lock cache key during update

oml/cache.py

@@ -1,3 +1,4 @@
+from threading import Lock
 import time
 
 class Cache(dict):
@@ -5,6 +6,12 @@ class Cache(dict):
     def __init__(self, ttl=10):
         self._ttl = ttl
         self._added = {}
+        self._lock = {}
+
+    def lock(self, key):
+        if key not in self._lock:
+            self._lock[key] = Lock()
+            self._lock[key].acquire()
 
     def get(self, key):
         now = time.time()
@@ -12,12 +19,18 @@ class Cache(dict):
             if value < now:
                 self._added.pop(k, None)
                 self.pop(k, None)
+                self._lock.pop(k, None)
+        if key in self._lock:
+            self._lock[key].acquire()
         return dict.get(self, key)
 
     def set(self, key, value, ttl=None):
         ttl = ttl or self._ttl
         self._added[key] = time.time() + ttl
         dict.__setitem__(self, key, value)
+        q = self._lock.pop(key, None)
+        if q:
+            q.release()
 
     def delete(self, key):
         if key in self._added:

oml/item/api.py

@@ -3,7 +3,6 @@
 import json
 import hashlib
 import os
-import unicodedata
 
 from sqlalchemy.orm import load_only
 from sqlalchemy.sql.expression import text
@@ -52,11 +51,13 @@ def find(data):
         key = 'group:' + hashlib.sha1(json.dumps(_keydata, sort_keys=True).encode('utf-8')).hexdigest()
         g = state.cache.get(key)
         if g is None:
+            state.cache.lock(key)
             items = q['qs'].options(load_only('id'))
             qs = models.Find.query.filter_by(key=q['group'])
             if items.first():
                 qs = qs.filter(models.Find.item_id.in_(items))
-                for f in qs.values('value', 'findvalue', 'sortvalue'):
+                values = list(qs.values('value', 'findvalue', 'sortvalue'))
+                for f in values:
                     value = f[0]
                     findvalue = f[1]
                     sortvalue = f[2]

oml/item/title_api.py

@@ -72,6 +72,7 @@ def findTitles(data):
     key = 'title:' + hashlib.sha1(json.dumps(_keydata, sort_keys=True).encode('utf-8')).hexdigest()
     titles = state.cache.get(key)
     if titles is None:
+        state.cache.lock(key)
         response['items'] = []
         _titles = {}
         for i in q['qs']: