From 598226a5c0c1f857280047e5d77b846c2afddf5d Mon Sep 17 00:00:00 2001
From: Damien Elmes <gpg@ankiweb.net>
Date: Fri, 21 Feb 2020 15:14:09 +1000
Subject: [PATCH] possible fix for race conditions in the sound code

https://anki.tenderapp.com/discussions/ankidesktop/39030-erro-ao-adicionar-arquivo-de-udio

the lock should at least ensure _process doesn't disappear in the
middle of our logic, and the longer wait should reduce the chances
of .stop() timing out and allowing multiple audio files to play

Not very happy with the current approach, as in the timeout case
you have multiple threads competing to access the same data
---
 qt/aqt/sound.py | 30 +++++++++++++++++++++---------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/qt/aqt/sound.py b/qt/aqt/sound.py
index 3bbcfaba6..0b0c5be8c 100644
--- a/qt/aqt/sound.py
+++ b/qt/aqt/sound.py
@@ -229,6 +229,7 @@ class SimpleProcessPlayer(Player):  # pylint: disable=abstract-method
         self._taskman = taskman
         self._terminate_flag = False
         self._process: Optional[subprocess.Popen] = None
+        self._lock = threading.Lock()
 
     def play(self, tag: AVTag, on_done: OnDoneCallback) -> None:
         self._taskman.run_in_background(
@@ -239,7 +240,7 @@ class SimpleProcessPlayer(Player):  # pylint: disable=abstract-method
         self._terminate_flag = True
         # block until stopped
         t = time.time()
-        while self._terminate_flag and time.time() - t < 1:
+        while self._terminate_flag and time.time() - t < 3:
             time.sleep(0.1)
 
     def _play(self, tag: AVTag) -> None:
@@ -254,21 +255,32 @@ class SimpleProcessPlayer(Player):  # pylint: disable=abstract-method
             lambda: gui_hooks.av_player_did_begin_playing(self, tag)
         )
 
-        try:
-            while True:
+        while True:
+            with self._lock:
+                # if .stop() timed out, another thread may run when
+                # there is no process
+                if not self._process:
+                    self._process = None
+                    self._terminate_flag = False
+                    return
+
+                # should we abort playing?
+                if self._terminate_flag:
+                    self._process.terminate()
+                    self._process = None
+                    self._terminate_flag = False
+                    raise PlayerInterrupted()
+
+                # wait for completion
                 try:
                     self._process.wait(0.1)
                     if self._process.returncode != 0:
                         print(f"player got return code: {self._process.returncode}")
+                    self._process = None
+                    self._terminate_flag = False
                     return
                 except subprocess.TimeoutExpired:
                     pass
-                if self._terminate_flag:
-                    self._process.terminate()
-                    raise PlayerInterrupted()
-        finally:
-            self._process = None
-            self._terminate_flag = False
 
     def _on_done(self, ret: Future, cb: OnDoneCallback) -> None:
         try: