Add support for connection pooling on RedisCacheStore

Gemfile

@@ -52,7 +52,7 @@ end
 gem "dalli", ">= 2.2.1"
 gem "listen", ">= 3.0.5", "< 3.2", require: false
 gem "libxml-ruby", platforms: :ruby
-gem "connection_pool"
+gem "connection_pool", require: false
 
 # for railties app_generator_test
 gem "bootsnap", ">= 1.1.0", require: false

activesupport/CHANGELOG.md

+*   Add support for connection pooling on RedisCacheStore.
 
+    *fatkodima*
 
 Please check [5-2-stable](https://github.com/rails/rails/blob/5-2-stable/activesupport/CHANGELOG.md) for previous changes.

activesupport/lib/active_support/cache.rb

@@ -160,6 +160,23 @@ class Store
       attr_reader :silence, :options
       alias :silence? :silence
 
+      class << self
+        private
+          def retrieve_pool_options(options)
+            {}.tap do |pool_options|
+              pool_options[:size] = options.delete(:pool_size) if options[:pool_size]
+              pool_options[:timeout] = options.delete(:pool_timeout) if options[:pool_timeout]
+            end
+          end
+
+          def ensure_connection_pool_added!
+            require "connection_pool"
+          rescue LoadError => e
+            $stderr.puts "You don't have connection_pool installed in your application. Please add it to your Gemfile and run bundle install"
+            raise e
+          end
+      end
+
       # Creates a new cache. The options will be passed to any write method calls
       # except for <tt>:namespace</tt> which can be used to set the global
       # namespace for the cache.

activesupport/lib/active_support/cache/mem_cache_store.rb

@@ -63,21 +63,12 @@ def self.build_mem_cache(*addresses) # :nodoc:
         addresses = addresses.flatten
         options = addresses.extract_options!
         addresses = ["localhost:11211"] if addresses.empty?
-
-        pool_options = {}
-        pool_options[:size] = options[:pool_size] if options[:pool_size]
-        pool_options[:timeout] = options[:pool_timeout] if options[:pool_timeout]
+        pool_options = retrieve_pool_options(options)
 
         if pool_options.empty?
           Dalli::Client.new(addresses, options)
         else
-          begin
-            require "connection_pool"
-          rescue LoadError => e
-            $stderr.puts "You don't have connection_pool installed in your application. Please add it to your Gemfile and run bundle install"
-            raise e
-          end
-
+          ensure_connection_pool_added!
           ConnectionPool.new(pool_options) { Dalli::Client.new(addresses, options.merge(threadsafe: false)) }
         end
       end

activesupport/lib/active_support/cache/redis_cache_store.rb

@@ -20,6 +20,15 @@
 
 module ActiveSupport
   module Cache
+    module ConnectionPoolLike
+      def with
+        yield self
+      end
+    end
+
+    ::Redis.include(ConnectionPoolLike)
+    ::Redis::Distributed.include(ConnectionPoolLike)
+
     # Redis cache store.
     #
     # Deployment note: Take care to use a *dedicated Redis cache* rather
@@ -172,7 +181,16 @@ def initialize(namespace: nil, compress: true, compress_threshold: 1.kilobyte, e
       end
 
       def redis
-        @redis ||= self.class.build_redis(**redis_options)
+        @redis ||= begin
+          pool_options = self.class.send(:retrieve_pool_options, redis_options)
+
+          if pool_options.any?
+            self.class.send(:ensure_connection_pool_added!)
+            ::ConnectionPool.new(pool_options) { self.class.build_redis(**redis_options) }
+          else
+            self.class.build_redis(**redis_options)
+          end
+        end
       end
 
       def inspect
@@ -211,7 +229,7 @@ def delete_matched(matcher, options = nil)
         instrument :delete_matched, matcher do
           case matcher
           when String
-            redis.eval DELETE_GLOB_LUA, [], [namespace_key(matcher, options)]
+            redis.with { |c| c.eval DELETE_GLOB_LUA, [], [namespace_key(matcher, options)] }
           else
             raise ArgumentError, "Only Redis glob strings are supported: #{matcher.inspect}"
           end
@@ -229,7 +247,7 @@ def delete_matched(matcher, options = nil)
       def increment(name, amount = 1, options = nil)
         instrument :increment, name, amount: amount do
           failsafe :increment do
-            redis.incrby normalize_key(name, options), amount
+            redis.with { |c| c.incrby normalize_key(name, options), amount }
           end
         end
       end
@@ -245,7 +263,7 @@ def increment(name, amount = 1, options = nil)
       def decrement(name, amount = 1, options = nil)
         instrument :decrement, name, amount: amount do
           failsafe :decrement do
-            redis.decrby normalize_key(name, options), amount
+            redis.with { |c| c.decrby normalize_key(name, options), amount }
           end
         end
       end
@@ -267,7 +285,7 @@ def clear(options = nil)
           if namespace = merged_options(options)[namespace]
             delete_matched "*", namespace: namespace
           else
-            redis.flushdb
+            redis.with { |c| c.flushdb }
           end
         end
       end
@@ -298,7 +316,7 @@ def set_redis_capabilities
         # Read an entry from the cache.
         def read_entry(key, options = nil)
           failsafe :read_entry do
-            deserialize_entry redis.get(key)
+            deserialize_entry redis.with { |c| c.get(key) }
           end
         end
 
