rust/src/libstd/old_io/buffered.rs
Alex Crichton 5cf126ae2f std: Remove #[old_orphan_check] from PartialEq
This is a deprecated attribute that is slated for removal, and it also affects
all implementors of the trait. This commit removes the attribute and fixes up
implementors accordingly. The primary implementation which was lost was the
ability to compare `&[T]` and `Vec<T>` (in that order).

This change also modifies the `assert_eq!` macro to not consider both directions
of equality, only the one given in the left/right forms to the macro. This
modification is motivated due to the fact that `&[T] == Vec<T>` no longer
compiles, causing hundreds of errors in unit tests in the standard library (and
likely throughout the community as well).

cc #19470
[breaking-change]
2015-03-31 13:39:14 -07:00

703 lines
22 KiB
Rust

// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//
// ignore-lexer-test FIXME #15883
//! Buffering wrappers for I/O traits
use cmp;
use fmt;
use old_io::{Reader, Writer, Stream, Buffer, DEFAULT_BUF_SIZE, IoResult};
use iter::{Iterator, ExactSizeIterator, repeat};
use ops::Drop;
use option::Option;
use option::Option::{Some, None};
use result::Result::Ok;
use slice;
use vec::Vec;
/// Wraps a Reader and buffers input from it
///
/// It can be excessively inefficient to work directly with a `Reader`. For
/// example, every call to `read` on `TcpStream` results in a system call. A
/// `BufferedReader` performs large, infrequent reads on the underlying
/// `Reader` and maintains an in-memory buffer of the results.
///
/// # Examples
///
/// ```
/// # #![feature(old_io, old_path)]
/// use std::old_io::*;
/// use std::old_path::Path;
///
/// let file = File::open(&Path::new("message.txt"));
/// let mut reader = BufferedReader::new(file);
///
/// let mut buf = [0; 100];
/// match reader.read(&mut buf) {
/// Ok(nread) => println!("Read {} bytes", nread),
/// Err(e) => println!("error reading: {}", e)
/// }
/// ```
pub struct BufferedReader<R> {
inner: R,
buf: Vec<u8>,
pos: usize,
cap: usize,
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<R> fmt::Debug for BufferedReader<R> where R: fmt::Debug {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
write!(fmt, "BufferedReader {{ reader: {:?}, buffer: {}/{} }}",
self.inner, self.cap - self.pos, self.buf.len())
}
}
impl<R: Reader> BufferedReader<R> {
/// Creates a new `BufferedReader` with the specified buffer capacity
pub fn with_capacity(cap: usize, inner: R) -> BufferedReader<R> {
BufferedReader {
inner: inner,
// We can't use the same trick here as we do for BufferedWriter,
// since this memory is visible to the inner Reader.
buf: repeat(0).take(cap).collect(),
pos: 0,
cap: 0,
}
}
/// Creates a new `BufferedReader` with a default buffer capacity
pub fn new(inner: R) -> BufferedReader<R> {
BufferedReader::with_capacity(DEFAULT_BUF_SIZE, inner)
}
/// Gets a reference to the underlying reader.
pub fn get_ref<'a>(&self) -> &R { &self.inner }
/// Gets a mutable reference to the underlying reader.
///
/// # Warning
///
/// It is inadvisable to directly read from the underlying reader.
pub fn get_mut(&mut self) -> &mut R { &mut self.inner }
/// Unwraps this `BufferedReader`, returning the underlying reader.
///
/// Note that any leftover data in the internal buffer is lost.
