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 //! Buffering wrappers for I/O traits
14 use container::Container;
15 use io::{Reader, Writer, Stream, Buffer, DEFAULT_BUF_SIZE, IoResult};
18 use option::{Some, None, Option};
19 use result::{Ok, Err};
20 use slice::{ImmutableVector, MutableVector};
24 /// Wraps a Reader and buffers input from it
26 /// It can be excessively inefficient to work directly with a `Reader`. For
27 /// example, every call to `read` on `TcpStream` results in a system call. A
28 /// `BufferedReader` performs large, infrequent reads on the underlying
29 /// `Reader` and maintains an in-memory buffer of the results.
34 /// use std::io::{BufferedReader, File};
36 /// let file = File::open(&Path::new("message.txt"));
37 /// let mut reader = BufferedReader::new(file);
39 /// let mut buf = [0, ..100];
40 /// match reader.read(buf) {
41 /// Ok(nread) => println!("Read {} bytes", nread),
42 /// Err(e) => println!("error reading: {}", e)
45 pub struct BufferedReader<R> {
52 impl<R: Reader> BufferedReader<R> {
53 /// Creates a new `BufferedReader` with the specified buffer capacity
54 pub fn with_capacity(cap: uint, inner: R) -> BufferedReader<R> {
55 // It's *much* faster to create an uninitialized buffer than it is to
56 // fill everything in with 0. This buffer is entirely an implementation
57 // detail and is never exposed, so we're safe to not initialize
58 // everything up-front. This allows creation of BufferedReader instances
59 // to be very cheap (large mallocs are not nearly as expensive as large
61 let mut buf = Vec::with_capacity(cap);
62 unsafe { buf.set_len(cap); }
71 /// Creates a new `BufferedReader` with a default buffer capacity
72 pub fn new(inner: R) -> BufferedReader<R> {
73 BufferedReader::with_capacity(DEFAULT_BUF_SIZE, inner)
76 /// Gets a reference to the underlying reader.
78 /// This type does not expose the ability to get a mutable reference to the
79 /// underlying reader because that could possibly corrupt the buffer.
80 pub fn get_ref<'a>(&'a self) -> &'a R { &self.inner }
82 /// Unwraps this `BufferedReader`, returning the underlying reader.
84 /// Note that any leftover data in the internal buffer is lost.
85 pub fn unwrap(self) -> R { self.inner }
88 impl<R: Reader> Buffer for BufferedReader<R> {
89 fn fill_buf<'a>(&'a mut self) -> IoResult<&'a [u8]> {
90 if self.pos == self.cap {
91 self.cap = try!(self.inner.read(self.buf.as_mut_slice()));
94 Ok(self.buf.slice(self.pos, self.cap))
97 fn consume(&mut self, amt: uint) {
99 assert!(self.pos <= self.cap);
103 impl<R: Reader> Reader for BufferedReader<R> {
104 fn read(&mut self, buf: &mut [u8]) -> IoResult<uint> {
106 let available = try!(self.fill_buf());
107 let nread = cmp::min(available.len(), buf.len());
108 slice::bytes::copy_memory(buf, available.slice_to(nread));
116 /// Wraps a Writer and buffers output to it
118 /// It can be excessively inefficient to work directly with a `Writer`. For
119 /// example, every call to `write` on `TcpStream` results in a system call. A
120 /// `BufferedWriter` keeps an in memory buffer of data and writes it to the
121 /// underlying `Writer` in large, infrequent batches.
123 /// This writer will be flushed when it is dropped.
128 /// # #![allow(unused_must_use)]
129 /// use std::io::{BufferedWriter, File};
131 /// let file = File::open(&Path::new("message.txt"));
132 /// let mut writer = BufferedWriter::new(file);
134 /// writer.write_str("hello, world");
137 pub struct BufferedWriter<W> {
143 impl<W: Writer> BufferedWriter<W> {
144 /// Creates a new `BufferedWriter` with the specified buffer capacity
145 pub fn with_capacity(cap: uint, inner: W) -> BufferedWriter<W> {
146 // See comments in BufferedReader for why this uses unsafe code.
