diff options
Diffstat (limited to 'library/std/src/io')
| -rw-r--r-- | library/std/src/io/buffered/bufreader.rs | 31 | ||||
| -rw-r--r-- | library/std/src/io/buffered/bufwriter.rs | 140 | ||||
| -rw-r--r-- | library/std/src/io/buffered/linewriter.rs | 50 | ||||
| -rw-r--r-- | library/std/src/io/buffered/linewritershim.rs | 6 | ||||
| -rw-r--r-- | library/std/src/io/copy.rs | 110 | ||||
| -rw-r--r-- | library/std/src/io/copy/tests.rs | 108 | ||||
| -rw-r--r-- | library/std/src/io/mod.rs | 13 | ||||
| -rw-r--r-- | library/std/src/io/util/tests.rs | 61 |
8 files changed, 330 insertions, 189 deletions
diff --git a/library/std/src/io/buffered/bufreader.rs b/library/std/src/io/buffered/bufreader.rs index 4f339a18a..7097dfef8 100644 --- a/library/std/src/io/buffered/bufreader.rs +++ b/library/std/src/io/buffered/bufreader.rs @@ -47,13 +47,13 @@ use buffer::Buffer; /// } /// ``` #[stable(feature = "rust1", since = "1.0.0")] -pub struct BufReader<R> { - inner: R, +pub struct BufReader<R: ?Sized> { buf: Buffer, + inner: R, } impl<R: Read> BufReader<R> { - /// Creates a new `BufReader<R>` with a default buffer capacity. The default is currently 8 KB, + /// Creates a new `BufReader<R>` with a default buffer capacity. The default is currently 8 KiB, /// but may change in the future. /// /// # Examples @@ -95,7 +95,7 @@ impl<R: Read> BufReader<R> { } } -impl<R> BufReader<R> { +impl<R: ?Sized> BufReader<R> { /// Gets a reference to the underlying reader. /// /// It is inadvisable to directly read from the underlying reader. @@ -213,26 +213,29 @@ impl<R> BufReader<R> { /// } /// ``` #[stable(feature = "rust1", since = "1.0.0")] - pub fn into_inner(self) -> R { + pub fn into_inner(self) -> R + where + R: Sized, + { self.inner } /// Invalidates all data in the internal buffer. #[inline] - fn discard_buffer(&mut self) { + pub(in crate::io) fn discard_buffer(&mut self) { self.buf.discard_buffer() } } // This is only used by a test which asserts that the initialization-tracking is correct. #[cfg(test)] -impl<R> BufReader<R> { +impl<R: ?Sized> BufReader<R> { pub fn initialized(&self) -> usize { self.buf.initialized() } } -impl<R: Seek> BufReader<R> { +impl<R: ?Sized + Seek> BufReader<R> { /// Seeks relative to the current position. If the new position lies within the buffer, /// the buffer will not be flushed, allowing for more efficient seeks. /// This method does not return the location of the underlying reader, so the caller @@ -257,7 +260,7 @@ impl<R: Seek> BufReader<R> { } #[stable(feature = "rust1", since = "1.0.0")] -impl<R: Read> Read for BufReader<R> { +impl<R: ?Sized + Read> Read for BufReader<R> { fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> { // If we don't have any buffered data and we're doing a massive read // (larger than our internal buffer), bypass our internal buffer @@ -371,7 +374,7 @@ impl<R: Read> Read for BufReader<R> { } #[stable(feature = "rust1", since = "1.0.0")] -impl<R: Read> BufRead for BufReader<R> { +impl<R: ?Sized + Read> BufRead for BufReader<R> { fn fill_buf(&mut self) -> io::Result<&[u8]> { self.buf.fill_buf(&mut self.inner) } @@ -384,11 +387,11 @@ impl<R: Read> BufRead for BufReader<R> { #[stable(feature = "rust1", since = "1.0.0")] impl<R> fmt::Debug for BufReader<R> where - R: fmt::Debug, + R: ?Sized + fmt::Debug, { fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { fmt.debug_struct("BufReader") - .field("reader", &self.inner) + .field("reader", &&self.inner) .field( "buffer", &format_args!