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;
20 use option::Option::{Some, None};
21 use result::Result::{Ok, Err};
22 use slice::{SliceExt};
26 /// Wraps a Reader and buffers input from it
28 /// It can be excessively inefficient to work directly with a `Reader`. For
29 /// example, every call to `read` on `TcpStream` results in a system call. A
30 /// `BufferedReader` performs large, infrequent reads on the underlying
31 /// `Reader` and maintains an in-memory buffer of the results.
36 /// use std::io::{BufferedReader, File};
38 /// let file = File::open(&Path::new("message.txt"));
39 /// let mut reader = BufferedReader::new(file);
41 /// let mut buf = [0; 100];
42 /// match reader.read(&mut buf) {
43 /// Ok(nread) => println!("Read {} bytes", nread),
44 /// Err(e) => println!("error reading: {}", e)
47 pub struct BufferedReader<R> {
54 impl<R: Reader> BufferedReader<R> {
55 /// Creates a new `BufferedReader` with the specified buffer capacity
56 pub fn with_capacity(cap: uint, inner: R) -> BufferedReader<R> {
57 // It's *much* faster to create an uninitialized buffer than it is to
58 // fill everything in with 0. This buffer is entirely an implementation
59 // detail and is never exposed, so we're safe to not initialize
60 // everything up-front. This allows creation of BufferedReader instances
61 // to be very cheap (large mallocs are not nearly as expensive as large
63 let mut buf = Vec::with_capacity(cap);
64 unsafe { buf.set_len(cap); }
73 /// Creates a new `BufferedReader` with a default buffer capacity
74 pub fn new(inner: R) -> BufferedReader<R> {
75 BufferedReader::with_capacity(DEFAULT_BUF_SIZE, inner)
78 /// Gets a reference to the underlying reader.
79 pub fn get_ref<'a>(&self) -> &R { &self.inner }
81 /// Gets a mutable reference to the underlying reader.
85 /// It is inadvisable to directly read from the underlying reader.
86 pub fn get_mut(&mut self) -> &mut R { &mut self.inner }
88 /// Unwraps this `BufferedReader`, returning the underlying reader.
90 /// Note that any leftover data in the internal buffer is lost.
91 pub fn into_inner(self) -> R { self.inner }
93 /// Deprecated, use into_inner() instead
94 #[deprecated = "renamed to into_inner()"]
95 pub fn unwrap(self) -> R { self.into_inner() }
98 impl<R: Reader> Buffer for BufferedReader<R> {
99 fn fill_buf<'a>(&'a mut self) -> IoResult<&'a [u8]> {
100 if self.pos == self.cap {
101 self.cap = try!(self.inner.read(self.buf.as_mut_slice()));
104 Ok(self.buf[self.pos..self.cap])
107 fn consume(&mut self, amt: uint) {
109 assert!(self.pos <= self.cap);
113 impl<R: Reader> Reader for BufferedReader<R> {
114 fn read(&mut self, buf: &mut [u8]) -> IoResult<uint> {
115 if self.pos == self.cap && buf.len() >= self.buf.capacity() {
116 return self.inner.read(buf);
119 let available = try!(self.fill_buf());
120 let nread = cmp::min(available.len(), buf.len());
121 slice::bytes::copy_memory(buf, available[..nread]);
129 /// Wraps a Writer and buffers output to it
131 /// It can be excessively inefficient to work directly with a `Writer`. For
132 /// example, every call to `write` on `TcpStream` results in a system call. A
133 /// `BufferedWriter` keeps an in memory buffer of data and writes it to the
134 /// underlying `Writer` in large, infrequent batches.
136 /// This writer will be flushed when it is dropped.
141 /// use std::io::{BufferedWriter, File};
143 /// let file = File::create(&Path::new("message.txt")).unwrap();
144 /// let mut writer = BufferedWriter::new(file);
146 /// writer.write_str("hello, world").unwrap();
147 /// writer.flush().unwrap();
149 pub struct BufferedWriter<W> {
155 impl<W: Writer> BufferedWriter<W> {
156 /// Creates a new `BufferedWriter` with the specified buffer capacity
157 pub fn with_capacity(cap: uint, inner: W) -> BufferedWriter<W> {
158 // See comments in BufferedReader for why this uses unsafe code.
