Skip to main content

MemoryProvider

wasm_dbms_memory

Trait MemoryProvider 

Source 
pub trait MemoryProvider {
    const PAGE_SIZE: u64;

    // Required methods
    fn size(&self) -> u64;
    fn pages(&self) -> u64;
    fn grow(&mut self, new_pages: u64) -> MemoryResult<u64>;
    fn read(&mut self, offset: u64, buf: &mut [u8]) -> MemoryResult<()>;
    fn write(&mut self, offset: u64, buf: &[u8]) -> MemoryResult<()>;

    // Provided method
    fn flush(&mut self) -> MemoryResult<()> { ... }
}
Expand description

Memory Provider trait defines the interface for interacting with the underlying memory.

Abstracting memory access allows different implementations for production (e.g. stable memory) and testing (heap-based).

Required Associated Constants§

Source

const PAGE_SIZE: u64

The size of a memory page in bytes.

Required Methods§

Source

fn size(&self) -> u64

Gets the current size of the memory in bytes.

Source

fn pages(&self) -> u64

Gets the amount of pages currently allocated.

Source

fn grow(&mut self, new_pages: u64) -> MemoryResult<u64>

Attempts to grow the memory by new_pages (added pages).

Returns an error if it wasn’t possible. Otherwise, returns the previous size in bytes that was reserved.

Actual reserved size after the growth will be previous_size + (new_pages * PAGE_SIZE).

Source

fn read(&mut self, offset: u64, buf: &mut [u8]) -> MemoryResult<()>

Reads data from memory starting at offset into the provided buffer buf.

Returns an error if offset + buf.len() exceeds the current memory size.

Source

fn write(&mut self, offset: u64, buf: &[u8]) -> MemoryResult<()>

Writes data from the provided buffer buf into memory starting at offset.

Returns an error if offset + buf.len() exceeds the current memory size.

Provided Methods§

Source

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

Publishes pending changes to the provider’s durable storage.

Providers without an explicit persistence boundary use the default no-op implementation. This hook does not flush active transaction overlays held by the DBMS context.

Dyn Compatibility§

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors§