[Performance Optimization] Use read instead of readfull

CHANGELOG.md

@@ -7,6 +7,7 @@ Unreleased
 - Fix cannot read response data included terminator `\r\n` when use meta protocol (matsubara0507)
 - Support SERVER_ERROR response from Memcached as per the [memcached spec](https://github.com/memcached/memcached/blob/e43364402195c8e822bb8f88755a60ab8bbed62a/doc/protocol.txt#L172) (grcooper)
 - Update Socket timeout handling to use Socket#timeout= when available (nickamorim)
+- Remove Socket#readfull and replace with standard read method (grcooper)
 
 3.2.8
 ==========

lib/dalli/protocol/connection_manager.rb

@@ -155,7 +155,7 @@ def read_line
       end
 
       def read(count)
-        @sock.readfull(count)
+        @sock.read(count)
       rescue SystemCallError, *TIMEOUT_ERRORS, EOFError => e
         error_on_request!(e)
       end

lib/dalli/socket.rb

@@ -12,16 +12,7 @@ module Socket
     # Common methods for all socket implementations.
     ##
     module InstanceMethods
-      def readfull(count)
-        value = String.new(capacity: count + 1)
-        loop do
-          result = read_nonblock(count - value.bytesize, exception: false)
-          value << result if append_to_buffer?(result)
-          break if value.bytesize == count
-        end
-        value
-      end
-
+      WAIT_RCS = %i[wait_writable wait_readable].freeze
       def read_available
         value = +''
         loop do
@@ -34,22 +25,6 @@ def read_available
         value
       end
 
-      WAIT_RCS = %i[wait_writable wait_readable].freeze
-
-      def append_to_buffer?(result)
-        raise Timeout::Error, "IO timeout: #{logged_options.inspect}" if nonblock_timed_out?(result)
-        raise Errno::ECONNRESET, "Connection reset: #{logged_options.inspect}" unless result
-
-        !WAIT_RCS.include?(result)
-      end
-
-      def nonblock_timed_out?(result)
-        return true if result == :wait_readable && !wait_readable(options[:socket_timeout])
-
-        # TODO: Do we actually need this?  Looks to be only used in read_nonblock
-        result == :wait_writable && !wait_writable(options[:socket_timeout])
-      end
-
       FILTERED_OUT_OPTIONS = %i[username password].freeze
       def logged_options
         options.reject { |k, _| FILTERED_OUT_OPTIONS.include? k }