Struct StableStorage 

pub struct StableStorage {
    pub offset: Offset,
    /* private fields */
}

Reader/Writer of the canister stable memory.

It keeps track of the current read/write offset, and will attempt to grow the stable memory as needed.

Fields

offset: Offset

Offset of the next read or write.

Implementations

impl StableStorage

pub fn new() -> Self

Create a new instance of StableStorage.

pub fn finalize(self) -> Result<(), Error>

Write current offset value to the last 8 bytes (in little-endian) of the stable memory. This is an important step if you plan to later resume by reconstructing StableStorage from the stable memory.

Trait Implementations

impl Default for StableStorage

The default instance of StableStorage starts at offset 0 if the current stable memory capacity is 0 (which means it is never used).

Otherwise it reads the offset value from the last 8 bytes (in little endian) of the stable memory.

fn default() -> Self

Returns the “default value” for a type.

impl Read for StableStorage

fn read(&mut self, buf: &mut [u8]) -> Result<usize, Error>

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize, Error>

Like read, except that it reads into a slice of buffers.

fn is_read_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector)

Determines if this Reader has an efficient read_vectored implementation.

fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize, Error>

Reads all bytes until EOF in this source, placing them into buf.

fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>

Reads all bytes until EOF in this source, appending them to buf.

fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>

Reads the exact number of bytes required to fill buf.

fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> Result<(), Error>

🔬This is a nightly-only experimental API. (read_buf)

Pull some bytes from this source into the specified buffer.

fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<(), Error>

🔬This is a nightly-only experimental API. (read_buf)

Reads the exact number of bytes required to fill cursor.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adapter for this instance of Read.

fn bytes(self) -> Bytes<Self>

where Self: Sized,

Transforms this Read instance to an Iterator over its bytes.

fn chain<R>(self, next: R) -> Chain<Self, R>

where R: Read, Self: Sized,

Creates an adapter which will chain this stream with another.

fn take(self, limit: u64) -> Take<Self>

where Self: Sized,

Creates an adapter which will read at most limit bytes from it.

impl StorageStack for StableStorage

fn new_with(&self, offset: Offset) -> Self

Return a new StorageStack object with the given offset.

fn offset(&self) -> Offset

Return the current read/write offset.

fn push<T>(&mut self, t: T) -> Result<(), Error>

where T: ArgumentEncoder,

Push a value to the end of the stack.

fn pop<T>(&mut self) -> Result<T, Error>

where T: for<'de> ArgumentDecoder<'de>,

Pop a value from the end of the stack. In case of OutOfBounds error, offset is not changed. In case of Candid decoding error, offset may be changed.

fn seek_prev(&mut self) -> Result<(), Error>

Seek to the start of previous value by changing the offset. This is similar to pop but without reading the actual value.

impl Write for StableStorage

fn write(&mut self, buf: &[u8]) -> Result<usize, Error>

Writes a buffer into this writer, returning how many bytes were written.

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

Flushes this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>

Like write, except that it writes from a slice of buffers.

fn is_write_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector)

Determines if this Writer has an efficient write_vectored implementation.

fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>

Attempts to write an entire buffer into this writer.

fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<(), Error>

🔬This is a nightly-only experimental API. (write_all_vectored)

Attempts to write multiple buffers into this writer.

fn write_fmt(&mut self, args: Arguments<'_>) -> Result<(), Error>

Writes a formatted string into this writer, returning any error encountered.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adapter for this instance of Write.