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mux: reduce context switching when parsing output

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Now that we use Arc<Pane> we can directly pass the pane to the
background thread that we're using to parse the terminal output, cutting
out some context switching and reducing the latency between output and
rendering that output.
This commit is contained in:
Wez Furlong 2022-11-23 09:46:48 -07:00
parent aa3d722e1f
commit 9e67ad7861
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GPG Key ID: 7A7F66A31EC9B387
1 changed files with 23 additions and 33 deletions
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56
mux/src/lib.rs
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@ -96,37 +96,20 @@ pub struct Mux {
const BUFSIZE: usize = 1024 * 1024;
/// This function bounces parsed actions over to the main thread to feed to
/// the pty in the mux.
/// It blocks until the mux has finished consuming the data, which provides
/// some back-pressure so that eg: ctrl-c can remain responsive.
fn send_actions_to_mux(pane_id: PaneId, dead: &Arc<AtomicBool>, actions: Vec<Action>) {
/// This function applies parsed actions to the pane and notifies any
/// mux subscribers about the output event
fn send_actions_to_mux(pane: &Arc<dyn Pane>, actions: Vec<Action>) {
let start = Instant::now();
promise::spawn::block_on(promise::spawn::spawn_into_main_thread({
let dead = Arc::clone(&dead);
async move {
let mux = Mux::get().unwrap();
if let Some(pane) = mux.get_pane(pane_id) {
let start = Instant::now();
pane.perform_actions(actions);
histogram!(
"send_actions_to_mux.perform_actions.latency",
start.elapsed()
);
mux.notify(MuxNotification::PaneOutput(pane_id));
} else {
// Something else removed the pane from
// the mux, so signal that we should stop
// trying to process it in read_from_pane_pty.
dead.store(true, Ordering::Relaxed);
}
}
}));
histogram!("send_actions_to_mux.latency", start.elapsed());
pane.perform_actions(actions);
histogram!(
"send_actions_to_mux.perform_actions.latency",
start.elapsed()
);
Mux::notify_from_any_thread(MuxNotification::PaneOutput(pane.pane_id()));
histogram!("send_actions_to_mux.rate", 1.);
}
fn parse_buffered_data(pane_id: PaneId, dead: &Arc<AtomicBool>, mut rx: FileDescriptor) {
fn parse_buffered_data(pane: Arc<dyn Pane>, dead: &Arc<AtomicBool>, mut rx: FileDescriptor) {
let mut buf = vec![0; configuration().mux_output_parser_buffer_size];
let mut parser = termwiz::escape::parser::Parser::new();
let mut actions = vec![];
@ -155,7 +138,7 @@ fn parse_buffered_data(pane_id: PaneId, dead: &Arc<AtomicBool>, mut rx: FileDesc
// Flush prior actions
if !actions.is_empty() {
send_actions_to_mux(pane_id, dead, std::mem::take(&mut actions));
send_actions_to_mux(&pane, std::mem::take(&mut actions));
action_size = 0;
}
}
@ -174,7 +157,7 @@ fn parse_buffered_data(pane_id: PaneId, dead: &Arc<AtomicBool>, mut rx: FileDesc
action.append_to(&mut actions);
if flush && !actions.is_empty() {
send_actions_to_mux(pane_id, dead, std::mem::take(&mut actions));
send_actions_to_mux(&pane, std::mem::take(&mut actions));
action_size = 0;
}
});
@ -202,7 +185,7 @@ fn parse_buffered_data(pane_id: PaneId, dead: &Arc<AtomicBool>, mut rx: FileDesc
}
}
send_actions_to_mux(pane_id, dead, std::mem::take(&mut actions));
send_actions_to_mux(&pane, std::mem::take(&mut actions));
action_size = 0;
}
@ -243,13 +226,19 @@ fn allocate_socketpair() -> anyhow::Result<(FileDescriptor, FileDescriptor)> {
/// blocking reads from the pty (non-blocking reads are not portable to
/// all platforms and pty/tty types), parse the escape sequences and
/// relay the actions to the mux thread to apply them to the pane.
fn read_from_pane_pty(pane_id: PaneId, banner: Option<String>, mut reader: Box<dyn std::io::Read>) {
fn read_from_pane_pty(
pane: Arc<dyn Pane>,
banner: Option<String>,
mut reader: Box<dyn std::io::Read>,
) {
let mut buf = vec![0; BUFSIZE];
// This is used to signal that an error occurred either in this thread,
// or in the main mux thread. If `true`, this thread will terminate.
let dead = Arc::new(AtomicBool::new(false));
let pane_id = pane.pane_id();
let (mut tx, rx) = match allocate_socketpair() {
Ok(pair) => pair,
Err(err) => {
@ -267,7 +256,7 @@ fn read_from_pane_pty(pane_id: PaneId, banner: Option<String>, mut reader: Box<d
std::thread::spawn({
let dead = Arc::clone(&dead);
move || parse_buffered_data(pane_id, &dead, rx)
move || parse_buffered_data(pane, &dead, rx)
});
if let Some(banner) = banner {
@ -656,7 +645,8 @@ impl Mux {
let pane_id = pane.pane_id();
if let Some(reader) = pane.reader()? {
let banner = self.banner.borrow().clone();
thread::spawn(move || read_from_pane_pty(pane_id, banner, reader));
let pane = Arc::clone(pane);
thread::spawn(move || read_from_pane_pty(pane, banner, reader));
}
self.recompute_pane_count();
self.notify(MuxNotification::PaneAdded(pane_id));