147 let mut buf = Vec::with_capacity(cap);
148 unsafe { buf.set_len(cap); }
156 /// Creates a new `BufferedWriter` with a default buffer capacity
157 pub fn new(inner: W) -> BufferedWriter<W> {
158 BufferedWriter::with_capacity(DEFAULT_BUF_SIZE, inner)
161 fn flush_buf(&mut self) -> IoResult<()> {
163 let ret = self.inner.get_mut_ref().write(self.buf.slice_to(self.pos));
171 /// Gets a reference to the underlying writer.
173 /// This type does not expose the ability to get a mutable reference to the
174 /// underlying reader because that could possibly corrupt the buffer.
175 pub fn get_ref<'a>(&'a self) -> &'a W { self.inner.get_ref() }
177 /// Unwraps this `BufferedWriter`, returning the underlying writer.
179 /// The buffer is flushed before returning the writer.
180 pub fn unwrap(mut self) -> W {
181 // FIXME(#12628): is failing the right thing to do if flushing fails?
182 self.flush_buf().unwrap();
183 self.inner.take_unwrap()
187 impl<W: Writer> Writer for BufferedWriter<W> {
188 fn write(&mut self, buf: &[u8]) -> IoResult<()> {
189 if self.pos + buf.len() > self.buf.len() {
190 try!(self.flush_buf());
193 if buf.len() > self.buf.len() {
194 self.inner.get_mut_ref().write(buf)
196 let dst = self.buf.mut_slice_from(self.pos);
197 slice::bytes::copy_memory(dst, buf);
198 self.pos += buf.len();
203 fn flush(&mut self) -> IoResult<()> {
204 self.flush_buf().and_then(|()| self.inner.get_mut_ref().flush())
209 impl<W: Writer> Drop for BufferedWriter<W> {
211 if self.inner.is_some() {
212 // FIXME(#12628): should this error be ignored?
213 let _ = self.flush_buf();
218 /// Wraps a Writer and buffers output to it, flushing whenever a newline (`0x0a`,
219 /// `'\n'`) is detected.
221 /// This writer will be flushed when it is dropped.
222 pub struct LineBufferedWriter<W> {
223 inner: BufferedWriter<W>,
226 impl<W: Writer> LineBufferedWriter<W> {
227 /// Creates a new `LineBufferedWriter`
228 pub fn new(inner: W) -> LineBufferedWriter<W> {
229 // Lines typically aren't that long, don't use a giant buffer
231 inner: BufferedWriter::with_capacity(1024, inner)
235 /// Gets a reference to the underlying writer.
237 /// This type does not expose the ability to get a mutable reference to the
238 /// underlying reader because that could possibly corrupt the buffer.
239 pub fn get_ref<'a>(&'a self) -> &'a W { self.inner.get_ref() }
241 /// Unwraps this `LineBufferedWriter`, returning the underlying writer.
243 /// The internal buffer is flushed before returning the writer.
244 pub fn unwrap(self) -> W { self.inner.unwrap() }
247 impl<W: Writer> Writer for LineBufferedWriter<W> {
248 fn write(&mut self, buf: &[u8]) -> IoResult<()> {
249 match buf.iter().rposition(|&b| b == '\n' as u8) {
251 try!(self.inner.write(buf.slice_to(i + 1)));
252 try!(self.inner.flush());
253 try!(self.inner.write(buf.slice_from(i + 1)));
256 None => self.inner.write(buf),
260 fn flush(&mut self) -> IoResult<()> { self.inner.flush() }
263 struct InternalBufferedWriter<W>(BufferedWriter<W>);
265 impl<W> InternalBufferedWriter<W> {
266 fn get_mut_ref<'a>(&'a mut self) -> &'a mut BufferedWriter<W> {
267 let InternalBufferedWriter(ref mut w) = *self;
272 impl<W: Reader> Reader for InternalBufferedWriter<W> {
273 fn read(&mut self, buf: &mut [u8]) -> IoResult<uint> {
274 self.get_mut_ref().inner.get_mut_ref().read(buf)
278 /// Wraps a Stream and buffers input and output to and from it.
