Struct BufferedStableWriter

pub struct BufferedStableWriter<M: StableMemory = CanisterStableMemory> { /* private fields */ }

A writer to the stable memory which first writes the bytes to an in memory buffer and flushes the buffer to stable memory each time it becomes full.

Warning: This will overwrite any existing data in stable memory as it writes, so ensure you set the offset value accordingly if you wish to preserve existing data.

Note: Each call to grow or write to stable memory is a relatively expensive operation, so pick a buffer size large enough to avoid excessive calls to stable memory.

Implementations

impl BufferedStableWriter

pub fn new(buffer_size: usize) -> BufferedStableWriter

Creates a new BufferedStableWriter

impl<M: StableMemory> BufferedStableWriter<M>

pub fn with_writer( buffer_size: usize, writer: StableWriter<M>, ) -> BufferedStableWriter<M>

Creates a new BufferedStableWriter which writes to the selected memory

pub fn offset(&self) -> u64

Returns the offset of the writer

Trait Implementations

impl<M: Debug + StableMemory> Debug for BufferedStableWriter<M>

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

Formats the value using the given formatter.

impl<M: StableMemory> Seek for BufferedStableWriter<M>

fn seek(&mut self, pos: SeekFrom) -> Result<u64>

Seek to an offset, in bytes, in a stream.

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

Rewind to the beginning of a stream.

fn stream_len(&mut self) -> Result<u64, Error>

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

Returns the length of this stream (in bytes).

fn stream_position(&mut self) -> Result<u64, Error>

Returns the current seek position from the start of the stream.

fn seek_relative(&mut self, offset: i64) -> Result<(), Error>

Seeks relative to the current position.

impl<M: StableMemory> Write for BufferedStableWriter<M>

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

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

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

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, fmt: 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.