1 // Copyright 2013 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 // ignore-lexer-test FIXME #15883
13 //! Buffering wrappers for I/O traits
16 use io::{Reader, Writer, Stream, Buffer, DEFAULT_BUF_SIZE, IoResult};
17 use iter::ExactSizeIterator;
19 use option::{Some, None, Option};
20 use result::{Ok, Err};
21 use slice::{SlicePrelude};
25 /// Wraps a Reader and buffers input from it
27 /// It can be excessively inefficient to work directly with a `Reader`. For
28 /// example, every call to `read` on `TcpStream` results in a system call. A
29 /// `BufferedReader` performs large, infrequent reads on the underlying
30 /// `Reader` and maintains an in-memory buffer of the results.
35 /// use std::io::{BufferedReader, File};
37 /// let file = File::open(&Path::new("message.txt"));
38 /// let mut reader = BufferedReader::new(file);
40 /// let mut buf = [0, ..100];
41 /// match reader.read(&mut buf) {
42 /// Ok(nread) => println!("Read {} bytes", nread),
43 /// Err(e) => println!("error reading: {}", e)
46 pub struct BufferedReader<R> {
53 impl<R: Reader> BufferedReader<R> {
54 /// Creates a new `BufferedReader` with the specified buffer capacity
55 pub fn with_capacity(cap: uint, inner: R) -> BufferedReader<R> {
56 // It's *much* faster to create an uninitialized buffer than it is to
57 // fill everything in with 0. This buffer is entirely an implementation
58 // detail and is never exposed, so we're safe to not initialize
59 // everything up-front. This allows creation of BufferedReader instances
60 // to be very cheap (large mallocs are not nearly as expensive as large
62 let mut buf = Vec::with_capacity(cap);
63 unsafe { buf.set_len(cap); }
72 /// Creates a new `BufferedReader` with a default buffer capacity
73 pub fn new(inner: R) -> BufferedReader<R> {
74 BufferedReader::with_capacity(DEFAULT_BUF_SIZE, inner)
77 /// Gets a reference to the underlying reader.
78 pub fn get_ref<'a>(&self) -> &R { &self.inner }
80 /// Gets a mutable reference to the underlying reader.
84 /// It is inadvisable to directly read from the underlying reader.
85 pub fn get_mut(&mut self) -> &mut R { &mut self.inner }
87 /// Unwraps this `BufferedReader`, returning the underlying reader.
89 /// Note that any leftover data in the internal buffer is lost.
90 pub fn into_inner(self) -> R { self.inner }
92 /// Deprecated, use into_inner() instead
93 #[deprecated = "renamed to into_inner()"]
94 pub fn unwrap(self) -> R { self.into_inner() }
97 impl<R: Reader> Buffer for BufferedReader<R> {
98 fn fill_buf<'a>(&'a mut self) -> IoResult<&'a [u8]> {
99 if self.pos == self.cap {
100 self.cap = try!(self.inner.read(self.buf[mut]));
103 Ok(self.buf[self.pos..self.cap])
106 fn consume(&mut self, amt: uint) {
108 assert!(self.pos <= self.cap);
112 impl<R: Reader> Reader for BufferedReader<R> {
113 fn read(&mut self, buf: &mut [u8]) -> IoResult<uint> {
114 if self.pos == self.cap && buf.len() >= self.buf.capacity() {
115 return self.inner.read(buf);
118 let available = try!(self.fill_buf());
119 let nread = cmp::min(available.len(), buf.len());
120 slice::bytes::copy_memory(buf, available[..nread]);
128 /// Wraps a Writer and buffers output to it
130 /// It can be excessively inefficient to work directly with a `Writer`. For
131 /// example, every call to `write` on `TcpStream` results in a system call. A
132 /// `BufferedWriter` keeps an in memory buffer of data and writes it to the
133 /// underlying `Writer` in large, infrequent batches.
135 /// This writer will be flushed when it is dropped.
140 /// use std::io::{BufferedWriter, File};
142 /// let file = File::create(&Path::new("message.txt")).unwrap();
143 /// let mut writer = BufferedWriter::new(file);
145 /// writer.write_str("hello, world").unwrap();
146 /// writer.flush().unwrap();
148 pub struct BufferedWriter<W> {
154 impl<W: Writer> BufferedWriter<W> {
155 /// Creates a new `BufferedWriter` with the specified buffer capacity
156 pub fn with_capacity(cap: uint, inner: W) -> BufferedWriter<W> {
157 // See comments in BufferedReader for why this uses unsafe code.