159 let mut buf = Vec::with_capacity(cap);
160 unsafe { buf.set_len(cap); }
168 /// Creates a new `BufferedWriter` with a default buffer capacity
169 pub fn new(inner: W) -> BufferedWriter<W> {
170 BufferedWriter::with_capacity(DEFAULT_BUF_SIZE, inner)
173 fn flush_buf(&mut self) -> IoResult<()> {
175 let ret = self.inner.as_mut().unwrap().write(self.buf[..self.pos]);
183 /// Gets a reference to the underlying writer.
184 pub fn get_ref(&self) -> &W { self.inner.as_ref().unwrap() }
186 /// Gets a mutable reference to the underlying write.
190 /// It is inadvisable to directly read from the underlying writer.
191 pub fn get_mut(&mut self) -> &mut W { self.inner.as_mut().unwrap() }
193 /// Unwraps this `BufferedWriter`, returning the underlying writer.
195 /// The buffer is flushed before returning the writer.
196 pub fn into_inner(mut self) -> W {
197 // FIXME(#12628): is panicking the right thing to do if flushing panicks?
198 self.flush_buf().unwrap();
199 self.inner.take().unwrap()
202 /// Deprecated, use into_inner() instead
203 #[deprecated = "renamed to into_inner()"]
204 pub fn unwrap(self) -> W { self.into_inner() }
207 impl<W: Writer> Writer for BufferedWriter<W> {
208 fn write(&mut self, buf: &[u8]) -> IoResult<()> {
209 if self.pos + buf.len() > self.buf.len() {
210 try!(self.flush_buf());
213 if buf.len() > self.buf.len() {
214 self.inner.as_mut().unwrap().write(buf)
216 let dst = self.buf.slice_from_mut(self.pos);
217 slice::bytes::copy_memory(dst, buf);
218 self.pos += buf.len();
223 fn flush(&mut self) -> IoResult<()> {
224 self.flush_buf().and_then(|()| self.inner.as_mut().unwrap().flush())
229 impl<W: Writer> Drop for BufferedWriter<W> {
231 if self.inner.is_some() {
232 // dtors should not panic, so we ignore a panicked flush
233 let _ = self.flush_buf();
238 /// Wraps a Writer and buffers output to it, flushing whenever a newline (`0x0a`,
239 /// `'\n'`) is detected.
241 /// This writer will be flushed when it is dropped.
242 pub struct LineBufferedWriter<W> {
243 inner: BufferedWriter<W>,
246 impl<W: Writer> LineBufferedWriter<W> {
247 /// Creates a new `LineBufferedWriter`
248 pub fn new(inner: W) -> LineBufferedWriter<W> {
249 // Lines typically aren't that long, don't use a giant buffer
251 inner: BufferedWriter::with_capacity(1024, inner)
255 /// Gets a reference to the underlying writer.
257 /// This type does not expose the ability to get a mutable reference to the
258 /// underlying reader because that could possibly corrupt the buffer.
259 pub fn get_ref<'a>(&'a self) -> &'a W { self.inner.get_ref() }
261 /// Unwraps this `LineBufferedWriter`, returning the underlying writer.
263 /// The internal buffer is flushed before returning the writer.
