Support br encoding/decoding in response bank

Gemfile.lock

@@ -1,7 +1,8 @@
 PATH
   remote: .
   specs:
-    response_bank (1.2.0)
+    response_bank (1.3.0)
+      brotli
       msgpack
 
 GEM
@@ -73,7 +74,9 @@ GEM
       minitest (>= 5.1)
       tzinfo (~> 2.0)
     ast (2.4.2)
+    brotli (0.4.0)
     builder (3.2.4)
+    coderay (1.1.3)
     concurrent-ruby (1.2.2)
     crass (1.0.6)
     date (3.3.3)
@@ -116,6 +119,9 @@ GEM
     parallel (1.22.1)
     parser (3.2.1.1)
       ast (~> 2.4.1)
+    pry (0.14.2)
+      coderay (~> 1.1)
+      method_source (~> 1.0)
     racc (1.6.2)
     rack (2.2.6.4)
     rack-test (2.1.0)
@@ -186,6 +192,7 @@ PLATFORMS
 DEPENDENCIES
   minitest (>= 5.18.0)
   mocha
+  pry
   rails (~> 7.0.4)
   rake
   response_bank!

lib/response_bank.rb

@@ -3,6 +3,7 @@
 require 'response_bank/railtie' if defined?(Rails)
 require 'response_bank/response_cache_handler'
 require 'msgpack'
+require 'brotli'
 
 module ResponseBank
   class << self
@@ -29,17 +30,26 @@ def read_from_backing_cache_store(_env, cache_key, backing_cache_store: cache_st
       backing_cache_store.read(cache_key, raw: true)
     end
 
-    def compress(content)
-      io = StringIO.new
-      gz = Zlib::GzipWriter.new(io)
-      gz.write(content)
-      io.string
-    ensure
-      gz.close
+    def compress(content, encoding = "gzip")
+      case encoding
+      when 'gzip'
+        Zlib.gzip(content, level: Zlib::BEST_COMPRESSION)
+      when 'br'
+        Brotli.deflate(content, mode: :text, quality: 7)
+      else
+        raise ArgumentError, "Unsupported encoding: #{encoding}"
+      end
     end
 
-    def decompress(content)
-      Zlib::GzipReader.new(StringIO.new(content)).read
+    def decompress(content, encoding = "gzip")
+      case encoding
+      when 'gzip'
+        Zlib.gunzip(content)
+      when 'br'
+        Brotli.inflate(content)
+      else
+        raise ArgumentError, "Unsupported encoding: #{encoding}"
+      end
     end
 
     def cache_key_for(data)
@@ -53,6 +63,9 @@ def cache_key_for(data)
 
         key = %{#{key}:#{hash_value_str(data[:version])}} if data[:version]
 
+        # add the encoding to only the cache key but don't expose this detail in the entity_tag
+        key = %{#{key}:#{hash_value_str(data[:encoding])}} if data[:encoding] && data[:encoding] != "gzip"
+
         key
       when Array
         data.inspect
@@ -67,6 +80,17 @@ def cache_key_for(data)
       end
     end
 
+    def check_encoding(env, default_encoding = 'br')
+      if env['HTTP_ACCEPT_ENCODING'].to_s.include?('br')
+        'br'
+      elsif env['HTTP_ACCEPT_ENCODING'].to_s.include?('gzip')
+        'gzip'
+      else
+        # No encoding requested from client, but we still need to cache the page in server cache
+        default_encoding
+      end
+    end
+
     private
 
     def hash_value_str(data)

lib/response_bank/middleware.rb

@@ -16,7 +16,7 @@ def initialize(app)
 
     def call(env)
       env['cacheable.cache'] = false
-      gzip = env['gzip'] = env['HTTP_ACCEPT_ENCODING'].to_s.include?("gzip")
+      content_encoding = env['response_bank.server_cache_encoding'] = ResponseBank.check_encoding(env)
 
       status, headers, body = @app.call(env)
 
@@ -35,11 +35,15 @@ def call(env)
             body.each { |part| body_string << part }
           end
 
-          body_gz = ResponseBank.compress(body_string)
+          body_compressed = nil
+          if body_string && body_string != ""
+            headers['Content-Encoding'] = content_encoding
+            body_compressed = ResponseBank.compress(body_string, content_encoding)
+          end
 
           cached_headers = headers.slice(*CACHEABLE_HEADERS)
           # Store result
-          cache_data = [status, cached_headers, body_gz, timestamp]
+          cache_data = [status, cached_headers, body_compressed, timestamp]
 
