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LibLine: Avoid excessive write() syscalls when refreshing the display

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Previously, we were generating the display update one character at a
time, and writing them one at a time to stderr, which is not buffered,
doing so caused one syscall per character printed which is s l o w (TM)
This commit makes LibLine write the update contents into a buffer, and
flush it after all the update is generated :^)
This commit is contained in:
Ali Mohammad Pur 2021-07-19 23:12:28 +04:30 • committed by Ali Mohammad Pur
parent 0f6654fef2
commit 3184086679
5 changed files with 126 additions and 110 deletions
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12
Userland/Libraries/LibLine/InternalFunctions.cpp
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@ -342,12 +342,13 @@ void Editor::enter_search()
auto& search_string = search_string_result.value();
// Manually cleanup the search line.
reposition_cursor();
OutputFileStream stderr_stream { stderr };
reposition_cursor(stderr_stream);
auto search_metrics = actual_rendered_string_metrics(search_string);
auto metrics = actual_rendered_string_metrics(search_prompt);
VT::clear_lines(0, metrics.lines_with_addition(search_metrics, m_num_columns) + search_end_row - m_origin_row - 1);
VT::clear_lines(0, metrics.lines_with_addition(search_metrics, m_num_columns) + search_end_row - m_origin_row - 1, stderr_stream);
reposition_cursor();
reposition_cursor(stderr_stream);
m_refresh_needed = true;
m_cached_prompt_valid = false;
@ -432,8 +433,9 @@ void Editor::go_end()
void Editor::clear_screen()
{
fprintf(stderr, "\033[3J\033[H\033[2J"); // Clear screen.
VT::move_absolute(1, 1);
warn("\033[3J\033[H\033[2J");
OutputFileStream stream { stderr };
VT::move_absolute(1, 1, stream);
set_origin(1, 1);
m_refresh_needed = true;
m_cached_prompt_valid = false;