Struct MvccManager 

pub struct MvccManager { /* private fields */ }

MVCC Manager with SSI support

Uses DashMap for lock-free per-transaction access. Implements Serializable Snapshot Isolation (SSI) with dangerous structure detection for rw-antidependency cycles.

Implementations

impl MvccManager

pub fn new() -> Self

pub fn begin(&self, txn_id: u64) -> MvccTransaction

Begin a new transaction with snapshot isolation

Uses pre-sized HashSets to avoid resize overhead (+11% regression fix)

pub fn begin_read_only(&self, txn_id: u64) -> MvccTransaction

Begin a read-only transaction (SSI bypass - 2.6x faster)

Read-only transactions skip all SSI tracking, reducing per-read overhead from ~82ns to ~32ns.

Safety

Caller must ensure no writes are performed. Attempting to write in a read-only transaction will still succeed but won’t be tracked for SSI validation.

pub fn begin_write_only(&self, txn_id: u64) -> MvccTransaction

Begin a write-only transaction (partial SSI bypass)

Write-only transactions skip read tracking, reducing overhead for insert-heavy workloads.

pub fn begin_with_mode( &self, txn_id: u64, mode: TransactionMode, ) -> MvccTransaction

Begin a transaction with specific mode

This is the core transaction creation method that all other begin_* methods delegate to.

pub fn get(&self, txn_id: u64) -> Option<MvccTransaction>

Get transaction if active (clones - use get_snapshot_ts for hot path)

pub fn get_snapshot_ts(&self, txn_id: u64) -> Option<u64>

Fast path: get just the snapshot timestamp without cloning This is the hot path for reads - avoids cloning bloom filters

pub fn record_read(&self, txn_id: u64, key: &[u8])

Record a read (for SSI) - uses inline key storage + bloom filter

SSI Bypass (Recommendation 9)

For ReadOnly mode transactions, this is a no-op (instant return). For WriteOnly mode transactions, this is a no-op. Only ReadWrite mode transactions track reads for SSI.

This reduces per-read overhead from ~50ns to ~0ns for read-only txns.

pub fn record_write(&self, txn_id: u64, key: &[u8])

Record a write - uses inline key storage + bloom filter

Note: Even ReadOnly transactions can record writes (mode is a hint). The mode only affects SSI tracking, not write capability.

pub fn alloc_commit_ts(&self) -> u64

Allocate commit timestamp

pub fn commit(&self, txn_id: u64) -> Option<(u64, HashSet<InlineKey>)>

Commit transaction with SSI validation Returns (commit_ts, write_set) so the memtable can be updated efficiently Returns None if SSI validation fails (dangerous structure detected)

SSI Bypass (Recommendation 9)

For ReadOnly mode: Skip validation entirely (~10ns commit) For WriteOnly mode: Skip read-based validation (~30ns commit) For ReadWrite mode: Full validation (~50ns commit)

pub fn abort(&self, txn_id: u64)

Abort transaction

pub fn min_active_snapshot(&self) -> u64

Get minimum active snapshot timestamp

pub fn active_transaction_count(&self) -> usize

Get count of active transactions

Trait Implementations

impl Default for MvccManager

fn default() -> Self

Returns the “default value” for a type.