264 pub fn into_inner(self) -> W { self.inner.into_inner() }
266 /// Deprecated, use into_inner() instead
267 #[deprecated = "renamed to into_inner()"]
268 pub fn unwrap(self) -> W { self.into_inner() }
271 impl<W: Writer> Writer for LineBufferedWriter<W> {
272 fn write(&mut self, buf: &[u8]) -> IoResult<()> {
273 match buf.iter().rposition(|&b| b == b'\n') {
275 try!(self.inner.write(buf[..i + 1]));
276 try!(self.inner.flush());
277 try!(self.inner.write(buf[i + 1..]));
280 None => self.inner.write(buf),
284 fn flush(&mut self) -> IoResult<()> { self.inner.flush() }
287 struct InternalBufferedWriter<W>(BufferedWriter<W>);
289 impl<W> InternalBufferedWriter<W> {
290 fn get_mut<'a>(&'a mut self) -> &'a mut BufferedWriter<W> {
291 let InternalBufferedWriter(ref mut w) = *self;
296 impl<W: Reader> Reader for InternalBufferedWriter<W> {
297 fn read(&mut self, buf: &mut [u8]) -> IoResult<uint> {
298 self.get_mut().inner.as_mut().unwrap().read(buf)
302 /// Wraps a Stream and buffers input and output to and from it.
304 /// It can be excessively inefficient to work directly with a `Stream`. For
305 /// example, every call to `read` or `write` on `TcpStream` results in a system
306 /// call. A `BufferedStream` keeps in memory buffers of data, making large,
307 /// infrequent calls to `read` and `write` on the underlying `Stream`.
309 /// The output half will be flushed when this stream is dropped.
314 /// # #![allow(unused_must_use)]
315 /// use std::io::{BufferedStream, File};
317 /// let file = File::open(&Path::new("message.txt"));
318 /// let mut stream = BufferedStream::new(file);
320 /// stream.write("hello, world".as_bytes());
323 /// let mut buf = [0; 100];
324 /// match stream.read(&mut buf) {
325 /// Ok(nread) => println!("Read {} bytes", nread),
326 /// Err(e) => println!("error reading: {}", e)
329 pub struct BufferedStream<S> {
330 inner: BufferedReader<InternalBufferedWriter<S>>
333 impl<S: Stream> BufferedStream<S> {
334 /// Creates a new buffered stream with explicitly listed capacities for the
335 /// reader/writer buffer.
336 pub fn with_capacities(reader_cap: uint, writer_cap: uint, inner: S)
337 -> BufferedStream<S> {
338 let writer = BufferedWriter::with_capacity(writer_cap, inner);
339 let internal_writer = InternalBufferedWriter(writer);
340 let reader = BufferedReader::with_capacity(reader_cap,
342 BufferedStream { inner: reader }
345 /// Creates a new buffered stream with the default reader/writer buffer
347 pub fn new(inner: S) -> BufferedStream<S> {
348 BufferedStream::with_capacities(DEFAULT_BUF_SIZE, DEFAULT_BUF_SIZE,
352 /// Gets a reference to the underlying stream.
353 pub fn get_ref(&self) -> &S {
354 let InternalBufferedWriter(ref w) = self.inner.inner;
358 /// Gets a mutable reference to the underlying stream.
362 /// It is inadvisable to read directly from or write directly to the
363 /// underlying stream.
364 pub fn get_mut(&mut self) -> &mut S {
365 let InternalBufferedWriter(ref mut w) = self.inner.inner;
369 /// Unwraps this `BufferedStream`, returning the underlying stream.
371 /// The internal buffer is flushed before returning the stream. Any leftover
372 /// data in the read buffer is lost.
