Struct MvccTransaction 

pub struct MvccTransaction {
    pub txn_id: u64,
    pub snapshot_ts: u64,
    pub write_set: HashSet<InlineKey>,
    pub read_set: HashSet<InlineKey>,
    pub write_bloom: SsiBloomFilter,
    pub read_bloom: SsiBloomFilter,
    pub state: TxnState,
    pub mode: TransactionMode,
}

Transaction state for MVCC

Fields

txn_id: u64

Transaction ID

snapshot_ts: u64

Snapshot timestamp (reads see commits before this)

write_set: HashSet<InlineKey>

Keys written by this transaction - uses SmallVec for inline storage Pre-sized to WRITE_SET_INITIAL_CAPACITY to avoid resize overhead

read_set: HashSet<InlineKey>

Keys read by this transaction (for SSI validation) - uses SmallVec for inline storage Pre-sized to READ_SET_INITIAL_CAPACITY to avoid resize overhead

write_bloom: SsiBloomFilter

Bloom filter for write set - fast SSI pre-filtering

read_bloom: SsiBloomFilter

Bloom filter for read set - fast SSI pre-filtering

state: TxnState

Transaction state

mode: TransactionMode

Transaction mode for SSI optimization (Recommendation 9) ReadOnly/WriteOnly modes skip SSI tracking for 2.6x improvement

Implementations

impl MvccTransaction

pub fn new(txn_id: u64, snapshot_ts: u64) -> Self

Create a new transaction with pre-sized collections

This avoids HashSet resize overhead during the transaction which was causing +11% regression on write_set.insert().

pub fn read_only(txn_id: u64, snapshot_ts: u64) -> Self

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

Read-only transactions skip all SSI tracking:

• No read_set allocation
• No read_bloom allocation
• No commit validation

Performance

For N=100 reads: 8350ns → 3230ns (2.6× improvement)

pub fn write_only(txn_id: u64, snapshot_ts: u64) -> Self

Create a write-only transaction (partial SSI bypass)

Write-only transactions skip read tracking:

• No read_set tracking
• No read_bloom inserts
• Still needs write_set for commit

pub fn with_mode(txn_id: u64, snapshot_ts: u64, mode: TransactionMode) -> Self

Create transaction with specific mode

pub fn with_capacity( txn_id: u64, snapshot_ts: u64, write_capacity: usize, read_capacity: usize, mode: TransactionMode, ) -> Self

Create with custom capacities for expected workload

Use this when you know the transaction will write many keys to avoid resize overhead entirely.

pub fn is_read_only(&self) -> bool

Check if this is a read-only transaction

pub fn is_single_key_write(&self) -> bool

Check if this is a single-key write transaction

Trait Implementations

impl Clone for MvccTransaction

fn clone(&self) -> MvccTransaction

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for MvccTransaction

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.