("{}/{}", self.buf.filled() - self.buf.pos(), self.capacity()), @@ -398,7 +401,7 @@ where } #[stable(feature = "rust1", since = "1.0.0")] -impl<R: Seek> Seek for BufReader<R> { +impl<R: ?Sized + Seek> Seek for BufReader<R> { /// Seek to an offset, in bytes, in the underlying reader. /// /// The position used for seeking with <code>[SeekFrom::Current]\(_)</code> is the @@ -491,7 +494,7 @@ impl<R: Seek> Seek for BufReader<R> { } } -impl<T> SizeHint for BufReader<T> { +impl<T: ?Sized> SizeHint for BufReader<T> { #[inline] fn lower_bound(&self) -> usize { SizeHint::lower_bound(self.get_ref()) + self.buffer().len() diff --git a/library/std/src/io/buffered/bufwriter.rs b/library/std/src/io/buffered/bufwriter.rs index 14c455d4f..0f04f2911 100644 --- a/library/std/src/io/buffered/bufwriter.rs +++ b/library/std/src/io/buffered/bufwriter.rs @@ -67,8 +67,7 @@ use crate::ptr; /// [`TcpStream`]: crate::net::TcpStream /// [`flush`]: BufWriter::flush #[stable(feature = "rust1", since = "1.0.0")] -pub struct BufWriter<W: Write> { - inner: W, +pub struct BufWriter<W: ?Sized + Write> { // The buffer. Avoid using this like a normal `Vec` in common code paths. // That is, don't use `buf.push`, `buf.extend_from_slice`, or any other // methods that require bounds checking or the like. This makes an enormous @@ -78,10 +77,11 @@ pub struct BufWriter<W: Write> { // write the buffered data a second time in BufWriter's destructor. This // flag tells the Drop impl if it should skip the flush. panicked: bool, + inner: W, } impl<W: Write> BufWriter<W> { - /// Creates a new `BufWriter<W>` with a default buffer capacity. The default is currently 8 KB, + /// Creates a new `BufWriter<W>` with a default buffer capacity. The default is currently 8 KiB, /// but may change in the future. /// /// # Examples @@ -115,6 +115,69 @@ impl<W: Write> BufWriter<W> { BufWriter { inner, buf: Vec::with_capacity(capacity), panicked: false } } + /// Unwraps this `BufWriter<W>`, returning the underlying writer. + /// + /// The buffer is written out before returning the writer. + /// + /// # Errors + /// + /// An [`Err`] will be returned if an error occurs while flushing the buffer. + /// + /// # Examples + /// + /// ```no_run + /// use std::io::BufWriter; + /// use std::net::TcpStream; + /// + /// let mut buffer = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap()); + /// + /// // unwrap the TcpStream and flush the buffer + /// let stream = buffer.into_inner().unwrap(); + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn into_inner(mut self) -> Result<W, IntoInnerError<BufWriter<W>>> { + match self.flush_buf() { + Err(e) => Err(IntoInnerError::new(self, e)), + Ok(()) => Ok(self.into_parts().0), + } + } + + /// Disassembles this `BufWriter<W>`, returning the underlying writer, and any buffered but + /// unwritten data. + /// + /// If the underlying writer panicked, it is not known what portion of the data was written. + /// In this case, we return `WriterPanicked` for the buffered data (from which the buffer + /// contents can still be recovered). + /// + /// `into_parts` makes no attempt to flush data and cannot fail. + /// + /// # Examples + /// + /// ``` + /// use std::io::{BufWriter, Write}; + /// + /// let mut buffer = [0u8; 10]; + /// let mut stream = BufWriter::new(buffer.as_mut()); + /// write!(stream, "too much data").unwrap(); + /// stream.flush().expect_err("it doesn't fit"); + /// let (recovered_writer, buffered_data) = stream.into_parts(); + /// assert_eq!(recovered_writer.len(), 0); + /// assert_eq!