Drop redis prior to 4.0 support

README.rst

@@ -19,7 +19,7 @@ And there is more to it:
 Requirements
 ------------
 
-| Python 3.5+, Django 2.1+ and Redis 2.6+ (4.0+ recommended)
+| Python 3.5+, Django 2.1+ and Redis 4.0+
 
 
 Installation

cacheops/invalidation.py

@@ -3,7 +3,6 @@
 from funcy import memoize, post_processing, ContextDecorator
 from django.db import DEFAULT_DB_ALIAS
 from django.db.models.expressions import F, Expression
-from distutils.version import StrictVersion
 
 from .conf import settings
 from .sharding import get_prefix
@@ -15,27 +14,14 @@
 __all__ = ('invalidate_obj', 'invalidate_model', 'invalidate_all', 'no_invalidation')
 
 
-@memoize
-def redis_can_unlink():
-    redis_version = redis_client.info()['redis_version']
-    return StrictVersion(redis_version) >= StrictVersion('4.0')
-
-
-def invalidate_keys(*keys):
-    if redis_can_unlink():
-        redis_client.execute_command('UNLINK', *keys)
-    else:
-        redis_client.delete(*keys)
-
-
 @queue_when_in_transaction
 @handle_connection_failure
 def invalidate_dict(model, obj_dict, using=DEFAULT_DB_ALIAS):
     if no_invalidation.active or not settings.CACHEOPS_ENABLED:
         return
     model = model._meta.concrete_model
     prefix = get_prefix(_cond_dnfs=[(model._meta.db_table, list(obj_dict.items()))], dbs=[using])
-    load_script('invalidate', strip=redis_can_unlink())(keys=[prefix], args=[
+    load_script('invalidate')(keys=[prefix], args=[
         model._meta.db_table,
         json.dumps(obj_dict, default=str)
     ])
@@ -68,7 +54,7 @@ def invalidate_model(model, using=DEFAULT_DB_ALIAS):
     if conjs_keys:
         cache_keys = redis_client.sunion(conjs_keys)
         keys = list(cache_keys) + conjs_keys
-        invalidate_keys(*keys)
+        redis_client.unlink(*keys)
     cache_invalidated.send(sender=model, obj_dict=None)
 
 

cacheops/lua/invalidate.lua

@@ -1,11 +1,6 @@
 local prefix = KEYS[1]
 local db_table = ARGV[1]
 local obj = cjson.decode(ARGV[2])
-local conj_del_fn = 'unlink'
--- If Redis version < 4.0 we can't use UNLINK
--- TOSTRIP
-conj_del_fn = 'del'
--- /TOSTRIP
 
 -- Utility functions
 local conj_cache_key = function (db_table, scheme, obj)
@@ -38,7 +33,7 @@ if next(conj_keys) ~= nil then
     local cache_keys = redis.call('sunion', unpack(conj_keys))
     -- we delete cache keys since they are invalid
     -- and conj keys as they will refer only deleted keys
-    redis.call(conj_del_fn, unpack(conj_keys))
+    redis.call("unlink", unpack(conj_keys))
     if next(cache_keys) ~= nil then
         -- NOTE: can't just do redis.call('del', unpack(...)) cause there is limit on number
         --       of return values in lua.