158 let mut buf = Vec::with_capacity(cap);
159 unsafe { buf.set_len(cap); }
167 /// Creates a new `BufferedWriter` with a default buffer capacity
168 pub fn new(inner: W) -> BufferedWriter<W> {
169 BufferedWriter::with_capacity(DEFAULT_BUF_SIZE, inner)
172 fn flush_buf(&mut self) -> IoResult<()> {
174 let ret = self.inner.as_mut().unwrap().write(self.buf[..self.pos]);
182 /// Gets a reference to the underlying writer.
183 pub fn get_ref(&self) -> &W { self.inner.as_ref().unwrap() }
185 /// Gets a mutable reference to the underlying write.
189 /// It is inadvisable to directly read from the underlying writer.
190 pub fn get_mut(&mut self) -> &mut W { self.inner.as_mut().unwrap() }
192 /// Unwraps this `BufferedWriter`, returning the underlying writer.
194 /// The buffer is flushed before returning the writer.
195 pub fn into_inner(mut self) -> W {
196 // FIXME(#12628): is panicking the right thing to do if flushing panicks?
197 self.flush_buf().unwrap();
198 self.inner.take().unwrap()
201 /// Deprecated, use into_inner() instead
202 #[deprecated = "renamed to into_inner()"]
203 pub fn unwrap(self) -> W { self.into_inner() }
206 impl<W: Writer> Writer for BufferedWriter<W> {
207 fn write(&mut self, buf: &[u8]) -> IoResult<()> {
208 if self.pos + buf.len() > self.buf.len() {
209 try!(self.flush_buf());
212 if buf.len() > self.buf.len() {
213 self.inner.as_mut().unwrap().write(buf)
215 let dst = self.buf[mut self.pos..];
216 slice::bytes::copy_memory(dst, buf);
217 self.pos += buf.len();
222 fn flush(&mut self) -> IoResult<()> {
223 self.flush_buf().and_then(|()| self.inner.as_mut().unwrap().flush())
228 impl<W: Writer> Drop for BufferedWriter<W> {
230 if self.inner.is_some() {
231 // dtors should not panic, so we ignore a panicked flush
232 let _ = self.flush_buf();
237 /// Wraps a Writer and buffers output to it, flushing whenever a newline (`0x0a`,
238 /// `'\n'`) is detected.
240 /// This writer will be flushed when it is dropped.
241 pub struct LineBufferedWriter<W> {
242 inner: BufferedWriter<W>,
245 impl<W: Writer> LineBufferedWriter<W> {
246 /// Creates a new `LineBufferedWriter`
247 pub fn new(inner: W) -> LineBufferedWriter<W> {
248 // Lines typically aren't that long, don't use a giant buffer
250 inner: BufferedWriter::with_capacity(1024, inner)
254 /// Gets a reference to the underlying writer.
256 /// This type does not expose the ability to get a mutable reference to the
257 /// underlying reader because that could possibly corrupt the buffer.
258 pub fn get_ref<'a>(&'a self) -> &'a W { self.inner.get_ref() }
260 /// Unwraps this `LineBufferedWriter`, returning the underlying writer.
262 /// The internal buffer is flushed before returning the writer.
263 pub fn into_inner(self) -> W { self.inner.into_inner() }
265 /// Deprecated, use into_inner() instead
266 #[deprecated = "renamed to into_inner()"]
267 pub fn unwrap(self) -> W { self.into_inner() }
270 impl<W: Writer> Writer for LineBufferedWriter<W> {
271 fn write(&mut self, buf: &[u8]) -> IoResult<()> {
272 match buf.iter().rposition(|&b| b == b'\n') {
274 try!(self.inner.write(buf[..i + 1]));
275 try!(self.inner.flush());
276 try!(self.inner.write(buf[i + 1..]));
279 None => self.inner.write(buf),
283 fn flush(&mut self) -> IoResult<()> { self.inner.flush() }
286 struct InternalBufferedWriter<W>(BufferedWriter<W>);
288 impl<W> InternalBufferedWriter<W> {
289 fn get_mut<'a>(&'a mut self) -> &'a mut BufferedWriter<W> {
290 let InternalBufferedWriter(ref mut w) = *self;
295 impl<W: Reader> Reader for InternalBufferedWriter<W> {
296 fn read(&mut self, buf: &mut [u8]) -> IoResult<uint> {
297 self.get_mut().inner.as_mut().unwrap().read(buf)
301 /// Wraps a Stream and buffers input and output to and from it.
