        let db_config = MassaDBConfig {
            path: tempdir.path().to_path_buf(),
            max_history_length: 10,
            max_final_state_elements_size: 100,
            max_versioning_elements_size: 100,
            thread_count: 2,
            max_ledger_backups: 10,
            enable_metrics: false,
        };
        let db = Arc::new(RwLock::new(
            Box::new(MassaDB::new(db_config)) as Box<dyn MassaDBController + 'static>
        ));
        let selector_controller = Box::new(MockSelectorController::new());

        let pos_config = PoSConfig {
            periods_per_cycle: 2,
            thread_count: 2,
            cycle_history_length: POS_SAVED_CYCLES,
            max_rolls_length: MAX_ROLLS_COUNT_LENGTH,
            max_production_stats_length: MAX_PRODUCTION_STATS_LENGTH,
            max_credit_length: MAX_DEFERRED_CREDITS_LENGTH,
            initial_deferred_credits_path: Some(initial_deferred_credits_file.path().to_path_buf()),
        };

        let init_seed = "";
        let mut pos_state_0 = PoSFinalState::new(
            pos_config,
            init_seed,
            &initial_rolls_file_0.path().to_path_buf(),
            selector_controller,
            db.clone(),
        )
        .unwrap();

        let cycle_info_0 = CycleInfo::new(
            0,
            true,
            Default::default(),
            Default::default(),
            Default::default(),
        );
        let cycle_info_1 = CycleInfo {
            cycle: 1,
            ..cycle_info_0.clone()
        };
        let cycle_info_2 = CycleInfo {
            cycle: 2,
            ..cycle_info_0.clone()
        };
        let cycle_info_3 = CycleInfo {
            cycle: 3,
            ..cycle_info_0.clone()
        };
        let cycle_info_4 = CycleInfo {
            cycle: 4,
            complete: false,
            ..cycle_info_0.clone()
        };

        let mut batch = DBBatch::new();
        pos_state_0.put_new_cycle_info(&cycle_info_0, &mut batch);
        pos_state_0.put_new_cycle_info(&cycle_info_1, &mut batch);
        pos_state_0.put_new_cycle_info(&cycle_info_2, &mut batch);
        pos_state_0.put_new_cycle_info(&cycle_info_3, &mut batch);
        pos_state_0.put_new_cycle_info(&cycle_info_4, &mut batch);
        pos_state_0
            .db
            .write()
            .write_batch(batch, DBBatch::new(), None);

        // Test feed selector with unfinished cycle
        assert_matches!(
            pos_state_0.feed_selector(4 + 3),
            Err(PosError::CycleUnfinished(4))
        );

        // F100: complete cycles without a final state hash snapshot must error, not panic
        assert_matches!(
            pos_state_0.feed_selector(4),
            Err(PosError::ContainerInconsistency(_))
        );
        assert_matches!(
            pos_state_0.validate_selector_history(),
            Err(PosError::ContainerInconsistency(_))
        );
    }

    #[test]
    fn test_feed_selector_2() {
        let initial_deferred_credits_file =
            tempfile::NamedTempFile::new().expect("could not create temporary initial rolls file");

        let initial_rolls_file_0 =
            tempfile::NamedTempFile::new().expect("could not create temporary initial rolls file");

        // write down some rolls info
        let rolls_file_contents_0 = "{}";
        std::fs::write(
            initial_rolls_file_0.path(),
            rolls_file_contents_0.as_bytes(),
        )
        .expect("failed writing initial rolls file 0");

        // write down some deferred credits
        let deferred_credits_file_contents = "{}";
        std::fs::write(
            initial_deferred_credits_file.path(),
            deferred_credits_file_contents.as_bytes(),
        )
        .expect("failed writing initial deferred credits file");

