From eb8218b5fc602fa8d89a3fc4317eb9482f42b71d Mon Sep 17 00:00:00 2001
From: Alexander Schepanovski <suor.web@gmail.com>
Date: Tue, 4 Apr 2023 17:56:02 +0700
Subject: [PATCH] Make it work with Redis 6.x and older again

Fixes #449
---
 cacheops/lua/cache_thing.lua           | 10 ++++++++++
 cacheops/lua/cache_thing_insideout.lua | 10 ++++++++++
 cacheops/redis.py                      | 11 +++++++++++
 3 files changed, 31 insertions(+)

diff --git a/cacheops/lua/cache_thing.lua b/cacheops/lua/cache_thing.lua
index 8bf6995d..f4468f41 100644
--- a/cacheops/lua/cache_thing.lua
+++ b/cacheops/lua/cache_thing.lua
@@ -47,6 +47,16 @@ for db_table, disj in pairs(dnfs) do
         redis.call('sadd', conj_key, key)
         -- NOTE: an invalidator should live longer than any key it references.
         --       So we update its ttl on every key if needed.
+        -- REDIS_7
         redis.call('expire', conj_key, timeout, 'gt')
+        -- /REDIS_7
+        -- REDIS_6
+        local conj_ttl = redis.call('ttl', conj_key)
+        if conj_ttl < timeout then
+            -- We set conj_key life with a margin over key life to call expire rarer
+            -- And add few extra seconds to be extra safe
+            redis.call('expire', conj_key, timeout * 2 + 10)
+        end
+        -- /REDIS_6
     end
 end
diff --git a/cacheops/lua/cache_thing_insideout.lua b/cacheops/lua/cache_thing_insideout.lua
index d66f05a8..21f40820 100644
--- a/cacheops/lua/cache_thing_insideout.lua
+++ b/cacheops/lua/cache_thing_insideout.lua
@@ -19,7 +19,17 @@ for _, conj_key in ipairs(conj_keys) do
     table.insert(stamps, stamp)
     -- NOTE: an invalidator should live longer than any key it references.
     --       So we update its ttl on every key if needed.
+    -- REDIS_7
     redis.call('expire', conj_key, timeout, 'gt')
+    -- /REDIS_7
+    -- REDIS_6
+    local conj_ttl = redis.call('ttl', conj_key)
+    if conj_ttl < timeout then
+        -- We set conj_key life with a margin over key life to call expire rarer
+        -- And add few extra seconds to be extra safe
+        redis.call('expire', conj_key, timeout * 2 + 10)
+    end
+    -- /REDIS_6
 end
 
 -- Write data to cache along with a checksum of the stamps to see if any of them changed
diff --git a/cacheops/redis.py b/cacheops/redis.py
index d4ee32c0..e9bc78ae 100644
--- a/cacheops/redis.py
+++ b/cacheops/redis.py
@@ -54,6 +54,7 @@ def redis_client():
 ### Lua script loader
 
 import os.path
+import re
 
 
 @memoize
@@ -61,4 +62,14 @@ def load_script(name):
     filename = os.path.join(os.path.dirname(__file__), 'lua/%s.lua' % name)
     with open(filename) as f:
         code = f.read()
+    if is_redis_7():
+        code = re.sub(r'REDIS_6.*?/REDIS_6', '', code, flags=re.S)
+    else:
+        code = re.sub(r'REDIS_7.*?/REDIS_7', '', code, flags=re.S)
     return redis_client.register_script(code)
+
+
+@memoize
+def is_redis_7():
+    redis_version = redis_client.info('server')['redis_version']
+    return int(redis_version.split('.')[0]) >= 7