Add pluggable cache adapters with Redis support

lib/hawk/http/cache_adapters.rb

@@ -0,0 +1,90 @@
+# frozen_string_literal: true
+
+module Hawk
+  class HTTP
+    module CacheAdapters
+      # Adapter for Memcached via Dalli, preserving existing behavior.
+      class DalliAdapter
+        def initialize(server, options)
+          @server = server
+          @client = Dalli::Client.new(server, options)
+        end
+
+        def get(key)
+          @client.get(key)
+        end
+
+        # For Dalli, the third parameter is TTL in seconds.
+        def set(key, value, ttl)
+          @client.set(key, value, ttl)
+        end
+
+        def delete(key)
+          @client.delete(key)
+        end
+
+        def version
+          @client.version.fetch(@server, nil)
+        rescue StandardError
+          nil
+        end
+      end
+
+      # Adapter for Redis.
+      # Note: requires the 'redis' gem in the host application.
+      class RedisAdapter
+        def initialize(server, options)
+          load_redis_library
+
+          @namespace = options[:namespace]
+          @client    = build_client(server)
+        end
+
+        def get(key)
+          @client.get(namespaced(key))
+        end
+
+        # TTL semantics: seconds, same as Dalli usage.
+        def set(key, value, ttl)
+          k = namespaced(key)
+          if ttl&.to_i&.positive?
+            @client.set(k, value, ex: ttl.to_i)
+          else
+            @client.set(k, value)
+          end
+        end
+
+        def delete(key)
+          @client.del(namespaced(key))
+        end
+
+        def version
+          info = @client.info
+          info['redis_version'] || (info.is_a?(Hash) && info.dig('Server', 'redis_version'))
+        rescue StandardError
+          nil
+        end
+
+        private
+
+        def load_redis_library
+          require 'redis' # lazy load; add `gem 'redis'` to your Gemfile to use
+        end
+
+        def namespaced(key)
+          @namespace ? "#{@namespace}:#{key}" : key
+        end
+
+        def build_client(server)
+          s = server.to_s
+          if s.start_with?('redis://', 'rediss://')
+            Redis.new(url: s)
+          else
+            host, port = s.split(':', 2)
+            Redis.new(host: host || '127.0.0.1', port: (port || 6379).to_i)
+          end
+        end
+      end
+    end
+  end
+end

lib/hawk/http/caching.rb

@@ -1,12 +1,15 @@
 # frozen_string_literal: true
 
 require 'dalli'
+require 'multi_json'
+require 'hawk/http/cache_adapters'
 
 module Hawk
   class HTTP
     module Caching
       DEFAULTS = {
-        server: 'localhost:11211',
+        driver: :dalli,                 # :dalli (default) or :redis
+        server: 'localhost:11211',      # memcached default; for redis use 'redis://host:port' or 'host:port'
         namespace: 'hawk',
         compress: true,
         expires_in: 60,
@@ -112,18 +115,35 @@ def initialize_cache(options)
         end
       end
 
+      def detect_driver(server, explicit = nil)
+        return explicit.to_sym if explicit
+
+        s = server.to_s
+        return :redis if s.start_with?('redis://', 'rediss://')
+
+        :dalli
+      end
+
       def connect_cache(options)
         static_options = options.dup
         static_options.delete(:expires_in)
+        driver = detect_driver(options[:server], options[:driver])
 
-        cache_servers[static_options] ||= begin
+        cache_servers[{ driver: driver, **static_options }] ||= begin
           server = options[:server]
-          client = Dalli::Client.new(server, static_options)
 
-          if version = client.version.fetch(server, nil)
+          client =
+            case driver
+            when :redis
+              Hawk::HTTP::CacheAdapters::RedisAdapter.new(server, static_options)
+            else
+              Hawk::HTTP::CacheAdapters::DalliAdapter.new(server, static_options)
+            end
+
+          if (version = client.version)
             [client, server, version]
           else
-            warn "Hawk: can't connect to memcached server #{server}"
+            warn "Hawk: can't connect to #{driver} cache server #{server}"
             nil
           end
         end

