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// SPDX-License-Identifier: BUSL-1.1
//! KV WAL replay: rebuilds in-memory hash tables after crash.
use crate::data::executor::core_loop::CoreLoop;
use crate::data::executor::core_loop::write_index::KeyRepr;
impl CoreLoop {
/// Whether a KV WAL record must NOT be re-applied during boot replay.
///
/// Two independent reasons to skip, each a correctness bug if missed:
///
/// * **Tombstoned** — the collection was dropped at or after this LSN, so
/// the record is shadowed by a delete that may itself have fallen out of
/// the live WAL.
/// * **Below the checkpoint floor** — the record's effect is already inside
/// the KV checkpoint restored before replay. Skipping is mandatory rather
/// than merely wasteful: most KV records are DELTAS (`kv_incr`, `kv_cas`,
/// `kv_field_set`, `kv_transfer`, `kv_insert_on_conflict_update`) whose
/// replay re-executes against current state instead of overwriting it, so
/// re-applying one already folded into the checkpoint double-counts it.
///
/// Records ABOVE the floor are safe to replay on top of the restored table:
/// the checkpoint reproduces exactly the state that existed at its stamped
/// LSN, so applying the remaining records in LSN order reaches the same
/// state a full from-zero replay would.
///
/// The floor is engine-wide rather than per-collection because a KV
/// checkpoint publishes every collection at ONE LSN atomically — see
/// `kv_checkpoint.rs` for why a per-collection floor is unsound for the
/// records that span two collections.
pub(in crate::data::executor) fn skip_kv_replay_record(
&self,
tombstones: &nodedb_wal::DatabaseTombstones<'_>,
tenant_id: u64,
collection: &str,
record_lsn: u64,
) -> bool {
tombstones.is_tombstoned(tenant_id, collection, record_lsn)
|| self.floors.replay_floors.kv.covers(record_lsn)
}
/// Replay WAL KV records to rebuild in-memory hash tables after crash.
///
/// KV records use generic `RecordType::Put` and `RecordType::Delete` with
/// a discriminator prefix in the MessagePack payload: `("kv_put", ...)`
/// or `("kv_delete", ...)`.
///
/// Called once during startup, after `open()` but before the event loop.
/// Each core only replays records routed to its vShard.
pub fn replay_kv_wal(
&mut self,
records: &[nodedb_wal::WalRecord],
num_cores: usize,
tombstones: &nodedb_wal::TombstoneSet,
) {
use nodedb_wal::record::RecordType;
let mut puts = 0usize;
let mut deletes = 0usize;
let now_ms = crate::engine::kv::current_ms();
for record in records {
let logical_type = record.logical_record_type();
let record_type = RecordType::from_raw(logical_type);
let is_put = record_type == Some(RecordType::Put);
let is_delete = record_type == Some(RecordType::Delete);
if !is_put && !is_delete {
continue;
}
// Route to the correct core by vShard.
let vshard_id = record.header.vshard_id as usize;
let target_core = if num_cores > 0 {
vshard_id % num_cores
} else {
0
};
if target_core != self.core_id {
continue;
}
let tenant_id = record.header.tenant_id;
let database_id = record.header.database_id;
let record_lsn = record.header.lsn;
let tombstones = &tombstones.for_database(database_id);
// Try to detect KV records by discriminator prefix in the payload.
if is_put {
// kv_put with absolute expiry (redo sub-record):
// ("kv_put", collection, key, value, ttl_ms, expire_at_ms)
//
// zerompk enforces a strict array length, so this six-element
// tuple decodes ONLY the extended shape and never the historical
// five-element one below (and vice versa). When present, the
// resolved absolute instant is installed verbatim instead of
// recomputing `now_ms + ttl_ms`, which would drift the expiry
// forward by the crash-to-restart delay.
if let Ok((disc, collection, key, value, ttl_ms, expire_at_ms)) =
zerompk::from_msgpack::<(&str, String, Vec<u8>, Vec<u8>, u64, u64)>(
&record.payload,
)
&& disc == "kv_put"
{
if self.skip_kv_replay_record(tombstones, tenant_id, &collection, record_lsn) {
continue;
}
self.kv_engine.put_with_absolute_expiry(
crate::engine::kv::KvPutParams {
database_id,
tenant_id,
collection: &collection,
key: &key,
value: &value,
ttl_ms,
now_ms,
surrogate: nodedb_types::Surrogate::ZERO,
},
expire_at_ms,
);
self.note_replay_write_lsn(
database_id,
tenant_id,
&collection,
Some(KeyRepr::KvKey(Box::from(key.as_slice()))),
record_lsn,
);
puts += 1;
continue;
}
// kv_put: ("kv_put", collection, key, value, ttl_ms)
if let Ok((disc, collection, key, value, ttl_ms)) =
zerompk::from_msgpack::<(&str, String, Vec<u8>, Vec<u8>, u64)>(&record.payload)
&& disc == "kv_put"
{
if self.skip_kv_replay_record(tombstones, tenant_id, &collection, record_lsn) {
continue;
}
self.kv_engine.put(crate::engine::kv::KvPutParams {
database_id,
tenant_id,
collection: &collection,
key: &key,
value: &value,
ttl_ms,
now_ms,
surrogate: nodedb_types::Surrogate::ZERO,
});
self.note_replay_write_lsn(
database_id,
tenant_id,
&collection,
Some(KeyRepr::KvKey(Box::from(key.as_slice()))),
record_lsn,
);
puts += 1;
continue;
}
// kv_batch_put with absolute expiry (redo sub-record):
// ("kv_batch_put", collection, entries, ttl_ms, expire_at_ms)
//
// Same rationale as the six-element `kv_put` arm above: zerompk's
// strict array-length check means this five-element tuple decodes
// ONLY the extended shape, never the historical four-element one
// below (and vice versa). The resolved absolute instant is
// installed verbatim on every entry instead of recomputing
// `now_ms + ttl_ms`, which would drift the expiry forward by the
// crash-to-restart delay.
if let Ok((disc, collection, entries, ttl_ms, expire_at_ms)) =
zerompk::from_msgpack::<(&str, String, Vec<(Vec<u8>, Vec<u8>)>, u64, u64)>(
&record.payload,
)
&& disc == "kv_batch_put"
{
if self.skip_kv_replay_record(tombstones, tenant_id, &collection, record_lsn) {
continue;
}
let surrogates = vec![nodedb_types::Surrogate::ZERO; entries.len()];
self.kv_engine.batch_put_with_absolute_expiry(
crate::engine::kv::KvBatchPutParams {
database_id,
tenant_id,
collection: &collection,
entries: &entries,
ttl_ms,
now_ms,
surrogates: &surrogates,
},
expire_at_ms,
);
for (entry_key, _entry_value) in &entries {
self.note_replay_write_lsn(
database_id,
tenant_id,
&collection,
Some(KeyRepr::KvKey(Box::from(entry_key.as_slice()))),
record_lsn,
);
}
puts += entries.len();
continue;
}
// kv_batch_put: ("kv_batch_put", collection, entries, ttl_ms)
if let Ok((disc, collection, entries, ttl_ms)) =
zerompk::from_msgpack::<(&str, String, Vec<(Vec<u8>, Vec<u8>)>, u64)>(
&record.payload,
)
&& disc == "kv_batch_put"
{
if self.skip_kv_replay_record(tombstones, tenant_id, &collection, record_lsn) {
continue;
}
// Same as the `kv_put` replay arm above: this local WAL
// record does not carry the surrogate (it lives in the
// separately-durable, redb-backed surrogate catalog, not
// this per-core WAL), so replay passes `Surrogate::ZERO`
// for every entry, matching single-`Put` replay exactly.
let surrogates = vec![nodedb_types::Surrogate::ZERO; entries.len()];
self.kv_engine
.batch_put(crate::engine::kv::KvBatchPutParams {
database_id,
tenant_id,
collection: &collection,
entries: &entries,
ttl_ms,
now_ms,
surrogates: &surrogates,
});
for (entry_key, _entry_value) in &entries {
self.note_replay_write_lsn(
database_id,
tenant_id,
&collection,
Some(KeyRepr::KvKey(Box::from(entry_key.as_slice()))),
record_lsn,
);
}
puts += entries.len();
continue;
}
// kv_transfer (delta record, not a post-image): re-executes
// `compute_transfer` against whatever source/dest values are
// present in this core's KV engine at this point in LSN
// order — see `wal_replay_kv_transfer.rs` for the full
// rationale and the missing-source / compute-error policy.
if let Some(applied) = self.try_replay_kv_transfer(
&record.payload,
tenant_id,
database_id,
now_ms,
record_lsn,
tombstones,
) {
puts += applied;
continue;
}
// kv_transfer_item (delta record): re-verifies source
// ownership and re-executes the delete+insert pair — see
// `wal_replay_kv_transfer.rs`.
