Implement incr/decr commands

https://github.com/membase/memcached/blob/61cb72e0/include/memcached/protocol_binary.h#L339-L371

README.markdown

@@ -13,5 +13,12 @@ Like any Deferrable eventmachine-based protocol implementation, using EM-Couchba
           end
         end
       end
+      couchbase.incr "bar", :initial => 100500 do |response|
+        if response.success?
+          couchbase.get "bar" do |response|
+            puts response.inspect
+            EM.stop
+          end
+        end
+      end
     end
-

lib/em-couchbase/client.rb

@@ -164,6 +164,28 @@ def get(*keys, &block)
           end
         end
 
+        def incr(key, options = {}, &block)
+          callback do
+            opaque = opaque_inc
+            register_handler(opaque, key, block)
+            vbucket, node = locate(key)
+            node.callback do
+              node.arithm(:incr, opaque, vbucket, key, options)
+            end
+          end
+        end
+
+        def decr(key, options = {}, &block)
+          callback do
+            opaque = opaque_inc
+            register_handler(opaque, key, block)
+            vbucket, node = locate(key)
+            node.callback do
+              node.arithm(:decr, opaque, vbucket, key, options)
+            end
+          end
+        end
+
         protected
 
         def unbind

lib/em-couchbase/node.rb

@@ -71,6 +71,20 @@ def set(opaque, vbucket, key, value, options = {})
           send_data(packet)
         end
 
+        def arithm(opcode, opaque, vbucket, key, options = {})
+          if options.is_a?(Fixnum)
+            options = {:delta => options}
+          end
+          packet = Packet.build(opaque, vbucket,
+                                opcode, key,
+                                options[:delta],
+                                options[:initial],
+                                options[:expiration],
+                                options[:cas])
+          client.register_packet(opaque, packet)
+          send_data(packet)
+        end
+
         # @param opaque [Fixnum]
         # @param pairs [Array] array of tuples +[opaque, vbucket, key]+
         # @param options [Hash]

lib/em-couchbase/packet.rb

@@ -117,6 +117,29 @@ def self.build(opaque, vbucket, opcode, *args)
               0,                # uint64_t  cas
               key
             ].pack("#{REQUEST_HEADER_FMT}a*")
+          when :incr, :decr
+            cmd_id = opcode == :incr ? CMD_INCREMENT : CMD_DECREMENT
+            key, delta, initial, expiration, cas = args.shift(5)
+            delta ||= 1
+            initial ||= 0
+            bodylen = key.size + 20
+            [
+              0x80,                   # uint8_t   magic
+              cmd_id,                 # uint8_t   opcode
+              key.size,               # uint16_t  keylen
+              20,                     # uint8_t   extlen (delta + initial + expiration)
+              0,                      # uint8_t   datatype
+              vbucket,                # uint16_t  vbucket
+              bodylen,                # uint32_t  bodylen
+              opaque || 0,            # uint32_t  opaque
+              cas || 0,               # uint64_t  cas
+              delta >> 32,            # uint64_t
+              delta & 0xffffffff,     #
+              initial >> 32,          # uint64_t
+              initial & 0xffffffff,   #
+              expiration || 0,        # uint32_t
+              key
+            ].pack("#{REQUEST_HEADER_FMT}NNNNNa*")
           when :sasl_auth
             mech, username, password = args.shift(3)
             value = "\0#{username}\0#{password}"
@@ -185,6 +208,14 @@ def self.parse(data)
             when CMD_GET
               result.operation = :get
               result.flags, _ = ext.unpack("N")
+            when CMD_INCREMENT
+              result.operation = :incr
+              hi, lo = result.value.unpack("NN")
+              result.value = hi << 32 | lo
+            when CMD_DECREMENT
+              result.operation = :decr
+              hi, lo = result.value.unpack("NN")
+              result.value = hi << 32 | lo
             else
               raise Couchbase::Error::UnknownCommand, header.inspect
             end