io.rb in lightio-0.4.3

- old
+ new

@@ -19,32 +19,41 @@
     # @return [LightIO::Watchers::IO]
     def initialize(io, interests=:rw)
       @io = io
       @ioloop = LightIO::Core::IOloop.current
       @waiting = false
-      ObjectSpace.define_finalizer(self, self.class.finalizer(@monitor))
       @error = nil
       # maintain socket status, see https://github.com/socketry/lightio/issues/1
       @readiness = nil
+      @monitor = nil
     end
 
     # NIO::Monitor
     def monitor(interests=:rw)
       @monitor ||= begin
-        @ioloop.add_io_wait(@io, interests) {callback_on_waiting}
+        raise @error if @error
+        monitor = @ioloop.add_io_wait(@io, interests) {callback_on_waiting}
+        ObjectSpace.define_finalizer(self, self.class.finalizer(monitor))
+        monitor
       end
     end
 
     class << self
       def finalizer(monitor)
         proc {monitor.close if monitor && !monitor.close?}
       end
     end
 
     extend Forwardable
-    def_delegators :monitor, :interests, :interests=, :closed?
+    def_delegators :monitor, :interests, :interests=
 
+    def closed?
+      # check @monitor exists, avoid unnecessary monitor created
+      return true unless @monitor
+      monitor.closed?
+    end
+
     # this method return previous IO.select status
     # should avoid to directly use
     def readable?
       check_monitor_read
       @readiness == :r || @readiness == :rw
@@ -88,13 +97,13 @@
     rescue Timeout::Error
       nil
     end
 
     def close
+      set_close_error
       return if closed?
       monitor.close
-      @error = IOError.new('closed stream')
       callback_on_waiting
     end
 
 
     # just implement IOloop#wait watcher interface
@@ -105,9 +114,13 @@
     def set_callback(&blk)
       @callback = blk
     end
 
     private
+    def set_close_error
+      @error ||= IOError.new('closed stream')
+    end
+
     def check_monitor(mode)
       case mode
         when :read
           check_monitor_read
         when :write
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