From 06eaf109f0b59a4faa0a911d6daacf3b416f584c Mon Sep 17 00:00:00 2001
From: David Phillips <david@yeah.nah.nz>
Date: Sat, 13 Mar 2021 21:09:55 +1300
Subject: ui_remote: make event sending async

This makes the UI a bit snappier, as we no longer have to interrupt for each
event, just on groups of them.
---
 ui_remote.py | 80 +++++++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 52 insertions(+), 28 deletions(-)

diff --git a/ui_remote.py b/ui_remote.py
index c4f5c99..a13a5e0 100755
--- a/ui_remote.py
+++ b/ui_remote.py
@@ -7,35 +7,51 @@
 # never be allowed to happen in normal use.
 # Useful nonetheless.
 #
-# FIXME allow smarter queueing of UI events in this script so they can be
-#       batched into the same (slow) interrupt-and-continue window.
-#
 
 import atexit
 import curses
 import pygdbmi.gdbcontroller
+import queue
+import threading
 import sys
 
 
-def interrupt_run_continue(mi, command):
-    mi.write('interrupt')
-    mi.write(command)
-    mi.write('continue &')
+def command_consumer(quit_event, command_queue, gdbmi):
+    while not quit_event.is_set():
+        # block until a command is ready to send
+        # non-blocking read so we can respond to quit_event as needed
+        command = None
+        try:
+            command = command_queue.get(block=True, timeout=0.1)
+        except queue.Empty:
+            continue
 
+        # stop the remote program while run the command and run any other
+        # commands in the queue since `interrupt` is expensive
+        gdbmi.write('interrupt')
+        gdbmi.write(command)
+        try:
+            while command := command_queue.get(block=False):
+                gdbmi.write(command)
+        except queue.Empty:
+            gdbmi.write('continue &')
+
+
+def curses_init():
+    stdscr = curses.initscr()
+    curses.cbreak()
+    curses.noecho()
+    return stdscr
 
-def main():
-    def curses_init():
-        stdscr = curses.initscr()
-        curses.cbreak()
-        curses.noecho()
-        return stdscr
-
-    def curses_end():
-        curses.nocbreak()
-        stdscr.keypad(False)
-        curses.echo()
-        curses.endwin()
 
+def curses_end(stdscr):
+    curses.nocbreak()
+    stdscr.keypad(False)
+    curses.echo()
+    curses.endwin()
+
+
+def main():
     # Give pygdbmi hardcoded GDB, ELF paths, remote. Good enough for now
     mi = pygdbmi.gdbcontroller.GdbController(
         command=["/usr/bin/avr-gdb", '--interpreter=mi3'])
@@ -44,31 +60,39 @@ def main():
     mi.write('continue &')
 
     # atexit covers crash cases which is nice
-    atexit.register(curses_end)
     stdscr = curses_init()
+    atexit.register(lambda: curses_end(stdscr))
+
+    # queue and thread so we can push UI events to the remote asynchronously
+    quit_event = threading.Event()
+    command_queue = queue.Queue(maxsize=1024)
+    gdb_handler_thread = threading.Thread(
+        target=command_consumer,
+        args=(quit_event, command_queue, mi))
+    gdb_handler_thread.start()
 
     stdscr.addstr(0, 0, "UI remote control via GDB. Press q to quit")
     stdscr.addstr(1, 0, "w: up  s: down  a: hold  d: short press")
+    global running
     running = True
     while running:
-        stdscr.addstr(2, 0, "ready")
         stdscr.clrtoeol()
         key = stdscr.getch()
-        stdscr.addstr(2, 0, "busy")
         stdscr.clrtoeol()
         stdscr.refresh()
         if key == ord('q'):
             running = False
+            quit_event.set()
         elif key == ord('w'):
-            interrupt_run_continue(mi, 'call up()')
+            command_queue.put('call up()')
         elif key == ord('s'):
-            interrupt_run_continue(mi, 'call down()')
+            command_queue.put('call down()')
         elif key == ord('a'):
-            interrupt_run_continue(mi, 'call hold()')
+            command_queue.put('call hold()')
         elif key == ord('d'):
-            interrupt_run_continue(mi, 'call press()')
-        else:
-            stdscr.addstr(1, 0, str(key))
+            command_queue.put('call press()')
+
+    gdb_handler_thread.join()
 
 
 if __name__ == "__main__":
-- 
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