pub fn into_inner(self) -> R { self.inner }
}
impl<R: Reader> Buffer for BufferedReader<R> {
fn fill_buf<'a>(&'a mut self) -> IoResult<&'a [u8]> {
if self.pos == self.cap {
self.cap = try!(self.inner.read(&mut self.buf));
self.pos = 0;
}
Ok(&self.buf[self.pos..self.cap])
}
fn consume(&mut self, amt: usize) {
self.pos += amt;
assert!(self.pos <= self.cap);
}
}
impl<R: Reader> Reader for BufferedReader<R> {
fn read(&mut self, buf: &mut [u8]) -> IoResult<usize> {
if self.pos == self.cap && buf.len() >= self.buf.len() {
return self.inner.read(buf);
}
let nread = {
let available = try!(self.fill_buf());
let nread = cmp::min(available.len(), buf.len());
slice::bytes::copy_memory(&available[..nread], buf);
nread
};
self.pos += nread;
Ok(nread)
}
}
/// Wraps a Writer and buffers output to it
///
/// It can be excessively inefficient to work directly with a `Writer`. For
/// example, every call to `write` on `TcpStream` results in a system call. A
/// `BufferedWriter` keeps an in memory buffer of data and writes it to the
/// underlying `Writer` in large, infrequent batches.
///
/// This writer will be flushed when it is dropped.
///
/// # Examples
///
/// ```
/// # #![feature(old_io, old_path)]
/// use std::old_io::*;
/// use std::old_path::Path;
///
/// let file = File::create(&Path::new("message.txt")).unwrap();
/// let mut writer = BufferedWriter::new(file);
///
/// writer.write_str("hello, world").unwrap();
/// writer.flush().unwrap();
/// ```
pub struct BufferedWriter<W: Writer> {
inner: Option<W>,
buf: Vec<u8>,
pos: usize
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<W: Writer> fmt::Debug for BufferedWriter<W> where W: fmt::Debug {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
write!(fmt, "BufferedWriter {{ writer: {:?}, buffer: {}/{} }}",
self.inner.as_ref().unwrap(), self.pos, self.buf.len())
}
}
impl<W: Writer> BufferedWriter<W> {
/// Creates a new `BufferedWriter` with the specified buffer capacity
pub fn with_capacity(cap: usize, inner: W) -> BufferedWriter<W> {
// It's *much* faster to create an uninitialized buffer than it is to
// fill everything in with 0. This buffer is entirely an implementation
// detail and is never exposed, so we're safe to not initialize
// everything up-front. This allows creation of BufferedWriter instances
// to be very cheap (large mallocs are not nearly as expensive as large
// callocs).
let mut buf = Vec::with_capacity(cap);
unsafe { buf.set_len(cap); }
BufferedWriter {
inner: Some(inner),
buf: buf,
pos: 0
}
}
/// Creates a new `BufferedWriter` with a default buffer capacity
pub fn new(inner: W) -> BufferedWriter<W> {
BufferedWriter::with_capacity(DEFAULT_BUF_SIZE, inner)
}
fn flush_buf(&mut self) -> IoResult<()> {
if self.pos != 0 {
let ret = self.inner.as_mut().unwrap().write_all(&self.buf[..self.pos]);
self.pos = 0;
ret
} else {
Ok(())
}
}
/// Gets a reference to the underlying writer.
pub fn get_ref(&self) -> &W { self.inner.as_ref().unwrap() }
/// Gets a mutable reference to the underlying write.
///
/// # Warning
///
/// It is inadvisable to directly read from the underlying writer.
pub fn get_mut(&mut self) -> &mut W { self.inner.as_mut().unwrap() }
/// Unwraps this `BufferedWriter`, returning the underlying writer.
///
/// The buffer is flushed before returning the writer.
pub fn into_inner(mut self) -> W {
// FIXME(#12628): is panicking the right thing to do if flushing panicks?
self.flush_buf().unwrap();
self.inner.take().unwrap()
}
}
impl<W: Writer> Writer for BufferedWriter<W> {
fn write_all(&mut self, buf: &[u8]) -> IoResult<()> {
if self.pos + buf.len() > self.buf.len() {
try!(self.flush_buf());
}
if buf.len() > self.buf.len() {
self.inner.as_mut().unwrap().write_all(buf)
} else {
let dst = &mut self.buf[self.pos..];
slice::bytes::copy_memory(buf, dst);
self.pos += buf.len();
Ok(())
}
}
fn flush(&mut self) -> IoResult<()> {
self.flush_buf().and_then(|()| self.inner.as_mut().unwrap().flush())
}
}
#[unsafe_destructor]
impl<W: Writer> Drop for BufferedWriter<W> {
fn drop(&mut self) {
if self.inner.is_some() {
// dtors should not panic, so we ignore a panicked flush
let _ = self.flush_buf();
}
}
}
/// Wraps a Writer and buffers output to it, flushing whenever a newline (`0x0a`,
/// `'\n'`) is detected.
