replace watchdog with active polling thread

watchdog does not work on windows. For some
reason file modification events are not
emitted.
Fixed by replacing watchdog with a thread
that polls the modification date ever 0.5s.

Also fixed a bug that the hit view was not
properly destructed.

src/plugins/krowlog/aboutdialog.py

@@ -1,7 +1,6 @@
 import textwrap
 
 import PySide6
-from watchdog import version as watchdog_version
 from PySide6.QtCore import Qt
 from PySide6.QtGui import QFont, QPalette
 from PySide6.QtWidgets import *
@@ -75,11 +74,9 @@ class AboutDialog(QDialog):
         <ul>
         <li>PySide6-Essentials {pyside} (LGPL v3) - <a href="https://doc.qt.io/qtforpython-6/">https://doc.qt.io/qtforpython-6/</a></li>
         <li>Qt6 {qt} (LGPL v3) - <a href="https://code.qt.io/cgit/qt/qtbase.git/">https://code.qt.io/cgit/qt/qtbase.git/</a></li>
-        <li>watchdog {watchdog} (Apache 2.0) - <a href="https://github.com/gorakhargosh/watchdog">https://github.com/gorakhargosh/watchdog</a></li>
         </ul>""".format(
             pyside=PySide6.__version__,
-            qt=PySide6.QtCore.__version__,
-            watchdog=watchdog_version.VERSION_STRING)
+            qt=PySide6.QtCore.__version__)
         label = textwrap.dedent(dependencies)
 
         result = QWidget()

src/plugins/logfile/filterwidget.py

@@ -279,6 +279,7 @@ class FilterWidget(QWidget):
 
     def destruct(self):
         self._cancel_search()
+        self.hits_view.destruct()
         os.remove(self.tmp_filename)
 
     def _cancel_search(self):

src/ui/bigtext/bigtext.py

@@ -23,55 +23,31 @@ from src.ui.icon import Icon
 from src.ui.rangeslider import RangeSlider
 from src.util.conversion import humanbytes
 from src.pluginregistry import PluginRegistry
+from threading import Event
 
-from src.settings.settings import Settings
-from watchdog.observers import Observer
-from watchdog.events import FileSystemEventHandler
 from src.i18n import _
 
 log = logging.getLogger("bigtext")
 
-
-class FileObserver(FileSystemEventHandler):
-
-    def __init__(self, big_text):
-        super(FileObserver, self).__init__()
-        self.big_text = big_text
-        self._last_mtime = -1
-
-    def on_modified(self, event):
-        # slow down the updates. This is needed, because the file is modified
-        # constantly, which would lead to constant re-rendering, which would
-        # block the UI thread and make the UI unresponsive.
-        # Note: we don't miss events, because they are queued and de-duplicated
-        if not event.is_directory:
-            try:
-                mtime = os.stat(event.src_path).st_mtime
-                if mtime != self._last_mtime:
-                    self._last_mtime = mtime
-                    time.sleep(0.5)
-                    self.big_text.trigger_update.emit()
-            except FileNotFoundError:
-                # ignore: happens when closing the application, because tmp files are deleted,
-                # which triggers a modification event
-                pass
-
-
 class FileWatchdogThread(QRunnable):
 
     def __init__(self, big_text, file: str):
         super(FileWatchdogThread, self).__init__()
         self.file = file
         self.big_text = big_text
-        self.observer = Observer()
+        self.stop = Event()
 
     def run(self) -> None:
-        self.observer.schedule(FileObserver(self.big_text), self.file)
-        self.observer.start()
+        _last_mtime = None
+        while not self.stop.is_set():
+            mtime = os.stat(self.file).st_mtime
+            if mtime != _last_mtime:
+                _last_mtime = mtime
+                self.big_text.trigger_update.emit()
+            self.stop.wait(0.5)
 
     def destruct(self):
-        self.observer.stop()
-        # self.observer.join(1)
+        self.stop.set()
 
 
 class BigText(QWidget):