spec/hawk/http/cache_adapters_spec.rb

@@ -0,0 +1,176 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Hawk::HTTP::CacheAdapters do
+  describe Hawk::HTTP::CacheAdapters::DalliAdapter do
+    let(:server) { 'localhost:11211' }
+    let(:options) { { namespace: 'test', compress: true } }
+    let(:dalli_client) { instance_double(Dalli::Client) }
+    let(:adapter) { described_class.new(server, options) }
+
+    before do
+      allow(Dalli::Client).to receive(:new).with(server, options).and_return(dalli_client)
+    end
+
+    describe '#get' do
+      it 'delegates to Dalli client' do
+        expect(dalli_client).to receive(:get).with('key1').and_return('value1')
+        expect(adapter.get('key1')).to eq('value1')
+      end
+    end
+
+    describe '#set' do
+      it 'delegates to Dalli client with TTL' do
+        expect(dalli_client).to receive(:set).with('key1', 'value1', 60)
+        adapter.set('key1', 'value1', 60)
+      end
+    end
+
+    describe '#delete' do
+      it 'delegates to Dalli client' do
+        expect(dalli_client).to receive(:delete).with('key1')
+        adapter.delete('key1')
+      end
+    end
+
+    describe '#version' do
+      it 'fetches version from Dalli client' do
+        version_hash = { server => '1.6.0' }
+        allow(dalli_client).to receive(:version).and_return(version_hash)
+        expect(adapter.version).to eq('1.6.0')
+      end
+
+      it 'returns nil when version fetch fails' do
+        allow(dalli_client).to receive(:version).and_raise(StandardError)
+        expect(adapter.version).to be_nil
+      end
+    end
+  end
+
+  describe Hawk::HTTP::CacheAdapters::RedisAdapter do
+    let(:server) { 'redis://localhost:6379' }
+    let(:adapter) { described_class.new(server, options) }
+    let(:options) { { namespace: 'hawk' } }
+    let(:redis_client) { instance_double(Redis) }
+
+    before do
+      # Stub the Redis gem loading
+      allow_any_instance_of(described_class).to receive(:load_redis_library)
+
+      # Create a mock Redis class that accepts new with any arguments
+      redis_class = Class.new do
+        def self.new(*_args, **_kwargs)
+          # This will be stubbed in individual tests
+        end
+      end
+      stub_const('Redis', redis_class)
+      allow(Redis).to receive(:new).and_return(redis_client)
+    end
+
+    describe '#initialize' do
+      context 'with redis:// URL' do
+        it 'creates Redis client with URL' do
+          expect(Redis).to receive(:new).with(url: 'redis://localhost:6379')
+          described_class.new('redis://localhost:6379', options)
+        end
+      end
+
+      context 'with rediss:// URL' do
+        it 'creates Redis client with URL' do
+          expect(Redis).to receive(:new).with(url: 'rediss://localhost:6379')
+          described_class.new('rediss://localhost:6379', options)
+        end
+      end
+
+      context 'with host:port format' do
+        it 'creates Redis client with host and port' do
+          expect(Redis).to receive(:new).with(host: 'localhost', port: 6380)
+          described_class.new('localhost:6380', { namespace: 'test' })
+        end
+      end
+
+      context 'with just host' do
+        it 'creates Redis client with default port' do
+          expect(Redis).to receive(:new).with(host: 'myredis', port: 6379)
+          described_class.new('myredis', { namespace: 'test' })
+        end
+      end
+    end
+
+    describe '#get' do
+      it 'delegates to Redis client with namespaced key' do
+        expect(redis_client).to receive(:get).with('hawk:key1').and_return('value1')
+        expect(adapter.get('key1')).to eq('value1')
+      end
+
+      context 'without namespace' do
+        let(:options) { {} }
+
+        it 'uses key without namespace' do
+          expect(redis_client).to receive(:get).with('key1').and_return('value1')
+          expect(adapter.get('key1')).to eq('value1')
+        end
+      end
+    end
+
+    describe '#set' do
+      it 'delegates to Redis client with namespaced key and TTL' do
+        expect(redis_client).to receive(:set).with('hawk:key1', 'value1', ex: 60)
+        adapter.set('key1', 'value1', 60)
+      end
+
+      it 'sets without TTL when ttl is nil' do
+        expect(redis_client).to receive(:set).with('hawk:key1', 'value1')
+        adapter.set('key1', 'value1', nil)
+      end
+
+      it 'sets without TTL when ttl is 0' do
+        expect(redis_client).to receive(:set).with('hawk:key1', 'value1')
+        adapter.set('key1', 'value1', 0)
+      end
+
+      context 'without namespace' do
+        let(:options) { {} }
+
+        it 'uses key without namespace' do
+          expect(redis_client).to receive(:set).with('key1', 'value1', ex: 60)
+          adapter.set('key1', 'value1', 60)
+        end
+      end
+    end
+
+    describe '#delete' do
+      it 'delegates to Redis client with namespaced key' do
+        expect(redis_client).to receive(:del).with('hawk:key1')
+        adapter.delete('key1')
+      end
+
+      context 'without namespace' do
+        let(:options) { {} }
+
+        it 'uses key without namespace' do
+          expect(redis_client).to receive(:del).with('key1')
+          adapter.delete('key1')
+        end
+      end
+    end
+
+    describe '#version' do
+      it 'fetches version from Redis INFO' do
+        allow(redis_client).to receive(:info).and_return({ 'redis_version' => '6.2.0' })
+        expect(adapter.version).to eq('6.2.0')
+      end
+
+      it 'fetches version from nested Server hash' do
+        allow(redis_client).to receive(:info).and_return({ 'Server' => { 'redis_version' => '7.0.0' } })
+        expect(adapter.version).to eq('7.0.0')
+      end
+
+      it 'returns nil when version fetch fails' do
+        allow(redis_client).to receive(:info).and_raise(StandardError)
+        expect(adapter.version).to be_nil
+      end
+    end
+  end
+end