use std::mem::swap; use std::ops::Range; use std::sync::Arc; use helix_core::{Rope, RopeSlice}; use imara_diff::intern::InternedInput; use parking_lot::Mutex; use tokio::sync::mpsc::UnboundedReceiver; use tokio::sync::Notify; use tokio::time::{timeout, timeout_at, Duration}; use crate::diff::{ DiffInner, Event, RenderLock, ALGORITHM, DIFF_DEBOUNCE_TIME_ASYNC, DIFF_DEBOUNCE_TIME_SYNC, }; use super::line_cache::InternedRopeLines; use super::Hunk; #[cfg(test)] mod test; pub(super) struct DiffWorker { pub channel: UnboundedReceiver, pub diff: Arc>, pub new_hunks: Vec, pub redraw_notify: Arc, pub diff_finished_notify: Arc, } impl DiffWorker { async fn accumulate_events(&mut self, event: Event) -> (Option, Option) { let mut accumulator = EventAccumulator::new(); accumulator.handle_event(event).await; accumulator .accumulate_debounced_events( &mut self.channel, self.redraw_notify.clone(), self.diff_finished_notify.clone(), ) .await; (accumulator.doc, accumulator.diff_base) } pub async fn run(mut self, diff_base: Rope, doc: Rope) { let mut interner = InternedRopeLines::new(diff_base, doc); if let Some(lines) = interner.interned_lines() { self.perform_diff(lines); } self.apply_hunks(interner.diff_base(), interner.doc()); while let Some(event) = self.channel.recv().await { let (doc, diff_base) = self.accumulate_events(event).await; let process_accumulated_events = || { if let Some(new_base) = diff_base { interner.update_diff_base(new_base, doc) } else { interner.update_doc(doc.unwrap()) } if let Some(lines) = interner.interned_lines() { self.perform_diff(lines) } }; // Calculating diffs is computationally expensive and should // not run inside an async function to avoid blocking other futures. // Note: tokio::task::block_in_place does not work during tests #[cfg(test)] process_accumulated_events(); #[cfg(not(test))] tokio::task::block_in_place(process_accumulated_events); self.apply_hunks(interner.diff_base(), interner.doc()); } } /// update the hunks (used by the gutter) by replacing it with `self.new_hunks`. /// `self.new_hunks` is always empty after this function runs. /// To improve performance this function tries to reuse the allocation of the old diff previously stored in `self.line_diffs` fn apply_hunks(&mut self, diff_base: Rope, doc: Rope) { let mut diff = self.diff.lock(); diff.diff_base = diff_base; diff.doc = doc; swap(&mut diff.hunks, &mut self.new_hunks); self.diff_finished_notify.notify_waiters(); self.new_hunks.clear(); } fn perform_diff(&mut self, input: &InternedInput) { imara_diff::diff(ALGORITHM, input, |before: Range, after: Range| { self.new_hunks.push(Hunk { before, after }) }) } } struct EventAccumulator { diff_base: Option, doc: Option, render_lock: Option, } impl<'a> EventAccumulator { fn new() -> EventAccumulator { EventAccumulator { diff_base: None, doc: None, render_lock: None, } } async fn handle_event(&mut self, event: Event) { let dst = if event.is_base { &mut self.diff_base } else { &mut self.doc }; *dst = Some(event.text); // always prefer the most synchronous requested render mode if let Some(render_lock) = event.render_lock { match &mut self.render_lock { Some(RenderLock { timeout, .. }) => { // A timeout of `None` means that the render should // always wait for the diff to complete (so no timeout) // remove the existing timeout, otherwise keep the previous timeout // because it will be shorter then the current timeout if render_lock.timeout.is_none() { timeout.take(); } } None => self.render_lock = Some(render_lock), } } } async fn accumulate_debounced_events( &mut self, channel: &mut UnboundedReceiver, redraw_notify: Arc, diff_finished_notify: Arc, ) { let async_debounce = Duration::from_millis(DIFF_DEBOUNCE_TIME_ASYNC); let sync_debounce = Duration::from_millis(DIFF_DEBOUNCE_TIME_SYNC); loop { // if we are not blocking rendering use a much longer timeout let debounce = if self.render_lock.is_none() { async_debounce } else { sync_debounce }; if let Ok(Some(event)) = timeout(debounce, channel.recv()).await { self.handle_event(event).await; } else { break; } } // setup task to trigger the rendering match self.render_lock.take() { // diff is performed outside of the rendering loop // request a redraw after the diff is done None => { tokio::spawn(async move { diff_finished_notify.notified().await; redraw_notify.notify_one(); }); } // diff is performed inside the rendering loop // block redraw until the diff is done or the timeout is expired Some(RenderLock { lock, timeout: Some(timeout), }) => { tokio::spawn(async move { let res = { // Acquire a lock on the redraw handle. // The lock will block the rendering from occurring while held. // The rendering waits for the diff if it doesn't time out timeout_at(timeout, diff_finished_notify.notified()).await }; // we either reached the timeout or the diff is finished, release the render lock drop(lock); if res.is_ok() { // Diff finished in time we are done. return; } // Diff failed to complete in time log the event // and wait until the diff occurs to trigger an async redraw log::info!("Diff computation timed out, update of diffs might appear delayed"); diff_finished_notify.notified().await; redraw_notify.notify_one(); }); } // a blocking diff is performed inside the rendering loop // block redraw until the diff is done Some(RenderLock { lock, timeout: None, }) => { tokio::spawn(async move { diff_finished_notify.notified().await; // diff is done release the lock drop(lock) }); } }; } }