Added thumbnails

Merge remote-tracking branch 'cover/thumbnails' into development

# Conflicts:
#	cps/admin.py
#	cps/templates/layout.html
#	cps/ub.py
#	cps/web.py
Update join for sqlalchemy 1.4

cps/services/background_scheduler.py

@@ -0,0 +1,52 @@
+# -*- coding: utf-8 -*-
+
+#   This file is part of the Calibre-Web (https://github.com/janeczku/calibre-web)
+#     Copyright (C) 2020 mmonkey
+#
+#   This program is free software: you can redistribute it and/or modify
+#   it under the terms of the GNU General Public License as published by
+#   the Free Software Foundation, either version 3 of the License, or
+#   (at your option) any later version.
+#
+#   This program is distributed in the hope that it will be useful,
+#   but WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#   GNU General Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License
+#   along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+from __future__ import division, print_function, unicode_literals
+import atexit
+
+from .. import logger
+from .worker import WorkerThread
+from apscheduler.schedulers.background import BackgroundScheduler as BScheduler
+
+
+class BackgroundScheduler:
+    _instance = None
+
+    def __new__(cls):
+        if cls._instance is None:
+            cls._instance = super(BackgroundScheduler, cls).__new__(cls)
+
+            scheduler = BScheduler()
+            atexit.register(lambda: scheduler.shutdown())
+
+            cls.log = logger.create()
+            cls.scheduler = scheduler
+            cls.scheduler.start()
+
+        return cls._instance
+
+    def add(self, func, trigger, **trigger_args):
+        self.scheduler.add_job(func=func, trigger=trigger, **trigger_args)
+
+    def add_task(self, user, task, trigger, **trigger_args):
+        def scheduled_task():
+            worker_task = task()
+            self.log.info('Running scheduled task in background: ' + worker_task.name + ': ' + worker_task.message)
+            WorkerThread.add(user, worker_task)
+
+        self.add(func=scheduled_task, trigger=trigger, **trigger_args)

cps/services/worker.py

@@ -35,7 +35,6 @@ def _get_main_thread():
     raise Exception("main thread not found?!")
 
 
-
 class ImprovedQueue(queue.Queue):
     def to_list(self):
         """
@@ -45,7 +44,8 @@ class ImprovedQueue(queue.Queue):
         with self.mutex:
             return list(self.queue)
 
-#Class for all worker tasks in the background
+
+# Class for all worker tasks in the background
 class WorkerThread(threading.Thread):
     _instance = None
 
@@ -127,6 +127,10 @@ class WorkerThread(threading.Thread):
                 # CalibreTask.start() should wrap all exceptions in it's own error handling
                 item.task.start(self)
 
+            # remove self_cleanup tasks from list
+            if item.task.self_cleanup:
+                self.dequeued.remove(item)
+
             self.queue.task_done()
 
 
@@ -141,6 +145,7 @@ class CalibreTask:
         self.end_time = None
         self.message = message
         self.id = uuid.uuid4()
+        self.self_cleanup = False
 
     @abc.abstractmethod
     def run(self, worker_thread):
@@ -209,6 +214,14 @@ class CalibreTask:
         # todo: throw error if outside of [0,1]
         self._progress = x
 
+    @property
+    def self_cleanup(self):
+        return self._self_cleanup
+
+    @self_cleanup.setter
+    def self_cleanup(self, is_self_cleanup):
+        self._self_cleanup = is_self_cleanup
+
     def _handleError(self, error_message):
         self.stat = STAT_FAIL
         self.progress = 1