Merge branch 'session' into Develop

cps/__init__.py

@@ -94,7 +94,8 @@ def create_app():
         app.root_path = app.root_path.decode('utf-8')
         app.instance_path = app.instance_path.decode('utf-8')
 
-    cache_buster.init_cache_busting(app)
+    if os.environ.get('FLASK_DEBUG'):
+    	cache_buster.init_cache_busting(app)
 
     log.info('Starting Calibre Web...')
     Principal(app)

cps/admin.py

@@ -206,7 +206,10 @@ def edit_domain(allow):
     vals = request.form.to_dict()
     answer = ub.session.query(ub.Registration).filter(ub.Registration.id == vals['pk']).first()
     answer.domain = vals['value'].replace('*', '%').replace('?', '_').lower()
-    ub.session.commit()
+    try:
+        ub.session.commit()
+    except OperationalError:
+        ub.session.rollback()
     return ""
 
 
@@ -220,7 +223,10 @@ def add_domain(allow):
     if not check:
         new_domain = ub.Registration(domain=domain_name, allow=allow)
         ub.session.add(new_domain)
-        ub.session.commit()
+        try:
+            ub.session.commit()
+        except OperationalError:
+            ub.session.rollback()
     return ""
 
 
@@ -230,12 +236,18 @@ def add_domain(allow):
 def delete_domain():
     domain_id = request.form.to_dict()['domainid'].replace('*', '%').replace('?', '_').lower()
     ub.session.query(ub.Registration).filter(ub.Registration.id == domain_id).delete()
-    ub.session.commit()
+    try:
+        ub.session.commit()
+    except OperationalError:
+        ub.session.rollback()
     # If last domain was deleted, add all domains by default
     if not ub.session.query(ub.Registration).filter(ub.Registration.allow==1).count():
         new_domain = ub.Registration(domain="%.%",allow=1)
         ub.session.add(new_domain)
-        ub.session.commit()
+        try:
+            ub.session.commit()
+        except OperationalError:
+            ub.session.rollback()
     return ""
 
 
@@ -275,7 +287,10 @@ def edit_restriction(res_type):
             elementlist = usr.list_allowed_tags()
             elementlist[int(element['id'][1:])]=element['Element']
             usr.allowed_tags = ','.join(elementlist)
-            ub.session.commit()
+            try:
+                ub.session.commit()
+            except OperationalError:
+                ub.session.rollback()
         if res_type == 3:  # CColumn per user
             usr_id = os.path.split(request.referrer)[-1]
             if usr_id.isdigit() == True:
@@ -285,7 +300,10 @@ def edit_restriction(res_type):
             elementlist = usr.list_allowed_column_values()
             elementlist[int(element['id'][1:])]=element['Element']
             usr.allowed_column_value = ','.join(elementlist)
-            ub.session.commit()
+            try:
+                ub.session.commit()
+            except OperationalError:
+                ub.session.rollback()
     if element['id'].startswith('d'):
         if res_type == 0:  # Tags as template
             elementlist = config.list_denied_tags()
@@ -306,7 +324,10 @@ def edit_restriction(res_type):
             elementlist = usr.list_denied_tags()
             elementlist[int(element['id'][1:])]=element['Element']
             usr.denied_tags = ','.join(elementlist)
-            ub.session.commit()
+            try:
+                ub.session.commit()
+            except OperationalError:
+                ub.session.rollback()
         if res_type == 3:  # CColumn per user
             usr_id = os.path.split(request.referrer)[-1]
             if usr_id.isdigit() == True:
@@ -316,7 +337,10 @@ def edit_restriction(res_type):
             elementlist = usr.list_denied_column_values()
             elementlist[int(element['id'][1:])]=element['Element']
             usr.denied_column_value = ','.join(elementlist)
-            ub.session.commit()
+            try:
+                ub.session.commit()
+            except OperationalError:
+                ub.session.rollback()
     return ""
 
