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};
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> {
55 impl<R> fmt::Show for BufferedReader<R> where R: fmt::Show {
56 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
57 write!(fmt, "BufferedReader {{ reader: {:?}, buffer: {}/{} }}",
58 self.inner, self.cap - self.pos, self.buf.len())
62 impl<R: Reader> BufferedReader<R> {
63 /// Creates a new `BufferedReader` with the specified buffer capacity
64 pub fn with_capacity(cap: uint, inner: R) -> BufferedReader<R> {
65 // It's *much* faster to create an uninitialized buffer than it is to
66 // fill everything in with 0. This buffer is entirely an implementation
67 // detail and is never exposed, so we're safe to not initialize
68 // everything up-front. This allows creation of BufferedReader instances
69 // to be very cheap (large mallocs are not nearly as expensive as large
71 let mut buf = Vec::with_capacity(cap);
72 unsafe { buf.set_len(cap); }
81 /// Creates a new `BufferedReader` with a default buffer capacity
82 pub fn new(inner: R) -> BufferedReader<R> {
83 BufferedReader::with_capacity(DEFAULT_BUF_SIZE, inner)
86 /// Gets a reference to the underlying reader.
87 pub fn get_ref<'a>(&self) -> &R { &self.inner }
89 /// Gets a mutable reference to the underlying reader.
93 /// It is inadvisable to directly read from the underlying reader.
94 pub fn get_mut(&mut self) -> &mut R { &mut self.inner }
96 /// Unwraps this `BufferedReader`, returning the underlying reader.
98 /// Note that any leftover data in the internal buffer is lost.
99 pub fn into_inner(self) -> R { self.inner }
102 impl<R: Reader> Buffer for BufferedReader<R> {
103 fn fill_buf<'a>(&'a mut self) -> IoResult<&'a [u8]> {
104 if self.pos == self.cap {
105 self.cap = try!(self.inner.read(self.buf.as_mut_slice()));
108 Ok(&self.buf[self.pos..self.cap])
111 fn consume(&mut self, amt: uint) {
113 assert!(self.pos <= self.cap);
117 impl<R: Reader> Reader for BufferedReader<R> {
118 fn read(&mut self, buf: &mut [u8]) -> IoResult<uint> {
119 if self.pos == self.cap && buf.len() >= self.buf.capacity() {
120 return self.inner.read(buf);
123 let available = try!(self.fill_buf());
124 let nread = cmp::min(available.len(), buf.len());
125 slice::bytes::copy_memory(buf, &available[0..nread]);
133 /// Wraps a Writer and buffers output to it
135 /// It can be excessively inefficient to work directly with a `Writer`. For
136 /// example, every call to `write` on `TcpStream` results in a system call. A
137 /// `BufferedWriter` keeps an in memory buffer of data and writes it to the
138 /// underlying `Writer` in large, infrequent batches.
140 /// This writer will be flushed when it is dropped.
145 /// use std::io::{BufferedWriter, File};
147 /// let file = File::create(&Path::new("message.txt")).unwrap();
148 /// let mut writer = BufferedWriter::new(file);
150 /// writer.write_str("hello, world").unwrap();
151 /// writer.flush().unwrap();
153 pub struct BufferedWriter<W> {
159 impl<W> fmt::Show for BufferedWriter<W> where W: fmt::Show {
160 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
161 write!(fmt, "BufferedWriter {{ writer: {:?}, buffer: {}/{} }}",
162 self.inner.as_ref().unwrap(), self.pos, self.buf.len())
166 impl<W: Writer> BufferedWriter<W> {
167 /// Creates a new `BufferedWriter` with the specified buffer capacity
168 pub fn with_capacity(cap: uint, inner: W) -> BufferedWriter<W> {
169 // See comments in BufferedReader for why this uses unsafe code.
170 let mut buf = Vec::with_capacity(cap);
171 unsafe { buf.set_len(cap); }
179 /// Creates a new `BufferedWriter` with a default buffer capacity
180 pub fn new(inner: W) -> BufferedWriter<W> {
181 BufferedWriter::with_capacity(DEFAULT_BUF_SIZE, inner)
184 fn flush_buf(&mut self) -> IoResult<()> {
186 let ret = self.inner.as_mut().unwrap().write(&self.buf[0..self.pos]);
194 /// Gets a reference to the underlying writer.