373 pub fn into_inner(self) -> S {
374 let InternalBufferedWriter(w) = self.inner.inner;
378 /// Deprecated, use into_inner() instead
379 #[deprecated = "renamed to into_inner()"]
380 pub fn unwrap(self) -> S { self.into_inner() }
383 impl<S: Stream> Buffer for BufferedStream<S> {
384 fn fill_buf<'a>(&'a mut self) -> IoResult<&'a [u8]> { self.inner.fill_buf() }
385 fn consume(&mut self, amt: uint) { self.inner.consume(amt) }
388 impl<S: Stream> Reader for BufferedStream<S> {
389 fn read(&mut self, buf: &mut [u8]) -> IoResult<uint> {
394 impl<S: Stream> Writer for BufferedStream<S> {
395 fn write(&mut self, buf: &[u8]) -> IoResult<()> {
396 self.inner.inner.get_mut().write(buf)
398 fn flush(&mut self) -> IoResult<()> {
399 self.inner.inner.get_mut().flush()
409 use super::super::{IoResult, EndOfFile};
410 use super::super::mem::MemReader;
411 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 if self.lengths.is_empty() {
437 Err(io::standard_error(io::EndOfFile))
439 Ok(self.lengths.remove(0))
445 fn test_buffered_reader() {
446 let inner = MemReader::new(vec!(5, 6, 7, 0, 1, 2, 3, 4));
447 let mut reader = BufferedReader::with_capacity(2, inner);
449 let mut buf = [0, 0, 0];
450 let nread = reader.read(&mut buf);
451 assert_eq!(Ok(3), nread);
452 let b: &[_] = &[5, 6, 7];
455 let mut buf = [0, 0];
456 let nread = reader.read(&mut buf);
457 assert_eq!(Ok(2), nread);
458 let b: &[_] = &[0, 1];
462 let nread = reader.read(&mut buf);
463 assert_eq!(Ok(1), nread);
467 let mut buf = [0, 0, 0];
468 let nread = reader.read(&mut buf);
469 assert_eq!(Ok(1), nread);
470 let b: &[_] = &[3, 0, 0];
473 let nread = reader.read(&mut buf);
474 assert_eq!(Ok(1), nread);
475 let b: &[_] = &[4, 0, 0];
478 assert!(reader.read(&mut buf).is_err());
482 fn test_buffered_writer() {
483 let inner = Vec::new();
484 let mut writer = BufferedWriter::with_capacity(2, inner);
486 writer.write(&[0, 1]).unwrap();
488 assert_eq!(writer.get_ref()[], b);
490 writer.write(&[2]).unwrap();
491 let b: &[_] = &[0, 1];
492 assert_eq!(writer.get_ref()[], b);
494 writer.write(&[3]).unwrap();
495 assert_eq!(writer.get_ref()[], b);
497 writer.flush().unwrap();
498 let a: &[_] = &[0, 1, 2, 3];
499 assert_eq!(a, writer.get_ref()[]);
501 writer.write(&[4]).unwrap();
502 writer.write(&[5]).unwrap();
503 assert_eq!(a, writer.get_ref()[]);
505 writer.write(&[6]).unwrap();
506 let a: &[_] = &[0, 1, 2, 3, 4, 5];
510 writer.write(&[7, 8]).unwrap();
511 let a: &[_] = &[0, 1, 2, 3, 4, 5, 6];
515 writer.write(&[9, 10, 11]).unwrap();
516 let a: &[_] = &[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11];
520 writer.flush().unwrap();
526 fn test_buffered_writer_inner_flushes() {
527 let mut w = BufferedWriter::with_capacity(3, Vec::new());
528 w.write(&[0, 1]).unwrap();
530 assert_eq!(a, w.get_ref()[]);
531 let w = w.into_inner();
532 let a: &[_] = &[0, 1];
536 // This is just here to make sure that we don't infinite loop in the
537 // newtype struct autoderef weirdness
539 fn test_buffered_stream() {
542 impl io::Writer for S {
543 fn write(&mut self, _: &[u8]) -> io::IoResult<()> { Ok(()) }
546 impl io::Reader for S {
547 fn read(&mut self, _: &mut [u8]) -> io::IoResult<uint> {
548 Err(io::standard_error(io::EndOfFile))
552 let mut stream = BufferedStream::new(S);
554 assert!(stream.read(&mut buf).is_err());
555 stream.write(&buf).unwrap();
556 stream.flush().unwrap();
