Struct BStackReader 

pub struct BStackReader<'a> { /* private fields */ }

A cursor-based reader over a BStack payload.

BStackReader implements io::Read and io::Seek, allowing the stack’s payload to be consumed through any interface that expects a readable, seekable byte stream.

Construction

use bstack::BStack;

let stack = BStack::open("log.bin")?;
stack.push(b"hello world")?;

// Start reading from the beginning.
let mut reader = stack.reader();

// Or start from an arbitrary offset.
let mut mid = stack.reader_at(6);

Concurrency

BStackReader borrows the stack immutably, so multiple readers can coexist and run concurrently with each other and with peek / get calls. Concurrent push or pop operations are not blocked by an active reader, but reading interleaved with writes may observe different snapshots of the payload across calls — callers are responsible for synchronisation when that matters.

Implementations

impl<'a> BStackReader<'a>

pub fn position(&self) -> u64

Return the current logical read offset within the payload.

Trait Implementations

impl<'a> From<&'a BStack> for BStackReader<'a>

fn from(stack: &'a BStack) -> Self

Converts to this type from the input type.

impl<'a> Read for BStackReader<'a>

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

Read bytes from the current position into buf.

Returns the number of bytes read, which may be less than buf.len() if the end of the payload is reached. Returns Ok(0) at EOF.

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.

fn read_array<const N: usize>(&mut self) -> Result<[u8; N], Error>

where Self: Sized,

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

Read and return a fixed array of bytes from this source.

impl<'a> Seek for BStackReader<'a>

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

Move the read cursor.

SeekFrom::Start and SeekFrom::Current with a non-negative delta may advance the cursor past the current end of the payload; subsequent read calls will return Ok(0) until the payload grows past that point. Seeking before the start of the payload returns io::ErrorKind::InvalidInput.

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.