 def restriction_addition(element, list_func):
@@ -362,10 +386,16 @@ def add_restriction(res_type):
             usr = current_user
         if 'submit_allow' in element:
             usr.allowed_tags = restriction_addition(element, usr.list_allowed_tags)
-            ub.session.commit()
+            try:
+                ub.session.commit()
+            except OperationalError:
+                ub.session.rollback()
         elif 'submit_deny' in element:
             usr.denied_tags = restriction_addition(element, usr.list_denied_tags)
-            ub.session.commit()
+            try:
+                ub.session.commit()
+            except OperationalError:
+                ub.session.rollback()
     if res_type == 3:  # CustomC per user
         usr_id = os.path.split(request.referrer)[-1]
         if usr_id.isdigit() == True:
@@ -374,10 +404,16 @@ def add_restriction(res_type):
             usr = current_user
         if 'submit_allow' in element:
             usr.allowed_column_value = restriction_addition(element, usr.list_allowed_column_values)
-            ub.session.commit()
+            try:
+                ub.session.commit()
+            except OperationalError:
+                ub.session.rollback()
         elif 'submit_deny' in element:
             usr.denied_column_value = restriction_addition(element, usr.list_denied_column_values)
-            ub.session.commit()
+            try:
+                ub.session.commit()
+            except OperationalError:
+                ub.session.rollback()
     return ""
 
 @admi.route("/ajax/deleterestriction/<int:res_type>", methods=['POST'])
@@ -407,10 +443,16 @@ def delete_restriction(res_type):
             usr = current_user
         if element['id'].startswith('a'):
             usr.allowed_tags = restriction_deletion(element, usr.list_allowed_tags)
-            ub.session.commit()
+            try:
+                ub.session.commit()
+            except OperationalError:
+                ub.session.rollback()
         elif element['id'].startswith('d'):
             usr.denied_tags = restriction_deletion(element, usr.list_denied_tags)
-            ub.session.commit()
+            try:
+                ub.session.commit()
+            except OperationalError:
+                ub.session.rollback()
     elif res_type == 3:  # Columns per user
         usr_id = os.path.split(request.referrer)[-1]
         if usr_id.isdigit() == True:    # select current user if admins are editing their own rights
@@ -419,10 +461,16 @@ def delete_restriction(res_type):
             usr = current_user
         if element['id'].startswith('a'):
             usr.allowed_column_value = restriction_deletion(element, usr.list_allowed_column_values)
-            ub.session.commit()
+            try:
+                ub.session.commit()
+            except OperationalError:
+                ub.session.rollback()
         elif element['id'].startswith('d'):
             usr.denied_column_value = restriction_deletion(element, usr.list_denied_column_values)
-            ub.session.commit()
+            try:
+                ub.session.commit()
+            except OperationalError:
+                ub.session.rollback()
     return ""
 
 
@@ -815,7 +863,10 @@ def _handle_new_user(to_save, content,languages, translations, kobo_support):
         content.allowed_column_value = config.config_allowed_column_value
         content.denied_column_value = config.config_denied_column_value
         ub.session.add(content)
-        ub.session.commit()
+        try:
+            ub.session.commit()
+        except OperationalError:
+            ub.session.rollback()
         flash(_(u"User '%(user)s' created", user=content.nickname), category="success")
         return redirect(url_for('admin.admin'))
     except IntegrityError:
@@ -831,7 +882,10 @@ def _handle_edit_user(to_save, content,languages, translations, kobo_support):
         if ub.session.query(ub.User).filter(ub.User.role.op('&')(constants.ROLE_ADMIN) == constants.ROLE_ADMIN,
                                             ub.User.id != content.id).count():
             ub.session.query(ub.User).filter(ub.User.id == content.id).delete()
-            ub.session.commit()
+            try:
+                ub.session.commit()
+            except OperationalError:
+                ub.session.rollback()
             flash(_(u"User '%(nick)s' deleted", nick=content.nickname), category="success")
             return redirect(url_for('admin.admin'))
         else:
@@ -906,7 +960,10 @@ def _handle_edit_user(to_save, content,languages, translations, kobo_support):
         if "kindle_mail" in to_save and to_save["kindle_mail"] != content.kindle_mail:
             content.kindle_mail = to_save["kindle_mail"]
     try:
-        ub.session.commit()
+        try:
+            ub.session.commit()
+        except OperationalError:
+            ub.session.rollback()
         flash(_(u"User '%(nick)s' updated", nick=content.nickname), category="success")
     except IntegrityError:
         ub.session.rollback()