if let Some((item_puts, item_deletes)) = self.try_replay_kv_transfer_item(
&record.payload,
tenant_id,
database_id,
now_ms,
record_lsn,
tombstones,
) {
puts += item_puts;
deletes += item_deletes;
continue;
}
// kv_cas / kv_incr_float / kv_getset (delta records, not
// post-images): re-run the same live computation against
// whatever value is present in this core's KV engine at this
// point in LSN order — see `wal_replay_kv_atomic.rs`.
if let Some(applied) = self.try_replay_kv_atomic(
&record.payload,
tenant_id,
database_id,
now_ms,
record_lsn,
tombstones,
) {
puts += applied;
continue;
}
// kv_field_set (delta record, not a post-image): re-runs the
// same field merge against whatever value is present in this
// core's KV engine at this point in LSN order — see
// `wal_replay_kv_field.rs`.
if let Some(applied) = self.try_replay_kv_field_set(
&record.payload,
tenant_id,
database_id,
now_ms,
record_lsn,
tombstones,
) {
puts += applied;
continue;
}
// kv_insert_on_conflict_update (delta record, not a
// post-image): re-runs the same `apply_on_conflict_updates`
// RMW merge against whatever value is present in this core's
// KV engine at this point in LSN order — see
// `wal_replay_kv_insert_conflict.rs`.
if let Some(applied) = self.try_replay_kv_insert_on_conflict_update(
&record.payload,
tenant_id,
database_id,
now_ms,
record_lsn,
tombstones,
) {
puts += applied;
continue;
}
// kv_register_index / kv_drop_index — see `wal_replay_kv_index.rs`.
if let Some(applied) = self.try_replay_kv_index(
&record.payload,
tenant_id,
database_id,
now_ms,
record_lsn,
tombstones,
) {
puts += applied;
continue;
}
// kv_register_sorted_index — see `wal_replay_kv_sorted_index.rs`.
if let Some(applied) = self.try_replay_kv_register_sorted_index(
&record.payload,
tenant_id,
database_id,
record_lsn,
tombstones,
) {
puts += applied;
continue;
}
// kv_expire — see `wal_replay_kv_expiry.rs`.
if let Some(applied) = self.try_replay_kv_expire(
&record.payload,
tenant_id,
database_id,
record_lsn,
tombstones,
) {
puts += applied;
continue;
}
// kv_persist — see `wal_replay_kv_expiry.rs`.
if let Some(applied) = self.try_replay_kv_persist(
&record.payload,
tenant_id,
database_id,
record_lsn,
tombstones,
) {
puts += applied;
continue;
}
// kv_incr (delta record, not a post-image): re-runs the same
// integer increment against whatever value is present in
// this core's KV engine at this point in LSN order — see
// `wal_replay_kv_incr.rs`.
if let Some(applied) = self.try_replay_kv_incr(
&record.payload,
tenant_id,
database_id,
now_ms,
record_lsn,
tombstones,
) {
puts += applied;
continue;
}
}
if is_delete {
// kv_delete: ("kv_delete", collection, keys)
if let Ok((disc, collection, keys)) =
zerompk::from_msgpack::<(&str, String, Vec<Vec<u8>>)>(&record.payload)
&& disc == "kv_delete"
{
if self.skip_kv_replay_record(tombstones, tenant_id, &collection, record_lsn) {
continue;
}
self.kv_engine
.delete(database_id, tenant_id, &collection, &keys, now_ms);
for deleted_key in &keys {
self.note_replay_write_lsn(
database_id,
tenant_id,
&collection,
Some(KeyRepr::KvKey(Box::from(deleted_key.as_slice()))),
record_lsn,
);
}
deletes += keys.len();
continue;
}
// kv_truncate: ("kv_truncate", collection)
if let Ok((disc, collection)) =
zerompk::from_msgpack::<(&str, String)>(&record.payload)
&& disc == "kv_truncate"
{
if self.skip_kv_replay_record(tombstones, tenant_id, &collection, record_lsn) {
continue;
}
self.kv_engine.truncate(database_id, tenant_id, &collection);
self.note_replay_write_lsn(
database_id,
tenant_id,
&collection,
None,
record_lsn,
);
deletes += 1;
continue;
}
// kv_drop_sorted_index — see `wal_replay_kv_sorted_index.rs`.
// No tombstone gate here: the record carries only
// `index_name`, no collection to gate on. See that module's
// doc comment for why this is safe.
if let Some(applied) =
self.try_replay_kv_drop_sorted_index(&record.payload, tenant_id, database_id)
{
deletes += applied;
}
}
}
if puts > 0 || deletes > 0 {
tracing::info!(
core = self.core_id,
puts,
deletes,
collections = self.kv_engine.stats().collection_count,
"WAL KV replay complete"
);
}
}
}