///
/// This writer will be flushed when it is dropped.
pub struct LineBufferedWriter<W: Writer> {
inner: BufferedWriter<W>,
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<W: Writer> fmt::Debug for LineBufferedWriter<W> where W: fmt::Debug {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
write!(fmt, "LineBufferedWriter {{ writer: {:?}, buffer: {}/{} }}",
self.inner.inner, self.inner.pos, self.inner.buf.len())
}
}
impl<W: Writer> LineBufferedWriter<W> {
/// Creates a new `LineBufferedWriter`
pub fn new(inner: W) -> LineBufferedWriter<W> {
// Lines typically aren't that long, don't use a giant buffer
LineBufferedWriter {
inner: BufferedWriter::with_capacity(1024, inner)
}
}
/// Gets a reference to the underlying writer.
///
/// This type does not expose the ability to get a mutable reference to the
/// underlying reader because that could possibly corrupt the buffer.
pub fn get_ref<'a>(&'a self) -> &'a W { self.inner.get_ref() }
/// Unwraps this `LineBufferedWriter`, returning the underlying writer.
///
/// The internal buffer is flushed before returning the writer.
pub fn into_inner(self) -> W { self.inner.into_inner() }
}
impl<W: Writer> Writer for LineBufferedWriter<W> {
fn write_all(&mut self, buf: &[u8]) -> IoResult<()> {
match buf.iter().rposition(|&b| b == b'\n') {
Some(i) => {
try!(self.inner.write_all(&buf[..i + 1]));
try!(self.inner.flush());
try!(self.inner.write_all(&buf[i + 1..]));
Ok(())
}
None => self.inner.write_all(buf),
}
}
fn flush(&mut self) -> IoResult<()> { self.inner.flush() }
}
struct InternalBufferedWriter<W: Writer>(BufferedWriter<W>);
impl<W: Writer> InternalBufferedWriter<W> {
fn get_mut<'a>(&'a mut self) -> &'a mut BufferedWriter<W> {
let InternalBufferedWriter(ref mut w) = *self;
return w;
}
}
impl<W: Reader + Writer> Reader for InternalBufferedWriter<W> {
fn read(&mut self, buf: &mut [u8]) -> IoResult<usize> {
self.get_mut().inner.as_mut().unwrap().read(buf)
}
}
/// Wraps a Stream and buffers input and output to and from it.
///
/// It can be excessively inefficient to work directly with a `Stream`. For
/// example, every call to `read` or `write` on `TcpStream` results in a system
/// call. A `BufferedStream` keeps in memory buffers of data, making large,
/// infrequent calls to `read` and `write` on the underlying `Stream`.
///
/// The output half will be flushed when this stream is dropped.
///
/// # Examples
///
/// ```
/// # #![feature(old_io, old_path)]
/// # #![allow(unused_must_use)]
/// use std::old_io::*;
/// use std::old_path::Path;
///
/// let file = File::open(&Path::new("message.txt"));
/// let mut stream = BufferedStream::new(file);
///
/// stream.write_all("hello, world".as_bytes());
/// stream.flush();
///
/// let mut buf = [0; 100];
/// match stream.read(&mut buf) {
/// Ok(nread) => println!("Read {} bytes", nread),
/// Err(e) => println!("error reading: {}", e)
/// }
/// ```
pub struct BufferedStream<S: Writer> {
inner: BufferedReader<InternalBufferedWriter<S>>
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<S: Writer> fmt::Debug for BufferedStream<S> where S: fmt::Debug {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
let reader = &self.inner;
let writer = &self.inner.inner.0;
write!(fmt, "BufferedStream {{ stream: {:?}, write_buffer: {}/{}, read_buffer: {}/{} }}",
writer.inner,
writer.pos, writer.buf.len(),
reader.cap - reader.pos, reader.buf.len())
}
}
impl<S: Stream> BufferedStream<S> {
/// Creates a new buffered stream with explicitly listed capacities for the
/// reader/writer buffer.