303 /// It can be excessively inefficient to work directly with a `Stream`. For
304 /// example, every call to `read` or `write` on `TcpStream` results in a system
305 /// call. A `BufferedStream` keeps in memory buffers of data, making large,
306 /// infrequent calls to `read` and `write` on the underlying `Stream`.
308 /// The output half will be flushed when this stream is dropped.
313 /// # #![allow(unused_must_use)]
314 /// use std::io::{BufferedStream, File};
316 /// let file = File::open(&Path::new("message.txt"));
317 /// let mut stream = BufferedStream::new(file);
319 /// stream.write("hello, world".as_bytes());
322 /// let mut buf = [0, ..100];
323 /// match stream.read(&mut buf) {
324 /// Ok(nread) => println!("Read {} bytes", nread),
325 /// Err(e) => println!("error reading: {}", e)
328 pub struct BufferedStream<S> {
329 inner: BufferedReader<InternalBufferedWriter<S>>
332 impl<S: Stream> BufferedStream<S> {
333 /// Creates a new buffered stream with explicitly listed capacities for the
334 /// reader/writer buffer.
335 pub fn with_capacities(reader_cap: uint, writer_cap: uint, inner: S)
336 -> BufferedStream<S> {
337 let writer = BufferedWriter::with_capacity(writer_cap, inner);
338 let internal_writer = InternalBufferedWriter(writer);
339 let reader = BufferedReader::with_capacity(reader_cap,
341 BufferedStream { inner: reader }
344 /// Creates a new buffered stream with the default reader/writer buffer
346 pub fn new(inner: S) -> BufferedStream<S> {
347 BufferedStream::with_capacities(DEFAULT_BUF_SIZE, DEFAULT_BUF_SIZE,
351 /// Gets a reference to the underlying stream.
352 pub fn get_ref(&self) -> &S {
353 let InternalBufferedWriter(ref w) = self.inner.inner;
357 /// Gets a mutable reference to the underlying stream.
361 /// It is inadvisable to read directly from or write directly to the
362 /// underlying stream.
363 pub fn get_mut(&mut self) -> &mut S {
364 let InternalBufferedWriter(ref mut w) = self.inner.inner;
368 /// Unwraps this `BufferedStream`, returning the underlying stream.
370 /// The internal buffer is flushed before returning the stream. Any leftover
371 /// data in the read buffer is lost.
372 pub fn into_inner(self) -> S {
373 let InternalBufferedWriter(w) = self.inner.inner;
377 /// Deprecated, use into_inner() instead
378 #[deprecated = "renamed to into_inner()"]
379 pub fn unwrap(self) -> S { self.into_inner() }
382 impl<S: Stream> Buffer for BufferedStream<S> {
383 fn fill_buf<'a>(&'a mut self) -> IoResult<&'a [u8]> { self.inner.fill_buf() }
384 fn consume(&mut self, amt: uint) { self.inner.consume(amt) }
387 impl<S: Stream> Reader for BufferedStream<S> {
388 fn read(&mut self, buf: &mut [u8]) -> IoResult<uint> {
393 impl<S: Stream> Writer for BufferedStream<S> {
394 fn write(&mut self, buf: &[u8]) -> IoResult<()> {
395 self.inner.inner.get_mut().write(buf)
397 fn flush(&mut self) -> IoResult<()> {
398 self.inner.inner.get_mut().flush()
408 use super::super::{IoResult, EndOfFile};
409 use super::super::mem::{MemReader, BufReader};
410 use self::test::Bencher;
413 /// A type, free to create, primarily intended for benchmarking creation of
414 /// wrappers that, just for construction, don't need a Reader/Writer that
415 /// does anything useful. Is equivalent to `/dev/null` in semantics.
