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-rw-r--r--src/tty/tty.zig280
1 files changed, 190 insertions, 90 deletions
diff --git a/src/tty/tty.zig b/src/tty/tty.zig
index efccd98e..f5ae078a 100644
--- a/src/tty/tty.zig
+++ b/src/tty/tty.zig
@@ -132,7 +132,14 @@ fn readInput(loop: *Loop, tty: anytype, cache: *vaxis.GraphemeCache) !void {
if (carried == buf.len) return error.InputSequenceTooLong;
const received = try tty.read(buf[carried..]);
if (received == 0) return;
- const end = carried + received;
+ // The terminal's answers to frames (FrameAck) come out first,
+ // wherever they sit: never events, and never glued to a key (an
+ // Escape pressed just before one would read as Alt on it).
+ const end = FrameAck.take(buf[0 .. carried + received], loop);
+ if (end == 0) {
+ carried = 0;
+ continue;
+ }
if (kitty_shm_probing.load(.acquire)) if (std.mem.indexOf(u8, buf[0..end], std.fmt.comptimePrint("\x1b_Gi={d};", .{kitty_shm_probe_id}))) |at| {
kitty_shm_probing.store(false, .release);
kitty_shm.store(std.mem.startsWith(u8, buf[at..end], std.fmt.comptimePrint("\x1b_Gi={d};OK", .{kitty_shm_probe_id})), .release);
@@ -153,7 +160,8 @@ fn readInput(loop: *Loop, tty: anytype, cache: *vaxis.GraphemeCache) !void {
// its writes whole, so no sequence arrives cut right after its ESC.
// Waiting on it cost every Escape press 50 ms on a legacy terminal
// (tmux, most ssh sessions), and 1 s before kitty's flags were on.
- var waited = carried == 0 and received == 1;
+ // (A terminal's answer to a frame is one write too: FrameAck.)
+ var waited = carried == 0 and end == 1;
while (consumed < parse_end) {
// A lone ESC that ends a longer read is the Escape key, or the
// first byte of a sequence whose rest the read boundary held
@@ -162,6 +170,9 @@ fn readInput(loop: *Loop, tty: anytype, cache: *vaxis.GraphemeCache) !void {
// kitty keyboard protocol Escape is `CSI 27 u`, so there the ESC
// can only start a sequence and the wait can be long.
const rest = buf[consumed..parse_end];
+ // A frame's answer cut short by the read waits for its rest.
+ if (parse_end == end and rest.len > 1 and rest.len < FrameAck.answer.len and
+ std.mem.startsWith(u8, FrameAck.answer, rest)) break;
if (!waited and parse_end == end and rest[0] == 0x1b and (rest.len == 1 or (rest.len == 2 and rest[1] == 0x1b))) {
waited = true;
if (try inputFollows(tty, loop.io, if (loop.vaxis.caps.kitty_keyboard) 1000 else 50)) break;
@@ -191,6 +202,63 @@ fn readInput(loop: *Loop, tty: anytype, cache: *vaxis.GraphemeCache) !void {
}
}
+/// One frame in flight at most. Each frame the tty draws ends with a device
+/// status request (`CSI 5 n`), and no other frame is drawn until the
+/// terminal's `CSI 0 n` comes back: over ssh the frames a burst of scrolling
+/// or typing would queue behind each other (sshd's window holds megabytes)
+/// are never drawn, and the burst ends one frame and one round trip after
+/// its last input. On a local terminal the answer is back in well under a
+/// millisecond. A terminal that never answers turns this off for good after
+/// `timeout_ns`.
+const FrameAck = struct {
+ const request = "\x1b[5n";
+ const answer = "\x1b[0n";
+ const timeout_ns: u64 = std.time.ns_per_s;
+ var waiting = std.atomic.Value(bool).init(false);
+ var off = std.atomic.Value(bool).init(false);
+ /// When the request went out (the loop's thread only).
+ var sent_ns: u64 = 0;
+
+ /// Take every answer out of `bytes`, closing up the rest; the new
+ /// length. The loop is woken for the frame that waited on one.
