Use a thread locker and cleaner separation of concerns between main thread and site status fetch

backend/store.py

@@ -3,35 +3,37 @@ import uuid as uuid_builder
 import validators
 import os.path
 from os import path
+from threading import Lock, Thread
+
 
 # Is there an existing library to ensure some data store (JSON etc) is in sync with CRUD methods?
 # Open a github issue if you know something :)
 # https://stackoverflow.com/questions/6190468/how-to-trigger-function-on-value-change
 class ChangeDetectionStore:
+    lock = Lock()
 
     def __init__(self):
         self.needs_write = False
 
         self.__data = {
-            'note' : "Hello! If you change this file manually, please be sure to restart your changedetection.io instance!",
+            'note': "Hello! If you change this file manually, please be sure to restart your changedetection.io instance!",
             'watching': {},
-            'tag': "0.22",
+            'tag': "0.23",
             'settings': {
                 'headers': {
                     'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.66 Safari/537.36',
                     'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9',
-                    'Accept-Encoding': 'gzip, deflate', # No support for brolti in python requests yet.
+                    'Accept-Encoding': 'gzip, deflate',  # No support for brolti in python requests yet.
                     'Accept-Language': 'en-GB,en-US;q=0.9,en;'
                 },
                 'requests': {
-                    'timeout': 15, # Default 15 seconds
-                    'minutes_between_check': 3 * 60, # Default 3 hours
-                    'workers': 10 # Number of threads, lower is better for slow connections
+                    'timeout': 15,  # Default 15 seconds
+                    'minutes_between_check': 3 * 60,  # Default 3 hours
+                    'workers': 10  # Number of threads, lower is better for slow connections
                 }
             }
         }
 
-
         # Base definition for all watchers
         self.generic_definition = {
             'url': None,
@@ -41,8 +43,8 @@ class ChangeDetectionStore:
             'title': None,
             'previous_md5': None,
             'uuid': str(uuid_builder.uuid4()),
-            'headers' : {}, # Extra headers to send
-            'history' : {} # Dict of timestamp and output stripped filename
+            'headers': {},  # Extra headers to send
+            'history': {}  # Dict of timestamp and output stripped filename
         }
 
         if path.isfile('/source.txt'):
@@ -67,7 +69,6 @@ class ChangeDetectionStore:
                     if 'requests' in from_disk['settings']:
                         self.__data['settings']['requests'].update(from_disk['settings']['requests'])
 
-
                 # Reinitialise each `watching` with our generic_definition in the case that we add a new var in the future.
                 # @todo pretty sure theres a python we todo this with an abstracted(?) object!
                 i = 0
@@ -85,20 +86,28 @@ class ChangeDetectionStore:
             self.add_watch(url='https://www.gov.uk/coronavirus', tag='Covid')
             self.add_watch(url='https://changedetection.io', tag='Tech news')
 
-            
-#        self.entryVariable.get()
-    def update_watch(self, uuid, val, var):
+    def update_watch(self, uuid, update_obj):
+
+        self.lock.acquire()
+
+        # In python 3.9 we have the |= dict operator, but that still will lose data on nested structures...
+        for dict_key, d in self.generic_definition.items():
+            if isinstance(d, dict) and dict_key in update_obj:
+                self.__data['watching'][uuid][dict_key].update(update_obj[dict_key])
+                del(update_obj[dict_key])
+
+        # Update with the remaining values
+        self.__data['watching'][uuid].update(update_obj)
 
-        self.__data['watching'][uuid].update({val: var})
         self.needs_write = True
-
+        self.lock.release()
 
     @property
     def data(self):
         return self.__data
 
     def get_all_tags(self):
-        tags=[]
+        tags = []
         for uuid, watch in self.data['watching'].items():
 
             # Support for comma separated list of tags.
@@ -111,10 +120,11 @@ class ChangeDetectionStore:
         return tags
 
     def delete(self, uuid):
-        # Probably their should be dict...
-        del(self.__data['watching'][uuid])
-        self.needs_write = True
 
+        self.lock.acquire()
+        del (self.__data['watching'][uuid])
+        self.needs_write = True
+        self.lock.release()
 
     def url_exists(self, url):
 
@@ -130,7 +140,7 @@ class ChangeDetectionStore:
         return self.data['watching'][uuid].get(val)
 
     def add_watch(self, url, tag):
-
+        self.lock.acquire()
         print("Adding", url, tag)
         #        # @todo deal with exception
         #        validators.url(url)
@@ -146,13 +156,15 @@ class ChangeDetectionStore:
 
         self.data['watching'][new_uuid] = _blank
         self.needs_write = True
+        self.lock.release()
         return new_uuid
 
-
     def sync_to_json(self):
-        print ("Saving index")
+        print("Saving index")
+        self.lock.acquire()
         with open('/datastore/url-watches.json', 'w') as json_file:
             json.dump(self.data, json_file, indent=4)
         self.needs_write = False
+        self.lock.release()
 
 # body of the constructor