pub fn with_capacities(reader_cap: usize, writer_cap: usize, inner: S)
-> BufferedStream<S> {
let writer = BufferedWriter::with_capacity(writer_cap, inner);
let internal_writer = InternalBufferedWriter(writer);
let reader = BufferedReader::with_capacity(reader_cap,
internal_writer);
BufferedStream { inner: reader }
}
/// Creates a new buffered stream with the default reader/writer buffer
/// capacities.
pub fn new(inner: S) -> BufferedStream<S> {
BufferedStream::with_capacities(DEFAULT_BUF_SIZE, DEFAULT_BUF_SIZE,
inner)
}
/// Gets a reference to the underlying stream.
pub fn get_ref(&self) -> &S {
let InternalBufferedWriter(ref w) = self.inner.inner;
w.get_ref()
}
/// Gets a mutable reference to the underlying stream.
///
/// # Warning
///
/// It is inadvisable to read directly from or write directly to the
/// underlying stream.
pub fn get_mut(&mut self) -> &mut S {
let InternalBufferedWriter(ref mut w) = self.inner.inner;
w.get_mut()
}
/// Unwraps this `BufferedStream`, returning the underlying stream.
///
/// The internal buffer is flushed before returning the stream. Any leftover
/// data in the read buffer is lost.
pub fn into_inner(self) -> S {
let InternalBufferedWriter(w) = self.inner.inner;
w.into_inner()
}
}
impl<S: Stream> Buffer for BufferedStream<S> {
fn fill_buf<'a>(&'a mut self) -> IoResult<&'a [u8]> { self.inner.fill_buf() }
fn consume(&mut self, amt: usize) { self.inner.consume(amt) }
}
impl<S: Stream> Reader for BufferedStream<S> {
fn read(&mut self, buf: &mut [u8]) -> IoResult<usize> {
self.inner.read(buf)
}
}
impl<S: Stream> Writer for BufferedStream<S> {
fn write_all(&mut self, buf: &[u8]) -> IoResult<()> {
self.inner.inner.get_mut().write_all(buf)
}
fn flush(&mut self) -> IoResult<()> {
self.inner.inner.get_mut().flush()
}
}
#[cfg(test)]
mod test {
extern crate test;
use old_io::{self, Reader, Writer, Buffer, BufferPrelude};
use prelude::v1::*;
use super::*;
use super::super::{IoResult, EndOfFile};
use super::super::mem::MemReader;
use self::test::Bencher;
/// A type, free to create, primarily intended for benchmarking creation of
/// wrappers that, just for construction, don't need a Reader/Writer that
/// does anything useful. Is equivalent to `/dev/null` in semantics.
#[derive(Clone,PartialEq,PartialOrd)]
pub struct NullStream;
impl Reader for NullStream {
fn read(&mut self, _: &mut [u8]) -> old_io::IoResult<usize> {
Err(old_io::standard_error(old_io::EndOfFile))
}
}
impl Writer for NullStream {
fn write_all(&mut self, _: &[u8]) -> old_io::IoResult<()> { Ok(()) }
}
/// A dummy reader intended at testing short-reads propagation.
