Struct WasiMemoryProvider 

pub struct WasiMemoryProvider { /* private fields */ }

File-backed MemoryProvider for WASI runtimes.

Persists database pages as a single flat file on the filesystem. Each page is 64 KiB, matching the WASM memory page size. The file layout is byte-for-byte equivalent to IC stable memory, enabling portable database snapshots.

Single-writer access is the caller’s responsibility. WASM is single-threaded by default and WASI lock support varies across runtimes.

Examples

use wasi_dbms_memory::WasiMemoryProvider;
use wasm_dbms_memory::MemoryProvider;

let mut provider = WasiMemoryProvider::new("./data/mydb.bin").unwrap();
provider.grow(1).unwrap(); // allocate 1 page (64 KiB)

let data = b"hello";
provider.write(0, data).unwrap();

let mut buf = vec![0u8; 5];
provider.read(0, &mut buf).unwrap();
assert_eq!(&buf, data);

Implementations

impl WasiMemoryProvider

pub fn new(path: impl AsRef<Path>) -> MemoryResult<Self>

Opens or creates a file-backed memory provider at path.

If the file exists, the page count is inferred from the file size. If the file does not exist, it is created empty (0 pages).

Errors

Returns MemoryError::ProviderError if:

• The file cannot be opened or created.
• The existing file size is not a multiple of the page size (64 KiB).

pub fn path(&self) -> &Path

Returns the path to the backing file.

Trait Implementations

impl Debug for WasiMemoryProvider

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

Formats the value using the given formatter.

impl MemoryProvider for WasiMemoryProvider

const PAGE_SIZE: u64 = PAGE_SIZE

The size of a memory page in bytes.

fn size(&self) -> u64

Gets the current size of the memory in bytes.

fn pages(&self) -> u64

Gets the amount of pages currently allocated.

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

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

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

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

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

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

impl TryFrom<&Path> for WasiMemoryProvider

type Error = MemoryError

The type returned in the event of a conversion error.

fn try_from(path: &Path) -> Result<Self, Self::Error>

Performs the conversion.

impl TryFrom<PathBuf> for WasiMemoryProvider

type Error = MemoryError

The type returned in the event of a conversion error.

fn try_from(path: PathBuf) -> Result<Self, Self::Error>

Performs the conversion.