Struct Database

pub struct Database {
    uuid: Uuid,
    index: HashMap<Box<[u8]>, u64>,
    current_file_offset: u64,
    file: BufWriter<LockedFile>,
    buffer: Vec<u8>,
    filename: PathBuf,
}

Fields

uuid: Uuid

index: HashMap<Box<[u8]>, u64>

Index of keys to their values offset

current_file_offset: u64

Points to end of file

file: BufWriter<LockedFile>

buffer: Vec<u8>

Read buffer

filename: PathBuf

Filename of the inner file

Implementations

impl Database

pub fn create(directory: impl AsRef<Path>) -> Result<Self>

Creates a new instance of the database at the specified directory. If the directory contains an existing database, its content will be loaded.

Arguments

• directory - The path where the database will be created or opened.

Returns

• Result<Self> - Returns an instance of the database if successful, otherwise returns an error.

Errors

This method will return an error in the following cases:

• Unable to open or create the directory.
• Another process is already using the database.
• The database is corrupted (when the path contains an existing database).
• The database version is incompatible

fn create_impl(directory: impl AsRef<Path>, mode: CreateMode) -> Result<Self>

fn reload(filename: PathBuf) -> Result<Self>

Reload the database at the specified path

pub fn get_uuid(&self) -> &Uuid

Retrieves the UUID of the current database instance.

Returns

• &Uuid - Returns a reference to the UUID of the instance.

pub fn close(&self)

Closes the current database instance.

Any usage of this database after this call will return an error.

fn read_header(&mut self, header_offset: u64) -> Result<EntryHeader>

fn read_value(&mut self, offset: u64, length: usize) -> Result<&[u8]>

pub fn get(&mut self, key: &[u8]) -> Result<Option<Box<[u8]>>>

Retrieves the value associated with a given key.

Arguments

• key - Bytes representing the key to fetch the value of.

Returns

• Result<Option<Box<[u8]>>> - Returns an optional values if the key exists; otherwise, None. Returns an error if something goes wrong.

fn set_impl(&mut self, key: Box<[u8]>, value: Option<Box<[u8]>>) -> Result<()>

pub fn set(&mut self, key: Box<[u8]>, value: Box<[u8]>) -> Result<()>

Adds or updates an entry (key-value pair) in the database.

Arguments

• key - Bytes representing the key to store.
• value - Bytes representing the value to store.

Returns

• Result<()> - Returns () if successful, otherwise returns an error.

pub fn set_batch<KV, R>( &mut self, key_data_pairs: KV, remove_keys: R, ) -> Result<()>

where KV: IntoIterator<Item = (Box<[u8]>, Box<[u8]>)>, R: IntoIterator<Item = Box<[u8]>>,

Processes multiple entries (key-value pairs) to set and keys to remove in a single batch operation.

Arguments

• key_data_pairs - An iterable of key-value pairs to add or update.
• remove_keys - An iterable of keys to remove from the database.

Returns

• Result<()> - Returns () if successful, otherwise returns an error.

pub fn get_batch<K>(&mut self, keys: K) -> Result<Vec<Option<Box<[u8]>>>>

where K: IntoIterator<Item = Box<[u8]>>,

Fetches a batch of values for the given keys.

Arguments

• keys - An iterable of keys to fetch the values of

Returns

• Result<Vec<Option<Box<[u8]>>>> - Returns a vector of optional values corresponding to each key; if a key is not found, returns None.

pub fn make_checkpoint(&mut self, directory: impl AsRef<Path>) -> Result<()>

Creates a new checkpoint, saving a consistent snapshot of the current state of the database.

Arguments

• directory - The path where the checkpoint files will be created.

Returns

• Result<()> - Returns () if checkpoint creation is successful, otherwise returns an error.

pub fn create_checkpoint(&mut self, directory: impl AsRef<Path>) -> Result<Self>

Creates a new checkpoint, and instantiates a new database from it.

Arguments

• directory - The path where the checkpoint files will be created.

Returns

• Result<Self> - Returns a new instance of the database if successful, otherwise returns an error.

fn flush(&mut self) -> Result<()>

Flush writes buffer to fs and call fsync

fn remove_impl(&mut self, key: Box<[u8]>) -> Result<()>

pub fn remove(&mut self, key: Box<[u8]>) -> Result<()>

Removes a key-value pair from the database.

Arguments

• key - Bytes representing the key to remove.

Returns

• Result<()> - Returns () if the key is removed successfully, otherwise returns an error.

pub fn to_alist(&mut self) -> Result<Vec<(Box<[u8]>, Box<[u8]>)>>

Retrieves all entries (key-value pairs) from the database.

Returns

• Result<Vec<(Box<[u8]>, Box<[u8]>)>> - Returns a vector containing all key-value pairs as boxed byte arrays. Returns an error if retrieval fails.

pub fn run_batch(&mut self, batch: &mut Batch) -> Result<()>

Processes a pre-built batch of operations, effectively running the batch on the database.

Arguments

• batch - A mutable reference to a Batch struct containing the operations to execute.

Returns

• Result<()> - Returns () if the batch is executed successfully, otherwise returns an error.

pub fn gc(&mut self) -> Result<()>

Triggers garbage collection for the database, cleaning up obsolete data and potentially freeing up storage space.

Returns

• Result<()> - Returns () if garbage collection is successful, otherwise returns an error.