416 #[deriving(Clone,PartialEq,PartialOrd)]
417 pub struct NullStream;
419 impl Reader for NullStream {
420 fn read(&mut self, _: &mut [u8]) -> io::IoResult<uint> {
421 Err(io::standard_error(io::EndOfFile))
425 impl Writer for NullStream {
426 fn write(&mut self, _: &[u8]) -> io::IoResult<()> { Ok(()) }
429 /// A dummy reader intended at testing short-reads propagation.
430 pub struct ShortReader {
434 impl Reader for ShortReader {
435 fn read(&mut self, _: &mut [u8]) -> io::IoResult<uint> {
436 match self.lengths.remove(0) {
438 None => Err(io::standard_error(io::EndOfFile))
444 fn test_buffered_reader() {
445 let inner = MemReader::new(vec!(5, 6, 7, 0, 1, 2, 3, 4));
446 let mut reader = BufferedReader::with_capacity(2, inner);
448 let mut buf = [0, 0, 0];
449 let nread = reader.read(&mut buf);
450 assert_eq!(Ok(3), nread);
451 let b: &[_] = &[5, 6, 7];
452 assert_eq!(buf.as_slice(), b);
454 let mut buf = [0, 0];
455 let nread = reader.read(&mut buf);
456 assert_eq!(Ok(2), nread);
457 let b: &[_] = &[0, 1];
458 assert_eq!(buf.as_slice(), b);
461 let nread = reader.read(&mut buf);
462 assert_eq!(Ok(1), nread);
464 assert_eq!(buf.as_slice(), b);
466 let mut buf = [0, 0, 0];
467 let nread = reader.read(&mut buf);
468 assert_eq!(Ok(1), nread);
469 let b: &[_] = &[3, 0, 0];
470 assert_eq!(buf.as_slice(), b);
472 let nread = reader.read(&mut buf);
473 assert_eq!(Ok(1), nread);
474 let b: &[_] = &[4, 0, 0];
475 assert_eq!(buf.as_slice(), b);
477 assert!(reader.read(&mut buf).is_err());
481 fn test_buffered_writer() {
482 let inner = Vec::new();
483 let mut writer = BufferedWriter::with_capacity(2, inner);
485 writer.write(&[0, 1]).unwrap();
487 assert_eq!(writer.get_ref()[], b);
489 writer.write(&[2]).unwrap();
490 let b: &[_] = &[0, 1];
491 assert_eq!(writer.get_ref()[], b);
493 writer.write(&[3]).unwrap();
494 assert_eq!(writer.get_ref()[], b);
496 writer.flush().unwrap();
497 let a: &[_] = &[0, 1, 2, 3];
498 assert_eq!(a, writer.get_ref()[]);
500 writer.write(&[4]).unwrap();
501 writer.write(&[5]).unwrap();
502 assert_eq!(a, writer.get_ref()[]);
504 writer.write(&[6]).unwrap();
505 let a: &[_] = &[0, 1, 2, 3, 4, 5];
509 writer.write(&[7, 8]).unwrap();
510 let a: &[_] = &[0, 1, 2, 3, 4, 5, 6];
514 writer.write(&[9, 10, 11]).unwrap();
515 let a: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11];
519 writer.flush().unwrap();
525 fn test_buffered_writer_inner_flushes() {
526 let mut w = BufferedWriter::with_capacity(3, Vec::new());
527 w.write(&[0, 1]).unwrap();
529 assert_eq!(a, w.get_ref()[]);
531 let a: &[_] = &[0, 1];
535 // This is just here to make sure that we don't infinite loop in the
536 // newtype struct autoderef weirdness
538 fn test_buffered_stream() {
541 impl io::Writer for S {
542 fn write(&mut self, _: &[u8]) -> io::IoResult<()> { Ok(()) }
545 impl io::Reader for S {
546 fn read(&mut self, _: &mut [u8]) -> io::IoResult<uint> {
547 Err(io::standard_error(io::EndOfFile))
551 let mut stream = BufferedStream::new(S);
553 assert!(stream.read(&mut buf).is_err());
554 stream.write(&buf).unwrap();
555 stream.flush().unwrap();
559 fn test_read_until() {
560 let inner = MemReader::new(vec!(0, 1, 2, 1, 0));
561 let mut reader = BufferedReader::with_capacity(2, inner);
562 assert_eq!(reader.read_until(0), Ok(vec!(0)));