        // initialize the database
        let tempdir = tempfile::TempDir::new().expect("cannot create temp directory");
        let db_config = MassaDBConfig {
            path: tempdir.path().to_path_buf(),
            max_history_length: 10,
            thread_count: 2,
            max_final_state_elements_size: 100,
            max_versioning_elements_size: 100,
            max_ledger_backups: 10,
            enable_metrics: false,
        };
        let db = Arc::new(RwLock::new(
            Box::new(MassaDB::new(db_config)) as Box<dyn MassaDBController + 'static>
        ));
        let mut selector_controller = Box::new(MockSelectorController::new());
        selector_controller
            .expect_feed_cycle()
            .times(1)
            .returning(|_, _, _| Ok(()));

        let pos_config = PoSConfig {
            periods_per_cycle: 2,
            thread_count: 2,
            cycle_history_length: POS_SAVED_CYCLES,
            max_rolls_length: MAX_ROLLS_COUNT_LENGTH,
            max_production_stats_length: MAX_PRODUCTION_STATS_LENGTH,
            max_credit_length: MAX_DEFERRED_CREDITS_LENGTH,
            initial_deferred_credits_path: Some(initial_deferred_credits_file.path().to_path_buf()),
        };

        let init_seed = "";
        let mut pos_state_0 = PoSFinalState::new(
            pos_config,
            init_seed,
            &initial_rolls_file_0.path().to_path_buf(),
            selector_controller,
            db.clone(),
        )
        .unwrap();

        let cycle_info_0 = CycleInfo::new(
            0,
            true,
            Default::default(),
            Default::default(),
            Default::default(),
        );
        let cycle_info_1 = CycleInfo {
            cycle: 1,
            ..cycle_info_0.clone()
        };
        let cycle_info_2 = CycleInfo {
            cycle: 2,
            ..cycle_info_0.clone()
        };
        let cycle_info_3 = CycleInfo {
            cycle: 3,
            ..cycle_info_0.clone()
        };
        let cycle_info_4 = CycleInfo {
            cycle: 4,
            complete: false,
            ..cycle_info_0.clone()
        };

        let mut batch = DBBatch::new();
        pos_state_0.put_new_cycle_info(&cycle_info_0, &mut batch);
        pos_state_0.put_new_cycle_info(&cycle_info_1, &mut batch);
        pos_state_0.put_new_cycle_info(&cycle_info_2, &mut batch);
        pos_state_0.put_new_cycle_info(&cycle_info_3, &mut batch);
        pos_state_0.put_new_cycle_info(&cycle_info_4, &mut batch);
        pos_state_0
            .db
            .write()
            .write_batch(batch, DBBatch::new(), None);

        // Note: by using cycle 2, feed_selector will use initial_rolls & initial_seeds
        let _ = pos_state_0.feed_selector(2);
    }

    /// Oversized RNG seeds must be rejected by DB key/value validation (bootstrap/DoS hardening).
    #[test]
    fn test_rng_seed_validation_rejects_oversized_seed() {
        let pos_config = PoSConfig {
            periods_per_cycle: 2,
            thread_count: 2, // slots_per_cycle = 4
            cycle_history_length: POS_SAVED_CYCLES,
            max_rolls_length: MAX_ROLLS_COUNT_LENGTH,
            max_production_stats_length: MAX_PRODUCTION_STATS_LENGTH,
            max_credit_length: MAX_DEFERRED_CREDITS_LENGTH,
            initial_deferred_credits_path: None,
        };

        let tempdir = TempDir::new().expect("cannot create temp directory");
        let db_config = MassaDBConfig {
            path: tempdir.path().to_path_buf(),
            max_history_length: 10,
            max_final_state_elements_size: 100_000,
            max_versioning_elements_size: 100_000,
            thread_count: 2,
            max_ledger_backups: 10,
            enable_metrics: false,
        };
        let db = Arc::new(RwLock::new(
            Box::new(MassaDB::new(db_config)) as Box<dyn MassaDBController + 'static>
        ));
        let selector_controller = Box::new(MockSelectorController::new());
        let init_seed = Hash::compute_from(b"");
        let initial_seeds = vec![Hash::compute_from(init_seed.to_bytes()), init_seed];

        let cycle_info_deserializer = CycleInfoDeserializer::new(
            pos_config.max_rolls_length,
            pos_config.max_production_stats_length,
        );