+ fn take(bytes: []u8, loop: *Loop) usize {
+ var len = bytes.len;
+ var found = false;
+ while (std.mem.indexOf(u8, bytes[0..len], answer)) |at| {
+ std.mem.copyForwards(u8, bytes[at..], bytes[at + answer.len .. len]);
+ len -= answer.len;
+ found = true;
+ }
+ if (found and waiting.swap(false, .acq_rel)) loop.postEvent(.nop) catch {};
+ return len;
+ }
+
+ /// Whether a new frame must wait (and the loop has a wake at the
+ /// timeout); past the timeout the terminal is taken to never answer.
+ fn holds(now_ns: u64, io: std.Io) bool {
+ if (off.load(.acquire) or !waiting.load(.acquire)) return false;
+ const waited_ns = now_ns -| sent_ns;
+ if (waited_ns >= timeout_ns) {
+ off.store(true, .release);
+ waiting.store(false, .release);
+ return false;
+ }
+ requestWake(io, @intCast((timeout_ns - waited_ns + std.time.ns_per_ms - 1) / std.time.ns_per_ms));
+ return true;
+ }
+
+ /// After a frame that wrote something: ask for the answer.
+ fn ask(w: *std.Io.Writer, now_ns: u64) void {
+ if (off.load(.acquire)) return;
+ // Waiting before the request goes: a local terminal can answer
+ // before the write returns, and an answer nobody waited for is lost.
+ sent_ns = now_ns;
+ waiting.store(true, .release);
+ w.writeAll(request) catch return waiting.store(false, .release);
+ w.flush() catch return waiting.store(false, .release);
+ }
+};
+
/// Whether more input is readable within `ms`, polled in short slices so
/// that a cancel of the input thread is still seen. A test reader answers
/// for itself.
@@ -521,6 +589,98 @@ test "an ESC read by itself is the Escape key at once" {
vx.caps.kitty_keyboard = false;
}
+test "a frame's answer is taken wherever the reads cut it, and never typed" {
+ if (comptime builtin.os.tag == .windows) return error.SkipZigTest;
+ const gpa = std.testing.allocator;
+ const io = std.testing.io;
+ var env = try std.testing.environ.createMap(gpa);
+ defer env.deinit();
+ var vx = try vaxis.init(io, gpa, &env, .{});
+ var output: std.Io.Writer.Allocating = .init(gpa);
+ defer output.deinit();
+ defer vx.deinit(gpa, &output.writer);
+ var tty: vaxis.Tty = undefined;
+ var loop: Loop = .init(io, &tty, &vx);
+ var cache: vaxis.GraphemeCache = .{};
+ const Reader = struct {
+ parts: [2][]const u8,
+ next: usize = 0,
+ fn getWinsize(_: *@This()) !vaxis.Winsize {
+ return .{ .rows = 24, .cols = 80, .x_pixel = 0, .y_pixel = 0 };
+ }
+ fn inputFollows(self: *@This(), _: u32) bool {
+ return self.next < self.parts.len;
+ }
+ fn read(self: *@This(), buf: []u8) !usize {
+ while (self.next < self.parts.len) {
+ const part = self.parts[self.next];
+ self.next += 1;
+ if (part.len == 0) continue;
+ @memcpy(buf[0..part.len], part);
+ return part.len;
+ }
+ return 0;
+ }
+ };
+ const all = "x" ++ FrameAck.answer ++ "y";
+ defer FrameAck.waiting.store(false, .release);
+ for (0..all.len) |cut| {
+ FrameAck.waiting.store(true, .release);
+ var reader: Reader = .{ .parts = .{ all[0..cut], all[cut..] } };
+ try readInput(&loop, &reader, &cache);
+ try std.testing.expect(!FrameAck.waiting.load(.acquire));
+ var typed: std.ArrayList(u8) = .empty;
+ defer typed.deinit(gpa);
+ var woke = false;
+ while (try loop.tryEvent()) |event| switch (event) {
+ .winsize => {},
+ .nop => woke = true,
+ .key_press => |key| try typed.appendSlice(gpa, key.text orelse return error.UnexpectedInputKey),
+ else => return error.UnexpectedInputEvent,
+ };
+ std.testing.expectEqualStrings("xy", typed.items) catch |err| {
+ std.debug.print("cut at {d}\n", .{cut});
+ return err;
+ };
+ try std.testing.expect(woke);
+ }
+ // An Escape pressed just before an answer, in the same read, is the
+ // Escape key, not Alt on the answer.
+ FrameAck.waiting.store(true, .release);
+ var glued: Reader = .{ .parts = .{ "\x1b" ++ FrameAck.answer, "j" } };
+ try readInput(&loop, &glued, &cache);
+ try std.testing.expectEqual(.winsize, std.meta.activeTag((try loop.tryEvent()).?));
+ try std.testing.expectEqual(.nop, std.meta.activeTag((try loop.tryEvent()).?));
+ const escape = (try loop.tryEvent()).?.key_press;
+ try std.testing.expectEqual(vaxis.Key.escape, escape.codepoint);
+ try std.testing.expect(!escape.mods.alt);
+ try std.testing.expectEqual(@as(u21, 'j'), (try loop.tryEvent()).?.key_press.codepoint);
+ try std.testing.expect(try loop.tryEvent() == null);
+}
+
+test "a terminal that never answers a frame stops being asked after one timeout" {
+ const io = std.testing.io;
+ defer {
+ FrameAck.off.store(false, .release);
+ FrameAck.waiting.store(false, .release);
+ FrameAck.sent_ns = 0;
+ }
+ var out: std.Io.Writer.Allocating = .init(std.testing.allocator);
+ defer out.deinit();
+ const t0: u64 = 5 * std.time.ns_per_s;
+ FrameAck.ask(&out.writer, t0);
+ try std.testing.expectEqualStrings(FrameAck.request, out.written());
+ // Unanswered: the next frame waits, until the timeout.
+ try std.testing.expect(FrameAck.holds(t0 + 10 * std.time.ns_per_ms, io));
+ try std.testing.expect(FrameAck.holds(t0 + 999 * std.time.ns_per_ms, io));
+ try std.testing.expect(!FrameAck.holds(t0 + FrameAck.timeout_ns, io));
+ // Then never again: no request, no wait.
+ out.clearRetainingCapacity();
+ FrameAck.ask(&out.writer, t0 + 2 * std.time.ns_per_s);
+ try std.testing.expectEqual(@as(usize, 0), out.written().len);
+ try std.testing.expect(!FrameAck.holds(t0 + 2 * std.time.ns_per_s, io));
+}
+
test "terminal input cancellation joins blocked reads and queued EOF" {
if (comptime builtin.os.tag == .windows) return error.SkipZigTest;
const gpa = std.testing.allocator;
@@ -1438,6 +1598,12 @@ const Shell = struct {
const s = of(ctx);
const vx = s.vx;
s.tracks = canonical.panelTracks();
+ // The last frame is not answered yet: this one stays owed, and the
+ // answer's wake draws the state as it is then.
+ if (FrameAck.holds(host_io.monotonicNs(), s.io)) {
+ s.core.present_skipped = true;
+ return;
+ }
_ = s.frame.reset(.retain_capacity);
const surface = panel_compositor.compose(
s.frame.allocator(),
@@ -1453,7 +1619,7 @@ const Shell = struct {
const shadowed = chipShadows(s.frame.allocator(), surface, s.core, truecolor) catch surface;
const flashed = s.flash.apply(s.frame.allocator(), shadowed, s.core, truecolor) catch shadowed;
const trailed = s.trail.apply(s.frame.allocator(), flashed, s.core, truecolor) catch flashed;
- paintCells(vx, win, trailed.cells, trailed.cols, trailed.rows);
+ paintCells(win, trailed.cells, trailed.cols, trailed.rows);
tz_cells.end();
for (surface.images[0..surface.nimages]) |maybe| {
const place = maybe orelse continue;
@@ -1523,7 +1689,9 @@ const Shell = struct {
}
if (surface.cursor) |cur| paintCursor(win, cur.x, cur.y, cur.bar);
const tz_render = tracy.zone(@src(), "vx.render");
+ const before = s.tty.tty_writer.pos + s.tty.writer().end;
vx.render(s.tty.writer()) catch {};
+ if (s.tty.tty_writer.pos + s.tty.writer().end != before) FrameAck.ask(s.tty.writer(), host_io.monotonicNs());
tz_render.end();
}
@@ -2170,94 +2338,26 @@ fn mouseEvent(m: vaxis.Mouse) ?pardes.Event {
} };
}
-fn paintCells(vx: *const vaxis.Vaxis, win: vaxis.Window, cells: []const pardes.Cell, cols: u16, rows: u16) void {
+/// A blank whose ink alone changed is not sent: vaxis's render skips it
+/// (pardes's patch to Vaxis.zig in build.zig), since a blank's ink shows
+/// nowhere. Deciding that here cost every cell of every frame a look at the
+/// frame before; vaxis already makes that comparison.