pub struct ShortReader {
lengths: Vec<usize>,
}
impl Reader for ShortReader {
fn read(&mut self, _: &mut [u8]) -> old_io::IoResult<usize> {
if self.lengths.is_empty() {
Err(old_io::standard_error(old_io::EndOfFile))
} else {
Ok(self.lengths.remove(0))
}
}
}
#[test]
fn test_buffered_reader() {
let inner = MemReader::new(vec!(5, 6, 7, 0, 1, 2, 3, 4));
let mut reader = BufferedReader::with_capacity(2, inner);
let mut buf = [0, 0, 0];
let nread = reader.read(&mut buf);
assert_eq!(Ok(3), nread);
let b: &[_] = &[5, 6, 7];
assert_eq!(buf, b);
let mut buf = [0, 0];
let nread = reader.read(&mut buf);
assert_eq!(Ok(2), nread);
let b: &[_] = &[0, 1];
assert_eq!(buf, b);
let mut buf = [0];
let nread = reader.read(&mut buf);
assert_eq!(Ok(1), nread);
let b: &[_] = &[2];
assert_eq!(buf, b);
let mut buf = [0, 0, 0];
let nread = reader.read(&mut buf);
assert_eq!(Ok(1), nread);
let b: &[_] = &[3, 0, 0];
assert_eq!(buf, b);
let nread = reader.read(&mut buf);
assert_eq!(Ok(1), nread);
let b: &[_] = &[4, 0, 0];
assert_eq!(buf, b);
assert!(reader.read(&mut buf).is_err());
}
#[test]
fn test_buffered_writer() {
let inner = Vec::new();
let mut writer = BufferedWriter::with_capacity(2, inner);
writer.write_all(&[0, 1]).unwrap();
let b: &[_] = &[];
assert_eq!(&writer.get_ref()[..], b);
writer.write_all(&[2]).unwrap();
let b: &[_] = &[0, 1];
assert_eq!(&writer.get_ref()[..], b);
writer.write_all(&[3]).unwrap();
assert_eq!(&writer.get_ref()[..], b);
writer.flush().unwrap();
let a: &[_] = &[0, 1, 2, 3];
assert_eq!(a, &writer.get_ref()[..]);
writer.write_all(&[4]).unwrap();
writer.write_all(&[5]).unwrap();
assert_eq!(a, &writer.get_ref()[..]);
writer.write_all(&[6]).unwrap();
let a: &[_] = &[0, 1, 2, 3, 4, 5];
assert_eq!(a, &writer.get_ref()[..]);
writer.write_all(&[7, 8]).unwrap();
let a: &[_] = &[0, 1, 2, 3, 4, 5, 6];
assert_eq!(a, &writer.get_ref()[..]);
writer.write_all(&[9, 10, 11]).unwrap();
let a: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11];
assert_eq!(a, &writer.get_ref()[..]);
writer.flush().unwrap();
assert_eq!(a, &writer.get_ref()[..]);
}
#[test]
fn test_buffered_writer_inner_flushes() {
let mut w = BufferedWriter::with_capacity(3, Vec::new());
w.write_all(&[0, 1]).unwrap();
let a: &[_] = &[];
assert_eq!(&w.get_ref()[..], a);
let w = w.into_inner();
let a: &[_] = &[0, 1];
assert_eq!(a, &w[..]);
}
// This is just here to make sure that we don't infinite loop in the
// newtype struct autoderef weirdness
#[test]
fn test_buffered_stream() {
struct S;
impl old_io::Writer for S {
fn write_all(&mut self, _: &[u8]) -> old_io::IoResult<()> { Ok(()) }
}
impl old_io::Reader for S {
fn read(&mut self, _: &mut [u8]) -> old_io::IoResult<usize> {
Err(old_io::standard_error(old_io::EndOfFile))
}
}
let mut stream = BufferedStream::new(S);
let mut buf = [];
assert!(stream.read(&mut buf).is_err());
stream.write_all(&buf).unwrap();
stream.flush().unwrap();
}
#[test]
fn test_read_until() {
let inner = MemReader::new(vec!(0, 1, 2, 1, 0));
let mut reader = BufferedReader::with_capacity(2, inner);
assert_eq!(reader.read_until(0), Ok(vec!(0)));
assert_eq!(reader.read_until(2), Ok(vec!(1, 2)));