560 fn test_read_until() {
561 let inner = MemReader::new(vec!(0, 1, 2, 1, 0));
562 let mut reader = BufferedReader::with_capacity(2, inner);
563 assert_eq!(reader.read_until(0), Ok(vec!(0)));
564 assert_eq!(reader.read_until(2), Ok(vec!(1, 2)));
565 assert_eq!(reader.read_until(1), Ok(vec!(1)));
566 assert_eq!(reader.read_until(8), Ok(vec!(0)));
567 assert!(reader.read_until(9).is_err());
571 fn test_line_buffer() {
572 let mut writer = LineBufferedWriter::new(Vec::new());
573 writer.write(&[0]).unwrap();
575 assert_eq!(writer.get_ref()[], b);
576 writer.write(&[1]).unwrap();
577 assert_eq!(writer.get_ref()[], b);
578 writer.flush().unwrap();
579 let b: &[_] = &[0, 1];
580 assert_eq!(writer.get_ref()[], b);
581 writer.write(&[0, b'\n', 1, b'\n', 2]).unwrap();
582 let b: &[_] = &[0, 1, 0, b'\n', 1, b'\n'];
583 assert_eq!(writer.get_ref()[], b);
584 writer.flush().unwrap();
585 let b: &[_] = &[0, 1, 0, b'\n', 1, b'\n', 2];
586 assert_eq!(writer.get_ref()[], b);
587 writer.write(&[3, b'\n']).unwrap();
588 let b: &[_] = &[0, 1, 0, b'\n', 1, b'\n', 2, 3, b'\n'];
589 assert_eq!(writer.get_ref()[], b);
593 fn test_read_line() {
594 let in_buf = MemReader::new(b"a\nb\nc".to_vec());
595 let mut reader = BufferedReader::with_capacity(2, in_buf);
596 assert_eq!(reader.read_line(), Ok("a\n".to_string()));
597 assert_eq!(reader.read_line(), Ok("b\n".to_string()));
598 assert_eq!(reader.read_line(), Ok("c".to_string()));
599 assert!(reader.read_line().is_err());
604 let in_buf = MemReader::new(b"a\nb\nc".to_vec());
605 let mut reader = BufferedReader::with_capacity(2, in_buf);
606 let mut it = reader.lines();
607 assert_eq!(it.next(), Some(Ok("a\n".to_string())));
608 assert_eq!(it.next(), Some(Ok("b\n".to_string())));
609 assert_eq!(it.next(), Some(Ok("c".to_string())));
610 assert_eq!(it.next(), None);
614 fn test_short_reads() {
615 let inner = ShortReader{lengths: vec![0, 1, 2, 0, 1, 0]};
616 let mut reader = BufferedReader::new(inner);
617 let mut buf = [0, 0];
618 assert_eq!(reader.read(&mut buf), Ok(0));
619 assert_eq!(reader.read(&mut buf), Ok(1));
620 assert_eq!(reader.read(&mut buf), Ok(2));
621 assert_eq!(reader.read(&mut buf), Ok(0));
622 assert_eq!(reader.read(&mut buf), Ok(1));
623 assert_eq!(reader.read(&mut buf), Ok(0));
624 assert!(reader.read(&mut buf).is_err());
628 fn read_char_buffered() {
629 let buf = [195u8, 159u8];
630 let mut reader = BufferedReader::with_capacity(1, buf[]);
631 assert_eq!(reader.read_char(), Ok('ß'));
636 let buf = [195u8, 159u8, b'a'];
637 let mut reader = BufferedReader::with_capacity(1, buf[]);
638 let mut it = reader.chars();
639 assert_eq!(it.next(), Some(Ok('ß')));
640 assert_eq!(it.next(), Some(Ok('a')));
641 assert_eq!(it.next(), None);
646 fn dont_panic_in_drop_on_panicked_flush() {
647 struct FailFlushWriter;
649 impl Writer for FailFlushWriter {
650 fn write(&mut self, _buf: &[u8]) -> IoResult<()> { Ok(()) }
651 fn flush(&mut self) -> IoResult<()> { Err(io::standard_error(EndOfFile)) }
654 let writer = FailFlushWriter;
655 let _writer = BufferedWriter::new(writer);
657 // If writer panics *again* due to the flush error then the process will abort.
662 fn bench_buffered_reader(b: &mut Bencher) {
664 BufferedReader::new(NullStream)
669 fn bench_buffered_writer(b: &mut Bencher) {
671 BufferedWriter::new(NullStream)
676 fn bench_buffered_stream(b: &mut Bencher) {
678 BufferedStream::new(NullStream);