Update examples/logs.rs to use VecDeque
Instead of custom ring-buffer
extern crate cursive;
use cursive::{Cursive, Printer};
-use cursive::vec::Vec2;
use cursive::traits::*;
+use cursive::vec::Vec2;
+use std::collections::VecDeque;
+use std::iter::Chain;
+use std::slice::Iter;
use std::sync::mpsc;
use std::thread;
use std::time::Duration;
-use std::iter::Chain;
-use std::slice::Iter;
fn main() {
// As usual, create the Cursive root
@@ -22,9 +23,7 @@ fn main() {
let (tx, rx) = mpsc::channel();
// Generate data in a separate thread.
- thread::spawn(move || {
- generate_logs(&tx);
- });
+ thread::spawn(move || { generate_logs(&tx); });
// And sets the view to read from the other end of the channel.
siv.add_layer(BufferView::new(200, rx).full_screen());
@@ -50,10 +49,8 @@ fn generate_logs(tx: &mpsc::Sender<String>) {
// Let's define a buffer view, that shows the last lines from a stream.
struct BufferView {
- // We will emulate a ring buffer
- buffer: Vec<String>,
- // Current position in the buffer
- pos: usize,
+ // We'll use a ring buffer
+ buffer: VecDeque<String>,
// Receiving end of the stream
rx: mpsc::Receiver<String>,
}
@@ -61,29 +58,21 @@ struct BufferView {
impl BufferView {
// Creates a new view with the given buffer size
fn new(size: usize, rx: mpsc::Receiver<String>) -> Self {
+ let mut buffer = VecDeque::new();
+ buffer.resize(size, String::new());
BufferView {
rx: rx,
- buffer: (0..size).map(|_| String::new()).collect(),
- pos: 0,
+ buffer: buffer,
}
}
// Reads available data from the stream into the buffer
fn update(&mut self) {
- let mut i = self.pos;
+ // Add each available line to the end of the buffer.
while let Ok(line) = self.rx.try_recv() {
- self.buffer[i] = line;
- i = (i + 1) % self.buffer.len();
- }
- self.pos = i;
+ self.buffer.push_back(line);
+ self.buffer.pop_front();
}
-
- // Chain together the two parts of the buffer to appear as a circular one.
- // TODO: Use `-> impl Iterator<Item=String>`...
- fn ring(&self) -> Chain<Iter<String>, Iter<String>> {
- // The main buffer is "circular" starting at self.pos
- // So we chain the two parts as one
- self.buffer[self.pos..].iter().chain(self.buffer[..self.pos].iter())
}
}
@@ -94,18 +83,13 @@ impl View for BufferView {
}
fn draw(&self, printer: &Printer) {
-
- // If the buffer is large, we'll discard the beginning and keep the end.
- // If the buffer is too small, only print a part of it with an offset.
- let (discard, offset) = if self.buffer.len() >
- printer.size.y as usize {
- (self.buffer.len() - printer.size.y as usize, 0)
- } else {
- (0, printer.size.y - self.buffer.len())
- };
-
- for (i, line) in self.ring().skip(discard).enumerate() {
- printer.print((0, offset + i), line);
+ // Print the end of the buffer
+ for (i, line) in self.buffer
+ .iter()
+ .rev()
+ .take(printer.size.y)
+ .enumerate() {
+ printer.print((0, printer.size.y - 1 - i), line);
}
}
}