(&buffered_data.unwrap(), b"ata"); + /// ``` + #[stable(feature = "bufwriter_into_parts", since = "1.56.0")] + pub fn into_parts(mut self) -> (W, Result<Vec<u8>, WriterPanicked>) { + let buf = mem::take(&mut self.buf); + let buf = if !self.panicked { Ok(buf) } else { Err(WriterPanicked { buf }) }; + + // SAFETY: forget(self) prevents double dropping inner + let inner = unsafe { ptr::read(&self.inner) }; + mem::forget(self); + + (inner, buf) + } +} + +impl<W: ?Sized + Write> BufWriter<W> { /// Send data in our local buffer into the inner writer, looping as /// necessary until either it's all been sent or an error occurs. /// @@ -284,67 +347,6 @@ impl<W: Write> BufWriter<W> { self.buf.capacity() } - /// Unwraps this `BufWriter<W>`, returning the underlying writer. - /// - /// The buffer is written out before returning the writer. - /// - /// # Errors - /// - /// An [`Err`] will be returned if an error occurs while flushing the buffer. - /// - /// # Examples - /// - /// ```no_run - /// use std::io::BufWriter; - /// use std::net::TcpStream; - /// - /// let mut buffer = BufWriter::new(TcpStream::connect("127.0.0.1:34254").unwrap()); - /// - /// // unwrap the TcpStream and flush the buffer - /// let stream = buffer.into_inner().unwrap(); - /// ``` - #[stable(feature = "rust1", since = "1.0.0")] - pub fn into_inner(mut self) -> Result<W, IntoInnerError<BufWriter<W>>> { - match self.flush_buf() { - Err(e) => Err(IntoInnerError::new(self, e)), - Ok(()) => Ok(self.into_parts().0), - } - } - - /// Disassembles this `BufWriter<W>`, returning the underlying writer, and any buffered but - /// unwritten data. - /// - /// If the underlying writer panicked, it is not known what portion of the data was written. - /// In this case, we return `WriterPanicked` for the buffered data (from which the buffer - /// contents can still be recovered). - /// - /// `into_parts` makes no attempt to flush data and cannot fail. - /// - /// # Examples - /// - /// ``` - /// use std::io::{BufWriter, Write}; - /// - /// let mut buffer = [0u8; 10]; - /// let mut stream = BufWriter::new(buffer.as_mut()); - /// write!(stream, "too much data").unwrap(); - /// stream.flush().expect_err("it doesn't fit"); - /// let (recovered_writer, buffered_data) = stream.into_parts(); - /// assert_eq!(recovered_writer.len(), 0); - /// assert_eq!(&buffered_data.unwrap(), b"ata"); - /// ``` - #[stable(feature = "bufwriter_into_parts", since = "1.56.0")] - pub fn into_parts(mut self) -> (W, Result<Vec<u8>, WriterPanicked>) { - let buf = mem::take(&mut self.buf); - let buf = if !self.panicked { Ok(buf) } else { Err(WriterPanicked { buf }) }; - - // SAFETY: forget(self) prevents double dropping inner - let inner = unsafe { ptr::read(&self.inner) }; - mem::forget(self); - - (inner, buf) - } - // Ensure this function does not get inlined into `write`, so that it // remains inlineable and its common path remains as short as possible. // If this function ends up being called frequently relative to `write`, @@ -511,7 +513,7 @@ impl fmt::Debug for WriterPanicked { } #[stable(feature = "rust1", since = "1.0.0")] -impl<W: Write> Write for BufWriter<W> { +impl<W: ?Sized + Write> Write for BufWriter<W> { #[inline] fn write(&mut self, buf: &[u8]) -> io::Result<usize> { // Use < instead of <= to avoid a needless trip through the buffer in some cases. @@ -640,20 +642,20 @@ impl<W: Write> Write for BufWriter<W> { } #[stable(feature = "rust1", since = "1.0.0")] -impl<W: Write> fmt::Debug for BufWriter<W> +impl<W: ?Sized + Write> fmt::Debug for BufWriter<W> where W: fmt::Debug, { fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { fmt.debug_struct("BufWriter") - .field("writer", &self.inner) + .field("writer", &&self.inner) .field("buffer", &format_args!