Enum GetIntoBufferResult 

pub enum GetIntoBufferResult {
    NotFound,
    Found(usize),
    BufferTooSmall(usize),
}

Result of a get_into_buffer operation.

This enum represents the outcome of attempting to read a value directly into a caller-provided buffer, avoiding memory allocation. This is the most efficient way to read values when you have a pre-allocated buffer available.

Performance

Using get_into_buffer with a reusable buffer can significantly reduce allocation overhead in hot paths compared to get or even get_pinned:

• get: Allocates a new Vec<u8> for each call
• get_pinned: Pins memory in RocksDB’s block cache
• get_into_buffer: Zero allocation when buffer is large enough

Example

use rust_rocksdb::{DB, GetIntoBufferResult};

let db = DB::open_default(tempdir.path()).unwrap();
db.put(b"key", b"value").unwrap();

let mut buffer = [0u8; 1024];
match db.get_into_buffer(b"key", &mut buffer).unwrap() {
    GetIntoBufferResult::Found(len) => {
        println!("Value: {:?}", &buffer[..len]);
    }
    GetIntoBufferResult::NotFound => {
        println!("Key not found");
    }
    GetIntoBufferResult::BufferTooSmall(needed) => {
        println!("Need a buffer of at least {} bytes", needed);
    }
}

Variants

NotFound

The key was not found in the database.

Found(usize)

The value was found and successfully copied into the buffer. The usize contains the actual size of the value (number of bytes written).

BufferTooSmall(usize)

The value was found but the provided buffer was too small to hold it. The usize contains the actual size of the value, allowing the caller to allocate a larger buffer and retry.

Note: When this variant is returned, no data is written to the buffer.

Implementations

impl GetIntoBufferResult

pub fn is_found(&self) -> bool

Returns true if the key was found (regardless of buffer size).

pub fn is_not_found(&self) -> bool

Returns true if the key was not found.

pub fn value_size(&self) -> Option<usize>

Returns the value size if the key was found, None otherwise.

Trait Implementations

impl Clone for GetIntoBufferResult

fn clone(&self) -> GetIntoBufferResult

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for GetIntoBufferResult

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

Formats the value using the given formatter.

impl Hash for GetIntoBufferResult

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for GetIntoBufferResult

fn eq(&self, other: &GetIntoBufferResult) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for GetIntoBufferResult

impl Eq for GetIntoBufferResult

impl StructuralPartialEq for GetIntoBufferResult