        let mut pos_state = PoSFinalState {
            config: pos_config.clone(),
            db: db.clone(),
            cycle_history_cache: Default::default(),
            rng_seed_cache: None,
            selector: selector_controller,
            initial_rolls: Default::default(),
            initial_seeds,
            credits_serializer: DeferredCreditSerializer::new(),
            credits_deserializer: DeferredCreditDeserializer::new(pos_config.max_credit_length),
            cycle_info_serializer: CycleInfoSerializer::new(),
            cycle_info_deserializer,
        };

        let oversized = bitvec![u8, Lsb0; 0, 1, 0, 1, 0]; // 5 > 4
        let cycle_info = CycleInfo::new(
            0,
            false,
            BTreeMap::default(),
            oversized.clone(),
            PreHashMap::default(),
        );
        let mut batch = DBBatch::new();
        pos_state.put_new_cycle_info(&cycle_info, &mut batch);
        db.write().write_batch(batch, DBBatch::new(), None);

        let prefix = pos_state.cycle_history_cycle_prefix(0);
        let key = rng_seed_key!(prefix);
        let mut serialized_value = Vec::new();
        pos_state
            .cycle_info_serializer
            .bitvec_ser
            .serialize(&oversized, &mut serialized_value)
            .unwrap();

        assert!(
            !pos_state.is_cycle_history_key_value_valid(&key, &serialized_value),
            "oversized RNG seed must be rejected"
        );

        // Completing a cycle with a short seed must also be rejected
        let short_seed = bitvec![u8, Lsb0; 0, 1];
        let mut batch = DBBatch::new();
        pos_state.put_cycle_history_rng_seed(0, short_seed, &mut batch);
        pos_state.put_cycle_history_complete(0, true, &mut batch);
        db.write().write_batch(batch, DBBatch::new(), None);

        let complete_key = complete_key!(prefix);
        assert!(
            !pos_state.is_cycle_history_key_value_valid(&complete_key, &[1]),
            "complete cycle with wrong RNG seed length must be rejected"
        );
    }

    /// Cycle completion with a wrong seed length returns an error instead of panicking.
    #[test]
    fn test_apply_changes_returns_error_on_seed_length_mismatch() {
        let pos_config = PoSConfig {
            periods_per_cycle: 2,
            thread_count: 2, // slots_per_cycle = 4
            cycle_history_length: POS_SAVED_CYCLES,
            max_rolls_length: MAX_ROLLS_COUNT_LENGTH,
            max_production_stats_length: MAX_PRODUCTION_STATS_LENGTH,
            max_credit_length: MAX_DEFERRED_CREDITS_LENGTH,
            initial_deferred_credits_path: None,
        };

        let tempdir = TempDir::new().expect("cannot create temp directory");
        let db_config = MassaDBConfig {
            path: tempdir.path().to_path_buf(),
            max_history_length: 10,
            max_final_state_elements_size: 100_000,
            max_versioning_elements_size: 100_000,
            thread_count: 2,
            max_ledger_backups: 10,
            enable_metrics: false,
        };
        let db = Arc::new(RwLock::new(
            Box::new(MassaDB::new(db_config)) as Box<dyn MassaDBController + 'static>
        ));
        let selector_controller = Box::new(MockSelectorController::new());
        let init_seed = Hash::compute_from(b"");
        let initial_seeds = vec![Hash::compute_from(init_seed.to_bytes()), init_seed];

        let cycle_info_deserializer = CycleInfoDeserializer::new(
            pos_config.max_rolls_length,
            pos_config.max_production_stats_length,
        );

        let mut pos_state = PoSFinalState {
            config: pos_config.clone(),
            db: db.clone(),
            cycle_history_cache: Default::default(),
            rng_seed_cache: None,
            selector: selector_controller,
            initial_rolls: Default::default(),
            initial_seeds,
            credits_serializer: DeferredCreditSerializer::new(),
            credits_deserializer: DeferredCreditDeserializer::new(pos_config.max_credit_length),
            cycle_info_serializer: CycleInfoSerializer::new(),
            cycle_info_deserializer,
        };