("{}/{}", self.buf.len(), self.buf.capacity())) .finish() } } #[stable(feature = "rust1", since = "1.0.0")] -impl<W: Write + Seek> Seek for BufWriter<W> { +impl<W: ?Sized + Write + Seek> Seek for BufWriter<W> { /// Seek to the offset, in bytes, in the underlying writer. /// /// Seeking always writes out the internal buffer before seeking. @@ -664,7 +666,7 @@ impl<W: Write + Seek> Seek for BufWriter<W> { } #[stable(feature = "rust1", since = "1.0.0")] -impl<W: Write> Drop for BufWriter<W> { +impl<W: ?Sized + Write> Drop for BufWriter<W> { fn drop(&mut self) { if !self.panicked { // dtors should not panic, so we ignore a failed flush diff --git a/library/std/src/io/buffered/linewriter.rs b/library/std/src/io/buffered/linewriter.rs index a26a4ab33..3d4ae7041 100644 --- a/library/std/src/io/buffered/linewriter.rs +++ b/library/std/src/io/buffered/linewriter.rs @@ -64,7 +64,7 @@ use crate::io::{self, buffered::LineWriterShim, BufWriter, IntoInnerError, IoSli /// } /// ``` #[stable(feature = "rust1", since = "1.0.0")] -pub struct LineWriter<W: Write> { +pub struct LineWriter<W: ?Sized + Write> { inner: BufWriter<W>, } @@ -109,27 +109,6 @@ impl<W: Write> LineWriter<W> { LineWriter { inner: BufWriter::with_capacity(capacity, inner) } } - /// Gets a reference to the underlying writer. - /// - /// # Examples - /// - /// ```no_run - /// use std::fs::File; - /// use std::io::LineWriter; - /// - /// fn main() -> std::io::Result<()> { - /// let file = File::create("poem.txt")?; - /// let file = LineWriter::new(file); - /// - /// let reference = file.get_ref(); - /// Ok(()) - /// } - /// ``` - #[stable(feature = "rust1", since = "1.0.0")] - pub fn get_ref(&self) -> &W { - self.inner.get_ref() - } - /// Gets a mutable reference to the underlying writer. /// /// Caution must be taken when calling methods on the mutable reference @@ -184,8 +163,31 @@ impl<W: Write> LineWriter<W> { } } +impl<W: ?Sized + Write> LineWriter<W> { + /// Gets a reference to the underlying writer. + /// + /// # Examples + /// + /// ```no_run + /// use std::fs::File; + /// use std::io::LineWriter; + /// + /// fn main() -> std::io::Result<()> { + /// let file = File::create("poem.txt")?; + /// let file = LineWriter::new(file); + /// + /// let reference = file.get_ref(); + /// Ok(()) + /// } + /// ``` + #[stable(feature = "rust1", since = "1.0.0")] + pub fn get_ref(&self) -> &W { + self.inner.get_ref() + } +} + #[stable(feature = "rust1", since = "1.0.0")] -impl<W: Write> Write for LineWriter<W> { +impl<W: ?Sized + Write> Write for LineWriter<W> { fn write(&mut self, buf: &[u8]) -> io::Result<usize> { LineWriterShim::new(&mut self.inner).write(buf) } @@ -216,7 +218,7 @@ impl<W: Write> Write for LineWriter<W> { } #[stable(feature = "rust1", since = "1.0.0")] -impl<W: Write> fmt::Debug for LineWriter<W> +impl<W: ?Sized + Write> fmt::Debug for LineWriter<W> where W: fmt::Debug, { diff --git a/library/std/src/io/buffered/linewritershim.rs b/library/std/src/io/buffered/linewritershim.rs index 0175d2693..f2a55da05 100644 --- a/library/std/src/io/buffered/linewritershim.rs +++ b/library/std/src/io/buffered/linewritershim.rs @@ -11,11 +11,11 @@ use crate::sys_common::memchr; /// `BufWriters` to be temporarily given line-buffering logic; this is what /// enables Stdout to be alternately in line-buffered or block-buffered mode. #[derive(Debug)] -pub struct LineWriterShim<'a, W: Write> { +pub struct LineWriterShim<'a, W: ?Sized + Write> { buffer: &'a mut BufWriter<W>, } -impl<'a, W: Write> LineWriterShim<'a, W> { +impl<'a, W: ?Sized + Write> LineWriterShim<'a, W> { pub fn new(buffer: &'a mut BufWriter<W>) -> Self { Self { buffer } } @@ -49,7 +49,7 @@ impl<'a, W: Write> LineWriterShim<'a, W> { } } -impl<'a, W: Write> Write for LineWriterShim<'a, W> { +impl<'a, W: ?Sized + Write> Write for LineWriterShim<'a, W> { /// Write some data into this BufReader with line buffering. This means /// that, if any newlines are present in the data, the data up to the last /// newline is sent directly to the underlying