195 pub fn get_ref(&self) -> &W { self.inner.as_ref().unwrap() }
197 /// Gets a mutable reference to the underlying write.
201 /// It is inadvisable to directly read from the underlying writer.
202 pub fn get_mut(&mut self) -> &mut W { self.inner.as_mut().unwrap() }
204 /// Unwraps this `BufferedWriter`, returning the underlying writer.
206 /// The buffer is flushed before returning the writer.
207 pub fn into_inner(mut self) -> W {
208 // FIXME(#12628): is panicking the right thing to do if flushing panicks?
209 self.flush_buf().unwrap();
210 self.inner.take().unwrap()
214 impl<W: Writer> Writer for BufferedWriter<W> {
215 fn write(&mut self, buf: &[u8]) -> IoResult<()> {
216 if self.pos + buf.len() > self.buf.len() {
217 try!(self.flush_buf());
220 if buf.len() > self.buf.len() {
221 self.inner.as_mut().unwrap().write(buf)
223 let dst = self.buf.slice_from_mut(self.pos);
224 slice::bytes::copy_memory(dst, buf);
225 self.pos += buf.len();
230 fn flush(&mut self) -> IoResult<()> {
231 self.flush_buf().and_then(|()| self.inner.as_mut().unwrap().flush())
236 impl<W: Writer> Drop for BufferedWriter<W> {
238 if self.inner.is_some() {
239 // dtors should not panic, so we ignore a panicked flush
240 let _ = self.flush_buf();
245 /// Wraps a Writer and buffers output to it, flushing whenever a newline (`0x0a`,
246 /// `'\n'`) is detected.
248 /// This writer will be flushed when it is dropped.
249 pub struct LineBufferedWriter<W> {
250 inner: BufferedWriter<W>,
253 impl<W> fmt::Show for LineBufferedWriter<W> where W: fmt::Show {
254 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
255 write!(fmt, "LineBufferedWriter {{ writer: {:?}, buffer: {}/{} }}",
256 self.inner.inner, self.inner.pos, self.inner.buf.len())
260 impl<W: Writer> LineBufferedWriter<W> {
261 /// Creates a new `LineBufferedWriter`
262 pub fn new(inner: W) -> LineBufferedWriter<W> {
263 // Lines typically aren't that long, don't use a giant buffer
265 inner: BufferedWriter::with_capacity(1024, inner)
269 /// Gets a reference to the underlying writer.
271 /// This type does not expose the ability to get a mutable reference to the
272 /// underlying reader because that could possibly corrupt the buffer.
273 pub fn get_ref<'a>(&'a self) -> &'a W { self.inner.get_ref() }
275 /// Unwraps this `LineBufferedWriter`, returning the underlying writer.
277 /// The internal buffer is flushed before returning the writer.
278 pub fn into_inner(self) -> W { self.inner.into_inner() }
281 impl<W: Writer> Writer for LineBufferedWriter<W> {
282 fn write(&mut self, buf: &[u8]) -> IoResult<()> {
283 match buf.iter().rposition(|&b| b == b'\n') {
285 try!(self.inner.write(&buf[0..(i + 1)]));
286 try!(self.inner.flush());
287 try!(self.inner.write(&buf[(i + 1)..]));
290 None => self.inner.write(buf),
294 fn flush(&mut self) -> IoResult<()> { self.inner.flush() }
297 struct InternalBufferedWriter<W>(BufferedWriter<W>);
299 impl<W> InternalBufferedWriter<W> {
300 fn get_mut<'a>(&'a mut self) -> &'a mut BufferedWriter<W> {
301 let InternalBufferedWriter(ref mut w) = *self;
306 impl<W: Reader> Reader for InternalBufferedWriter<W> {
307 fn read(&mut self, buf: &mut [u8]) -> IoResult<uint> {
308 self.get_mut().inner.as_mut().unwrap().read(buf)
312 /// Wraps a Stream and buffers input and output to and from it.