assert_eq!(reader.read_until(1), Ok(vec!(1)));
assert_eq!(reader.read_until(8), Ok(vec!(0)));
assert!(reader.read_until(9).is_err());
}
#[test]
fn test_line_buffer() {
let mut writer = LineBufferedWriter::new(Vec::new());
writer.write_all(&[0]).unwrap();
let b: &[_] = &[];
assert_eq!(&writer.get_ref()[..], b);
writer.write_all(&[1]).unwrap();
assert_eq!(&writer.get_ref()[..], b);
writer.flush().unwrap();
let b: &[_] = &[0, 1];
assert_eq!(&writer.get_ref()[..], b);
writer.write_all(&[0, b'\n', 1, b'\n', 2]).unwrap();
let b: &[_] = &[0, 1, 0, b'\n', 1, b'\n'];
assert_eq!(&writer.get_ref()[..], b);
writer.flush().unwrap();
let b: &[_] = &[0, 1, 0, b'\n', 1, b'\n', 2];
assert_eq!(&writer.get_ref()[..], b);
writer.write_all(&[3, b'\n']).unwrap();
let b: &[_] = &[0, 1, 0, b'\n', 1, b'\n', 2, 3, b'\n'];
assert_eq!(&writer.get_ref()[..], b);
}
#[test]
fn test_read_line() {
let in_buf = MemReader::new(b"a\nb\nc".to_vec());
let mut reader = BufferedReader::with_capacity(2, in_buf);
assert_eq!(reader.read_line(), Ok("a\n".to_string()));
assert_eq!(reader.read_line(), Ok("b\n".to_string()));
assert_eq!(reader.read_line(), Ok("c".to_string()));
assert!(reader.read_line().is_err());
}
#[test]
fn test_lines() {
let in_buf = MemReader::new(b"a\nb\nc".to_vec());
let mut reader = BufferedReader::with_capacity(2, in_buf);
let mut it = reader.lines();
assert_eq!(it.next(), Some(Ok("a\n".to_string())));
assert_eq!(it.next(), Some(Ok("b\n".to_string())));
assert_eq!(it.next(), Some(Ok("c".to_string())));
assert_eq!(it.next(), None);
}
#[test]
fn test_short_reads() {
let inner = ShortReader{lengths: vec![0, 1, 2, 0, 1, 0]};
let mut reader = BufferedReader::new(inner);
let mut buf = [0, 0];
assert_eq!(reader.read(&mut buf), Ok(0));
assert_eq!(reader.read(&mut buf), Ok(1));
assert_eq!(reader.read(&mut buf), Ok(2));
assert_eq!(reader.read(&mut buf), Ok(0));
assert_eq!(reader.read(&mut buf), Ok(1));
assert_eq!(reader.read(&mut buf), Ok(0));
assert!(reader.read(&mut buf).is_err());
}
#[test]
fn read_char_buffered() {
let buf = [195, 159];
let mut reader = BufferedReader::with_capacity(1, &buf[..]);
assert_eq!(reader.read_char(), Ok('ß'));
}
#[test]
fn test_chars() {
let buf = [195, 159, b'a'];
let mut reader = BufferedReader::with_capacity(1, &buf[..]);
let mut it = reader.chars();
assert_eq!(it.next(), Some(Ok('ß')));
assert_eq!(it.next(), Some(Ok('a')));
assert_eq!(it.next(), None);
}
#[test]
#[should_panic]
fn dont_panic_in_drop_on_panicked_flush() {
struct FailFlushWriter;
impl Writer for FailFlushWriter {
fn write_all(&mut self, _buf: &[u8]) -> IoResult<()> { Ok(()) }
fn flush(&mut self) -> IoResult<()> { Err(old_io::standard_error(EndOfFile)) }
}
let writer = FailFlushWriter;
let _writer = BufferedWriter::new(writer);
// If writer panics *again* due to the flush error then the process will abort.
panic!();
}
#[bench]
fn bench_buffered_reader(b: &mut Bencher) {
b.iter(|| {
BufferedReader::new(NullStream)
});
}
#[bench]
fn bench_buffered_writer(b: &mut Bencher) {
b.iter(|| {
BufferedWriter::new(NullStream)
});
}
#[bench]
fn bench_buffered_stream(b: &mut Bencher) {
b.iter(|| {
BufferedStream::new(NullStream);
});
}
}