writer, and data after it diff --git a/library/std/src/io/copy.rs b/library/std/src/io/copy.rs index 1d9d93f5b..ef1f4031e 100644 --- a/library/std/src/io/copy.rs +++ b/library/std/src/io/copy.rs @@ -1,6 +1,9 @@ -use super::{BorrowedBuf, BufWriter, ErrorKind, Read, Result, Write, DEFAULT_BUF_SIZE}; +use super::{BorrowedBuf, BufReader, BufWriter, ErrorKind, Read, Result, Write, DEFAULT_BUF_SIZE}; use crate::mem::MaybeUninit; +#[cfg(test)] +mod tests; + /// Copies the entire contents of a reader into a writer. /// /// This function will continuously read data from `reader` and then @@ -71,32 +74,113 @@ where R: Read, W: Write, { - BufferedCopySpec::copy_to(reader, writer) + let read_buf = BufferedReaderSpec::buffer_size(reader); + let write_buf = BufferedWriterSpec::buffer_size(writer); + + if read_buf >= DEFAULT_BUF_SIZE && read_buf >= write_buf { + return BufferedReaderSpec::copy_to(reader, writer); + } + + BufferedWriterSpec::copy_from(writer, reader) +} + +/// Specialization of the read-write loop that reuses the internal +/// buffer of a BufReader. If there's no buffer then the writer side +/// should be used intead. +trait BufferedReaderSpec { + fn buffer_size(&self) -> usize; + + fn copy_to(&mut self, to: &mut (impl Write + ?Sized)) -> Result<u64>; +} + +impl<T> BufferedReaderSpec for T +where + Self: Read, + T: ?Sized, +{ + #[inline] + default fn buffer_size(&self) -> usize { + 0 + } + + default fn copy_to(&mut self, _to: &mut (impl Write + ?Sized)) -> Result<u64> { + unimplemented!("only called from specializations"); + } +} + +impl<I> BufferedReaderSpec for BufReader<I> +where + Self: Read, + I: ?Sized, +{ + fn buffer_size(&self) -> usize { + self.capacity() + } + + fn copy_to(&mut self, to: &mut (impl Write + ?Sized)) -> Result<u64> { + let mut len = 0; + + loop { + // Hack: this relies on `impl Read for BufReader` always calling fill_buf + // if the buffer is empty, even for empty slices. + // It can't be called directly here since specialization prevents us + // from adding I: Read + match self.read(&mut []) { + Ok(_) => {} + Err(e) if e.kind() == ErrorKind::Interrupted => continue, + Err(e) => return Err(e), + } + let buf = self.buffer(); + if self.buffer().len() == 0 { + return Ok(len); + } + + // In case the writer side is a BufWriter then its write_all + // implements an optimization that passes through large + // buffers to the underlying writer. That code path is #[cold] + // but we're still avoiding redundant memcopies when doing + // a copy between buffered inputs and outputs. + to.write_all(buf)?; + len += buf.len() as u64; + self.discard_buffer(); + } + } } /// Specialization of the read-write loop that either uses a stack buffer /// or reuses the internal buffer of a BufWriter -trait BufferedCopySpec: Write { - fn copy_to<R: Read + ?Sized>(reader: &mut R, writer: &mut Self) -> Result<u64>; +trait BufferedWriterSpec: Write { + fn buffer_size(&self) -> usize; + + fn copy_from<R: Read + ?Sized>(&mut self, reader: &mut R) -> Result<u64>; } -impl<W: Write + ?Sized> BufferedCopySpec for W { - default fn copy_to<R: Read + ?Sized>(reader: &mut R, writer: &mut Self) -> Result<u64> { - stack_buffer_copy(reader, writer) +impl<W: Write + ?Sized> BufferedWriterSpec for W { + #[inline] + default fn buffer_size(&self) -> usize { + 0 + } + + default fn copy_from<R: Read + ?Sized>(&mut self, reader: &mut R) -> Result<u64> { + stack_buffer_copy(reader, self) } } -impl<I: Write> BufferedCopySpec for BufWriter<I> { - fn copy_to<R: Read + ?Sized>(reader: &mut R, writer: &mut Self) -> Result<u64> { - if writer.capacity() < DEFAULT_BUF_SIZE { - return stack_buffer_copy(reader, writer); +impl<I: Write + ?Sized> BufferedWriterSpec