From 95e658d05b91d16b165b398b8bb9d84d291e3899 Mon Sep 17 00:00:00 2001
From: Tom Hubrecht <tom.hubrecht@ens.fr>
Date: Wed, 29 Jun 2022 14:37:28 +0200
Subject: [PATCH] Update redis, and implement a custom channel layer to send
 datetime/decimal objects

---
 gestioasso/settings/cof_prod.py |  2 +-
 requirements-prod.txt           |  2 +-
 shared/channels.py              | 45 +++++++++++++++++++++++++++++++++
 3 files changed, 47 insertions(+), 2 deletions(-)
 create mode 100644 shared/channels.py

diff --git a/gestioasso/settings/cof_prod.py b/gestioasso/settings/cof_prod.py
index 3e976952..05a7b2c9 100644
--- a/gestioasso/settings/cof_prod.py
+++ b/gestioasso/settings/cof_prod.py
@@ -148,7 +148,7 @@ CACHES = {
 
 CHANNEL_LAYERS = {
     "default": {
-        "BACKEND": "channels_redis.core.RedisChannelLayer",
+        "BACKEND": "shared.channels.ChannelLayer",
         "CONFIG": {
             "hosts": [
                 (
diff --git a/requirements-prod.txt b/requirements-prod.txt
index ffd21935..4037e7fe 100644
--- a/requirements-prod.txt
+++ b/requirements-prod.txt
@@ -5,7 +5,7 @@ psycopg2<2.8
 
 # Redis
 django-redis-cache==3.0.*
-redis~=2.10.6
+redis==3.5.*
 channels-redis==3.4.*
 
 # ASGI protocol and HTTP server
diff --git a/shared/channels.py b/shared/channels.py
new file mode 100644
index 00000000..ae8c1248
--- /dev/null
+++ b/shared/channels.py
@@ -0,0 +1,45 @@
+import datetime
+import random
+from decimal import Decimal
+
+import msgpack
+from channels_redis.core import RedisChannelLayer
+
+
+def encode_kf(obj):
+    if isinstance(obj, Decimal):
+        return {"__decimal__": True, "as_str": str(obj)}
+    elif isinstance(obj, datetime.datetime):
+        return {"__datetime__": True, "as_str": obj.strftime("%Y%m%dT%H:%M:%S.%f")}
+    return obj
+
+
+def decode_kf(obj):
+    if "__decimal__" in obj:
+        obj = Decimal(obj["as_str"])
+    elif "__datetime__" in obj:
+        obj = datetime.datetime.strptime(obj["as_str"], "%Y%m%dT%H:%M:%S.%f")
+    return obj
+
+
+class ChannelLayer(RedisChannelLayer):
+    def serialize(self, message):
+        """Serializes to a byte string."""
+        value = msgpack.packb(message, default=encode_kf, use_bin_type=True)
+
+        if self.crypter:
+            value = self.crypter.encrypt(value)
+
+        # As we use an sorted set to expire messages
+        # we need to guarantee uniqueness, with 12 bytes.
+        random_prefix = random.getrandbits(8 * 12).to_bytes(12, "big")
+        return random_prefix + value
+
+    def deserialize(self, message):
+        """Deserializes from a byte string."""
+        # Removes the random prefix
+        message = message[12:]
+
+        if self.crypter:
+            message = self.crypter.decrypt(message, self.expiry + 10)
+        return msgpack.unpackb(message, object_hook=decode_kf, raw=False)