cps/config_sql.py

@@ -22,6 +22,7 @@ import os
 import sys
 
 from sqlalchemy import exc, Column, String, Integer, SmallInteger, Boolean, BLOB, JSON
+from sqlalchemy.exc import OperationalError
 from sqlalchemy.ext.declarative import declarative_base
 
 from . import constants, cli, logger, ub
@@ -139,6 +140,7 @@ class _ConfigSQL(object):
     # pylint: disable=no-member
     def __init__(self, session):
         self._session = session
+        self._session.expire_on_commit = False
         self._settings = None
         self.db_configured = None
         self.config_calibre_dir = None
@@ -295,7 +297,11 @@ class _ConfigSQL(object):
             log.warning("Log path %s not valid, falling back to default", self.config_logfile)
             self.config_logfile = logfile
             self._session.merge(s)
-            self._session.commit()
+            try:
+                self._session.commit()
+            except OperationalError as e:
+                log.error('Database error: %s', e)
+                self._session.rollback()
 
     def save(self):
         '''Apply all configuration values to the underlying storage.'''
@@ -309,7 +315,11 @@ class _ConfigSQL(object):
 
         log.debug("_ConfigSQL updating storage")
         self._session.merge(s)
-        self._session.commit()
+        try:
+            self._session.commit()
+        except OperationalError as e:
+            log.error('Database error: %s', e)
+            self._session.rollback()
         self.load()
 
     def invalidate(self, error=None):
@@ -350,7 +360,10 @@ def _migrate_table(session, orm_class):
                 changed = True
 
     if changed:
-        session.commit()
+        try:
+            session.commit()
+        except OperationalError:
+            session.rollback()
 
 
 def autodetect_calibre_binary():

cps/db.py

@@ -32,9 +32,9 @@ from sqlalchemy.orm import relationship, sessionmaker, scoped_session
 from sqlalchemy.orm.collections import InstrumentedList
 from sqlalchemy.ext.declarative import declarative_base, DeclarativeMeta
 from sqlalchemy.pool import StaticPool
-from flask_login import current_user
 from sqlalchemy.sql.expression import and_, true, false, text, func, or_
 from sqlalchemy.ext.associationproxy import association_proxy
+from flask_login import current_user
 from babel import Locale as LC
 from babel.core import UnknownLocaleError
 from flask_babel import gettext as _
@@ -425,18 +425,19 @@ class CalibreDB():
     # instances alive once they reach the end of their respective scopes
     instances = WeakSet()
 
-    def __init__(self):
+    def __init__(self, expire_on_commit=True):
         """ Initialize a new CalibreDB session
         """
         self.session = None
         if self._init:
-            self.initSession()
+            self.initSession(expire_on_commit)
 
         self.instances.add(self)
 
 
-    def initSession(self):
+    def initSession(self, expire_on_commit=True):
         self.session = self.session_factory()
+        self.session.expire_on_commit = expire_on_commit
         self.update_title_sort(self.config)
 
     @classmethod

cps/gdriveutils.py

@@ -89,7 +89,7 @@ class Singleton:
         except AttributeError:
             self._instance = self._decorated()
             return self._instance
-        except ImportError as e:
+        except (ImportError, NameError) as e:
             log.debug(e)
             return None
 

cps/helper.py

@@ -24,10 +24,7 @@ import io
 import mimetypes
 import re
 import shutil
-import glob
 import time
-import zipfile
-import json
 import unicodedata
 from datetime import datetime, timedelta
 from tempfile import gettempdir

cps/kobo.py

@@ -43,6 +43,7 @@ from flask_login import current_user
 from werkzeug.datastructures import Headers
 from sqlalchemy import func
 from sqlalchemy.sql.expression import and_, or_
+from sqlalchemy.exc import OperationalError
 from sqlalchemy.orm import load_only
 from sqlalchemy.exc import StatementError
 import requests
@@ -451,8 +452,10 @@ def HandleTagCreate():
     items_unknown_to_calibre = add_items_to_shelf(items, shelf)
     if items_unknown_to_calibre:
         log.debug("Received request to add unknown books to a collection. Silently ignoring items.")
-    ub.session.commit()
-
+    try:
+        ub.session.commit()
+    except OperationalError:
+        ub.session.rollback()
     return make_response(jsonify(str(shelf.uuid)), 201)
 