280 /// It can be excessively inefficient to work directly with a `Stream`. For
281 /// example, every call to `read` or `write` on `TcpStream` results in a system
282 /// call. A `BufferedStream` keeps in memory buffers of data, making large,
283 /// infrequent calls to `read` and `write` on the underlying `Stream`.
285 /// The output half will be flushed when this stream is dropped.
290 /// # #![allow(unused_must_use)]
291 /// use std::io::{BufferedStream, File};
293 /// let file = File::open(&Path::new("message.txt"));
294 /// let mut stream = BufferedStream::new(file);
296 /// stream.write("hello, world".as_bytes());
299 /// let mut buf = [0, ..100];
300 /// match stream.read(buf) {
301 /// Ok(nread) => println!("Read {} bytes", nread),
302 /// Err(e) => println!("error reading: {}", e)
305 pub struct BufferedStream<S> {
306 inner: BufferedReader<InternalBufferedWriter<S>>
309 impl<S: Stream> BufferedStream<S> {
310 /// Creates a new buffered stream with explicitly listed capacities for the
311 /// reader/writer buffer.
312 pub fn with_capacities(reader_cap: uint, writer_cap: uint, inner: S)
313 -> BufferedStream<S> {
314 let writer = BufferedWriter::with_capacity(writer_cap, inner);
315 let internal_writer = InternalBufferedWriter(writer);
316 let reader = BufferedReader::with_capacity(reader_cap,
318 BufferedStream { inner: reader }
321 /// Creates a new buffered stream with the default reader/writer buffer
323 pub fn new(inner: S) -> BufferedStream<S> {
324 BufferedStream::with_capacities(DEFAULT_BUF_SIZE, DEFAULT_BUF_SIZE,
328 /// Gets a reference to the underlying stream.
330 /// This type does not expose the ability to get a mutable reference to the
331 /// underlying reader because that could possibly corrupt the buffer.
332 pub fn get_ref<'a>(&'a self) -> &'a S {
333 let InternalBufferedWriter(ref w) = self.inner.inner;
337 /// Unwraps this `BufferedStream`, returning the underlying stream.
339 /// The internal buffer is flushed before returning the stream. Any leftover
340 /// data in the read buffer is lost.
341 pub fn unwrap(self) -> S {
342 let InternalBufferedWriter(w) = self.inner.inner;
347 impl<S: Stream> Buffer for BufferedStream<S> {
348 fn fill_buf<'a>(&'a mut self) -> IoResult<&'a [u8]> { self.inner.fill_buf() }
349 fn consume(&mut self, amt: uint) { self.inner.consume(amt) }
352 impl<S: Stream> Reader for BufferedStream<S> {
353 fn read(&mut self, buf: &mut [u8]) -> IoResult<uint> {
358 impl<S: Stream> Writer for BufferedStream<S> {
359 fn write(&mut self, buf: &[u8]) -> IoResult<()> {
360 self.inner.inner.get_mut_ref().write(buf)
362 fn flush(&mut self) -> IoResult<()> {
363 self.inner.inner.get_mut_ref().flush()
373 use super::super::mem::{MemReader, MemWriter, BufReader};
374 use self::test::Bencher;
376 /// A type, free to create, primarily intended for benchmarking creation of
377 /// wrappers that, just for construction, don't need a Reader/Writer that
378 /// does anything useful. Is equivalent to `/dev/null` in semantics.
