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
17 use io::{Reader, Writer, Stream, Buffer, DEFAULT_BUF_SIZE, IoResult};
18 use iter::{IteratorExt, ExactSizeIterator, repeat};
21 use option::Option::{Some, None};
22 use result::Result::Ok;
23 use slice::{SliceExt};
27 /// Wraps a Reader and buffers input from it
29 /// It can be excessively inefficient to work directly with a `Reader`. For
30 /// example, every call to `read` on `TcpStream` results in a system call. A
31 /// `BufferedReader` performs large, infrequent reads on the underlying
32 /// `Reader` and maintains an in-memory buffer of the results.
37 /// use std::io::{BufferedReader, File};
39 /// let file = File::open(&Path::new("message.txt"));
40 /// let mut reader = BufferedReader::new(file);
42 /// let mut buf = [0; 100];
43 /// match reader.read(&mut buf) {
44 /// Ok(nread) => println!("Read {} bytes", nread),
45 /// Err(e) => println!("error reading: {}", e)
48 pub struct BufferedReader<R> {
56 impl<R> fmt::Debug for BufferedReader<R> where R: fmt::Debug {
57 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
58 write!(fmt, "BufferedReader {{ reader: {:?}, buffer: {}/{} }}",
59 self.inner, self.cap - self.pos, self.buf.len())
63 impl<R: Reader> BufferedReader<R> {
64 /// Creates a new `BufferedReader` with the specified buffer capacity
65 pub fn with_capacity(cap: uint, inner: R) -> BufferedReader<R> {
68 // We can't use the same trick here as we do for BufferedWriter,
69 // since this memory is visible to the inner Reader.
70 buf: repeat(0).take(cap).collect(),
76 /// Creates a new `BufferedReader` with a default buffer capacity
77 pub fn new(inner: R) -> BufferedReader<R> {
78 BufferedReader::with_capacity(DEFAULT_BUF_SIZE, inner)
81 /// Gets a reference to the underlying reader.
82 pub fn get_ref<'a>(&self) -> &R { &self.inner }
84 /// Gets a mutable reference to the underlying reader.
88 /// It is inadvisable to directly read from the underlying reader.
89 pub fn get_mut(&mut self) -> &mut R { &mut self.inner }
91 /// Unwraps this `BufferedReader`, returning the underlying reader.
93 /// Note that any leftover data in the internal buffer is lost.
94 pub fn into_inner(self) -> R { self.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.as_mut_slice()));
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> {
155 impl<W> fmt::Debug for BufferedWriter<W> where W: fmt::Debug {
156 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
157 write!(fmt, "BufferedWriter {{ writer: {:?}, buffer: {}/{} }}",
158 self.inner.as_ref().unwrap(), self.pos, self.buf.len())
162 impl<W: Writer> BufferedWriter<W> {
163 /// Creates a new `BufferedWriter` with the specified buffer capacity
164 pub fn with_capacity(cap: uint, inner: W) -> BufferedWriter<W> {
165 // It's *much* faster to create an uninitialized buffer than it is to
166 // fill everything in with 0. This buffer is entirely an implementation
167 // detail and is never exposed, so we're safe to not initialize
168 // everything up-front. This allows creation of BufferedWriter instances
169 // to be very cheap (large mallocs are not nearly as expensive as large
171 let mut buf = Vec::with_capacity(cap);
172 unsafe { buf.set_len(cap); }
180 /// Creates a new `BufferedWriter` with a default buffer capacity
181 pub fn new(inner: W) -> BufferedWriter<W> {
182 BufferedWriter::with_capacity(DEFAULT_BUF_SIZE, inner)
185 fn flush_buf(&mut self) -> IoResult<()> {
187 let ret = self.inner.as_mut().unwrap().write(&self.buf[..self.pos]);
195 /// Gets a reference to the underlying writer.
196 pub fn get_ref(&self) -> &W { self.inner.as_ref().unwrap() }
198 /// Gets a mutable reference to the underlying write.
202 /// It is inadvisable to directly read from the underlying writer.
