example adding support for arbitrary meta flags and for getting them back as part of the response

Author: danmayer

.gitignore

@@ -25,6 +25,7 @@ profile.html
 ## Environment normalisation:
 /.bundle/
 /lib/bundler/man/
+dev.yml
 
 # for a library or gem, you might want to ignore these files since the code is
 # intended to run in multiple environments; otherwise, check them in:

lib/dalli/protocol/base.rb

@@ -197,6 +197,12 @@ def ensure_connected!
         connected?
       end
 
+      def meta_flag_options(opts)
+        return nil unless opts.is_a?(Hash)
+
+        opts[:meta_flags]
+      end
+
       def cache_nils?(opts)
         return false unless opts.is_a?(Hash)
 

lib/dalli/protocol/meta.rb

@@ -25,9 +25,13 @@ def response_processor
       # Retrieval Commands
       def get(key, options = nil)
         encoded_key, base64 = KeyRegularizer.encode(key)
-        req = RequestFormatter.meta_get(key: encoded_key, base64: base64)
+        req = RequestFormatter.meta_get(key: encoded_key, base64: base64, meta_flags: meta_flag_options(options))
         write(req)
-        response_processor.meta_get_with_value(cache_nils: cache_nils?(options))
+        if meta_flag_options(options)
+          response_processor.meta_get_with_value_and_meta_flags(cache_nils: cache_nils?(options))
+        else
+          response_processor.meta_get_with_value(cache_nils: cache_nils?(options))
+        end
       end
 
       def quiet_get_request(key)
@@ -38,9 +42,13 @@ def quiet_get_request(key)
       def gat(key, ttl, options = nil)
         ttl = TtlSanitizer.sanitize(ttl)
         encoded_key, base64 = KeyRegularizer.encode(key)
-        req = RequestFormatter.meta_get(key: encoded_key, ttl: ttl, base64: base64)
+        req = RequestFormatter.meta_get(key: encoded_key, ttl: ttl, base64: base64, meta_flags: meta_flag_options(options))
         write(req)
-        response_processor.meta_get_with_value(cache_nils: cache_nils?(options))
+        if meta_flag_options(options)
+          response_processor.meta_get_with_value_and_meta_flags(cache_nils: cache_nils?(options))
+        else
+          response_processor.meta_get_with_value(cache_nils: cache_nils?(options))
+        end
       end
 
       def touch(key, ttl)

lib/dalli/protocol/meta/request_formatter.rb

@@ -16,12 +16,13 @@ class RequestFormatter
         # rubocop:disable Metrics/MethodLength
         # rubocop:disable Metrics/ParameterLists
         # rubocop:disable Metrics/PerceivedComplexity
-        def self.meta_get(key:, value: true, return_cas: false, ttl: nil, base64: false, quiet: false)
+        def self.meta_get(key:, value: true, return_cas: false, ttl: nil, base64: false, quiet: false, meta_flags: nil)
           cmd = "mg #{key}"
           cmd << ' v f' if value
           cmd << ' c' if return_cas
           cmd << ' b' if base64
           cmd << " T#{ttl}" if ttl
+          cmd << " #{meta_flags.join(' ')}" if meta_flags
           cmd << ' k q s' if quiet # Return the key in the response if quiet
           cmd + TERMINATOR
         end

lib/dalli/protocol/meta/response_processor.rb

@@ -45,6 +45,23 @@ def meta_get_with_value_and_cas
           [@value_marshaller.retrieve(read_data(tokens[1].to_i), bitflags_from_tokens(tokens)), cas]
         end
 
+        def meta_get_with_value_and_meta_flags(cache_nils: false)
+          tokens = error_on_unexpected!([VA, EN, HD])
+          return [(cache_nils ? ::Dalli::NOT_FOUND : nil), {}] if tokens.first == EN
+
+          meta_flags = {
+            c: cas_from_tokens(tokens),
+            h: hit_from_tokens(tokens),
+            l: last_accessed_from_tokens(tokens),
+            t: ttl_remaining_from_tokens(tokens),
+          }
+          return [(cache_nils ? ::Dalli::NOT_FOUND : nil), meta_flags] unless tokens.first == VA
+
+          value, bitflag = @value_marshaller.retrieve(read_data(tokens[1].to_i), bitflags_from_tokens(tokens))
+          meta_flags[:bitflag] = bitflag
+          [value, meta_flags]
+        end
+
         def meta_get_without_value
           tokens = error_on_unexpected!([EN, HD])
           tokens.first == EN ? nil : true
@@ -180,6 +197,18 @@ def cas_from_tokens(tokens)
           value_from_tokens(tokens, 'c')&.to_i
         end
 
+        def hit_from_tokens(tokens)
+          value_from_tokens(tokens, 'h')&.to_i != 0
+        end
+
+        def last_accessed_from_tokens(tokens)
+          value_from_tokens(tokens, 'l')&.to_i
+        end
+
+        def ttl_remaining_from_tokens(tokens)
+          value_from_tokens(tokens, 't')&.to_i
+        end
+
         def key_from_tokens(tokens)
           encoded_key = value_from_tokens(tokens, 'k')
           base64_encoded = tokens.any?('b')

test/integration/test_operations.rb

@@ -38,6 +38,27 @@
           end
         end
 
+        it 'return the value and the meta flags' do
+          memcached_persistent(p) do |dc|
+            skip 'not supported' if p == :binary
+            dc.flush
+
+            val1 = "meta"
+            dc.set('meta_key', val1)
+            response = dc.get('meta_key', meta_flags: [:l, :h, :t])
+            # ensure hit true and last accessed 0
+            response = dc.get('meta_key', meta_flags: [:l, :h, :t])
+            val2 = response.first
+            meta_flags = response.last
+
+            assert_equal val1, val2
+            assert_equal meta_flags, {c: 0, l: 0, h: true, t: -1, bitflag: nil}
+
+            assert op_addset_succeeds(dc.set('a', nil))
+            assert_nil dc.get('a')
+          end
+        end
+
         it 'returns nil on a miss' do
           memcached_persistent(p) do |dc|
             assert_nil dc.get('notexist')