379 #[deriving(Clone,Eq,Ord)]
380 pub struct NullStream;
382 impl Reader for NullStream {
383 fn read(&mut self, _: &mut [u8]) -> io::IoResult<uint> {
384 Err(io::standard_error(io::EndOfFile))
388 impl Writer for NullStream {
389 fn write(&mut self, _: &[u8]) -> io::IoResult<()> { Ok(()) }
392 /// A dummy reader intended at testing short-reads propagation.
393 pub struct ShortReader {
397 impl Reader for ShortReader {
398 fn read(&mut self, _: &mut [u8]) -> io::IoResult<uint> {
399 match self.lengths.shift() {
401 None => Err(io::standard_error(io::EndOfFile))
407 fn test_buffered_reader() {
408 let inner = MemReader::new(vec!(0, 1, 2, 3, 4));
409 let mut reader = BufferedReader::with_capacity(2, inner);
411 let mut buf = [0, 0, 0];
412 let nread = reader.read(buf);
413 assert_eq!(Ok(2), nread);
414 assert_eq!(buf.as_slice(), &[0, 1, 0]);
417 let nread = reader.read(buf);
418 assert_eq!(Ok(1), nread);
419 assert_eq!(buf.as_slice(), &[2]);
421 let mut buf = [0, 0, 0];
422 let nread = reader.read(buf);
423 assert_eq!(Ok(1), nread);
424 assert_eq!(buf.as_slice(), &[3, 0, 0]);
426 let nread = reader.read(buf);
427 assert_eq!(Ok(1), nread);
428 assert_eq!(buf.as_slice(), &[4, 0, 0]);
430 assert!(reader.read(buf).is_err());
434 fn test_buffered_writer() {
435 let inner = MemWriter::new();
436 let mut writer = BufferedWriter::with_capacity(2, inner);
438 writer.write([0, 1]).unwrap();
439 assert_eq!(writer.get_ref().get_ref(), &[]);
441 writer.write([2]).unwrap();
442 assert_eq!(writer.get_ref().get_ref(), &[0, 1]);
444 writer.write([3]).unwrap();
445 assert_eq!(writer.get_ref().get_ref(), &[0, 1]);
447 writer.flush().unwrap();
448 assert_eq!(&[0, 1, 2, 3], writer.get_ref().get_ref());
450 writer.write([4]).unwrap();
451 writer.write([5]).unwrap();
452 assert_eq!(&[0, 1, 2, 3], writer.get_ref().get_ref());
454 writer.write([6]).unwrap();
455 assert_eq!(&[0, 1, 2, 3, 4, 5],
456 writer.get_ref().get_ref());
458 writer.write([7, 8]).unwrap();
459 assert_eq!(&[0, 1, 2, 3, 4, 5, 6],
460 writer.get_ref().get_ref());
462 writer.write([9, 10, 11]).unwrap();
463 assert_eq!(&[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11],
464 writer.get_ref().get_ref());
466 writer.flush().unwrap();
467 assert_eq!(&[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11],
468 writer.get_ref().get_ref());
472 fn test_buffered_writer_inner_flushes() {
473 let mut w = BufferedWriter::with_capacity(3, MemWriter::new());
474 w.write([0, 1]).unwrap();
475 assert_eq!(&[], w.get_ref().get_ref());
477 assert_eq!(&[0, 1], w.get_ref());
480 // This is just here to make sure that we don't infinite loop in the
481 // newtype struct autoderef weirdness
483 fn test_buffered_stream() {
486 impl io::Writer for S {
487 fn write(&mut self, _: &[u8]) -> io::IoResult<()> { Ok(()) }
490 impl io::Reader for S {
491 fn read(&mut self, _: &mut [u8]) -> io::IoResult<uint> {
492 Err(io::standard_error(io::EndOfFile))
496 let mut stream = BufferedStream::new(S);
498 assert!(stream.read(buf).is_err());
