From c352949cd38bcb78459c679a7161f77833df0d7f Mon Sep 17 00:00:00 2001
From: Philipp Wolfer <ph.wolfer@gmail.com>
Date: Mon, 15 Feb 2021 14:29:38 +0100
Subject: [PATCH] PICARD-2088: Override QSettings config file syncing

As the default implementation for synchronizing the config file can lead to application freezes override it.
Ensure the config file is not updated by more than one process by locking the file using fasteners.
---
 picard/config.py             | 15 +++++++++++++++
 requirements-macos-10.12.txt |  1 +
 requirements-macos-10.14.txt |  1 +
 requirements-win.txt         |  1 +
 requirements.txt             |  1 +
 5 files changed, 19 insertions(+)

diff --git a/picard/config.py b/picard/config.py
index 9c77362e5..be1c31d10 100644
--- a/picard/config.py
+++ b/picard/config.py
@@ -32,6 +32,8 @@ import os
 import shutil
 import threading
 
+import fasteners
+
 from PyQt5 import QtCore
 
 from picard import (
@@ -129,6 +131,7 @@ class Config(QtCore.QSettings):
         """Common initializer method for :meth:`from_app` and
         :meth:`from_file`."""
 
+        self.setAtomicSyncRequired(False)
         self.application = ConfigSection(self, "application")
         self.setting = ConfigSection(self, "setting")
         self.persist = ConfigSection(self, "persist")
@@ -139,6 +142,18 @@ class Config(QtCore.QSettings):
         self._version = Version.from_string(self.application["version"])
         self._upgrade_hooks = dict()
 
+    def event(self, event):
+        if event.type() == QtCore.QEvent.UpdateRequest:
+            log.debug('Config file update requested on thread %r', threading.get_ident())
+            self.sync()
+            return True
+        else:
+            return super().event(event)
+
+    def sync(self):
+        with fasteners.InterProcessLock(self.fileName()):
+            super().sync()
+
     @classmethod
     def from_app(cls, parent):
         """Build a Config object using the default configuration file
diff --git a/requirements-macos-10.12.txt b/requirements-macos-10.12.txt
index 4dadc134b..30a04c0c8 100644
--- a/requirements-macos-10.12.txt
+++ b/requirements-macos-10.12.txt
@@ -1,5 +1,6 @@
 python-dateutil==2.8.1
 discid==1.2.0
+fasteners==0.16
 markdown==3.2.2
 mutagen==1.45.1
 pyobjc-core==6.2.2
diff --git a/requirements-macos-10.14.txt b/requirements-macos-10.14.txt
index c92cd4385..d5ff30c0e 100644
--- a/requirements-macos-10.14.txt
+++ b/requirements-macos-10.14.txt
@@ -1,5 +1,6 @@
 python-dateutil==2.8.1
 discid==1.2.0
+fasteners==0.16
 markdown==3.2.2
 mutagen==1.45.1
 pyobjc-core==6.2.2
diff --git a/requirements-win.txt b/requirements-win.txt
index b67811b21..0ff66fec5 100644
--- a/requirements-win.txt
+++ b/requirements-win.txt
@@ -1,5 +1,6 @@
 python-dateutil==2.8.1
 discid==1.2.0
+fasteners==0.16
 markdown==3.2.2
 mutagen==1.45.1
 PyQt5==5.15.2
diff --git a/requirements.txt b/requirements.txt
index 86b7ecfed..1e4ce674a 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,5 +1,6 @@
 python-dateutil>=2.7.3
 discid
+fasteners
 markdown
 mutagen>=1.37
 pyobjc-core<7.0; sys_platform == 'darwin'