Merge pull request #2891 from alphagov/cache-serialised-template

Cache serialised template in Redis and in memory

app/schemas.py

@@ -13,6 +13,7 @@ from marshmallow import (
     post_dump
 )
 from marshmallow_sqlalchemy import field_for
+from uuid import UUID
 
 from notifications_utils.recipients import (
     validate_email_address,
@@ -58,6 +59,14 @@ def _validate_datetime_not_in_past(dte, msg="Date cannot be in the past"):
         raise ValidationError(msg)
 
 
+class UUIDsAsStringsMixin:
+    @post_dump()
+    def __post_dump(self, data):
+        for key, value in data.items():
+            if isinstance(value, UUID):
+                data[key] = str(value)
+
+
 class BaseSchema(ma.ModelSchema):
 
     def __init__(self, load_json=False, *args, **kwargs):
@@ -341,7 +350,7 @@ class BaseTemplateSchema(BaseSchema):
         strict = True
 
 
-class TemplateSchema(BaseTemplateSchema):
+class TemplateSchema(BaseTemplateSchema, UUIDsAsStringsMixin):
 
     created_by_id = field_for(
         models.Template, 'created_by_id', dump_to='created_by', dump_only=True

app/serialised_models.py

@@ -1,7 +1,34 @@
 from abc import ABC, abstractmethod
+from collections import defaultdict
+from functools import partial
+from threading import RLock
 
+import cachetools
+from notifications_utils.clients.redis import RequestCache
+
+from app import redis_store
 from app.dao import templates_dao
 
+caches = defaultdict(partial(cachetools.TTLCache, maxsize=1024, ttl=2))
+locks = defaultdict(RLock)
+redis_cache = RequestCache(redis_store)
+
+
+def memory_cache(func):
+    @cachetools.cached(
+        cache=caches[func.__qualname__],
+        lock=locks[func.__qualname__],
+        key=ignore_first_argument_cache_key,
+    )
+    def wrapper(*args, **kwargs):
+        return func(*args, **kwargs)
+
+    return wrapper
+
+
+def ignore_first_argument_cache_key(cls, *args, **kwargs):
+    return cachetools.keys.hashkey(*args, **kwargs)
+
 
 class SerialisedModel(ABC):
 
@@ -40,10 +67,12 @@ class SerialisedTemplate(SerialisedModel):
     }
 
     @classmethod
+    @memory_cache
     def from_id_and_service_id(cls, template_id, service_id):
         return cls(cls.get_dict(template_id, service_id))
 
     @staticmethod
+    @redis_cache.set('template-{template_id}-version-None')
     def get_dict(template_id, service_id):
         from app.schemas import template_schema