        // Incomplete cycle with a short seed; completing it with one more bit yields length 3 ≠ 4.
        let mut batch = DBBatch::new();
        pos_state.put_new_cycle_info(
            &CycleInfo::new(
                0,
                false,
                BTreeMap::default(),
                bitvec![u8, Lsb0; 0, 1],
                PreHashMap::default(),
            ),
            &mut batch,
        );
        db.write()
            .write_batch(batch, Default::default(), Some(Slot::new(1, 0)));
        pos_state.recompute_pos_state_caches();

        // Last slot of cycle 0 with periods_per_cycle=2, thread_count=2 is (1, 1).
        let changes = PoSChanges {
            seed_bits: bitvec![u8, Lsb0; 1],
            roll_changes: PreHashMap::default(),
            production_stats: PreHashMap::default(),
            deferred_credits: DeferredCredits::new(),
        };
        let mut batch = DBBatch::new();
        let err = pos_state
            .apply_changes_to_batch(changes, Slot::new(1, 1), false, &mut batch)
            .expect_err("seed length mismatch on cycle completion must be an error");
        assert_matches!(err, PosError::ContainerInconsistency(_));
    }

    /// Completing a cycle during downtime interpolation must cap seed bits at slots_per_cycle
    /// when the existing seed already includes genesis padding.
    #[test]
    fn test_create_new_cycle_from_last_caps_seed_on_complete() {
        let pos_config = PoSConfig {
            periods_per_cycle: 2,
            thread_count: 2, // slots_per_cycle = 4
            cycle_history_length: POS_SAVED_CYCLES,
            max_rolls_length: MAX_ROLLS_COUNT_LENGTH,
            max_production_stats_length: MAX_PRODUCTION_STATS_LENGTH,
            max_credit_length: MAX_DEFERRED_CREDITS_LENGTH,
            initial_deferred_credits_path: None,
        };

        let tempdir = TempDir::new().expect("cannot create temp directory");
        let db_config = MassaDBConfig {
            path: tempdir.path().to_path_buf(),
            max_history_length: 10,
            max_final_state_elements_size: 100_000,
            max_versioning_elements_size: 100_000,
            thread_count: 2,
            max_ledger_backups: 10,
            enable_metrics: false,
        };
        let db = Arc::new(RwLock::new(
            Box::new(MassaDB::new(db_config)) as Box<dyn MassaDBController + 'static>
        ));
        let selector_controller = Box::new(MockSelectorController::new());
        let init_seed = Hash::compute_from(b"");
        let initial_seeds = vec![Hash::compute_from(init_seed.to_bytes()), init_seed];

        let cycle_info_deserializer = CycleInfoDeserializer::new(
            pos_config.max_rolls_length,
            pos_config.max_production_stats_length,
        );

        let mut pos_state = PoSFinalState {
            config: pos_config.clone(),
            db: db.clone(),
            cycle_history_cache: Default::default(),
            rng_seed_cache: None,
            selector: selector_controller,
            initial_rolls: Default::default(),
            initial_seeds,
            credits_serializer: DeferredCreditSerializer::new(),
            credits_deserializer: DeferredCreditDeserializer::new(pos_config.max_credit_length),
            cycle_info_serializer: CycleInfoSerializer::new(),
            cycle_info_deserializer,
        };

        // Same pattern as create_initial_cycle: thread_count padding bits already present.
        let last_cycle = CycleInfo::new(
            0,
            false,
            BTreeMap::default(),
            bitvec![u8, Lsb0; 0, 0],
            PreHashMap::default(),
        );
        let mut batch = DBBatch::new();
        pos_state
            .create_new_cycle_from_last(
                &last_cycle,
                Slot::new(0, 1),
                Slot::new(1, 1), // last slot of cycle 0
                &mut batch,
            )
            .expect("interpolation should cap seed length instead of overflowing");
        db.write()
            .write_batch(batch, Default::default(), Some(Slot::new(1, 1)));

        let cycle_info = pos_state.get_cycle_info(0).expect("cycle 0 should exist");
        assert!(cycle_info.complete);
        assert_eq!(cycle_info.rng_seed.len(), 4);
    }

    #[test]
    fn test_create_new_cycle_from_last_production_stats() {
        let pos_config = PoSConfig {
            periods_per_cycle: 2,
            thread_count: 2, // slots_per_cycle = 4
            cycle_history_length: POS_SAVED_CYCLES,
            max_rolls_length: MAX_ROLLS_COUNT_LENGTH,
            max_production_stats_length: MAX_PRODUCTION_STATS_LENGTH,
            max_credit_length: MAX_DEFERRED_CREDITS_LENGTH,
            initial_deferred_credits_path: None,
        };

        let tempdir = TempDir::new().expect("cannot create temp directory");
        let db_config = MassaDBConfig {
            path: tempdir.path().to_path_buf(),
            max_history_length: 10,
            max_final_state_elements_size: 100_000,
            max_versioning_elements_size: 100_000,
            thread_count: 2,
            max_ledger_backups: 10,
            enable_metrics: false,
        };
        let db = Arc::new(RwLock::new(
            Box::new(MassaDB::new(db_config)) as Box<dyn MassaDBController + 'static>
        ));
        let selector_controller = Box::new(MockSelectorController::new());
        let init_seed = Hash::compute_from(b"");
        let initial_seeds = vec![Hash::compute_from(init_seed.to_bytes()), init_seed];

        let cycle_info_deserializer = CycleInfoDeserializer::new(
            pos_config.max_rolls_length,
            pos_config.max_production_stats_length,
        );

        let mut pos_state = PoSFinalState {
            config: pos_config.clone(),
            db: db.clone(),
            cycle_history_cache: Default::default(),
            rng_seed_cache: None,
            selector: selector_controller,
            initial_rolls: Default::default(),
            initial_seeds,
            credits_serializer: DeferredCreditSerializer::new(),
            credits_deserializer: DeferredCreditDeserializer::new(pos_config.max_credit_length),
            cycle_info_serializer: CycleInfoSerializer::new(),
            cycle_info_deserializer,
        };

        // Snapshot cycle 0 with non-empty production stats and a partial seed.
        let stats_addr =
            Address::from_str("AU12pAcVUzsgUBJHaYSAtDKVTYnUT9NorBDjoDovMfAFTLFa16MNa").unwrap();
        let mut snapshot_stats = PreHashMap::default();
        snapshot_stats.insert(
            stats_addr,
            ProductionStats {
                block_success_count: 3,
                block_failure_count: 1,
            },
        );
        let snapshot = CycleInfo::new(
            0,
            false,
            BTreeMap::default(),
            bitvec![u8, Lsb0; 0, 0],
            snapshot_stats,
        );

        // Filling the gap in the SAME incomplete cycle keeps the production stats.
        let mut batch = DBBatch::new();
        pos_state
            .create_new_cycle_from_last(
                &snapshot,
                Slot::new(0, 1), // internal slot of cycle 0 (not first)
                Slot::new(0, 1),
                &mut batch,
            )
            .expect("same-cycle interpolation should succeed");
        db.write()
            .write_batch(batch, Default::default(), Some(Slot::new(0, 1)));

        let cycle_0 = pos_state.get_cycle_info(0).expect("cycle 0 should exist");
        let kept = cycle_0
            .production_stats
            .get(&stats_addr)
            .expect("continuing the same incomplete cycle must keep production stats");
        assert_eq!(kept.block_success_count, 3);
        assert_eq!(kept.block_failure_count, 1);

        // F65: interpolating a new cycle must NOT inherit the snapshot's production stats.
        let mut batch = DBBatch::new();
        pos_state
            .create_new_cycle_from_last(
                &snapshot,
                Slot::new(2, 0), // first slot of cycle 1
                Slot::new(3, 1), // last slot of cycle 1
                &mut batch,
            )
            .expect("new cycle interpolation should succeed");
        db.write()
            .write_batch(batch, Default::default(), Some(Slot::new(3, 1)));

        let cycle_1 = pos_state.get_cycle_info(1).expect("cycle 1 should exist");
        assert!(
            cycle_1.production_stats.is_empty(),
            "interpolated new cycle must have empty production stats, got {:?}",
            cycle_1.production_stats
        );
    }
}