+fn paintCells(win: vaxis.Window, cells: []const pardes.Cell, cols: u16, rows: u16) void {
win.clear();
var y: u16 = 0;
while (y < rows) : (y += 1) {
- const row = cells[@as(usize, y) * cols ..][0..cols];
var x: u16 = 0;
- // The cell to the left as written, for a blank that needs it.
- var left: ?Written = null;
while (x < cols) : (x += 1) {
- const cell = &row[x];
- if (cell.default) {
- left = null;
- continue;
- }
- const grapheme = cell.grapheme();
- var style = vaxisStyle(cell.style);
- if (inkless(grapheme, style)) blankInk(vx, row, x, y, &style, left);
- left = .{ .grapheme = grapheme, .style = style };
- win.writeCell(x, y, .{ .char = .{ .grapheme = grapheme }, .style = style });
+ const cell = &cells[@as(usize, y) * cols + x];
+ if (cell.default) continue;
+ win.writeCell(x, y, .{
+ .char = .{ .grapheme = cell.grapheme() },
+ .style = vaxisStyle(cell.style),
+ });
}
}
}
-const Written = struct { grapheme: []const u8, style: vaxis.Style };
-
-/// A blank's ink shows nowhere (no underline, strike or reverse to show it).
-fn inkless(grapheme: []const u8, style: vaxis.Style) bool {
- return std.mem.eql(u8, grapheme, " ") and !style.reverse and !style.strikethrough and style.ul_style == .off;
-}
-
-/// A blank whose ink alone changed (a fade: InactiveDim on a focus change)
-/// keeps the ink the terminal has there and so is not sent at all:
-/// otherwise every blank of every pane a fade touched went, 7 KB a click
-/// for three shells. Only a short gap between two cells that are sent
-/// anyway is cheaper sent than jumped (a cursor move): it takes the ink of
-/// the cell before it, so the run needs no colour change either.
-fn blankInk(vx: *const vaxis.Vaxis, row: []const pardes.Cell, x: u16, y: u16, style: *vaxis.Style, left: ?Written) void {
- const last = lastCell(vx, x, y) orelse return;
- if (vx.refresh or last.default or last.skipped or !std.mem.eql(u8, last.char.items, " ")) return;
- if (sameColor(last.style.fg, style.fg) or !sameButInk(last.style, style.*)) return;
- var kept = style.*;
- kept.fg = last.style.fg;
- if (left) |l| if (sends(vx, x - 1, y, l.grapheme, l.style)) {
- var end = x + 1;
- while (end < row.len and end - x < 8) : (end += 1) {
- const next = &row[end];
- if (next.default) break;
- const next_style = vaxisStyle(next.style);
- if (inkless(next.grapheme(), next_style)) continue;
- if (sends(vx, end, y, next.grapheme(), next_style)) {
- style.fg = l.style.fg;
- return;
- }
- break;
- }
- };
- style.* = kept;
-}
-
-/// `Style.eql` but for the ink, and cheap: this runs for every blank of
-/// every frame.
-fn sameButInk(a: vaxis.Style, b: vaxis.Style) bool {
- return sameColor(a.bg, b.bg) and sameColor(a.ul, b.ul) and a.ul_style == b.ul_style and
- a.bold == b.bold and a.dim == b.dim and a.italic == b.italic and a.blink == b.blink and
- a.reverse == b.reverse and a.invisible == b.invisible and a.strikethrough == b.strikethrough;
-}
-
-fn sameColor(a: vaxis.Color, b: vaxis.Color) bool {
- return switch (a) {
- .default => b == .default,
- .index => |i| b == .index and b.index == i,
- .rgb => |rgb| b == .rgb and std.mem.eql(u8, &rgb, &b.rgb),
- };
-}
-
-/// Whether vaxis sends this cell: it differs from what the terminal shows.