203 pub fn get_mut(&mut self) -> &mut W { self.inner.as_mut().unwrap() }
205 /// Unwraps this `BufferedWriter`, returning the underlying writer.
207 /// The buffer is flushed before returning the writer.
208 pub fn into_inner(mut self) -> W {
209 // FIXME(#12628): is panicking the right thing to do if flushing panicks?
210 self.flush_buf().unwrap();
211 self.inner.take().unwrap()
215 impl<W: Writer> Writer for BufferedWriter<W> {
216 fn write(&mut self, buf: &[u8]) -> IoResult<()> {
217 if self.pos + buf.len() > self.buf.len() {
218 try!(self.flush_buf());
221 if buf.len() > self.buf.len() {
222 self.inner.as_mut().unwrap().write(buf)
224 let dst = self.buf.slice_from_mut(self.pos);
225 slice::bytes::copy_memory(dst, buf);
226 self.pos += buf.len();
231 fn flush(&mut self) -> IoResult<()> {
232 self.flush_buf().and_then(|()| self.inner.as_mut().unwrap().flush())
237 impl<W: Writer> Drop for BufferedWriter<W> {
239 if self.inner.is_some() {
240 // dtors should not panic, so we ignore a panicked flush
241 let _ = self.flush_buf();
246 /// Wraps a Writer and buffers output to it, flushing whenever a newline (`0x0a`,
247 /// `'\n'`) is detected.
249 /// This writer will be flushed when it is dropped.
250 pub struct LineBufferedWriter<W> {
251 inner: BufferedWriter<W>,
255 impl<W> fmt::Debug for LineBufferedWriter<W> where W: fmt::Debug {
256 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
257 write!(fmt, "LineBufferedWriter {{ writer: {:?}, buffer: {}/{} }}",
258 self.inner.inner, self.inner.pos, self.inner.buf.len())
262 impl<W: Writer> LineBufferedWriter<W> {
263 /// Creates a new `LineBufferedWriter`
264 pub fn new(inner: W) -> LineBufferedWriter<W> {
265 // Lines typically aren't that long, don't use a giant buffer
267 inner: BufferedWriter::with_capacity(1024, inner)
271 /// Gets a reference to the underlying writer.
273 /// This type does not expose the ability to get a mutable reference to the
274 /// underlying reader because that could possibly corrupt the buffer.
275 pub fn get_ref<'a>(&'a self) -> &'a W { self.inner.get_ref() }
277 /// Unwraps this `LineBufferedWriter`, returning the underlying writer.
279 /// The internal buffer is flushed before returning the writer.
280 pub fn into_inner(self) -> W { self.inner.into_inner() }
283 impl<W: Writer> Writer for LineBufferedWriter<W> {
284 fn write(&mut self, buf: &[u8]) -> IoResult<()> {
285 match buf.iter().rposition(|&b| b == b'\n') {
287 try!(self.inner.write(&buf[..(i + 1)]));
288 try!(self.inner.flush());
289 try!(self.inner.write(&buf[(i + 1)..]));
292 None => self.inner.write(buf),
296 fn flush(&mut self) -> IoResult<()> { self.inner.flush() }
299 struct InternalBufferedWriter<W>(BufferedWriter<W>);
301 impl<W> InternalBufferedWriter<W> {
302 fn get_mut<'a>(&'a mut self) -> &'a mut BufferedWriter<W> {
303 let InternalBufferedWriter(ref mut w) = *self;
308 impl<W: Reader> Reader for InternalBufferedWriter<W> {
309 fn read(&mut self, buf: &mut [u8]) -> IoResult<uint> {
310 self.get_mut().inner.as_mut().unwrap().read(buf)
314 /// Wraps a Stream and buffers input and output to and from it.
316 /// It can be excessively inefficient to work directly with a `Stream`. For
317 /// example, every call to `read` or `write` on `TcpStream` results in a system
318 /// call. A `BufferedStream` keeps in memory buffers of data, making large,
319 /// infrequent calls to `read` and `write` on the underlying `Stream`.
321 /// The output half will be flushed when this stream is dropped.