@@ -309,7 +327,7 @@ def read_multi_mget(*names)
           keys = names.map { |name| normalize_key(name, options) }
 
           values = failsafe(:read_multi_mget, returning: {}) do
-            redis.mget(*keys)
+            redis.with { |c| c.mget(*keys) }
           end
 
           names.zip(values).each_with_object({}) do |(name, value), results|
@@ -341,9 +359,9 @@ def write_entry(key, entry, unless_exist: false, raw: false, expires_in: nil, ra
               modifiers[:nx] = unless_exist
               modifiers[:px] = (1000 * expires_in.to_f).ceil if expires_in
 
-              redis.set key, value, modifiers
+              redis.with { |c| c.set key, value, modifiers }
             else
-              redis.set key, value
+              redis.with { |c| c.set key, value }
             end
           end
         end
@@ -351,7 +369,7 @@ def write_entry(key, entry, unless_exist: false, raw: false, expires_in: nil, ra
         # Delete an entry from the cache.
         def delete_entry(key, options)
           failsafe :delete_entry, returning: false do
-            redis.del key
+            redis.with { |c| c.del key }
           end
         end
 
@@ -360,7 +378,7 @@ def write_multi_entries(entries, expires_in: nil, **options)
           if entries.any?
             if mset_capable? && expires_in.nil?
               failsafe :write_multi_entries do
-                redis.mapped_mset(entries)
+                redis.with { |c| c.mapped_mset(entries) }
               end
             else
               super

activesupport/test/cache/behaviors/connection_pool_behavior.rb

@@ -6,7 +6,7 @@ def test_connection_pool
 
     emulating_latency do
       begin
-        cache = ActiveSupport::Cache.lookup_store(store, pool_size: 2, pool_timeout: 1)
+        cache = ActiveSupport::Cache.lookup_store(store, { pool_size: 2, pool_timeout: 1 }.merge(store_options))
         cache.clear
 
         threads = []
@@ -33,7 +33,7 @@ def test_connection_pool
   def test_no_connection_pool
     emulating_latency do
       begin
-        cache = ActiveSupport::Cache.lookup_store(store)
+        cache = ActiveSupport::Cache.lookup_store(store, store_options)
         cache.clear
 
         threads = []
@@ -54,4 +54,7 @@ def test_no_connection_pool
       end
     end
   end
+
+  private
+    def store_options; {}; end
 end

activesupport/test/cache/stores/redis_cache_store_test.rb

@@ -5,6 +5,24 @@
 require "active_support/cache/redis_cache_store"
 require_relative "../behaviors"
 
+driver_name = %w[ ruby hiredis ].include?(ENV["REDIS_DRIVER"]) ? ENV["REDIS_DRIVER"] : "hiredis"
+driver = Object.const_get("Redis::Connection::#{driver_name.camelize}")
+
+Redis::Connection.drivers.clear
+Redis::Connection.drivers.append(driver)
+
+# Emulates a latency on Redis's back-end for the key latency to facilitate
+# connection pool testing.
+class SlowRedis < Redis
+  def get(key, options = {})
+    if key =~ /latency/
+      sleep 3
+    else
+      super
+    end
+  end
+end
+
 module ActiveSupport::Cache::RedisCacheStoreTests
   DRIVER = %w[ ruby hiredis ].include?(ENV["REDIS_DRIVER"]) ? ENV["REDIS_DRIVER"] : "hiredis"
 
@@ -110,6 +128,33 @@ class RedisCacheStoreCommonBehaviorTest < StoreTest
     include AutoloadingCacheBehavior
   end
 
+  class ConnectionPoolBehaviourTest < StoreTest
+    include ConnectionPoolBehavior
+
+    private
+
+      def store
+        :redis_cache_store
+      end
+
+      def emulating_latency
+        old_redis = Object.send(:remove_const, :Redis)
+        Object.const_set(:Redis, SlowRedis)
+
+        yield
+      ensure
+        Object.send(:remove_const, :Redis)
+        Object.const_set(:Redis, old_redis)
+      end
+  end
+
+  class RedisDistributedConnectionPoolBehaviourTest < ConnectionPoolBehaviourTest
+    private
+      def store_options
+        { url: %w[ redis://localhost:6379/0 redis://localhost:6379/0 ] }
+      end
+  end
+
   # Separate test class so we can omit the namespace which causes expected,
   # appropriate complaints about incompatible string encodings.
   class KeyEncodingSafetyTest < StoreTest