REPL: try to coalesce updates (#39538)

When input is arriving too fast, delay computing and rendering the full
screen until a short delay after typing stops.

Author: vtjnash

stdlib/REPL/src/LineEdit.jl

@@ -102,6 +102,8 @@ mutable struct PromptState <: ModeState
     beeping::Float64
     # this option is to detect when code is pasted in non-"bracketed paste mode" :
     last_newline::Float64 # register when last newline was entered
+    # this option is to speed up output
+    refresh_wait::Union{Timer,Nothing}
 end
 
 options(s::PromptState) =
@@ -371,8 +373,17 @@ function complete_line(s::PromptState, repeats::Int)
     return true
 end
 
+function clear_input_area(terminal::AbstractTerminal, s::PromptState)
+    if s.refresh_wait !== nothing
+        close(s.refresh_wait)
+        s.refresh_wait = nothing
+    end
+    _clear_input_area(terminal, s.ias)
+    s.ias = InputAreaState(0, 0)
+end
 clear_input_area(terminal::AbstractTerminal, s::ModeState) = (_clear_input_area(terminal, s.ias); s.ias = InputAreaState(0, 0))
 clear_input_area(s::ModeState) = clear_input_area(s.terminal, s)
+
 function _clear_input_area(terminal::AbstractTerminal, state::InputAreaState)
     # Go to the last line
     if state.curs_row < state.num_rows
@@ -395,6 +406,13 @@ prompt_string(p::Prompt) = prompt_string(p.prompt)
 prompt_string(s::AbstractString) = s
 prompt_string(f::Function) = Base.invokelatest(f)
 
+function refresh_multi_line(s::PromptState; kw...)
+    if s.refresh_wait !== nothing
+        close(s.refresh_wait)
+        s.refresh_wait = nothing
+    end
+    refresh_multi_line(terminal(s), s; kw...)
+end
 refresh_multi_line(s::ModeState; kw...) = refresh_multi_line(terminal(s), s; kw...)
 refresh_multi_line(termbuf::TerminalBuffer, s::ModeState; kw...) = refresh_multi_line(termbuf, terminal(s), s; kw...)
 refresh_multi_line(termbuf::TerminalBuffer, term, s::ModeState; kw...) = (@assert term === terminal(s); refresh_multi_line(termbuf,s; kw...))
@@ -738,7 +756,7 @@ function edit_insert(s::PromptState, c::StringLike)
     buf = s.input_buffer
 
     if ! options(s).auto_indent_bracketed_paste
-        pos=position(buf)
+        pos = position(buf)
         if pos > 0
             if buf.data[pos] != _space && string(c) != " "
                 options(s).auto_indent_tmp_off = false
@@ -757,20 +775,46 @@ function edit_insert(s::PromptState, c::StringLike)
         end
     end
 
+    old_wait = s.refresh_wait !== nothing
+    if old_wait
+        close(s.refresh_wait)
+        s.refresh_wait = nothing
+    end
     str = string(c)
     edit_insert(buf, str)
-    offset = s.ias.curs_row == 1 || s.indent < 0 ?
-        sizeof(prompt_string(s.p.prompt)::String) : s.indent
-    if !('\n' in str) && eof(buf) &&
-        ((position(buf) - beginofline(buf) + # size of current line
-          offset + sizeof(str) - 1) < width(terminal(s)))
-        # Avoid full update when appending characters to the end
-        # and an update of curs_row isn't necessary (conservatively estimated)
-        write(terminal(s), str)
-    else
+    if '\n' in str
         refresh_line(s)
+    else
+        after = options(s).auto_refresh_time_delay
+        termbuf = terminal(s)
+        w = width(termbuf)
+        delayup = !eof(buf) || old_wait
+        offset = s.ias.curs_row == 1 || s.indent < 0 ?
+            sizeof(prompt_string(s.p.prompt)::String) : s.indent
+        offset += position(buf) - beginofline(buf) # size of current line
+        if offset + textwidth(str) <= w
+            # Avoid full update when appending characters to the end
+            # and an update of curs_row isn't necessary (conservatively estimated)
+            write(termbuf, str)
+        elseif after == 0
+            refresh_line(s)
+            delayup = false
+        else
+            delayup = true
+        end
+        if delayup
+            write(termbuf, spin_seq[mod1(position(buf) - w, length(spin_seq))])
+            cmove_left(termbuf)
+            s.refresh_wait = Timer(after) do t
+                s.refresh_wait === t || return
+                s.refresh_wait = nothing
+                refresh_line(s)
+            end
+        end
     end
+    nothing
 end
+const spin_seq = ("⋯", "⋱", "⋮", "⋰")
 
 function edit_insert(buf::IOBuffer, c::StringLike)
     if eof(buf)
@@ -804,6 +848,7 @@ function edit_insert_newline(s::PromptState, align::Int = 0 - options(s).auto_in
     if ! options(s).auto_indent_bracketed_paste
         s.last_newline = time()
     end
+    nothing
 end
 
 # align: delete up to 4 spaces to align to a multiple of 4 chars
@@ -2420,7 +2465,7 @@ run_interface(::Prompt) = nothing
 
 init_state(terminal, prompt::Prompt) =
     PromptState(terminal, prompt, IOBuffer(), :off, IOBuffer[], 1, InputAreaState(1, 1),
-                #=indent(spaces)=# -1, Threads.SpinLock(), 0.0, -Inf)
+                #=indent(spaces)=# -1, Threads.SpinLock(), 0.0, -Inf, nothing)
 
 function init_state(terminal, m::ModalInterface)
     s = MIState(m, m.modes[1], false, IdDict{Any,Any}())

stdlib/REPL/src/options.jl

@@ -25,6 +25,8 @@ mutable struct Options
     auto_indent_bracketed_paste::Bool # set to true if terminal knows paste mode
     # cancel auto-indent when next character is entered within this time frame :
     auto_indent_time_threshold::Float64
+    # refresh after time delay
+    auto_refresh_time_delay::Float64
     # default IOContext settings at the REPL
     iocontext::Dict{Symbol,Any}
 end
@@ -44,14 +46,15 @@ Options(;
         auto_indent_tmp_off = false,
         auto_indent_bracketed_paste = false,
         auto_indent_time_threshold = 0.005,
+        auto_refresh_time_delay = 0.05,
         iocontext = Dict{Symbol,Any}()) =
             Options(hascolor, extra_keymap, tabwidth,
                     kill_ring_max, region_animation_duration,
                     beep_duration, beep_blink, beep_maxduration,
                     beep_colors, beep_use_current,
                     backspace_align, backspace_adjust, confirm_exit,
                     auto_indent, auto_indent_tmp_off, auto_indent_bracketed_paste,
-                    auto_indent_time_threshold,
+                    auto_indent_time_threshold, auto_refresh_time_delay,
                     iocontext)
 
 # for use by REPLs not having an options field