Struct LockState 

pub struct LockState { /* private fields */ }

The aggregate lock state of a single file, shared by every open handle to it.

This encodes SQLite’s lock-compatibility rules (os.c / pager.c): many SHARED readers may coexist; a single RESERVED write-intent lock coexists with readers; PENDING stops new readers while a writer drains the existing ones; and EXCLUSIVE excludes everything else. A VFS shares one LockState per path among its handles so concurrent connections in the same process serialize exactly as separate SQLite connections would.

Implementations

impl LockState

pub fn acquire(&mut self, from: LockLevel, to: LockLevel) -> Result<()>

Move a handle from lock level from up to to, mutating the shared state. Returns Error::Busy if another handle holds an incompatible lock. A request at or below the current level is a no-op success.

pub fn has_write_intent(&self) -> bool

Whether any write-intent lock (RESERVED/PENDING/EXCLUSIVE) is held by some handle in this process. Used by the std VFS to decide when the process must hold an OS-level exclusive lock (ROADMAP C9b).

pub fn reader_count(&self) -> usize

Number of SHARED (read) locks currently held across all handles.

pub fn release(&mut self, from: LockLevel, to: LockLevel)

Release a handle from from down to to, clearing whatever it held above to. Never fails.

Trait Implementations

impl Debug for LockState

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

Formats the value using the given formatter.

impl Default for LockState

fn default() -> LockState

Returns the “default value” for a type.