326 /// # #![allow(unused_must_use)]
327 /// use std::io::{BufferedStream, File};
329 /// let file = File::open(&Path::new("message.txt"));
330 /// let mut stream = BufferedStream::new(file);
332 /// stream.write("hello, world".as_bytes());
335 /// let mut buf = [0; 100];
336 /// match stream.read(&mut buf) {
337 /// Ok(nread) => println!("Read {} bytes", nread),
338 /// Err(e) => println!("error reading: {}", e)
341 pub struct BufferedStream<S> {
342 inner: BufferedReader<InternalBufferedWriter<S>>
346 impl<S> fmt::Debug for BufferedStream<S> where S: fmt::Debug {
347 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
348 let reader = &self.inner;
349 let writer = &self.inner.inner.0;
350 write!(fmt, "BufferedStream {{ stream: {:?}, write_buffer: {}/{}, read_buffer: {}/{} }}",
352 writer.pos, writer.buf.len(),
353 reader.cap - reader.pos, reader.buf.len())
357 impl<S: Stream> BufferedStream<S> {
358 /// Creates a new buffered stream with explicitly listed capacities for the
359 /// reader/writer buffer.
360 pub fn with_capacities(reader_cap: uint, writer_cap: uint, inner: S)
361 -> BufferedStream<S> {
362 let writer = BufferedWriter::with_capacity(writer_cap, inner);
363 let internal_writer = InternalBufferedWriter(writer);
364 let reader = BufferedReader::with_capacity(reader_cap,
366 BufferedStream { inner: reader }
369 /// Creates a new buffered stream with the default reader/writer buffer
371 pub fn new(inner: S) -> BufferedStream<S> {
372 BufferedStream::with_capacities(DEFAULT_BUF_SIZE, DEFAULT_BUF_SIZE,
376 /// Gets a reference to the underlying stream.
377 pub fn get_ref(&self) -> &S {
378 let InternalBufferedWriter(ref w) = self.inner.inner;
382 /// Gets a mutable reference to the underlying stream.
386 /// It is inadvisable to read directly from or write directly to the
387 /// underlying stream.
388 pub fn get_mut(&mut self) -> &mut S {
389 let InternalBufferedWriter(ref mut w) = self.inner.inner;
393 /// Unwraps this `BufferedStream`, returning the underlying stream.
395 /// The internal buffer is flushed before returning the stream. Any leftover
396 /// data in the read buffer is lost.
397 pub fn into_inner(self) -> S {
398 let InternalBufferedWriter(w) = self.inner.inner;
403 impl<S: Stream> Buffer for BufferedStream<S> {
404 fn fill_buf<'a>(&'a mut self) -> IoResult<&'a [u8]> { self.inner.fill_buf() }
405 fn consume(&mut self, amt: uint) { self.inner.consume(amt) }
408 impl<S: Stream> Reader for BufferedStream<S> {
409 fn read(&mut self, buf: &mut [u8]) -> IoResult<uint> {
414 impl<S: Stream> Writer for BufferedStream<S> {
415 fn write(&mut self, buf: &[u8]) -> IoResult<()> {
416 self.inner.inner.get_mut().write(buf)
418 fn flush(&mut self) -> IoResult<()> {
419 self.inner.inner.get_mut().flush()
429 use super::super::{IoResult, EndOfFile};
430 use super::super::mem::MemReader;
431 use self::test::Bencher;
433 /// A type, free to create, primarily intended for benchmarking creation of
434 /// wrappers that, just for construction, don't need a Reader/Writer that
435 /// does anything useful. Is equivalent to `/dev/null` in semantics.
436 #[derive(Clone,PartialEq,PartialOrd)]
437 pub struct NullStream;
439 impl Reader for NullStream {
440 fn read(&mut self, _: &mut [u8]) -> io::IoResult<uint> {
441 Err(io::standard_error(io::EndOfFile))
445 impl Writer for NullStream {
446 fn write(&mut self, _: &[u8]) -> io::IoResult<()> { Ok(()) }
449 /// A dummy reader intended at testing short-reads propagation.
