Struct Engine 

pub struct Engine { /* private fields */ }

The Noxu DB engine.

Wires together all internal subsystems:

• EnvironmentImpl (dbi layer)
• Evictor (cache management)
• Cleaner (log GC)
• Checkpointer (durability)
• DaemonManager (background threads)

This is the internal engine that noxu-db wraps. It coordinates all subsystems and provides a unified interface for database operations.

Implementations

impl Engine

pub fn open(config: EngineConfig) -> Result<Self>

Opens a Noxu DB environment with the given configuration.

This is the main entry point for opening an environment. It:

1. Validates configuration
2. Creates the environment directory if needed
3. Creates EnvironmentImpl (dbi layer)
4. Creates Evictor, Cleaner, Checkpointer
5. Runs recovery (RecoveryManager)
6. Starts daemon threads
7. Returns the Engine

Errors

Returns an error if:

• Configuration is invalid
• Environment directory cannot be created
• Recovery fails
• Any subsystem initialization fails

pub fn close(&self) -> Result<()>

Closes the environment.

Performs orderly shutdown:

1. Stop engine daemon threads
2. Flush final checkpoint
3. Close EnvironmentImpl (stops its own daemons, forces a final checkpoint, and fsyncs the WAL)

After close(), the Engine cannot be used. Dropping the Engine afterwards relies on EnvironmentImpl’s own RAII Drop as a backstop; EnvironmentImpl::close is idempotent, so the explicit call here and the eventual Drop do not conflict.

pub fn is_open(&self) -> bool

Returns whether the engine is open.

pub fn get_env_impl(&self) -> &Arc<Mutex<EnvironmentImpl>>

Gets a reference to the EnvironmentImpl.

pub fn get_evictor(&self) -> &Arc<Evictor>

Gets a reference to the Evictor.

pub fn get_cleaner(&self) -> &Arc<Cleaner>

Gets a reference to the Cleaner.

pub fn get_checkpointer(&self) -> &Arc<Checkpointer>

Gets a reference to the Checkpointer.

pub fn get_config(&self) -> &EngineConfig

Gets the engine configuration.

pub fn checkpoint(&self, invoker: &str) -> Result<CheckpointResult>

Performs a checkpoint.

Arguments

• invoker - Description of who invoked the checkpoint (for logging)

Returns

Information about the checkpoint that was performed.

Errors

• EngineError::EnvironmentClosed if the engine has been closed.
• EngineError::InvalidConfig if the engine is opened read-only.
• Any error returned by the underlying checkpointer (e.g. EngineError::DatabaseError propagated from log/tree I/O).

pub fn clean(&self, n_files: u32) -> Result<CleanResult>

Performs log cleaning.

Arguments

• n_files - Maximum number of files to clean

Returns

Information about the cleaning operation.

Errors

• EngineError::EnvironmentClosed if the engine has been closed.
• EngineError::InvalidConfig if the engine is opened read-only.
• EngineError::DatabaseError for any I/O or tree error returned by the underlying cleaner.

pub fn clean_adaptive(&self) -> Result<(CleanResult, u64)>

Throttle-driven cleaning pass for use by the cleaner daemon.

Reads the current log write-byte counter, updates the throttle, then cleans n_files recommended by the throttle.

Returns (CleanResult, sleep_ms) — the daemon should sleep sleep_ms milliseconds before its next pass.

Errors

• EngineError::EnvironmentClosed if the engine has been closed.
• EngineError::InvalidConfig if the engine is opened read-only.
• EngineError::DatabaseError for any I/O or tree error returned by the underlying cleaner.

pub fn evict(&self) -> Result<EvictResult>

Performs cache eviction.

Returns

Information about the eviction operation.

Errors

• EngineError::EnvironmentClosed if the engine has been closed.

pub fn get_stats(&self) -> EnvironmentStats

Collects environment statistics.

Returns a snapshot of statistics from all subsystems.

pub fn get_cache_usage(&self) -> u64

Gets the current cache usage in bytes.

pub fn get_cache_budget(&self) -> u64

Gets the cache budget in bytes.

pub fn is_cache_over_budget(&self) -> bool

Checks if the cache is over budget.

Trait Implementations

impl Drop for Engine

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.