Struct marble::Marble

pub struct Marble { /* private fields */ }

Garbage-collecting object store. A nice solution to back a pagecache, for people building their own databases.

Writes should generally be performed by some background process whose job it is to clean logs etc…

Implementations

impl Marble

pub fn maintenance(&self) -> Result<usize>

Defragments backing storage files, blocking concurrent calls to write_batch but not blocking concurrent calls to read. Returns the number of rewritten objects.

impl Marble

pub fn read(&self, object_id: u64) -> Result<Option<Box<[u8]>>>

Read a object out of storage. If this object is unknown or has been removed, returns Ok(None). If there is an IO problem, returns Err.

impl Marble

pub fn write_batch<B, I>(&self, write_batch: I) -> Result<()>where B: AsRef<[u8]>, I: IntoIterator<Item = (u64, Option<B>)>,

Write a batch of objects to disk. This function is crash-atomic but NOT runtime atomic. If you are concurrently serving reads, and require atomic batch semantics, you should serve reads out of an in-memory cache until this function returns. Creates one file per call. May perform several fsync calls per call. Ideally, you will heavily batch objects being written using a logger of some sort before calling this function occasionally in the background, then deleting corresponding logs after this function returns.

impl Marble

pub fn stats(&self) -> Stats

Statistics about current files, intended to inform decisions about when to call maintenance based on desired write and space amplification characteristics.

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

If Config::fsync_each_batch is false, this method can be called at a desired interval to ensure that the written batches are durable on disk.

pub fn free_object_ids<'a>(&'a self) -> (u64, impl 'a + Iterator<Item = u64>)

Intended for use in recovery, to bootstrap a higher level object ID allocator.

Returns a tuple of 1 higher than the current max allocated object ID, and an iterator over all object IDs beneath that which are currently deleted (due to being stored as a None in a write batch).

pub fn allocated_object_ids<'a>(&'a self) -> impl 'a + Iterator<Item = u64>

Returns an Iterator over all currently allocated object IDs.

Trait Implementations

impl Clone for Marble

fn clone(&self) -> Marble

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Marble

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

Formats the value using the given formatter.

impl Display for Marble

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

Formats the value using the given formatter.