Struct VersionChain 

pub struct VersionChain { /* private fields */ }

Chain of versions for a single key, sorted by commit_ts descending

Optimized for:

• O(log V) reads via binary search
• O(1) writes (prepend to front)
• O(V) GC (linear scan with compaction)

Rec 11: Consolidated

Delegates binary-search logic to BinarySearchChain<VersionEntry> from sochdb-core, eliminating duplication with durable_storage::VersionChain.

Implementations

impl VersionChain

pub fn new() -> Self

Create empty version chain

pub fn add_uncommitted( &mut self, value: Option<Vec<u8>>, txn_id: u64, epoch: u32, )

Add uncommitted version

pub fn commit(&mut self, txn_id: u64, commit_ts: u64) -> bool

Commit the uncommitted version

pub fn abort(&mut self, txn_id: u64)

Abort uncommitted version

pub fn read_at( &self, snapshot_ts: u64, current_txn_id: Option<u64>, ) -> Option<&VersionEntry>

Read at snapshot timestamp

Complexity: O(log V) via binary search

pub fn has_write_conflict(&self, my_txn_id: u64) -> bool

Check if there’s a write conflict

pub fn gc(&mut self, min_epoch: u32, min_snapshot_ts: u64) -> usize

Garbage collect old versions

Custom GC: filters by both epoch AND snapshot timestamp. Returns number of versions reclaimed.

pub fn len(&self) -> usize

Get number of versions

pub fn is_empty(&self) -> bool

Check if empty

Trait Implementations

impl Debug for VersionChain

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

Formats the value using the given formatter.

impl Default for VersionChain

fn default() -> VersionChain

Returns the “default value” for a type.

impl MvccVersionChain for VersionChain

type Value = Option<Vec<u8>>

The value type stored in versions

fn get_visible(&self, ctx: &VisibilityContext) -> Option<&Self::Value>

Get the visible version for the given context

fn get_latest(&self) -> Option<&Self::Value>

Get the latest version (regardless of visibility)

fn version_count(&self) -> usize

Number of versions in the chain

fn is_empty(&self) -> bool

Check if the chain is empty

impl MvccVersionChainMut for VersionChain

fn add_uncommitted(&mut self, value: Self::Value, txn_id: TxnId)

Add a new uncommitted version

fn commit_version(&mut self, txn_id: TxnId, commit_ts: Timestamp) -> bool

Commit a version

fn delete_version(&mut self, txn_id: TxnId, _delete_ts: Timestamp) -> bool

Mark the latest visible version as deleted

fn gc(&mut self, min_visible_ts: Timestamp) -> (usize, usize)

Garbage collect versions older than the given timestamp Returns (versions_removed, bytes_freed)

impl WriteConflictDetection for VersionChain

fn has_write_conflict(&self, txn_id: TxnId) -> bool

Check if there’s a write-write conflict with another transaction