563 assert_eq!(reader.read_until(2), Ok(vec!(1, 2)));
564 assert_eq!(reader.read_until(1), Ok(vec!(1)));
565 assert_eq!(reader.read_until(8), Ok(vec!(0)));
566 assert!(reader.read_until(9).is_err());
570 fn test_line_buffer() {
571 let mut writer = LineBufferedWriter::new(Vec::new());
572 writer.write(&[0]).unwrap();
574 assert_eq!(writer.get_ref()[], b);
575 writer.write(&[1]).unwrap();
576 assert_eq!(writer.get_ref()[], b);
577 writer.flush().unwrap();
578 let b: &[_] = &[0, 1];
579 assert_eq!(writer.get_ref()[], b);
580 writer.write(&[0, b'\n', 1, b'\n', 2]).unwrap();
581 let b: &[_] = &[0, 1, 0, b'\n', 1, b'\n'];
582 assert_eq!(writer.get_ref()[], b);
583 writer.flush().unwrap();
584 let b: &[_] = &[0, 1, 0, b'\n', 1, b'\n', 2];
585 assert_eq!(writer.get_ref()[], b);
586 writer.write(&[3, b'\n']).unwrap();
587 let b: &[_] = &[0, 1, 0, b'\n', 1, b'\n', 2, 3, b'\n'];
588 assert_eq!(writer.get_ref()[], b);
592 fn test_read_line() {
593 let in_buf = MemReader::new(b"a\nb\nc".to_vec());
594 let mut reader = BufferedReader::with_capacity(2, in_buf);
595 assert_eq!(reader.read_line(), Ok("a\n".to_string()));
596 assert_eq!(reader.read_line(), Ok("b\n".to_string()));
597 assert_eq!(reader.read_line(), Ok("c".to_string()));
598 assert!(reader.read_line().is_err());
603 let in_buf = MemReader::new(b"a\nb\nc".to_vec());
604 let mut reader = BufferedReader::with_capacity(2, in_buf);
605 let mut it = reader.lines();
606 assert_eq!(it.next(), Some(Ok("a\n".to_string())));
607 assert_eq!(it.next(), Some(Ok("b\n".to_string())));
608 assert_eq!(it.next(), Some(Ok("c".to_string())));
609 assert_eq!(it.next(), None);
613 fn test_short_reads() {
614 let inner = ShortReader{lengths: vec![0, 1, 2, 0, 1, 0]};
615 let mut reader = BufferedReader::new(inner);
616 let mut buf = [0, 0];
617 assert_eq!(reader.read(&mut buf), Ok(0));
618 assert_eq!(reader.read(&mut buf), Ok(1));
619 assert_eq!(reader.read(&mut buf), Ok(2));
620 assert_eq!(reader.read(&mut buf), Ok(0));
621 assert_eq!(reader.read(&mut buf), Ok(1));
622 assert_eq!(reader.read(&mut buf), Ok(0));
623 assert!(reader.read(&mut buf).is_err());
627 fn read_char_buffered() {
628 let buf = [195u8, 159u8];
629 let mut reader = BufferedReader::with_capacity(1, BufReader::new(&buf));
630 assert_eq!(reader.read_char(), Ok('ß'));
635 let buf = [195u8, 159u8, b'a'];
636 let mut reader = BufferedReader::with_capacity(1, BufReader::new(&buf));
637 let mut it = reader.chars();
638 assert_eq!(it.next(), Some(Ok('ß')));
639 assert_eq!(it.next(), Some(Ok('a')));
640 assert_eq!(it.next(), None);
645 fn dont_panic_in_drop_on_panicked_flush() {
646 struct FailFlushWriter;
648 impl Writer for FailFlushWriter {
649 fn write(&mut self, _buf: &[u8]) -> IoResult<()> { Ok(()) }
650 fn flush(&mut self) -> IoResult<()> { Err(io::standard_error(EndOfFile)) }
653 let writer = FailFlushWriter;
654 let _writer = BufferedWriter::new(writer);
656 // If writer panics *again* due to the flush error then the process will abort.
661 fn bench_buffered_reader(b: &mut Bencher) {
663 BufferedReader::new(NullStream)
668 fn bench_buffered_writer(b: &mut Bencher) {
670 BufferedWriter::new(NullStream)
675 fn bench_buffered_stream(b: &mut Bencher) {
677 BufferedStream::new(NullStream);