Struct VersionSet 

pub struct VersionSet { /* private fields */ }

VersionSet manages the current SuperVersion and provides atomic updates

This is the entry point for all metadata access. Readers call get() to acquire the current SuperVersion, writers call install() to atomically swap in a new version.

Thread Safety

• get(): Lock-free (atomic load)
• install(): Serialized through internal mutex (writers must coordinate)

Multiple readers can proceed in parallel with zero synchronization. Writers are serialized to ensure consistent version progression.

Implementations

impl VersionSet

pub fn new(db_path: PathBuf) -> Self

Create a new VersionSet

pub fn get(&self) -> Guard<Arc<SuperVersion>>

Get current SuperVersion (lock-free)

This is the hot path for reads. Returns a Guard that holds an Arc to the current SuperVersion. The Guard can be dereferenced to access the SuperVersion.

Performance

• Time: O(1) atomic load
• No locks acquired
• No memory allocation

pub fn get_arc(&self) -> Arc<SuperVersion>

Get current SuperVersion as owned Arc

Use this when you need to hold the SuperVersion across await points or store it for later use.

pub fn install(&self, new_version: SuperVersion)

Install a new SuperVersion (serialized)

This atomically swaps the new version into place. The old version remains valid for any readers that acquired it before the swap.

Safety

Only one writer should call this at a time. Use with_write_lock() to serialize concurrent updates.

pub fn with_write_lock<F>(&self, f: F) -> SuperVersion

where F: FnOnce(&SuperVersion) -> SuperVersion,

Execute a function with exclusive write access

Use this to ensure atomic read-modify-write operations on the version set. The function receives the current SuperVersion and should return the new SuperVersion to install.

pub fn register_snapshot(&self, seqno: u64) -> u64

Register a snapshot at the given sequence number

Returns the snapshot sequence number for later release.

pub fn release_snapshot(&self, seqno: u64)

Release a snapshot

pub fn min_preserved_seqno(&self) -> u64

Get minimum sequence number that must be preserved

Returns the oldest snapshot sequence number, or the current version’s min_snapshot_seqno if no snapshots are active.

pub fn update_min_snapshot_seqno(&self)

Update min_snapshot_seqno based on active snapshots

pub fn db_path(&self) -> &PathBuf

Get database path

pub fn version_number(&self) -> u64

Get current version number

Trait Implementations

impl Debug for VersionSet

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

Formats the value using the given formatter.