499 stream.write(buf).unwrap();
500 stream.flush().unwrap();
504 fn test_read_until() {
505 let inner = MemReader::new(vec!(0, 1, 2, 1, 0));
506 let mut reader = BufferedReader::with_capacity(2, inner);
507 assert_eq!(reader.read_until(0), Ok(vec!(0)));
508 assert_eq!(reader.read_until(2), Ok(vec!(1, 2)));
509 assert_eq!(reader.read_until(1), Ok(vec!(1)));
510 assert_eq!(reader.read_until(8), Ok(vec!(0)));
511 assert!(reader.read_until(9).is_err());
515 fn test_line_buffer() {
516 let mut writer = LineBufferedWriter::new(MemWriter::new());
517 writer.write([0]).unwrap();
518 assert_eq!(writer.get_ref().get_ref(), &[]);
519 writer.write([1]).unwrap();
520 assert_eq!(writer.get_ref().get_ref(), &[]);
521 writer.flush().unwrap();
522 assert_eq!(writer.get_ref().get_ref(), &[0, 1]);
523 writer.write([0, '\n' as u8, 1, '\n' as u8, 2]).unwrap();
524 assert_eq!(writer.get_ref().get_ref(),
525 &[0, 1, 0, '\n' as u8, 1, '\n' as u8]);
526 writer.flush().unwrap();
527 assert_eq!(writer.get_ref().get_ref(),
528 &[0, 1, 0, '\n' as u8, 1, '\n' as u8, 2]);
529 writer.write([3, '\n' as u8]).unwrap();
530 assert_eq!(writer.get_ref().get_ref(),
531 &[0, 1, 0, '\n' as u8, 1, '\n' as u8, 2, 3, '\n' as u8]);
535 fn test_read_line() {
536 let in_buf = MemReader::new(Vec::from_slice(bytes!("a\nb\nc")));
537 let mut reader = BufferedReader::with_capacity(2, in_buf);
538 assert_eq!(reader.read_line(), Ok(~"a\n"));
539 assert_eq!(reader.read_line(), Ok(~"b\n"));
540 assert_eq!(reader.read_line(), Ok(~"c"));
541 assert!(reader.read_line().is_err());
546 let in_buf = MemReader::new(Vec::from_slice(bytes!("a\nb\nc")));
547 let mut reader = BufferedReader::with_capacity(2, in_buf);
548 let mut it = reader.lines();
549 assert_eq!(it.next(), Some(Ok(~"a\n")));
550 assert_eq!(it.next(), Some(Ok(~"b\n")));
551 assert_eq!(it.next(), Some(Ok(~"c")));
552 assert_eq!(it.next(), None);
556 fn test_short_reads() {
557 let inner = ShortReader{lengths: vec![0, 1, 2, 0, 1, 0]};
558 let mut reader = BufferedReader::new(inner);
559 let mut buf = [0, 0];
560 assert_eq!(reader.read(buf), Ok(0));
561 assert_eq!(reader.read(buf), Ok(1));
562 assert_eq!(reader.read(buf), Ok(2));
563 assert_eq!(reader.read(buf), Ok(0));
564 assert_eq!(reader.read(buf), Ok(1));
565 assert_eq!(reader.read(buf), Ok(0));
566 assert!(reader.read(buf).is_err());
570 fn read_char_buffered() {
571 let buf = [195u8, 159u8];
572 let mut reader = BufferedReader::with_capacity(1, BufReader::new(buf));
573 assert_eq!(reader.read_char(), Ok('ß'));
578 let buf = [195u8, 159u8, 'a' as u8];
579 let mut reader = BufferedReader::with_capacity(1, BufReader::new(buf));
580 let mut it = reader.chars();
581 assert_eq!(it.next(), Some(Ok('ß')));
582 assert_eq!(it.next(), Some(Ok('a')));
583 assert_eq!(it.next(), None);
587 fn bench_buffered_reader(b: &mut Bencher) {
589 BufferedReader::new(NullStream)
594 fn bench_buffered_writer(b: &mut Bencher) {
596 BufferedWriter::new(NullStream)
601 fn bench_buffered_stream(b: &mut Bencher) {
603 BufferedStream::new(NullStream);