Handle read only access to cache dir gracefully. minor cleanup

cps.py

@@ -44,7 +44,7 @@ from cps.editbooks import editbook
 from cps.remotelogin import remotelogin
 from cps.search_metadata import meta
 from cps.error_handler import init_errorhandler
-from cps.schedule import register_jobs
+from cps.schedule import register_jobs, register_startup_jobs
 
 try:
     from cps.kobo import kobo, get_kobo_activated
@@ -83,6 +83,7 @@ def main():
 
     # Register scheduled jobs
     register_jobs()
+    # register_startup_jobs()
 
     success = web_server.start()
     sys.exit(0 if success else 1)

cps/fs.py

@@ -17,6 +17,7 @@
 #   along with this program. If not, see <http://www.gnu.org/licenses/>.
 
 from __future__ import division, print_function, unicode_literals
+from . import logger
 from .constants import CACHE_DIR
 from os import listdir, makedirs, remove
 from os.path import isdir, isfile, join
@@ -32,16 +33,26 @@ class FileSystem:
     def __new__(cls):
         if cls._instance is None:
             cls._instance = super(FileSystem, cls).__new__(cls)
+            cls.log = logger.create()
         return cls._instance
 
     def get_cache_dir(self, cache_type=None):
         if not isdir(self._cache_dir):
+            try:
                 makedirs(self._cache_dir)
+            except OSError:
+                self.log.info(f'Failed to create path {self._cache_dir} (Permission denied).')
+                return False
 
-        if cache_type and not isdir(join(self._cache_dir, cache_type)):
+        path = join(self._cache_dir, cache_type)
-            makedirs(join(self._cache_dir, cache_type))
+        if cache_type and not isdir(path):
+            try:
+                makedirs(path)
+            except OSError:
+                self.log.info(f'Failed to create path {path} (Permission denied).')
+                return False
 
-        return join(self._cache_dir, cache_type) if cache_type else self._cache_dir
+        return path if cache_type else self._cache_dir
 
     def get_cache_file_path(self, filename, cache_type=None):
         return join(self.get_cache_dir(cache_type), filename) if filename else None
@@ -60,10 +71,25 @@ class FileSystem:
 
     def delete_cache_dir(self, cache_type=None):
         if not cache_type and isdir(self._cache_dir):
+            try:
                 rmtree(self._cache_dir)
-        if cache_type and isdir(join(self._cache_dir, cache_type)):
+            except OSError:
-            rmtree(join(self._cache_dir, cache_type))
+                self.log.info(f'Failed to delete path {self._cache_dir} (Permission denied).')
+                return False
+
+        path = join(self._cache_dir, cache_type)
+        if cache_type and isdir(path):
+            try:
+                rmtree(path)
+            except OSError:
+                self.log.info(f'Failed to delete path {path} (Permission denied).')
+                return False
 
     def delete_cache_file(self, filename, cache_type=None):
-        if isfile(join(self.get_cache_dir(cache_type), filename)):
+        path = join(self.get_cache_dir(cache_type), filename)
-            remove(join(self.get_cache_dir(cache_type), filename))
+        if isfile(path):
+            try:
+                remove(path)
+            except OSError:
+                self.log.info(f'Failed to delete path {path} (Permission denied).')
+                return False

cps/schedule.py

@@ -18,8 +18,8 @@
 
 from __future__ import division, print_function, unicode_literals
 
-from datetime import datetime
 from .services.background_scheduler import BackgroundScheduler
+from .services.worker import WorkerThread
 from .tasks.database import TaskReconnectDatabase
 from .tasks.thumbnail import TaskSyncCoverThumbnailCache, TaskGenerateCoverThumbnails
 
@@ -29,10 +29,14 @@ def register_jobs():
 
     if scheduler:
         # Reconnect metadata.db once every 12 hours
-        scheduler.add_task(user=None, task=lambda: TaskReconnectDatabase(), trigger='interval', hours=12)
+        scheduler.add_task(user=None, task=lambda: TaskReconnectDatabase(), trigger='cron', hour='4,16')
 
         # Cleanup book cover cache once every 24 hours
-        scheduler.add_task(user=None, task=lambda: TaskSyncCoverThumbnailCache(), trigger='interval', days=1)
+        scheduler.add_task(user=None, task=lambda: TaskSyncCoverThumbnailCache(), trigger='cron', hour=4)
 
         # Generate all missing book cover thumbnails once every 24 hours
-        scheduler.add_task(user=None, task=lambda: TaskGenerateCoverThumbnails(), trigger='interval', days=1)
+        scheduler.add_task(user=None, task=lambda: TaskGenerateCoverThumbnails(), trigger='cron', hour=4)
+
+
+def register_startup_jobs():
+    WorkerThread.add(None, TaskGenerateCoverThumbnails())

cps/services/background_scheduler.py

@@ -28,7 +28,7 @@ try:
 except (ImportError, RuntimeError) as e:
     use_APScheduler = False
     log = logger.create()
-    log.info(f'APScheduler not found. Unable to schedule tasks.')
+    log.info('APScheduler not found. Unable to schedule tasks.')
 
 
 class BackgroundScheduler:
@@ -58,7 +58,7 @@ class BackgroundScheduler:
         if use_APScheduler:
             def scheduled_task():
                 worker_task = task()
-                self.log.info('Running scheduled task in background: ' + worker_task.name + ': ' + worker_task.message)
+                self.log.info(f'Running scheduled task in background: {worker_task.name} - {worker_task.message}')
                 WorkerThread.add(user, worker_task)
 
             return self.add(func=scheduled_task, trigger=trigger, **trigger_args)