From 16744040382bbdc12e4498b38dbc31e8f2ac7e0c Mon Sep 17 00:00:00 2001
From: Jian Weihang <tonytonyjan@gmail.com>
Date: Thu, 9 Apr 2026 21:14:53 +0800
Subject: [PATCH] feat: support redis v4

In redis v4, the client inside a `Redis` instance is stateful and it will [replace the client](https://github.com/redis/redis-rb/blob/v4.8.1/lib/redis.rb#L225) inside the `Redis#multi` block, which is different from v5.

It causes the issue that the `Redis::Future` instance is returned instead of the actual value when calling any command inside the `Redis#multi` block, which is not expected in our case.

```ruby
redis.multi do
  redis.get('foo').class
  # => Redis::Future in v4
  # => NilClass in v5
end
```
---
 lib/cover_rage/stores/redis.rb | 28 +++++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/lib/cover_rage/stores/redis.rb b/lib/cover_rage/stores/redis.rb
index a3e233b..f7aeacb 100644
--- a/lib/cover_rage/stores/redis.rb
+++ b/lib/cover_rage/stores/redis.rb
@@ -9,13 +9,10 @@ module CoverRage
   module Stores
     class Redis
       KEY = 'cover_rage_records'
+      IS_REDIS_BELOW_V5 = Gem::Version.new(::Redis::VERSION) < Gem::Version.new('5')
       def initialize(url)
-        @redis =
-          if url.start_with?('rediss')
-            ::Redis.new(url:, ssl_params: { verify_mode: OpenSSL::SSL::VERIFY_NONE })
-          else
-            ::Redis.new(url:)
-          end
+        @redis = new_redis(url)
+        @redis_for_below_v5 = new_redis(url) if IS_REDIS_BELOW_V5
       end
 
       def transaction(&)
@@ -42,7 +39,14 @@ def update(records)
       end
 
       def list
-        result = @redis.hgetall(KEY)
+        # For Redis versions below 5, we need to use the separate client to read
+        # the data while the transaction is in progress.
+        client = if Thread.current[:redis_multi] && IS_REDIS_BELOW_V5
+                   @redis_for_below_v5
+                 else
+                   @redis
+                 end
+        result = client.hgetall(KEY)
         return [] if result.empty?
 
         result.map { |_, value| Record.new(**JSON.parse(value)) }
@@ -51,6 +55,16 @@ def list
       def clear
         @redis.del(KEY)
       end
+
+      private
+
+      def new_redis(url)
+        if url.start_with?('rediss')
+          ::Redis.new(url:, ssl_params: { verify_mode: OpenSSL::SSL::VERIFY_NONE })
+        else
+          ::Redis.new(url:)
+        end
+      end
     end
   end
 end