for BufWriter<I> { + fn buffer_size(&self) -> usize { + self.capacity() + } + + fn copy_from<R: Read + ?Sized>(&mut self, reader: &mut R) -> Result<u64> { + if self.capacity() < DEFAULT_BUF_SIZE { + return stack_buffer_copy(reader, self); } let mut len = 0; let mut init = 0; loop { - let buf = writer.buffer_mut(); + let buf = self.buffer_mut(); let mut read_buf: BorrowedBuf<'_> = buf.spare_capacity_mut().into(); unsafe { @@ -127,7 +211,7 @@ impl<I: Write> BufferedCopySpec for BufWriter<I> { Err(e) => return Err(e), } } else { - writer.flush_buf()?; + self.flush_buf()?; init = 0; } } diff --git a/library/std/src/io/copy/tests.rs b/library/std/src/io/copy/tests.rs new file mode 100644 index 000000000..8c816af15 --- /dev/null +++ b/library/std/src/io/copy/tests.rs @@ -0,0 +1,108 @@ +use crate::cmp::{max, min}; +use crate::io::*; + +#[test] +fn copy_copies() { + let mut r = repeat(0).take(4); + let mut w = sink(); + assert_eq!(copy(&mut r, &mut w).unwrap(), 4); + + let mut r = repeat(0).take(1 << 17); + assert_eq!(copy(&mut r as &mut dyn Read, &mut w as &mut dyn Write).unwrap(), 1 << 17); +} + +struct ShortReader { + cap: usize, + read_size: usize, + observed_buffer: usize, +} + +impl Read for ShortReader { + fn read(&mut self, buf: &mut [u8]) -> Result<usize> { + let bytes = min(self.cap, self.read_size); + self.cap -= bytes; + self.observed_buffer = max(self.observed_buffer, buf.len()); + Ok(bytes) + } +} + +struct WriteObserver { + observed_buffer: usize, +} + +impl Write for WriteObserver { + fn write(&mut self, buf: &[u8]) -> Result<usize> { + self.observed_buffer = max(self.observed_buffer, buf.len()); + Ok(buf.len()) + } + + fn flush(&mut self) -> Result<()> { + Ok(()) + } +} + +#[test] +fn copy_specializes_bufwriter() { + let cap = 117 * 1024; + let buf_sz = 16 * 1024; + let mut r = ShortReader { cap, observed_buffer: 0, read_size: 1337 }; + let mut w = BufWriter::with_capacity(buf_sz, WriteObserver { observed_buffer: 0 }); + assert_eq!( + copy(&mut r, &mut w).unwrap(), + cap as u64, + "expected the whole capacity to be copied" + ); + assert_eq!(r.observed_buffer, buf_sz, "expected a large buffer to be provided to the reader"); + assert!(w.get_mut().observed_buffer > DEFAULT_BUF_SIZE, "expected coalesced writes"); +} + +#[test] +fn copy_specializes_bufreader() { + let mut source = vec![0; 768 * 1024]; + source[1] = 42; + let mut buffered = BufReader::with_capacity(256 * 1024, Cursor::new(&mut source)); + + let mut sink = Vec::new(); + assert_eq!(crate::io::copy(&mut buffered, &mut sink).unwrap(), source.len() as u64); + assert_eq!(source.as_slice(), sink.as_slice()); + + let buf_sz = 71 * 1024; + assert!(buf_sz > DEFAULT_BUF_SIZE, "test precondition"); + + let mut buffered = BufReader::with_capacity(buf_sz, Cursor::new(&mut source)); + let mut sink = WriteObserver { observed_buffer: 0 }; + assert_eq!(crate::io::copy(&mut buffered, &mut sink).unwrap(), source.len() as u64); + assert_eq!( + sink.observed_buffer, buf_sz, + "expected a large buffer to be provided to the writer" + ); +} + +#[cfg(unix)] +mod io_benches { + use crate::fs::File; + use crate::fs::OpenOptions; + use crate::io::prelude::*; + use crate::io::BufReader; + + use test::Bencher; + + #[bench] + fn bench_copy_buf_reader(b: &mut Bencher) { + let mut file_in = File::open("/dev/zero").expect("opening /dev/zero failed"); + // use dyn to avoid specializations unrelated to readbuf + let dyn_in = &mut file_in as &mut dyn Read; + let mut reader = BufReader::with_capacity(256 * 1024, dyn_in.take(0)); + let mut writer = + OpenOptions::new().write(true).open("/dev/null").expect("opening /dev/null failed"); + + const BYTES: u64 = 1024 * 1024; + + b.bytes = BYTES; + + b.iter(|| { + reader.get_mut().set_limit(BYTES); + crate::io::copy(&mut reader, &mut writer).unwrap() + }); + } +} diff --git a/library/std/src/io/mod.rs b/library/std/src/io/mod.rs index 8a007d095..71d91f213 100644 --- a/library/std/src/io/mod.rs +++ b/library/std/src/io/mod.rs @@ -1416,17 +1416,18 @@ pub trait Write { /// /// This function will attempt to write the entire contents of `buf`, but /// the entire write might not succeed, or the write may also generate an - /// error. A call to `write` represents *at most one* attempt to write to + /// error. Typically, a call to `write` represents one attempt to write to /// any wrapped object. /// /// Calls to `write` are not guaranteed to block waiting for data to be /// written, and a write which would otherwise block can be indicated through /// an [`Err`] variant. /// - /// If the return value is [`Ok(n)`] then it must be guaranteed that - /// `n <= buf.len()`. A return value of `0` typically means that the - /// underlying object is no longer able to accept bytes and will likely not - /// be able to in the future as well, or that the buffer provided is empty. + /// If this method consumed `n > 0` bytes of `buf` it must return [`Ok(n)`]. + /// If the return value is `Ok(n)` then `n` must satisfy `n <= buf.len()`. + /// A return value of `Ok(0)` typically means that the underlying object is + /// no longer able to accept bytes and will likely not be able to in the + /// future as well, or that the buffer provided is empty. /// /// # Errors /// @@ -2754,7 +2755,7 @@ trait SizeHint { } } -impl<T> SizeHint for T { +impl<T: ?Sized> SizeHint for T { #[inline] default fn lower_bound(&self) -> usize { 0 diff --git a/library/std/src/io/util/tests.rs b/library/std/src/io/util/tests.rs index ce5e2c9da..1baa94e64 100644 --- a/library/std/src/io/util/tests.rs +++ b/library/std/src/io/util/tests.rs @@ -1,68 +1,9 @@ -use crate::cmp::{max, min}; use crate::io::prelude::*; -use crate::io::{ - copy, empty, repeat, sink, BorrowedBuf, BufWriter, Empty, Repeat, Result, SeekFrom, Sink, - DEFAULT_BUF_SIZE, -}; +use crate::io::{empty, repeat, sink, BorrowedBuf, Empty, Repeat, SeekFrom, Sink}; use crate::mem::MaybeUninit; #[test] -fn copy_copies() { - let mut r = repeat(0).take(4); - let mut w = sink(); - assert_eq!(copy(&mut r, &mut w).unwrap(), 4); - - let mut r = repeat(0).take(1 << 17); - assert_eq!(copy(&mut r as &mut dyn Read, &mut w as &mut dyn Write).unwrap(), 1 << 17); -} - -struct ShortReader { - cap: usize, - read_size: usize, - observed_buffer: usize, -} - -impl Read for ShortReader { - fn read(&mut self, buf: &mut [u8]) -> Result<usize> { - let bytes = min(self.cap, self.read_size); - self.cap -= bytes; - self.observed_buffer = max(self.observed_buffer, buf.len()); - Ok(bytes) - } -} - -struct WriteObserver { - observed_buffer: usize, -} - -impl Write for WriteObserver { - fn write(&mut self, buf: &[u8]) -> Result<usize> { - self.observed_buffer = max(self.observed_buffer, buf.len()); - Ok(buf.len()) - } - - fn flush(&mut self) -> Result<()> { - Ok(()) - } -} - -#[test] -fn copy_specializes_bufwriter() { - let cap = 117 * 1024; - let buf_sz = 16 * 1024; - let mut r = ShortReader { cap, observed_buffer: 0, read_size: 1337 }; - let mut w = BufWriter::with_capacity(buf_sz, WriteObserver { observed_buffer: 0 }); - assert_eq!( - copy(&mut r, &mut w).unwrap(), - cap as u64, - "expected the whole capacity to be copied" - ); - assert_eq!(r.observed_buffer, buf_sz, "expected a large buffer to be provided to the reader"); - assert!(w.get_mut().observed_buffer > DEFAULT_BUF_SIZE, "expected coalesced writes"); -} - -#[test] fn sink_sinks() { let mut s = sink(); assert_eq!(s.write(&[]).unwrap(), 0); |