Struct NodeVersion 

pub struct NodeVersion { /* private fields */ }

A versioned lock for tree nodes.

Layout

Bit 31: is_leaf | Bit 30: root | Bit 29: deleted | BITS 9-27: split_version Bits 3-8: insert_version | Bit 2: splitting | Bit 1: inserting | Bit 0: locked

Implementations

impl NodeVersion

pub fn lock_bounded(&self) -> LockGuard<'_>

Acquire the lock with bounded spinning before yielding.

impl NodeVersion

pub const fn new(is_leaf: bool) -> Self

Create a new node version.

pub const fn from_value(value: u32) -> Self

Create from raw value. Testing only.

pub fn is_leaf(&self) -> bool

Check if this is a leaf node.

pub fn is_root(&self) -> bool

Check if this is a root node.

pub fn is_deleted(&self) -> bool

Check if this node is logically deleted.

pub const fn is_deleted_version(version: u32) -> bool

Static check on an already-loaded version value.

pub fn is_locked(&self) -> bool

Check if this node is locked.

pub fn is_unpublished(&self) -> bool

True if version counters are zero (freshly allocated, not yet linked into tree).

pub fn is_inserting(&self) -> bool

Check if this node is being inserted into.

pub fn is_splitting(&self) -> bool

Check if this node is being split.

pub fn is_dirty(&self) -> bool

Check if any dirty bit set (inserting or splitting).

pub fn value(&self) -> u32

Get the raw version value.

pub const fn as_ptr(&self) -> *const Self

Raw pointer for APIs that lock nodes via pointers (e.g., PropagationContext).

pub fn stable(&self) -> u32

Get a stable version for optimistic reading.

pub fn acquire_raw(&self) -> u32

Load version without spinning on dirty bits.

pub const fn is_dirty_value(v: u32) -> bool

Static check: does this version value have dirty bits set?

pub fn try_stable(&self) -> Option<u32>

Non-spinning stable: returns Some(version) if clean, None if dirty.

pub fn stable_yield(&self) -> u32

Variant of stable() that yields instead of exponential backoff.

pub fn has_changed(&self, old: u32) -> bool

Check if the version has changed since old.

Returns true if any version counter bits changed (ignoring lock/inserting bits).

C++ Divergence (INTENTIONAL)

C++ uses (x.v_ ^ v_) > lock_bit (ignores bit 0). We use > (LOCK_BIT | INSERTING_BIT) (ignores bits 0-1).

This is safe because version COUNTERS (VINSERT/VSPLIT) are the source of truth. INSERTING_BIT is only a progress indicator set while modifications are in-flight (not yet visible). If writer acquires lock after stable() but before this check, no data has been modified yet so returning false is correct. If writer has released, the version counter increment is detected.

Ordering

The Acquire load ensures all prior field reads are ordered before the version check on all architectures, not just x86/TSO.

pub fn has_split(&self, old: u32) -> bool

Check if a split has occurred since old.

Includes Acquire ordering. See has_changed().

pub fn has_split_no_compiler_fence(&self, old: u32) -> bool

Identical to has_split(). Both now use Acquire loads. Kept as a separate entry point for callers that document their ordering assumptions.

pub fn has_changed_or_locked(&self, old: u32) -> bool

Stronger than has_changed(): also returns true if dirty bits are set (modification in progress).

pub fn lock(&self) -> LockGuard<'_>

Acquire the lock with exponential backoff. Returns a guard.

pub fn try_lock(&self) -> Option<LockGuard<'_>>

Try to acquire the lock without blocking.

pub fn try_lock_for(&self, timeout: Duration) -> Option<LockGuard<'_>>

Try to acquire the lock within timeout.

pub fn lock_with_yield(&self) -> LockGuard<'_>

Acquire lock with yield-on-contention instead of exponential backoff.

pub fn mark_root(&self)

Mark as root. Does not require lock.

pub fn mark_nonroot(&self)

Clear root bit. Used when layer root is demoted.

pub fn new_for_split(source: &Self) -> Self

Create a version for a split sibling: locked + SPLITTING_BIT + same ISLEAF, zero version counters.

Caller must ensure source is locked and unlock_for_split() is called exactly once after the parent pointer is set.

pub fn unlock_for_split(&self)

Unlock a node created with new_for_split. Increments split version counter.

pub fn is_split_locked(&self) -> bool

True if LOCK_BIT and SPLITTING_BIT are both set. For debugging.

Trait Implementations

impl Clone for NodeVersion

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for NodeVersion

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

Formats the value using the given formatter.

impl Default for NodeVersion

fn default() -> Self

Returns the “default value” for a type.