Struct CountingWriter 

pub struct CountingWriter<W> { /* private fields */ }

Wrapper writer that tracks total bytes written.

This writer wraps any Write implementation and maintains a counter of the total bytes successfully written. This is useful for:

• Tracking compressed archive size for reports
• Monitoring write progress
• Validating expected output sizes

Implementation Notes

The counter only increments on successful writes. If a write operation fails partway through, only the successfully written bytes are counted.

Examples

use exarch_core::io::CountingWriter;
use std::io::Write;

let mut buffer = Vec::new();
let mut writer = CountingWriter::new(&mut buffer);

writer.write_all(b"Hello, ")?;
writer.write_all(b"World!")?;
writer.flush()?;

assert_eq!(writer.total_bytes(), 13);
assert_eq!(buffer, b"Hello, World!");

Implementations

impl<W> CountingWriter<W>

pub fn new(inner: W) -> Self

Creates a new counting writer.

Parameters

• inner: The writer to wrap

Examples

use exarch_core::io::CountingWriter;
use std::io::Write;

let buffer: Vec<u8> = Vec::new();
let writer = CountingWriter::new(buffer);

pub fn total_bytes(&self) -> u64

Returns the total number of bytes successfully written.

This count includes all bytes from successful write operations, including those from write, write_all, and write_fmt.

Examples

use exarch_core::io::CountingWriter;
use std::io::Write;

let mut buffer = Vec::new();
let mut writer = CountingWriter::new(&mut buffer);

writer.write_all(b"test")?;
assert_eq!(writer.total_bytes(), 4);

writer.write_all(b"data")?;
assert_eq!(writer.total_bytes(), 8);

pub fn into_inner(self) -> W

Consumes the counting writer and returns the inner writer.

This is useful when you need to retrieve the underlying writer after all writing is complete.

Examples

use exarch_core::io::CountingWriter;
use std::io::Write;

let buffer = Vec::new();
let mut writer = CountingWriter::new(buffer);

writer.write_all(b"test")?;

let buffer = writer.into_inner();
assert_eq!(buffer, b"test");

pub fn get_ref(&self) -> &W

Returns a reference to the inner writer.

Examples

use exarch_core::io::CountingWriter;

let buffer = Vec::new();
let writer = CountingWriter::new(buffer);

let inner_ref: &Vec<u8> = writer.get_ref();

pub fn get_mut(&mut self) -> &mut W

Returns a mutable reference to the inner writer.

Safety

If you write to the inner writer directly (bypassing the CountingWriter), the byte count will not be updated.

Examples

use exarch_core::io::CountingWriter;

let buffer = Vec::new();
let mut writer = CountingWriter::new(buffer);

let inner_mut: &mut Vec<u8> = writer.get_mut();

Trait Implementations

impl<W: Write> Write for CountingWriter<W>

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_all(&mut self, buf: &[u8]) -> Result<()>

Attempts to write an entire buffer into this writer.

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_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.