314 /// It can be excessively inefficient to work directly with a `Stream`. For
315 /// example, every call to `read` or `write` on `TcpStream` results in a system
316 /// call. A `BufferedStream` keeps in memory buffers of data, making large,
317 /// infrequent calls to `read` and `write` on the underlying `Stream`.
319 /// The output half will be flushed when this stream is dropped.
324 /// # #![allow(unused_must_use)]
325 /// use std::io::{BufferedStream, File};
327 /// let file = File::open(&Path::new("message.txt"));
328 /// let mut stream = BufferedStream::new(file);
330 /// stream.write("hello, world".as_bytes());
333 /// let mut buf = [0; 100];
334 /// match stream.read(&mut buf) {
335 /// Ok(nread) => println!("Read {} bytes", nread),
336 /// Err(e) => println!("error reading: {}", e)
339 pub struct BufferedStream<S> {
340 inner: BufferedReader<InternalBufferedWriter<S>>
343 impl<S> fmt::Show for BufferedStream<S> where S: fmt::Show {
344 fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
345 let reader = &self.inner;
346 let writer = &self.inner.inner.0;
347 write!(fmt, "BufferedStream {{ stream: {:?}, write_buffer: {}/{}, read_buffer: {}/{} }}",
349 writer.pos, writer.buf.len(),
350 reader.cap - reader.pos, reader.buf.len())
354 impl<S: Stream> BufferedStream<S> {
355 /// Creates a new buffered stream with explicitly listed capacities for the
356 /// reader/writer buffer.
357 pub fn with_capacities(reader_cap: uint, writer_cap: uint, inner: S)
358 -> BufferedStream<S> {
359 let writer = BufferedWriter::with_capacity(writer_cap, inner);
360 let internal_writer = InternalBufferedWriter(writer);
361 let reader = BufferedReader::with_capacity(reader_cap,
363 BufferedStream { inner: reader }
366 /// Creates a new buffered stream with the default reader/writer buffer
368 pub fn new(inner: S) -> BufferedStream<S> {
369 BufferedStream::with_capacities(DEFAULT_BUF_SIZE, DEFAULT_BUF_SIZE,
373 /// Gets a reference to the underlying stream.
374 pub fn get_ref(&self) -> &S {
375 let InternalBufferedWriter(ref w) = self.inner.inner;
379 /// Gets a mutable reference to the underlying stream.
383 /// It is inadvisable to read directly from or write directly to the
384 /// underlying stream.
385 pub fn get_mut(&mut self) -> &mut S {
386 let InternalBufferedWriter(ref mut w) = self.inner.inner;
390 /// Unwraps this `BufferedStream`, returning the underlying stream.
392 /// The internal buffer is flushed before returning the stream. Any leftover
393 /// data in the read buffer is lost.
394 pub fn into_inner(self) -> S {
395 let InternalBufferedWriter(w) = self.inner.inner;
400 impl<S: Stream> Buffer for BufferedStream<S> {
401 fn fill_buf<'a>(&'a mut self) -> IoResult<&'a [u8]> { self.inner.fill_buf() }
402 fn consume(&mut self, amt: uint) { self.inner.consume(amt) }
405 impl<S: Stream> Reader for BufferedStream<S> {
406 fn read(&mut self, buf: &mut [u8]) -> IoResult<uint> {
411 impl<S: Stream> Writer for BufferedStream<S> {
412 fn write(&mut self, buf: &[u8]) -> IoResult<()> {
413 self.inner.inner.get_mut().write(buf)
415 fn flush(&mut self) -> IoResult<()> {
416 self.inner.inner.get_mut().flush()
426 use super::super::{IoResult, EndOfFile};
427 use super::super::mem::MemReader;
428 use self::test::Bencher;
430 /// A type, free to create, primarily intended for benchmarking creation of
431 /// wrappers that, just for construction, don't need a Reader/Writer that
432 /// does anything useful. Is equivalent to `/dev/null` in semantics.
433 #[derive(Clone,PartialEq,PartialOrd)]
434 pub struct NullStream;
436 impl Reader for NullStream {
437 fn read(&mut self, _: &mut [u8]) -> io::IoResult<uint> {
438 Err(io::standard_error(io::EndOfFile))
442 impl Writer for NullStream {
443 fn write(&mut self, _: &[u8]) -> io::IoResult<()> { Ok(()) }
446 /// A dummy reader intended at testing short-reads propagation.
