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render: delay reflow for ‘resize-delay-ms’ milliseconds

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Reflowing a large scrollback is *slow*. During an interactive resize,
it can easily take long enough that the compositor fills the Wayland
socket with configure events. Eventually, the socket becomes full and
the compositor terminates the connection, causing foot to exit.

This patch is work-in-progress, and the first step towards alleviating
this.

It delays the reflow by:

* Snapshotting (copying) the original grid when an interactive resize
  is started.
* While resizing, we apply a simple truncation resize of the
  grid (like we handle the alt screen).
* When the resize is done, or paused for ‘resize-delay-ms’, the grid
  is reflowed.

TODO: we *must* not allow any changes to the temporary (truncated)
grid during the resize. Any changes to the grid would be lost when the
final reflow is applied. That is, we must completely pause the ptmx
pipe while a resize is in progress.

Future improvements:

The initial copy can be slow. We should be able to avoid it by
rewriting the reflow algorithm to not free anything. This is
complicated by the fact that some resources (e.g. sixel images) are
currently *moved* to the new grid. They’d instead have to be copied.
This commit is contained in:
Daniel Eklöf 2022-10-05 17:05:44 +02:00
parent a9fc7ce180
commit 8179d73daa
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GPG key ID: 5BBD4992C116573F
4 changed files with 123 additions and 20 deletions
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118
render.c
View file

@ -3663,13 +3663,54 @@ tiocswinsz(struct terminal *term)
}
}
static void
delayed_reflow_of_normal_grid(struct terminal *term)
{
if (term->render.resizing.grid == NULL)
return;
struct coord *const tracking_points[] = {
&term->selection.coords.start,
&term->selection.coords.end,
};
/* Reflow the original (since before the resize was started) grid,
* to the *current* dimensions */
grid_resize_and_reflow(
term->render.resizing.grid,
term->grid->num_rows, term->grid->num_cols,
term->render.resizing.screen_rows, term->rows,
term->selection.coords.end.row >= 0 ? ALEN(tracking_points) : 0,
tracking_points);
/* Replace the current, truncated, “normal” grid with the
* correctly reflowed one */
grid_free(&term->normal);
term->normal = *term->render.resizing.grid;
free(term->render.resizing.grid);
/* Reset */
term->render.resizing.grid = NULL;
term->render.resizing.screen_rows = 0;
/* Invalidate render pointers */
shm_unref(term->render.last_buf);
term->render.last_buf = NULL;
term->render.last_cursor.row = NULL;
if (term->grid == &term->normal)
term_damage_view(term);
}
static bool
fdm_tiocswinsz(struct fdm *fdm, int fd, int events, void *data)
{
struct terminal *term = data;
if (events & EPOLLIN)
if (events & EPOLLIN) {
tiocswinsz(term);
delayed_reflow_of_normal_grid(term);
}
if (term->window->resize_timeout_fd >= 0) {
fdm_del(fdm, term->window->resize_timeout_fd);
@ -3686,6 +3727,7 @@ send_dimensions_to_client(struct terminal *term)
if (!win->is_resizing || term->conf->resize_delay_ms == 0) {
/* Send new dimensions to client immediately */
tiocswinsz(term);
delayed_reflow_of_normal_grid(term);
/* And make sure to reset and deallocate a lingering timer */
if (win->resize_timeout_fd >= 0) {
@ -3846,9 +3888,30 @@ maybe_resize(struct terminal *term, int width, int height, bool force)
const uint32_t scrollback_lines = term->render.scrollback_lines;
/*
* Snapshot the “normal” grid.
*
* Since text reflow is slow, don’t do it *while* resizing. Only
* do it when done, or after “pausing” the resize for sufficiently
* long. We re-use the TIOCSWINSZ timer to handle this. See
* send_dimensions_to_client() and fdm_tiocswinsz().
*
* To be able to do the final reflow correctly, we need a copy of
* the original grid, before the resize started.
*/
if (term->window->is_resizing && term->render.resizing.grid == NULL) {
/*
* TODO: snapshotting a large grid is slow. To improve, move
* normal -> resizing.grid, and instantiate a small (screen
* sized) new “normal”
*/
term->render.resizing.grid = grid_snapshot(&term->normal);
term->render.resizing.screen_rows = term->rows;
}
/* Screen rows/cols before resize */
const int old_cols = term->cols;
const int old_rows = term->rows;
int old_cols = term->cols;
int old_rows = term->rows;
/* Screen rows/cols after resize */
const int new_cols = (term->width - 2 * pad_x) / term->cell_width;
@ -3882,7 +3945,9 @@ maybe_resize(struct terminal *term, int width, int height, bool force)
xassert(term->margins.top >= pad_y);
xassert(term->margins.bottom >= pad_y);
if (new_cols == old_cols && new_rows == old_rows) {
if (new_cols == old_cols && new_rows == old_rows &&
(term->render.resizing.grid == NULL || term->window->is_resizing))
{
LOG_DBG("grid layout unaffected; skipping reflow");
goto damage_view;
}
@ -3906,16 +3971,43 @@ maybe_resize(struct terminal *term, int width, int height, bool force)
* selection’s pivot point coordinates *must* be added to the
* tracking points list.
*/
struct coord *const tracking_points[] = {
&term->selection.coords.start,
&term->selection.coords.end,
};
/* Resize grids */
grid_resize_and_reflow(
&term->normal, new_normal_grid_rows, new_cols, old_rows, new_rows,
term->selection.coords.end.row >= 0 ? ALEN(tracking_points) : 0,
tracking_points);
if (term->window->is_resizing) {
/* Simple truncating resize, *while* an interactive resize is
* ongoing. */
xassert(term->render.resizing.grid != NULL);
grid_resize_without_reflow(
&term->normal,
new_normal_grid_rows, new_cols,
old_rows,
new_rows);
} else {
/* Full text reflow */
if (term->render.resizing.grid != NULL) {
/* Throw away the current, truncated, “normal” grid, and
* use the original grid instead (from before the resize
* started) */
grid_free(&term->normal);
term->normal = *term->render.resizing.grid;
free(term->render.resizing.grid);
old_rows = term->render.resizing.screen_rows;
term->render.resizing.grid = NULL;
term->render.resizing.screen_rows = 0;
}
struct coord *const tracking_points[] = {
&term->selection.coords.start,
&term->selection.coords.end,
};
grid_resize_and_reflow(
&term->normal, new_normal_grid_rows, new_cols, old_rows, new_rows,
term->selection.coords.end.row >= 0 ? ALEN(tracking_points) : 0,
tracking_points);
}
grid_resize_without_reflow(
&term->alt, new_alt_grid_rows, new_cols, old_rows, new_rows);