DEV: Readonly Redis support for `DiscourseRedis#multi/pipelined` (#16744)

Follow-up to 2df3c65ba9

lib/discourse_redis.rb

@@ -151,6 +151,7 @@ class DiscourseRedis
   end
 
   def multi
+    DiscourseRedis.ignore_readonly do
       if block_given?
         @redis.multi do |transaction|
           yield DiscourseRedis.new(@config, namespace: @namespace, raw_redis: transaction)
@@ -159,8 +160,10 @@ class DiscourseRedis
         @redis.multi
       end
     end
+  end
 
   def pipelined
+    DiscourseRedis.ignore_readonly do
       if block_given?
         @redis.pipelined do |transaction|
           yield DiscourseRedis.new(@config, namespace: @namespace, raw_redis: transaction)
@@ -169,6 +172,7 @@ class DiscourseRedis
         @redis.pipelined
       end
     end
+  end
 
   private
 

spec/lib/discourse_redis_spec.rb

@@ -52,7 +52,39 @@ describe DiscourseRedis do
 
         expect(redis.get('foo')).to eq("baz")
         expect(redis.get('baz')).to eq("1")
+      end
 
+      it 'should noop pipelined commands against a readonly redis' do
+        redis.without_namespace
+          .expects(:pipelined)
+          .raises(Redis::CommandError.new("READONLY"))
+
+        set, incr = nil
+
+        val = redis.pipelined do |pipeline|
+          set = pipeline.set "foo", "baz"
+          incr = pipeline.incr "baz"
+        end
+
+        expect(val).to eq(nil)
+        expect(redis.get('foo')).to eq(nil)
+        expect(redis.get('baz')).to eq(nil)
+      end
+
+      it 'should noop multi commands against a readonly redis' do
+        redis.without_namespace
+          .expects(:multi)
+          .raises(Redis::CommandError.new("READONLY"))
+
+        val = redis.multi do |transaction|
+          transaction.set 'foo', 'bar'
+          transaction.set 'bar', 'foo'
+          transaction.get 'bar'
+        end
+
+        expect(val).to eq(nil)
+        expect(redis.get('foo')).to eq(nil)
+        expect(redis.get('bar')).to eq(nil)
       end
     end