std::io::BufWriter
Struct std::io::BufWriter
pub struct BufWriter<W: Write> { /* fields omitted */ }
Wraps a writer and buffers its output.
It can be excessively inefficient to work directly with something that implements Write. For example, every call to write on TcpStream results in a system call. A BufWriter keeps an in-memory buffer of data and writes it to an underlying writer in large, infrequent batches.
The buffer will be written out when the writer is dropped.
Examples
Let's write the numbers one through ten to a TcpStream:
use std::io::prelude::*;
use std::net::TcpStream;
let mut stream = TcpStream::connect("127.0.0.1:34254").unwrap();
for i in 1..10 {
stream.write(&[i]).unwrap();
} Because we're not buffering, we write each one in turn, incurring the overhead of a system call per byte written. We can fix this with a BufWriter:
use std::io::prelude::*;
use std::io::BufWriter;
use std::net::TcpStream;
let mut stream = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
for i in 1..10 {
stream.write(&[i]).unwrap();
} By wrapping the stream with a BufWriter, these ten writes are all grouped together by the buffer, and will all be written out in one system call when the stream is dropped.
Methods
impl<W: Write> BufWriter<W>
[src]
fn new(inner: W) -> BufWriter<W>
Creates a new BufWriter with a default buffer capacity.
Examples
use std::io::BufWriter;
use std::net::TcpStream;
let mut buffer = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap()); fn with_capacity(cap: usize, inner: W) -> BufWriter<W>
Creates a new BufWriter with the specified buffer capacity.
Examples
Creating a buffer with a buffer of a hundred bytes.
use std::io::BufWriter;
use std::net::TcpStream;
let stream = TcpStream::connect("127.0.0.1:34254").unwrap();
let mut buffer = BufWriter::with_capacity(100, stream); fn get_ref(&self) -> &W
Gets a reference to the underlying writer.
Examples
use std::io::BufWriter;
use std::net::TcpStream;
let mut buffer = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
// we can use reference just like buffer
let reference = buffer.get_ref(); fn get_mut(&mut self) -> &mut W
Gets a mutable reference to the underlying writer.
It is inadvisable to directly write to the underlying writer.
Examples
use std::io::BufWriter;
use std::net::TcpStream;
let mut buffer = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
// we can use reference just like buffer
let reference = buffer.get_mut(); fn into_inner(self) -> Result<W, IntoInnerError<BufWriter<W>>>
Unwraps this BufWriter, returning the underlying writer.
The buffer is written out before returning the writer.
Examples
use std::io::BufWriter;
use std::net::TcpStream;
let mut buffer = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap());
// unwrap the TcpStream and flush the buffer
let stream = buffer.into_inner().unwrap(); Trait Implementations
impl<W: Write> Write for BufWriter<W>
[src]
fn write(&mut self, buf: &[u8]) -> Result<usize>
Write a buffer into this object, returning how many bytes were written. Read more
fn flush(&mut self) -> Result<()>
Flush this output stream, ensuring that all intermediately buffered contents reach their destination. Read more
fn write_all(&mut self, buf: &[u8]) -> Result<()>
Attempts to write an entire buffer into this write. Read more
fn write_fmt(&mut self, fmt: Arguments) -> Result<()>
Writes a formatted string into this writer, returning any error encountered. Read more
fn by_ref(&mut self) -> &mut Self where
Self: Sized,
Self: Sized,
Creates a "by reference" adaptor for this instance of Write. Read more
impl<W: Write> Debug for BufWriter<W> where
W: Debug,
[src]
W: Debug,
fn fmt(&self, fmt: &mut Formatter) -> Result
Formats the value using the given formatter.
impl<W: Write + Seek> Seek for BufWriter<W>
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fn seek(&mut self, pos: SeekFrom) -> Result<u64>
Seek to the offset, in bytes, in the underlying writer.
Seeking always writes out the internal buffer before seeking.
impl<W: Write> Drop for BufWriter<W>
[src]
fn drop(&mut self)
A method called when the value goes out of scope. Read more
© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/io/struct.BufWriter.html