 
@@ -484,7 +487,10 @@ def HandleTagUpdate(tag_id):
 
         shelf.name = name
         ub.session.merge(shelf)
-        ub.session.commit()
+        try:
+            ub.session.commit()
+        except OperationalError:
+            ub.session.rollback()
     return make_response(' ', 200)
 
 
@@ -536,7 +542,10 @@ def HandleTagAddItem(tag_id):
         log.debug("Received request to add an unknown book to a collection. Silently ignoring item.")
 
     ub.session.merge(shelf)
-    ub.session.commit()
+    try:
+        ub.session.commit()
+    except OperationalError:
+        ub.session.rollback()
 
     return make_response('', 201)
 
@@ -577,7 +586,10 @@ def HandleTagRemoveItem(tag_id):
             shelf.books.filter(ub.BookShelf.book_id == book.id).delete()
         except KeyError:
             items_unknown_to_calibre.append(item)
-    ub.session.commit()
+    try:
+        ub.session.commit()
+    except OperationalError:
+        ub.session.rollback()
 
     if items_unknown_to_calibre:
         log.debug("Received request to remove an unknown book to a collecition. Silently ignoring item.")
@@ -623,7 +635,10 @@ def sync_shelves(sync_token, sync_results):
                 "ChangedTag": tag
             })
     sync_token.tags_last_modified = new_tags_last_modified
-    ub.session.commit()
+    try:
+        ub.session.commit()
+    except OperationalError:
+        ub.session.rollback()
 
 
 # Creates a Kobo "Tag" object from a ub.Shelf object
@@ -704,7 +719,10 @@ def HandleStateRequest(book_uuid):
             abort(400, description="Malformed request data is missing 'ReadingStates' key")
 
         ub.session.merge(kobo_reading_state)
-        ub.session.commit()
+        try:
+            ub.session.commit()
+        except OperationalError:
+            ub.session.rollback()
         return jsonify({
             "RequestResult": "Success",
             "UpdateResults": [update_results_response],
@@ -742,7 +760,10 @@ def get_or_create_reading_state(book_id):
         kobo_reading_state.statistics = ub.KoboStatistics()
         book_read.kobo_reading_state = kobo_reading_state
     ub.session.add(book_read)
-    ub.session.commit()
+    try:
+        ub.session.commit()
+    except OperationalError:
+        ub.session.rollback()
     return book_read.kobo_reading_state
 
 
@@ -845,7 +866,10 @@ def HandleBookDeletionRequest(book_uuid):
     archived_book.last_modified = datetime.datetime.utcnow()
 
     ub.session.merge(archived_book)
-    ub.session.commit()
+    try:
+        ub.session.commit()
+    except OperationalError:
+        ub.session.rollback()
 
     return ("", 204)
 

cps/kobo_auth.py

@@ -66,6 +66,7 @@ from os import urandom
 from flask import g, Blueprint, url_for, abort, request
 from flask_login import login_user, login_required
 from flask_babel import gettext as _
+from sqlalchemy.exc import OperationalError
 
 from . import logger, ub, lm
 from .web import render_title_template
@@ -147,7 +148,10 @@ def generate_auth_token(user_id):
             auth_token.token_type = 1
 
             ub.session.add(auth_token)
-            ub.session.commit()
+            try:
+                ub.session.commit()
+            except OperationalError:
+                ub.session.rollback()
         return render_title_template(
             "generate_kobo_auth_url.html",
             title=_(u"Kobo Setup"),
@@ -164,5 +168,8 @@ def delete_auth_token(user_id):
     # Invalidate any prevously generated Kobo Auth token for this user.
     ub.session.query(ub.RemoteAuthToken).filter(ub.RemoteAuthToken.user_id == user_id)\
         .filter(ub.RemoteAuthToken.token_type==1).delete()
-    ub.session.commit()
+    try:
+        ub.session.commit()
+    except OperationalError:
+        ub.session.rollback()
     return ""

cps/oauth_bb.py

@@ -32,6 +32,7 @@ from flask_dance.contrib.github import make_github_blueprint, github
 from flask_dance.contrib.google import make_google_blueprint, google
 from flask_login import login_user, current_user
 from sqlalchemy.orm.exc import NoResultFound
+from sqlalchemy.exc import OperationalError
 
 from . import constants, logger, config, app, ub
 from .web import login_required
@@ -109,7 +110,10 @@ if ub.oauth_support:
         oauthProvider.provider_name = "google"
         oauthProvider.active = False
         ub.session.add(oauthProvider)
-        ub.session.commit()
+        try:
+            ub.session.commit()
+        except OperationalError:
+            ub.session.rollback()
 
     oauth_ids = ub.session.query(ub.OAuthProvider).all()
     ele1 = dict(provider_name='github',

cps/opds.py

@@ -33,7 +33,7 @@ from werkzeug.security import check_password_hash
 from . import constants, logger, config, db, calibre_db, ub, services, get_locale, isoLanguages
 from .helper import get_download_link, get_book_cover
 from .pagination import Pagination
-from .web import render_read_books, download_required, load_user_from_request
+from .web import render_read_books, load_user_from_request
 from flask_babel import gettext as _
 from babel import Locale as LC
 from babel.core import UnknownLocaleError

cps/shelf.py

@@ -322,8 +322,11 @@ def delete_shelf_helper(cur_shelf):
     ub.session.delete(cur_shelf)
     ub.session.query(ub.BookShelf).filter(ub.BookShelf.shelf == shelf_id).delete()
     ub.session.add(ub.ShelfArchive(uuid=cur_shelf.uuid, user_id=cur_shelf.user_id))
-    ub.session.commit()
-    log.info("successfully deleted %s", cur_shelf)
+    try:
+        ub.session.commit()
+        log.info("successfully deleted %s", cur_shelf)
+    except OperationalError:
+        ub.session.rollback()
 
 
 

cps/tasks/convert.py

@@ -9,7 +9,7 @@ from shutil import copyfile
 from sqlalchemy.exc import SQLAlchemyError
 
 from cps.services.worker import CalibreTask
-from cps import calibre_db, db
+from cps import db
 from cps import logger, config
 from cps.subproc_wrapper import process_open
 from flask_babel import gettext as _
@@ -33,8 +33,9 @@ class TaskConvert(CalibreTask):
     def run(self, worker_thread):
         self.worker_thread = worker_thread
         if config.config_use_google_drive:
-            cur_book = calibre_db.get_book(self.bookid)
-            data = calibre_db.get_book_format(self.bookid, self.settings['old_book_format'])
+            worker_db = db.CalibreDB(expire_on_commit=False)
+            cur_book = worker_db.get_book(self.bookid)
+            data = worker_db.get_book_format(self.bookid, self.settings['old_book_format'])
             df = gdriveutils.getFileFromEbooksFolder(cur_book.path,
                                                      data.name + "." + self.settings['old_book_format'].lower())
             if df:
@@ -44,10 +45,12 @@ class TaskConvert(CalibreTask):
                 if not os.path.exists(os.path.join(config.config_calibre_dir, cur_book.path)):
                     os.makedirs(os.path.join(config.config_calibre_dir, cur_book.path))
                 df.GetContentFile(datafile)
+                worker_db.session.close()
             else:
                 error_message = _(u"%(format)s not found on Google Drive: %(fn)s",
                                   format=self.settings['old_book_format'],
                                   fn=data.name + "." + self.settings['old_book_format'].lower())
+                worker_db.session.close()
                 return error_message
 
         filename = self._convert_ebook_format()
@@ -71,7 +74,7 @@ class TaskConvert(CalibreTask):
 
     def _convert_ebook_format(self):
         error_message = None
-        local_session = db.CalibreDB().session
+        local_db = db.CalibreDB(expire_on_commit=False)
         file_path = self.file_path
         book_id = self.bookid
         format_old_ext = u'.' + self.settings['old_book_format'].lower()
@@ -82,10 +85,11 @@ class TaskConvert(CalibreTask):
         # this will allow send to kindle workflow to continue to work
         if os.path.isfile(file_path + format_new_ext):
             log.info("Book id %d already converted to %s", book_id, format_new_ext)
-            cur_book = calibre_db.get_book(book_id)
+            cur_book = local_db.get_book(book_id)
             self.results['path'] = file_path
             self.results['title'] = cur_book.title
             self._handleSuccess()
+            local_db.session.close()
             return os.path.basename(file_path + format_new_ext)
         else:
             log.info("Book id %d - target format of %s does not exist. Moving forward with convert.",
@@ -105,18 +109,19 @@ class TaskConvert(CalibreTask):
             check, error_message = self._convert_calibre(file_path, format_old_ext, format_new_ext)
 