447 pub struct ShortReader {
451 impl Reader for ShortReader {
452 fn read(&mut self, _: &mut [u8]) -> io::IoResult<uint> {
453 if self.lengths.is_empty() {
454 Err(io::standard_error(io::EndOfFile))
456 Ok(self.lengths.remove(0))
462 fn test_buffered_reader() {
463 let inner = MemReader::new(vec!(5, 6, 7, 0, 1, 2, 3, 4));
464 let mut reader = BufferedReader::with_capacity(2, inner);
466 let mut buf = [0, 0, 0];
467 let nread = reader.read(&mut buf);
468 assert_eq!(Ok(3), nread);
469 let b: &[_] = &[5, 6, 7];
472 let mut buf = [0, 0];
473 let nread = reader.read(&mut buf);
474 assert_eq!(Ok(2), nread);
475 let b: &[_] = &[0, 1];
479 let nread = reader.read(&mut buf);
480 assert_eq!(Ok(1), nread);
484 let mut buf = [0, 0, 0];
485 let nread = reader.read(&mut buf);
486 assert_eq!(Ok(1), nread);
487 let b: &[_] = &[3, 0, 0];
490 let nread = reader.read(&mut buf);
491 assert_eq!(Ok(1), nread);
492 let b: &[_] = &[4, 0, 0];
495 assert!(reader.read(&mut buf).is_err());
499 fn test_buffered_writer() {
500 let inner = Vec::new();
501 let mut writer = BufferedWriter::with_capacity(2, inner);
503 writer.write(&[0, 1]).unwrap();
505 assert_eq!(&writer.get_ref()[], b);
507 writer.write(&[2]).unwrap();
508 let b: &[_] = &[0, 1];
509 assert_eq!(&writer.get_ref()[], b);
511 writer.write(&[3]).unwrap();
512 assert_eq!(&writer.get_ref()[], b);
514 writer.flush().unwrap();
515 let a: &[_] = &[0, 1, 2, 3];
516 assert_eq!(a, &writer.get_ref()[]);
518 writer.write(&[4]).unwrap();
519 writer.write(&[5]).unwrap();
520 assert_eq!(a, &writer.get_ref()[]);
522 writer.write(&[6]).unwrap();
523 let a: &[_] = &[0, 1, 2, 3, 4, 5];
524 assert_eq!(a, &writer.get_ref()[]);
526 writer.write(&[7, 8]).unwrap();
527 let a: &[_] = &[0, 1, 2, 3, 4, 5, 6];
528 assert_eq!(a, &writer.get_ref()[]);
530 writer.write(&[9, 10, 11]).unwrap();
531 let a: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11];
532 assert_eq!(a, &writer.get_ref()[]);
534 writer.flush().unwrap();
535 assert_eq!(a, &writer.get_ref()[]);
539 fn test_buffered_writer_inner_flushes() {
540 let mut w = BufferedWriter::with_capacity(3, Vec::new());
541 w.write(&[0, 1]).unwrap();
543 assert_eq!(a, &w.get_ref()[]);
544 let w = w.into_inner();
545 let a: &[_] = &[0, 1];
549 // This is just here to make sure that we don't infinite loop in the
550 // newtype struct autoderef weirdness
552 fn test_buffered_stream() {
555 impl io::Writer for S {
556 fn write(&mut self, _: &[u8]) -> io::IoResult<()> { Ok(()) }
559 impl io::Reader for S {
560 fn read(&mut self, _: &mut [u8]) -> io::IoResult<uint> {
561 Err(io::standard_error(io::EndOfFile))
565 let mut stream = BufferedStream::new(S);
567 assert!(stream.read(&mut buf).is_err());
568 stream.write(&buf).unwrap();
569 stream.flush().unwrap();
573 fn test_read_until() {
574 let inner = MemReader::new(vec!(0, 1, 2, 1, 0));
575 let mut reader = BufferedReader::with_capacity(2, inner);
576 assert_eq!(reader.read_until(0), Ok(vec!(0)));
577 assert_eq!(reader.read_until(2), Ok(vec!(1, 2)));
578 assert_eq!(reader.read_until(1), Ok(vec!(1)));