           ResponseBank.write_to_cache(env['cacheable.key']) do
             payload = MessagePack.dump(cache_data)
@@ -51,11 +55,15 @@ def call(env)
             )
           end
 
-          # since we had to generate the gz version above already we may
+          # since we had to generate the compressed version already we may
           # as well serve it if the client wants it
-          if gzip
-            headers['Content-Encoding'] = "gzip"
-            body = [body_gz]
+          if body_compressed
+            if env['HTTP_ACCEPT_ENCODING'].to_s.include?(content_encoding)
+              body = [body_compressed]
+            else
+              # Remove content-encoding header for response with compressed content
+              headers.delete('Content-Encoding')
+            end
           end
         end
 

lib/response_bank/response_cache_handler.rb

@@ -55,15 +55,15 @@ def cache_key_hash
     private
 
     def hash(key)
-      "cacheable:#{Digest::MD5.hexdigest(key)}"
+      "cacheable:" + Digest::MD5.hexdigest(key)
     end
 
     def entity_tag
       @entity_tag ||= ResponseBank.cache_key_for(key: @key_data, version: @version_data, key_schema_version: @key_schema_version)
     end
 
     def cache_key
-      @cache_key ||= ResponseBank.cache_key_for(key: @key_data, key_schema_version: @key_schema_version)
+      @cache_key ||= ResponseBank.cache_key_for(key: @key_data, key_schema_version: @key_schema_version, encoding: @env['response_bank.server_cache_encoding'])
     end
 
     def cacheable_info_dump
@@ -143,16 +143,17 @@ def serve_from_cache(cache_key_hash, match_entity_tag = "*", cache_age_tolerance
         # version check
         # unversioned but tolerance threshold
         # regen
-        @headers = @headers.merge(headers)
+        @headers.merge!(headers)
 
-        if @env["gzip"]
-          @headers['Content-Encoding'] = "gzip"
-        else
-          # we have to uncompress because the client doesn't support gzip
-          ResponseBank.log("uncompressing for client without gzip")
-          body = ResponseBank.decompress(body)
+        # if a cache key hit and client doesn't match encoding, return the raw body
+        if !@env['HTTP_ACCEPT_ENCODING'].to_s.include?(@headers['Content-Encoding'])
+          ResponseBank.log("uncompressing payload for client as client doesn't require encoding")
+          body = ResponseBank.decompress(body, @headers['Content-Encoding'])
+          @headers.delete('Content-Encoding')
         end
+
         [status, @headers, [body]]
+
       end
     end
 

lib/response_bank/version.rb

@@ -1,4 +1,4 @@
 # frozen_string_literal: true
 module ResponseBank
-  VERSION = "1.2.2"
+  VERSION = "1.3.0"
 end

response_bank.gemspec

@@ -20,9 +20,11 @@ Gem::Specification.new do |s|
   s.metadata["allowed_push_host"] = "https://rubygems.org"
 
   s.add_runtime_dependency("msgpack")
+  s.add_runtime_dependency("brotli")
 
   s.add_development_dependency("minitest", ">= 5.18.0")
   s.add_development_dependency("mocha", ">= 2.0.0")
   s.add_development_dependency("rake")
   s.add_development_dependency("rails", ">= 6.1")
+  s.add_development_dependency("pry")
 end

test/controller_test.rb

@@ -55,7 +55,7 @@ def test_cache_control_no_store_set_for_uncacheable_requests
   end
 
   def test_server_cache_hit
-    controller.request.env['gzip'] = false
+    controller.request.env['response_bank.server_cache_encoding'] = 'br'
     @cache_store.expects(:read).returns(page_serialized)
     ResponseBank::ResponseCacheHandler.any_instance.expects(:entity_tag_hash).returns('*').at_least_once
     controller.expects(:render).with(plain: '<body>hi.</body>', status: 200)
@@ -64,6 +64,7 @@ def test_server_cache_hit
   end
 
   def test_client_cache_hit
+    controller.request.env['response_bank.server_cache_encoding'] = 'br'
     controller.request.env['HTTP_IF_NONE_MATCH'] = 'deadbeef'
     ResponseBank::ResponseCacheHandler.any_instance.expects(:entity_tag_hash).returns('deadbeef').at_least_once
     controller.expects(:head).with(:not_modified)
@@ -78,6 +79,6 @@ def controller
   end
 
   def page_serialized
-    MessagePack.dump([200, {"Content-Type" => "text/html"}, ResponseBank.compress("<body>hi.</body>"), 1331765506])
+    MessagePack.dump([200, {"Content-Type" => "text/html", "Content-Encoding" => "br"}, ResponseBank.compress("<body>hi.</body>", "br"), 1331765506])
   end
 end