Update memcache settings

Updated to reflect current recommendations for Memcachier on Heroku.
It's unclear whether this was necessary (but it works); an error on
deploy may have been due to some other configuration issue.

open_humans/settings.py

@@ -449,28 +449,31 @@ def to_bool(env, default="false"):
 
 SITE_ID = 1
 
+
 # This way of setting the memcache options is advised by MemCachier here:
 # https://devcenter.heroku.com/articles/memcachier#django
 if ENV in ["production", "staging"]:
-    memcache_servers = os.getenv("MEMCACHIER_SERVERS", "").replace(",", ";")
+    memcache_servers = os.getenv("MEMCACHIER_SERVERS", None)
+    memcache_username = os.getenv("MEMCACHIER_USERNAME", None)
+    memcache_password = os.getenv("MEMCACHIER_PASSWORD", None)
 
-    memcache_username = os.getenv("MEMCACHIER_USERNAME")
-    memcache_password = os.getenv("MEMCACHIER_PASSWORD")
+    if memcache_servers and memcache_username and memcache_password:
+        CACHES = {
+            "default": {
+                # Use django-bmemcached
+                "BACKEND": "django_bmemcached.memcached.BMemcached",
 
-    if memcache_servers:
-        os.environ["MEMCACHE_SERVERS"] = memcache_servers
+                # TIMEOUT is default expiration for keys; None disables expiration.
+                "TIMEOUT": None,
 
-    if memcache_username and memcache_password:
-        os.environ["MEMCACHE_USERNAME"] = memcache_username
-        os.environ["MEMCACHE_PASSWORD"] = memcache_password
+                "LOCATION": memcache_servers,
 
-CACHES = {
-    "default": {
-        "BACKEND": "django_pylibmc.memcached.PyLibMCCache",
-        "BINARY": True,
-        "OPTIONS": {"ketama": True, "tcp_nodelay": True},
-    }
-}
+                "OPTIONS": {
+                    "username": memcache_username,
+                    "password": memcache_password,
+                }
+            }
+        }
 
 if DISABLE_CACHING:
     CACHES = {"default": {"BACKEND": "django.core.cache.backends.dummy.DummyCache"}}

requirements.in

@@ -14,6 +14,7 @@ dj-database-url
 Django==2.2.13
 django-appconf
 django-autoslug
+django-bmemcached
 django-bootstrap-pagination
 django-cors-headers
 django-debug-toolbar
@@ -23,7 +24,6 @@ django-forms-bootstrap
 django-heroku
 django-ipware
 django-oauth-toolkit
-django-pylibmc
 django-recaptcha
 django-storages
 django-waffle
@@ -39,7 +39,6 @@ mailchimp
 Markdown
 mock
 Pillow  # for sorl-thumbnail
-pylibmc==1.5.2 # Note that memcache on heroku doesn't like the new version, so lock it here.
 pyparsing
 raven
 redis

requirements.txt

@@ -74,6 +74,8 @@ django-appconf==1.0.4
     # via -r requirements.in
 django-autoslug==1.9.7
     # via -r requirements.in
+django-bmemcached==0.3.0
+    # via -r requirements.in
 django-bootstrap-pagination==1.7.1
     # via -r requirements.in
 django-cors-headers==3.2.1
@@ -98,8 +100,6 @@ django-ipware==2.1.0
     # via -r requirements.in
 django-oauth-toolkit==1.3.2
     # via -r requirements.in
-django-pylibmc==0.6.1
-    # via -r requirements.in
 django-recaptcha==2.0.6
     # via -r requirements.in
 django-storages==1.9.1
@@ -164,12 +164,10 @@ pycparser==2.20
     # via cffi
 pyjwt[crypto]==1.7.1
     # via django-allauth
-pylibmc==1.5.2
-    # via
-    #   -r requirements.in
-    #   django-pylibmc
 pyparsing==2.4.7
     # via -r requirements.in
+python-binary-memcached==0.30.1
+    # via django-bmemcached
 python-dateutil==2.8.1
     # via
     #   arrow
@@ -208,6 +206,7 @@ six==1.14.0
     #   django-extensions
     #   django-waffle
     #   env-tools
+    #   python-binary-memcached
     #   python-dateutil
     #   tini
 sorl-thumbnail==12.6.3
@@ -224,6 +223,8 @@ text-unidecode==1.3
     # via faker
 tini==3.0.1
     # via env-tools
+uhashring==2.1
+    # via python-binary-memcached
 urllib3==1.25.9
     # via
     #   botocore