579 assert_eq!(reader.read_until(8), Ok(vec!(0)));
580 assert!(reader.read_until(9).is_err());
584 fn test_line_buffer() {
585 let mut writer = LineBufferedWriter::new(Vec::new());
586 writer.write(&[0]).unwrap();
588 assert_eq!(&writer.get_ref()[], b);
589 writer.write(&[1]).unwrap();
590 assert_eq!(&writer.get_ref()[], b);
591 writer.flush().unwrap();
592 let b: &[_] = &[0, 1];
593 assert_eq!(&writer.get_ref()[], b);
594 writer.write(&[0, b'\n', 1, b'\n', 2]).unwrap();
595 let b: &[_] = &[0, 1, 0, b'\n', 1, b'\n'];
596 assert_eq!(&writer.get_ref()[], b);
597 writer.flush().unwrap();
598 let b: &[_] = &[0, 1, 0, b'\n', 1, b'\n', 2];
599 assert_eq!(&writer.get_ref()[], b);
600 writer.write(&[3, b'\n']).unwrap();
601 let b: &[_] = &[0, 1, 0, b'\n', 1, b'\n', 2, 3, b'\n'];
602 assert_eq!(&writer.get_ref()[], b);
606 fn test_read_line() {
607 let in_buf = MemReader::new(b"a\nb\nc".to_vec());
608 let mut reader = BufferedReader::with_capacity(2, in_buf);
609 assert_eq!(reader.read_line(), Ok("a\n".to_string()));
610 assert_eq!(reader.read_line(), Ok("b\n".to_string()));
611 assert_eq!(reader.read_line(), Ok("c".to_string()));
612 assert!(reader.read_line().is_err());
617 let in_buf = MemReader::new(b"a\nb\nc".to_vec());
618 let mut reader = BufferedReader::with_capacity(2, in_buf);
619 let mut it = reader.lines();
620 assert_eq!(it.next(), Some(Ok("a\n".to_string())));
621 assert_eq!(it.next(), Some(Ok("b\n".to_string())));
622 assert_eq!(it.next(), Some(Ok("c".to_string())));
623 assert_eq!(it.next(), None);
627 fn test_short_reads() {
628 let inner = ShortReader{lengths: vec![0, 1, 2, 0, 1, 0]};
629 let mut reader = BufferedReader::new(inner);
630 let mut buf = [0, 0];
631 assert_eq!(reader.read(&mut buf), Ok(0));
632 assert_eq!(reader.read(&mut buf), Ok(1));
633 assert_eq!(reader.read(&mut buf), Ok(2));
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(0));
637 assert!(reader.read(&mut buf).is_err());
641 fn read_char_buffered() {
642 let buf = [195u8, 159u8];
643 let mut reader = BufferedReader::with_capacity(1, &buf[]);
644 assert_eq!(reader.read_char(), Ok('ß'));
649 let buf = [195u8, 159u8, b'a'];
650 let mut reader = BufferedReader::with_capacity(1, &buf[]);
651 let mut it = reader.chars();
652 assert_eq!(it.next(), Some(Ok('ß')));
653 assert_eq!(it.next(), Some(Ok('a')));
654 assert_eq!(it.next(), None);
659 fn dont_panic_in_drop_on_panicked_flush() {
660 struct FailFlushWriter;
662 impl Writer for FailFlushWriter {
663 fn write(&mut self, _buf: &[u8]) -> IoResult<()> { Ok(()) }
664 fn flush(&mut self) -> IoResult<()> { Err(io::standard_error(EndOfFile)) }
667 let writer = FailFlushWriter;
668 let _writer = BufferedWriter::new(writer);
670 // If writer panics *again* due to the flush error then the process will abort.
675 fn bench_buffered_reader(b: &mut Bencher) {
677 BufferedReader::new(NullStream)
682 fn bench_buffered_writer(b: &mut Bencher) {
684 BufferedWriter::new(NullStream)
689 fn bench_buffered_stream(b: &mut Bencher) {
691 BufferedStream::new(NullStream);