-fn sends(vx: *const vaxis.Vaxis, x: u16, y: u16, grapheme: []const u8, style: vaxis.Style) bool {
- const last = lastCell(vx, x, y) orelse return true;
- return vx.refresh or last.default or last.skipped or !std.mem.eql(u8, last.char.items, grapheme) or
- !sameColor(last.style.fg, style.fg) or !sameButInk(last.style, style);
-}
-
-fn lastCell(vx: *const vaxis.Vaxis, x: u16, y: u16) ?*const vaxis.AllocatingScreen.InternalCell {
- if (x >= vx.screen.width) return null;
- const i = @as(usize, y) * vx.screen.width + x;
- return if (i < vx.screen_last.buf.len) &vx.screen_last.buf[i] else null;
-}
-
test "a fade sends the text it dims, not the blanks beside it" {
const gpa = std.testing.allocator;
var env = try std.testing.environ.createMap(gpa);
@@ -2267,8 +2367,8 @@ test "a fade sends the text it dims, not the blanks beside it" {
defer out.deinit();
defer vx.deinit(gpa, &out.writer);
try vx.resize(gpa, &out.writer, .{ .rows = 1, .cols = 32, .x_pixel = 0, .y_pixel = 0 });
- // `a`, a long gap, `b`, a two-cell gap, `c`, a long gap, an underlined
- // blank (which shows its ink) and one more blank.
+ // `a`, a gap, `b`, a two-cell gap, `c`, a gap, an underlined blank
+ // (which shows its ink) and one more blank.
var cells: [32]pardes.Cell = @splat(.{ .default = false });
cells[0].text[0] = 'a';
cells[12].text[0] = 'b';
@@ -2279,16 +2379,16 @@ test "a fade sends the text it dims, not the blanks beside it" {
for ([_][3]u8{ .{ 200, 200, 200 }, .{ 90, 90, 90 } }, 0..) |ink, frame| {
for (&cells) |*cell| cell.style.fg = .{ .rgb = ink };
out.clearRetainingCapacity();
- paintCells(&vx, vx.window(), &cells, 32, 1);
+ paintCells(vx.window(), &cells, 32, 1);
try vx.render(&out.writer);
sent[frame] = try out.toOwnedSlice();
}
// Against a cleared screen every cell goes. After the fade the letters
- // go, the short gap between two of them (cheaper than a cursor move),
- // and the underlined blank; the long gaps are jumped.
+ // go and the underlined blank; every plain blank is jumped.
try std.testing.expectEqual(@as(usize, 29), std.mem.count(u8, sent[0], " "));
- try std.testing.expectEqual(@as(usize, 3), std.mem.count(u8, sent[1], " "));
- try std.testing.expect(std.mem.indexOf(u8, sent[1], "b c") != null);
+ try std.testing.expectEqual(@as(usize, 1), std.mem.count(u8, sent[1], " "));
+ try std.testing.expect(std.mem.indexOfScalar(u8, sent[1], 'b') != null);
+ try std.testing.expect(std.mem.indexOfScalar(u8, sent[1], 'c') != null);
try std.testing.expect(std.mem.indexOf(u8, sent[1], "90:90:90") != null);
try std.testing.expect(std.mem.indexOfScalar(u8, sent[1], 'a') != null);
}
@@ -2688,7 +2788,7 @@ const Attach = struct {
fn paint(a: *Attach) void {
a.dirty = false;
const win = a.vx.window();
- paintCells(a.vx, win, a.client.grid.items, a.client.cols, a.client.rows);
+ paintCells(win, a.client.grid.items, a.client.cols, a.client.rows);
if (a.client.cursor) |cur| paintCursor(win, cur.x, cur.y, cur.bar);
a.vx.render(a.tty.writer()) catch {};
}
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