         if check == 0:
-            cur_book = calibre_db.get_book(book_id)
+            cur_book = local_db.get_book(book_id)
             if os.path.isfile(file_path + format_new_ext):
                 # self.db_queue.join()
                 new_format = db.Data(name=cur_book.data[0].name,
                                          book_format=self.settings['new_book_format'].upper(),
                                          book=book_id, uncompressed_size=os.path.getsize(file_path + format_new_ext))
                 try:
-                    local_session.merge(new_format)
-                    local_session.commit()
+                    local_db.session.merge(new_format)
+                    local_db.session.commit()
                 except SQLAlchemyError as e:
-                    local_session.rollback()
+                    local_db.rollback()
                     log.error("Database error: %s", e)
+                    local_db.session.close()
                     return
                 self.results['path'] = cur_book.path
                 self.results['title'] = cur_book.title
@@ -125,6 +130,7 @@ class TaskConvert(CalibreTask):
                 return os.path.basename(file_path + format_new_ext)
             else:
                 error_message = _('%(format)s format not found on disk', format=format_new_ext.upper())
+        local_db.session.close()
         log.info("ebook converter failed with error while converting book")
         if not error_message:
             error_message = _('Ebook converter failed with unknown error')

cps/ub.py

@@ -45,7 +45,7 @@ from sqlalchemy import Column, ForeignKey
 from sqlalchemy import String, Integer, SmallInteger, Boolean, DateTime, Float, JSON
 from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm.attributes import flag_modified
-from sqlalchemy.orm import backref, relationship, sessionmaker, Session
+from sqlalchemy.orm import backref, relationship, sessionmaker, Session, scoped_session
 from werkzeug.security import generate_password_hash
 
 from . import constants
@@ -677,14 +677,20 @@ def update_download(book_id, user_id):
 
     if not check:
         new_download = Downloads(user_id=user_id, book_id=book_id)
-        session.add(new_download)
-        session.commit()
+        ub.session.add(new_download)
+        try:
+            ub.session.commit()
+        except exc.OperationalError:
+            ub.session.rollback()
 
 
 # Delete non exisiting downloaded books in calibre-web's own database
 def delete_download(book_id):
-    session.query(Downloads).filter(book_id == Downloads.book_id).delete()
-    session.commit()
+    ub.session.query(Downloads).filter(book_id == Downloads.book_id).delete()
+    try:
+        ub.session.commit()
+    except exc.OperationalError:
+        ub.session.rollback()
 
 # Generate user Guest (translated text), as anonymous user, no rights
 def create_anonymous_user(session):
@@ -725,7 +731,7 @@ def init_db(app_db_path):
     app_DB_path = app_db_path
     engine = create_engine(u'sqlite:///{0}'.format(app_db_path), echo=False)
 
-    Session = sessionmaker()
+    Session = scoped_session(sessionmaker())
     Session.configure(bind=engine)
     session = Session()
 

cps/web.py

@@ -351,7 +351,6 @@ def import_ldap_users():
             username = user_data[user_login_field][0].decode('utf-8')
             # check for duplicate username
             if ub.session.query(ub.User).filter(func.lower(ub.User.nickname) == username.lower()).first():
-                # if ub.session.query(ub.User).filter(ub.User.nickname == username).first():
                 log.warning("LDAP User  %s Already in Database", user_data)
                 continue
 
@@ -432,7 +431,10 @@ def bookmark(book_id, book_format):
                                               ub.Bookmark.book_id == book_id,
                                               ub.Bookmark.format == book_format)).delete()
     if not bookmark_key:
-        ub.session.commit()
+        try:
+            ub.session.commit()
+        except OperationalError:
+            ub.session.rollback()
         return "", 204
 
     lbookmark = ub.Bookmark(user_id=current_user.id,
@@ -440,7 +442,10 @@ def bookmark(book_id, book_format):
                             format=book_format,
                             bookmark_key=bookmark_key)
     ub.session.merge(lbookmark)
-    ub.session.commit()
+    try:
+        ub.session.commit()
+    except OperationalError:
+        ub.session.rollback()
     return "", 201
 