450 pub struct ShortReader {
454 impl Reader for ShortReader {
455 fn read(&mut self, _: &mut [u8]) -> io::IoResult<uint> {
456 if self.lengths.is_empty() {
457 Err(io::standard_error(io::EndOfFile))
459 Ok(self.lengths.remove(0))
465 fn test_buffered_reader() {
466 let inner = MemReader::new(vec!(5, 6, 7, 0, 1, 2, 3, 4));
467 let mut reader = BufferedReader::with_capacity(2, inner);
469 let mut buf = [0, 0, 0];
470 let nread = reader.read(&mut buf);
471 assert_eq!(Ok(3), nread);
472 let b: &[_] = &[5, 6, 7];
475 let mut buf = [0, 0];
476 let nread = reader.read(&mut buf);
477 assert_eq!(Ok(2), nread);
478 let b: &[_] = &[0, 1];
482 let nread = reader.read(&mut buf);
483 assert_eq!(Ok(1), nread);
487 let mut buf = [0, 0, 0];
488 let nread = reader.read(&mut buf);
489 assert_eq!(Ok(1), nread);
490 let b: &[_] = &[3, 0, 0];
493 let nread = reader.read(&mut buf);
494 assert_eq!(Ok(1), nread);
495 let b: &[_] = &[4, 0, 0];
498 assert!(reader.read(&mut buf).is_err());
502 fn test_buffered_writer() {
503 let inner = Vec::new();
504 let mut writer = BufferedWriter::with_capacity(2, inner);
506 writer.write(&[0, 1]).unwrap();
508 assert_eq!(&writer.get_ref()[], b);
510 writer.write(&[2]).unwrap();
511 let b: &[_] = &[0, 1];
512 assert_eq!(&writer.get_ref()[], b);
514 writer.write(&[3]).unwrap();
515 assert_eq!(&writer.get_ref()[], b);
517 writer.flush().unwrap();
518 let a: &[_] = &[0, 1, 2, 3];
519 assert_eq!(a, &writer.get_ref()[]);
521 writer.write(&[4]).unwrap();
522 writer.write(&[5]).unwrap();
523 assert_eq!(a, &writer.get_ref()[]);
525 writer.write(&[6]).unwrap();
526 let a: &[_] = &[0, 1, 2, 3, 4, 5];
527 assert_eq!(a, &writer.get_ref()[]);
529 writer.write(&[7, 8]).unwrap();
530 let a: &[_] = &[0, 1, 2, 3, 4, 5, 6];
531 assert_eq!(a, &writer.get_ref()[]);
533 writer.write(&[9, 10, 11]).unwrap();
534 let a: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11];
535 assert_eq!(a, &writer.get_ref()[]);
537 writer.flush().unwrap();
538 assert_eq!(a, &writer.get_ref()[]);
542 fn test_buffered_writer_inner_flushes() {
543 let mut w = BufferedWriter::with_capacity(3, Vec::new());
544 w.write(&[0, 1]).unwrap();
546 assert_eq!(a, &w.get_ref()[]);
547 let w = w.into_inner();
548 let a: &[_] = &[0, 1];
552 // This is just here to make sure that we don't infinite loop in the
553 // newtype struct autoderef weirdness
555 fn test_buffered_stream() {
558 impl io::Writer for S {
559 fn write(&mut self, _: &[u8]) -> io::IoResult<()> { Ok(()) }
562 impl io::Reader for S {
563 fn read(&mut self, _: &mut [u8]) -> io::IoResult<uint> {
564 Err(io::standard_error(io::EndOfFile))
568 let mut stream = BufferedStream::new(S);
570 assert!(stream.read(&mut buf).is_err());
571 stream.write(&buf).unwrap();
572 stream.flush().unwrap();
576 fn test_read_until() {
577 let inner = MemReader::new(vec!(0, 1, 2, 1, 0));
578 let mut reader = BufferedReader::with_capacity(2, inner);
579 assert_eq!(reader.read_until(0), Ok(vec!(0)));
580 assert_eq!(reader.read_until(2), Ok(vec!(1, 2)));
581 assert_eq!(reader.read_until(1), Ok(vec!(1)));
582 assert_eq!(reader.read_until(8), Ok(vec!(0)));
