From e4cdcf4f5082f90abd9e259ccc215ecbb1973ab5 Mon Sep 17 00:00:00 2001
From: Ben Bridle <bridle.benjamin@gmail.com>
Date: Mon, 29 Jan 2024 18:31:45 +1300
Subject: Change stream device to use buffered streams
Wrapping stdin and stdout with BufReader and BufWriter makes reads and
writes more efficient by bundling multiple characters into a single
read or write operation. In practice, this hasn't made a difference to
running the numbers demo, but that demo spends the majority of processor
time converting values to decimal strings.
---
src/devices/stream.rs | 31 +++++++++++++++++--------------
1 file changed, 17 insertions(+), 14 deletions(-)
diff --git a/src/devices/stream.rs b/src/devices/stream.rs
index 3d376b6..7f69a7a 100644
--- a/src/devices/stream.rs
+++ b/src/devices/stream.rs
@@ -1,14 +1,15 @@
-use std::io::{Read, Write, Stdin, Stdout};
+use std::io::{Read, Write};
+use std::io::{BufReader, BufWriter};
+use std::io::{Stdin, Stdout};
pub struct StreamDevice {
pub wake_flag: bool,
pub input_control: bool,
pub output_control: bool,
- pub read_queue: Vec<u8>,
- pub stdin: Stdin,
- pub stdout: Stdout,
+ pub stdin: BufReader<Stdin>,
+ pub stdout: BufWriter<Stdout>,
}
impl StreamDevice {
@@ -18,24 +19,20 @@ impl StreamDevice {
input_control: true,
output_control: true,
- read_queue: Vec::with_capacity(256),
- stdin: std::io::stdin(),
- stdout: std::io::stdout(),
+ stdin: BufReader::new(std::io::stdin()),
+ stdout: BufWriter::new(std::io::stdout()),
}
}
- // pub fn fetch_stdin(&mut self) {
- // match self.stdin.read(&mut self.read_queue) {
- // Ok() => (),
- // Err() => (),
- // }
- // }
+ pub fn read_queue_len(&self) -> usize {
+ self.stdin.buffer().len()
+ }
pub fn read_stdin(&mut self) -> u8 {
let mut buffer = [0; 1];
match self.stdin.read_exact(&mut buffer) {
- Ok(()) => buffer[0],
+ Ok(_) => buffer[0],
Err(_) => 0,
}
}
@@ -44,3 +41,9 @@ impl StreamDevice {
self.stdout.write_all(&[val]).unwrap();
}
}
+
+impl Drop for StreamDevice {
+ fn drop(&mut self) {
+ self.stdout.flush().unwrap();
+ }
+}
--
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