 
@@ -465,7 +470,10 @@ def toggle_read(book_id):
             kobo_reading_state.statistics = ub.KoboStatistics()
             book.kobo_reading_state = kobo_reading_state
         ub.session.merge(book)
-        ub.session.commit()
+        try:
+            ub.session.commit()
+        except OperationalError:
+            ub.session.rollback()
     else:
         try:
             calibre_db.update_title_sort(config)
@@ -499,7 +507,10 @@ def toggle_archived(book_id):
         archived_book = ub.ArchivedBook(user_id=current_user.id, book_id=book_id)
         archived_book.is_archived = True
     ub.session.merge(archived_book)
-    ub.session.commit()
+    try:
+        ub.session.commit()
+    except OperationalError:
+        ub.session.rollback()
     return ""
 
 
@@ -749,8 +760,6 @@ def render_hot_books(page):
                 entries.append(downloadBook)
             else:
                 ub.delete_download(book.Downloads.book_id)
-                # ub.session.query(ub.Downloads).filter(book.Downloads.book_id == ub.Downloads.book_id).delete()
-                # ub.session.commit()
         numBooks = entries.__len__()
         pagination = Pagination(page, config.config_books_per_page, numBooks)
         return render_title_template('index.html', random=random, entries=entries, pagination=pagination,
@@ -1086,11 +1095,12 @@ def update_table_settings():
         except AttributeError:
             pass
         ub.session.commit()
-    except InvalidRequestError:
+    except (InvalidRequestError, OperationalError):
         log.error("Invalid request received: %r ", request, )
         return "Invalid request", 400
     return ""
 
+
 @web.route("/author")
 @login_required_if_no_ano
 def author_list():
@@ -1676,7 +1686,10 @@ def logout():
 def remote_login():
     auth_token = ub.RemoteAuthToken()
     ub.session.add(auth_token)
-    ub.session.commit()
+    try:
+        ub.session.commit()
+    except OperationalError:
+        ub.session.rollback()
 
     verify_url = url_for('web.verify_token', token=auth_token.auth_token, _external=true)
     log.debug(u"Remot Login request with token: %s", auth_token.auth_token)
@@ -1708,7 +1721,10 @@ def verify_token(token):
     # Update token with user information
     auth_token.user_id = current_user.id
     auth_token.verified = True
-    ub.session.commit()
+    try:
+        ub.session.commit()
+    except OperationalError:
+        ub.session.rollback()
 
     flash(_(u"Success! Please return to your device"), category="success")
     log.debug(u"Remote Login token for userid %s verified", auth_token.user_id)
@@ -1731,7 +1747,10 @@ def token_verified():
     # Token expired
     elif datetime.now() > auth_token.expiration:
         ub.session.delete(auth_token)
-        ub.session.commit()
+        try:
+            ub.session.commit()
+        except OperationalError:
+            ub.session.rollback()
 
         data['status'] = 'error'
         data['message'] = _(u"Token has expired")
@@ -1744,7 +1763,10 @@ def token_verified():
         login_user(user)
 
         ub.session.delete(auth_token)
-        ub.session.commit()
+        try:
+            ub.session.commit()
+        except OperationalError:
+            ub.session.rollback()
 
         data['status'] = 'success'
         log.debug(u"Remote Login for userid %s succeded", user.id)
@@ -1836,14 +1858,11 @@ def profile():
             ub.session.rollback()
             flash(_(u"Found an existing account for this e-mail address."), category="error")
             log.debug(u"Found an existing account for this e-mail address.")
-            '''return render_title_template("user_edit.html",
-                                         content=current_user,
-                                         translations=translations,
-                                         kobo_support=kobo_support,
-                                         title=_(u"%(name)s's profile", name=current_user.nickname),
-                                         page="me",
-                                         registered_oauth=local_oauth_check,
-                                         oauth_status=oauth_status)'''
+        except OperationalError as e:
+            ub.session.rollback()
+            log.error("Database error: %s", e)
+            flash(_(u"Database error: %(error)s.", error=e), category="error")
+
     return render_title_template("user_edit.html",
                                  translations=translations,
                                  profile=1,