583 assert!(reader.read_until(9).is_err());
587 fn test_line_buffer() {
588 let mut writer = LineBufferedWriter::new(Vec::new());
589 writer.write(&[0]).unwrap();
591 assert_eq!(&writer.get_ref()[], b);
592 writer.write(&[1]).unwrap();
593 assert_eq!(&writer.get_ref()[], b);
594 writer.flush().unwrap();
595 let b: &[_] = &[0, 1];
596 assert_eq!(&writer.get_ref()[], b);
597 writer.write(&[0, b'\n', 1, b'\n', 2]).unwrap();
598 let b: &[_] = &[0, 1, 0, b'\n', 1, b'\n'];
599 assert_eq!(&writer.get_ref()[], b);
600 writer.flush().unwrap();
601 let b: &[_] = &[0, 1, 0, b'\n', 1, b'\n', 2];
602 assert_eq!(&writer.get_ref()[], b);
603 writer.write(&[3, b'\n']).unwrap();
604 let b: &[_] = &[0, 1, 0, b'\n', 1, b'\n', 2, 3, b'\n'];
605 assert_eq!(&writer.get_ref()[], b);
609 fn test_read_line() {
610 let in_buf = MemReader::new(b"a\nb\nc".to_vec());
611 let mut reader = BufferedReader::with_capacity(2, in_buf);
612 assert_eq!(reader.read_line(), Ok("a\n".to_string()));
613 assert_eq!(reader.read_line(), Ok("b\n".to_string()));
614 assert_eq!(reader.read_line(), Ok("c".to_string()));
615 assert!(reader.read_line().is_err());
620 let in_buf = MemReader::new(b"a\nb\nc".to_vec());
621 let mut reader = BufferedReader::with_capacity(2, in_buf);
622 let mut it = reader.lines();
623 assert_eq!(it.next(), Some(Ok("a\n".to_string())));
624 assert_eq!(it.next(), Some(Ok("b\n".to_string())));
625 assert_eq!(it.next(), Some(Ok("c".to_string())));
626 assert_eq!(it.next(), None);
630 fn test_short_reads() {
631 let inner = ShortReader{lengths: vec![0, 1, 2, 0, 1, 0]};
632 let mut reader = BufferedReader::new(inner);
633 let mut buf = [0, 0];
634 assert_eq!(reader.read(&mut buf), Ok(0));
635 assert_eq!(reader.read(&mut buf), Ok(1));
636 assert_eq!(reader.read(&mut buf), Ok(2));
637 assert_eq!(reader.read(&mut buf), Ok(0));
638 assert_eq!(reader.read(&mut buf), Ok(1));
639 assert_eq!(reader.read(&mut buf), Ok(0));
640 assert!(reader.read(&mut buf).is_err());
644 fn read_char_buffered() {
645 let buf = [195u8, 159u8];
646 let mut reader = BufferedReader::with_capacity(1, &buf[]);
647 assert_eq!(reader.read_char(), Ok('ß'));
652 let buf = [195u8, 159u8, b'a'];
653 let mut reader = BufferedReader::with_capacity(1, &buf[]);
654 let mut it = reader.chars();
655 assert_eq!(it.next(), Some(Ok('ß')));
656 assert_eq!(it.next(), Some(Ok('a')));
657 assert_eq!(it.next(), None);
662 fn dont_panic_in_drop_on_panicked_flush() {
663 struct FailFlushWriter;
665 impl Writer for FailFlushWriter {
666 fn write(&mut self, _buf: &[u8]) -> IoResult<()> { Ok(()) }
667 fn flush(&mut self) -> IoResult<()> { Err(io::standard_error(EndOfFile)) }
670 let writer = FailFlushWriter;
671 let _writer = BufferedWriter::new(writer);
673 // If writer panics *again* due to the flush error then the process will abort.
678 fn bench_buffered_reader(b: &mut Bencher) {
680 BufferedReader::new(NullStream)
685 fn bench_buffered_writer(b: &mut Bencher) {
687 BufferedWriter::new(NullStream)
692 fn bench_buffered_stream(b: &mut Bencher) {
694 BufferedStream::new(NullStream);